This specification is available in the following formats: single page HTML, multipage HTML, web developer edition. This is Revision: 1.4938.
Copyright © 2011 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark and document use rules apply.
The bulk of the text of this specification is also available in the WHATWG Web Applications 1.0 specification, under a license that permits reuse of the specification text.
This specification defines the 5th major revision of the core language of the World Wide Web: the Hypertext Markup Language (HTML). In this version, new features are introduced to help Web application authors, new elements are introduced based on research into prevailing authoring practices, and special attention has been given to defining clear conformance criteria for user agents in an effort to improve interoperability.
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the most recently formally published revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
If you wish to make comments regarding this document in a manner that is tracked by the W3C, please submit them via using our public bug database. If you do not have an account then you can enter feedback using this form:
If you cannot do this then you can also e-mail feedback to public-html-comments@w3.org (subscribe, archives), and arrangements will be made to transpose the comments to our public bug database. Alternatively, you can e-mail feedback to whatwg@whatwg.org (subscribe, archives). The editor guarantees that all substantive feedback sent to this list will receive a reply. However, such feedback is not considered formal feedback for the W3C process. All feedback is welcome.
The working groups maintains a list of all bug reports that the editor has not yet tried to address and a list of issues for which the chairs have not yet declared a decision. The editor also maintains a list of all e-mails that he has not yet tried to address. These bugs, issues, and e-mails apply to multiple HTML-related specifications, not just this one.
Implementors should be aware that this specification is not stable. Implementors who are not taking part in the discussions are likely to find the specification changing out from under them in incompatible ways. Vendors interested in implementing this specification before it eventually reaches the Candidate Recommendation stage should join the aforementioned mailing lists and take part in the discussions.
This is a work in progress! For the latest updates from the HTML WG, possibly including important bug fixes, please look at the editor's draft instead.
The publication of this document by the W3C as a W3C Working Draft does not imply that all of the participants in the W3C HTML working group endorse the contents of the specification. Indeed, for any section of the specification, one can usually find many members of the working group or of the W3C as a whole who object strongly to the current text, the existence of the section at all, or the idea that the working group should even spend time discussing the concept of that section.
The latest stable version of the editor's draft of this specification is always available on the W3C CVS server and in the WHATWG Subversion repository. The latest editor's working copy (which may contain unfinished text in the process of being prepared) contains the latest draft text of this specification (amongst others). For more details, please see the WHATWG FAQ.
There are various ways to follow the change history for the HTML specifications:
svn checkout http://svn.whatwg.org/webapps/
The W3C HTML Working Group is the W3C working group responsible for this specification's progress along the W3C Recommendation track. This specification is the 24 May 2011 Working Draft.
Work on this specification is also done at the WHATWG. The W3C HTML working group actively pursues convergence with the WHATWG, as required by the W3C HTML working group charter.
This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.
a
elementem
elementstrong
elementsmall
elements
elementcite
elementq
elementdfn
elementabbr
elementtime
elementcode
elementvar
elementsamp
elementkbd
elementsub
and sup
elementsi
elementb
elementu
elementmark
elementruby
elementrt
elementrp
elementbdi
elementbdo
elementspan
elementbr
elementwbr
elementimg
element
iframe
elementembed
elementobject
elementparam
elementvideo
elementaudio
elementsource
elementtrack
elementcanvas
element
map
elementarea
elementtable
element
caption
elementcolgroup
elementcol
elementtbody
elementthead
elementtfoot
elementtr
elementtd
elementth
elementtd
and th
elementsform
elementfieldset
elementlegend
elementlabel
elementinput
element
type
attribute
input
element attributes
autocomplete
attributedirname
attributelist
attributereadonly
attributesize
attributerequired
attributemultiple
attributemaxlength
attributepattern
attributemin
and max
attributesstep
attributeplaceholder
attributeinput
element APIsbutton
elementselect
elementdatalist
elementoptgroup
elementoption
elementtextarea
elementkeygen
elementoutput
elementprogress
elementmeter
elementdetails
elementsummary
elementcommand
elementmenu
element
a
element to define a commandbutton
element to define a commandinput
element to define a commandoption
element to define a commandcommand
element to define
a commandaccesskey
attribute on a label
element to define a commandaccesskey
attribute on a legend
element to define a commandaccesskey
attribute to define a command on other elementsa
and area
elementsalternate
"author
"bookmark
"external
"help
"icon
"license
"nofollow
"noreferrer
"pingback
"prefetch
"search
"sidebar
"stylesheet
"tag
"Window
object
hidden
attributecontenteditable
attribute
button
elementdetails
elementinput
element as a text entry widgetinput
element as domain-specific widgetsinput
element as a range controlinput
element as a color wellinput
element as a checkbox and radio button widgetsinput
element as a file upload controlinput
element as a buttonmarquee
elementmeter
elementprogress
elementselect
elementtextarea
elementkeygen
elementtime
elementThis section is non-normative.
The World Wide Web's markup language has always been HTML. HTML was primarily designed as a language for semantically describing scientific documents, although its general design and adaptations over the years have enabled it to be used to describe a number of other types of documents.
The main area that has not been adequately addressed by HTML is a vague subject referred to as Web Applications. This specification attempts to rectify this, while at the same time updating the HTML specifications to address issues raised in the past few years.
This section is non-normative.
This specification is intended for authors of documents and scripts that use the features defined in this specification, implementors of tools that operate on pages that use the features defined in this specification, and individuals wishing to establish the correctness of documents or implementations with respect to the requirements of this specification.
This document is probably not suited to readers who do not already have at least a passing familiarity with Web technologies, as in places it sacrifices clarity for precision, and brevity for completeness. More approachable tutorials and authoring guides can provide a gentler introduction to the topic.
In particular, familiarity with the basics of DOM Core and DOM Events is necessary for a complete understanding of some of the more technical parts of this specification. An understanding of Web IDL, HTTP, XML, Unicode, character encodings, JavaScript, and CSS will also be helpful in places but is not essential.
This section is non-normative.
This specification is limited to providing a semantic-level markup language and associated semantic-level scripting APIs for authoring accessible pages on the Web ranging from static documents to dynamic applications.
The scope of this specification does not include providing mechanisms for media-specific customization of presentation (although default rendering rules for Web browsers are included at the end of this specification, and several mechanisms for hooking into CSS are provided as part of the language).
The scope of this specification is not to describe an entire operating system. In particular, hardware configuration software, image manipulation tools, and applications that users would be expected to use with high-end workstations on a daily basis are out of scope. In terms of applications, this specification is targeted specifically at applications that would be expected to be used by users on an occasional basis, or regularly but from disparate locations, with low CPU requirements. For instance online purchasing systems, searching systems, games (especially multiplayer online games), public telephone books or address books, communications software (e-mail clients, instant messaging clients, discussion software), document editing software, etc.
This section is non-normative.
For its first five years (1990-1995), HTML went through a number of revisions and experienced a number of extensions, primarily hosted first at CERN, and then at the IETF.
With the creation of the W3C, HTML's development changed venue again. A first abortive attempt at extending HTML in 1995 known as HTML 3.0 then made way to a more pragmatic approach known as HTML 3.2, which was completed in 1997. HTML4 followed, reaching completion in 1998.
At this time, the W3C membership decided to stop evolving HTML and instead begin work on an XML-based equivalent, called XHTML. This effort started with a reformulation of HTML4 in XML, known as XHTML 1.0, which added no new features except the new serialization, and which was completed in 2000. After XHTML 1.0, the W3C's focus turned to making it easier for other working groups to extend XHTML, under the banner of XHTML Modularization. In parallel with this, the W3C also worked on a new language that was not compatible with the earlier HTML and XHTML languages, calling it XHTML2.
Around the time that HTML's evolution was stopped in 1998, parts of the API for HTML developed by browser vendors were specified and published under the name DOM Level 1 (in 1998) and DOM Level 2 Core and DOM Level 2 HTML (starting in 2000 and culminating in 2003). These efforts then petered out, with some DOM Level 3 specifications published in 2004 but the working group being closed before all the Level 3 drafts were completed.
In 2003, the publication of XForms, a technology which was positioned as the next generation of Web forms, sparked a renewed interest in evolving HTML itself, rather than finding replacements for it. This interest was borne from the realization that XML's deployment as a Web technology was limited to entirely new technologies (like RSS and later Atom), rather than as a replacement for existing deployed technologies (like HTML).
A proof of concept to show that it was possible to extend HTML4's forms to provide many of the features that XForms 1.0 introduced, without requiring browsers to implement rendering engines that were incompatible with existing HTML Web pages, was the first result of this renewed interest. At this early stage, while the draft was already publicly available, and input was already being solicited from all sources, the specification was only under Opera Software's copyright.
The idea that HTML's evolution should be reopened was tested at a W3C workshop in 2004, where some of the principles that underlie the HTML5 work (described below), as well as the aforementioned early draft proposal covering just forms-related features, were presented to the W3C jointly by Mozilla and Opera. The proposal was rejected on the grounds that the proposal conflicted with the previously chosen direction for the Web's evolution; the W3C staff and membership voted to continue developing XML-based replacements instead.
Shortly thereafter, Apple, Mozilla, and Opera jointly announced their intent to continue working on the effort under the umbrella of a new venue called the WHATWG. A public mailing list was created, and the draft was moved to the WHATWG site. The copyright was subsequently amended to be jointly owned by all three vendors, and to allow reuse of the specification.
The WHATWG was based on several core principles, in particular that technologies need to be backwards compatible, that specifications and implementations need to match even if this means changing the specification rather than the implementations, and that specifications need to be detailed enough that implementations can achieve complete interoperability without reverse-engineering each other.
The latter requirement in particular required that the scope of the HTML5 specification include what had previously been specified in three separate documents: HTML4, XHTML1, and DOM2 HTML. It also meant including significantly more detail than had previously been considered the norm.
In 2006, the W3C indicated an interest to participate in the development of HTML5 after all, and in 2007 formed a working group chartered to work with the WHATWG on the development of the HTML5 specification. Apple, Mozilla, and Opera allowed the W3C to publish the specification under the W3C copyright, while keeping a version with the less restrictive license on the WHATWG site.
Since then, both groups have been working together.
The HTML specification published by the WHATWG is not identical to this specification. At the time of this publication, the main differences were that the WHATWG version included features not included in this W3C version: some features have been omitted, but may be considered for future revisions of HTML beyond HTML5; and other features were omitted because at the W3C they are published as separate specifications.
A separate document has been published by the W3C HTML working group to document the differences between this specification and the language described in the HTML4 specification. [HTMLDIFF]
This section is non-normative.
It must be admitted that many aspects of HTML appear at first glance to be nonsensical and inconsistent.
HTML, its supporting DOM APIs, as well as many of its supporting technologies, have been developed over a period of several decades by a wide array of people with different priorities who, in many cases, did not know of each other's existence.
Features have thus arisen from many sources, and have not always been designed in especially consistent ways. Furthermore, because of the unique characteristics of the Web, implementation bugs have often become de-facto, and now de-jure, standards, as content is often unintentionally written in ways that rely on them before they can be fixed.
Despite all this, efforts have been made to adhere to certain design goals. These are described in the next few subsections.
This section is non-normative.
To avoid exposing Web authors to the complexities of multithreading, the HTML and DOM APIs are designed such that no script can ever detect the simultaneous execution of other scripts. Even with workers, the intent is that the behavior of implementations can be thought of as completely serializing the execution of all scripts in all browsing contexts.
The navigator.yieldForStorageUpdates()
method, in this model, is equivalent to allowing other scripts to
run while the calling script is blocked.
This section is non-normative.
This specification interacts with and relies on a wide variety of other specifications. In certain circumstances, unfortunately, conflicting needs have led to this specification violating the requirements of these other specifications. Whenever this has occurred, the transgressions have each been noted as a "willful violation", and the reason for the violation has been noted.
This section is non-normative.
This specification defines an abstract language for describing documents and applications, and some APIs for interacting with in-memory representations of resources that use this language.
The in-memory representation is known as "DOM HTML", or "the DOM" for short. This specification defines version 5 of DOM HTML, known as "DOM5 HTML".
There are various concrete syntaxes that can be used to transmit resources that use this abstract language, two of which are defined in this specification.
The first such concrete syntax is the HTML syntax. This is the
format suggested for most authors. It is compatible with most legacy
Web browsers. If a document is transmitted with an HTML MIME
type, such as text/html
, then it will be
processed as an HTML document by Web browsers.
This specification defines version 5 of the HTML syntax, known as
"HTML5".
The second concrete syntax is the XHTML syntax, which is an
application of XML. When a document is transmitted with an XML
MIME type, such as application/xhtml+xml
, then
it is treated as an XML document by Web browsers, to be parsed by an
XML processor. Authors are reminded that the processing for XML and
HTML differs; in particular, even minor syntax errors will prevent a
document labeled as XML from being rendered fully, whereas they
would be ignored in the HTML syntax.
This specification defines version 5 of the XHTML syntax, known as
"XHTML5".
The DOM, the HTML syntax, and XML cannot all represent the same
content. For example, namespaces cannot be represented using the
HTML syntax, but they are supported in the DOM and in XML.
Similarly, documents that use the noscript
feature can
be represented using the HTML syntax, but cannot be represented with
the DOM or in XML. Comments that contain the string "-->
" can only be represented in the DOM, not in
the HTML and XML syntaxes.
This section is non-normative.
This specification is divided into the following major sections:
There are also some appendices, defining rendering rules for Web browsers and listing obsolete features and IANA considerations.
This specification should be read like all other specifications. First, it should be read cover-to-cover, multiple times. Then, it should be read backwards at least once. Then it should be read by picking random sections from the contents list and following all the cross-references.
This is a definition, requirement, or explanation.
This is a note.
This is an example.
This is an open issue.
This is a warning.
interface Example { // this is an IDL definition };
method
( [ optionalArgument ] )This is a note to authors describing the usage of an interface.
/* this is a CSS fragment */
The defining instance of a term is marked up like this. Uses of that term are marked up like this or like this.
The defining instance of an element, attribute, or API is marked
up like this
. References to
that element, attribute, or API are marked up like this
.
Other code fragments are marked up like
this
.
Variables are marked up like this.
This is an implementation requirement.
This section is non-normative.
A basic HTML document looks like this:
<!DOCTYPE html> <html> <head> <title>Sample page</title> </head> <body> <h1>Sample page</h1> <p>This is a <a href="demo.html">simple</a> sample.</p> <!-- this is a comment --> </body> </html>
HTML documents consist of a tree of elements and text. Each
element is denoted in the source by a start tag, such as "<body>
", and an end
tag, such as "</body>
". (Certain
start tags and end tags can in certain cases be omitted and are implied by other
tags.)
Tags have to be nested such that elements are all completely within each other, without overlapping:
<p>This is <em>very <strong>wrong</em>!</strong></p>
<p>This <em>is <strong>correct</strong>.</em></p>
This specification defines a set of elements that can be used in HTML, along with rules about the ways in which the elements can be nested.
Elements can have attributes, which control how the elements
work. In the example below, there is a hyperlink,
formed using the a
element and its href
attribute:
<a href="demo.html">simple</a>
Attributes are placed
inside the start tag, and consist of a name and a value, separated by an "=
" character. The attribute value can remain unquoted if it doesn't contain spaces or any of
"
'
`
=
<
or >
. Otherwise, it has to be quoted using
either single or double quotes. The value, along with the "=
" character, can be omitted altogether if the value
is the empty string.
<!-- empty attributes --> <input name=address disabled> <input name=address disabled=""> <!-- attributes with a value --> <input name=address maxlength=200> <input name=address maxlength='200'> <input name=address maxlength="200">
HTML user agents (e.g. Web browsers) then parse this markup, turning it into a DOM (Document Object Model) tree. A DOM tree is an in-memory representation of a document.
DOM trees contain several kinds of nodes, in particular a DOCTYPE node, elements, text nodes, and comment nodes.
The markup snippet at the top of this section would be turned into the following DOM tree:
html
html
The root element of this tree is the
html
element, which is the element always found at the
root of HTML documents. It contains two elements, head
and body
, as well as a text node between them.
There are many more text nodes in the DOM tree than one would
initially expect, because the source contains a number of spaces
(represented here by "␣") and line breaks ("⏎") that
all end up as text nodes in the DOM. However, for historical reasons
not all of the spaces and line breaks in the original markup appear
in the DOM. In particular, all the whitespace before
head
start tag ends up being dropped silently, and all
the whitespace after the body
end tag ends up placed at
the end of the body
.
The head
element contains a title
element, which itself contains a text node with the text "Sample
page". Similarly, the body
element contains an
h1
element, a p
element, and a
comment.
This DOM tree can be manipulated from scripts in the
page. Scripts (typically in JavaScript) are small programs that can
be embedded using the script
element or using
event handler content attributes. For example, here is
a form with a script that sets the value of the form's
output
element to say "Hello World":
<form name="main"> Result: <output name="result"></output> <script> document.forms.main.elements.result.value = 'Hello World'; </script> </form>
Each element in the DOM tree is represented by an object, and
these objects have APIs so that they can be manipulated. For
instance, a link (e.g. the a
element in the tree above)
can have its "href
"
attribute changed in several ways:
var a = document.links[0]; // obtain the first link in the document a.href = 'sample.html'; // change the destination URL of the link a.protocol = 'https'; // change just the scheme part of the URL a.setAttribute('href', 'http://example.com/'); // change the content attribute directly
Since DOM trees are used as the way to represent HTML documents when they are processed and presented by implementations (especially interactive implementations like Web browsers), this specification is mostly phrased in terms of DOM trees, instead of the markup described above.
HTML documents represent a media-independent description of interactive content. HTML documents might be rendered to a screen, or through a speech synthesizer, or on a braille display. To influence exactly how such rendering takes place, authors can use a styling language such as CSS.
In the following example, the page has been made yellow-on-blue using CSS.
<!DOCTYPE html> <html> <head> <title>Sample styled page</title> <style> body { background: navy; color: yellow; } </style> </head> <body> <h1>Sample styled page</h1> <p>This page is just a demo.</p> </body> </html>
For more details on how to use HTML, authors are encouraged to consult tutorials and guides. Some of the examples included in this specification might also be of use, but the novice author is cautioned that this specification, by necessity, defines the language with a level of detail that might be difficult to understand at first.
This section is non-normative.
Unlike previous versions of the HTML specification, this specification defines in some detail the required processing for invalid documents as well as valid documents.
However, even though the processing of invalid content is in most cases well-defined, conformance requirements for documents are still important: in practice, interoperability (the situation in which all implementations process particular content in a reliable and identical or equivalent way) is not the only goal of document conformance requirements. This section details some of the more common reasons for still distinguishing between a conforming document and one with errors.
This section is non-normative.
The majority of presentational features from previous versions of HTML are no longer allowed. Presentational markup in general has been found to have a number of problems:
While it is possible to use presentational markup in a way that provides users of assistive technologies (ATs) with an acceptable experience (e.g. using ARIA), doing so is significantly more difficult than doing so when using semantically-appropriate markup. Furthermore, even using such techniques doesn't help make pages accessible for non-AT non-graphical users, such as users of text-mode browsers.
Using media-independent markup, on the other hand, provides an easy way for documents to be authored in such a way that they work for more users (e.g. text browsers).
It is significantly easier to maintain a site written in such a
way that the markup is style-independent. For example, changing
the color of a site that uses <font color="">
throughout requires changes across the entire site, whereas a
similar change to a site based on CSS can be done by changing a
single file.
Presentational markup tends to be much more redundant, and thus results in larger document sizes.
For those reasons, presentational markup has been removed from HTML in this version. This change should not come as a surprise; HTML4 deprecated presentational markup many years ago and provided a mode (HTML4 Transitional) to help authors move away from presentational markup; later, XHTML 1.1 went further and obsoleted those features altogether.
The only remaining presentational markup features in HTML are the
style
attribute and the
style
element. Use of the style
attribute is somewhat discouraged in
production environments, but it can be useful for rapid prototyping
(where its rules can be directly moved into a separate style sheet
later) and for providing specific styles in unusual cases where a
separate style sheet would be inconvenient. Similarly, the
style
element can be useful in syndication or for
page-specific styles, but in general an external style sheet is
likely to be more convenient when the styles apply to multiple
pages.
It is also worth noting that some elements that were previously
presentational have been redefined in this specification to be
media-independent: b
, i
, hr
,
s
, small
, and u
.
This section is non-normative.
The syntax of HTML is constrained to avoid a wide variety of problems.
Certain invalid syntax constructs, when parsed, result in DOM trees that are highly unintuitive.
To allow user agents to be used in controlled environments without having to implement the more bizarre and convoluted error handling rules, user agents are permitted to fail whenever encountering a parse error.
Some error-handling behavior, such as the behavior for the
<table><hr>...
example mentioned
above, are incompatible with streaming user agents (user agents
that process HTML files in one pass, without storing state). To
avoid interoperability problems with such user agents, any syntax
resulting in such behavior is considered invalid.
When a user agent based on XML is connected to an HTML parser, it is possible that certain invariants that XML enforces, such as comments never containing two consecutive hyphens, will be violated by an HTML file. Handling this can require that the parser coerce the HTML DOM into an XML-compatible infoset. Most syntax constructs that require such handling are considered invalid.
Certain syntax constructs can result in disproportionally poor performance. To discourage the use of such constructs, they are typically made non-conforming.
For example, the following markup results in poor performance,
since all the unclosed i
elements have to be
reconstructed in each paragraph, resulting in progressively more
elements in each paragraph:
<p><i>He dreamt. <p><i>He dreamt that he ate breakfast. <p><i>Then lunch. <p><i>And finally dinner.
The resulting DOM for this fragment would be:
There are syntax constructs that, for historical reasons, are relatively fragile. To help reduce the number of users who accidentally run into such problems, they are made non-conforming.
For example, the parsing of certain named character references in attributes happens even with the closing semicolon being omitted. It is safe to include an ampersand followed by letters that do not form a named character reference, but if the letters are changed to a string that does form a named character reference, they will be interpreted as that character instead.
In this fragment, the attribute's value is "?bill&ted
":
<a href="?bill&ted">Bill and Ted</a>
In the following fragment, however, the attribute's value is
actually "?art©
", not the
intended "?art©
", because even
without the final semicolon, "©
" is
handled the same as "©
" and thus
gets interpreted as "©
":
<a href="?art©">Art and Copy</a>
To avoid this problem, all named character references are required to end with a semicolon, and uses of named character references without a semicolon are flagged as errors.
Thus, the correct way to express the above cases is as follows:
<a href="?bill&ted">Bill and Ted</a> <!-- &ted is ok, since it's not a named character reference -->
<a href="?art&copy">Art and Copy</a> <!-- the & has to be escaped, since © is a named character reference -->
Certain syntax constructs are known to cause especially subtle or serious problems in legacy user agents, and are therefore marked as non-conforming to help authors avoid them.
For example, this is why the U+0060 GRAVE ACCENT character (`) is not allowed in unquoted attributes. In certain legacy user agents, it is sometimes treated as a quote character.
Another example of this is the DOCTYPE, which is required to trigger no-quirks mode, because the behavior of legacy user agents in quirks mode is often largely undocumented.
Certain restrictions exist purely to avoid known security problems.
For example, the restriction on using UTF-7 exists purely to avoid authors falling prey to a known cross-site-scripting attack using UTF-7.
Markup where the author's intent is very unclear is often made non-conforming. Correcting these errors early makes later maintenance easier.
When a user makes a simple typo, it is helpful if the error can be caught early, as this can save the author a lot of debugging time. This specification therefore usually considers it an error to use element names, attribute names, and so forth, that do not match the names defined in this specification.
For example, if the author typed <capton>
instead of <caption>
, this would be flagged as an
error and the author could correct the typo immediately.
In order to allow the language syntax to be extended in the future, certain otherwise harmless features are disallowed.
For example, "attributes" in end tags are ignored currently, but they are invalid, in case a future change to the language makes use of that syntax feature without conflicting with already-deployed (and valid!) content.
Some authors find it helpful to be in the practice of always quoting all attributes and always including all optional tags, preferring the consistency derived from such custom over the minor benefits of terseness afforded by making use of the flexibility of the HTML syntax. To aid such authors, conformance checkers can provide modes of operation wherein such conventions are enforced.
This section is non-normative.
Beyond the syntax of the language, this specification also places restrictions on how elements and attributes can be specified. These restrictions are present for similar reasons:
To avoid misuse of elements with defined meanings, content models are defined that restrict how elements can be nested when such nestings would be of dubious value.
For example, this specification disallows
nesting a section
element inside a kbd
element, since it is highly unlikely for an author to indicate
that an entire section should be keyed in.
Similarly, to draw the author's attention to mistakes in the use of elements, clear contradictions in the semantics expressed are also considered conformance errors.
In the fragments below, for example, the semantics are nonsensical: a separator cannot simultaneously be a cell, nor can a radio button be a progress bar.
<hr role="cell">
<input type=radio role=progressbar>
Another example is the restrictions on the
content models of the ul
element, which only allows
li
element children. Lists by definition consist just
of zero or more list items, so if a ul
element
contains something other than an li
element, it's not
clear what was meant.
Certain elements have default styles or behaviors that make certain combinations likely to lead to confusion. Where these have equivalent alternatives without this problem, the confusing combinations are disallowed.
For example, div
elements are
rendered as block boxes, and span
elements as inline
boxes. Putting a block box in an inline box is unnecessarily
confusing; since either nesting just div
elements, or
nesting just span
elements, or nesting
span
elements inside div
elements all
serve the same purpose as nesting a div
element in a
span
element, but only the latter involves a block
box in an inline box, the latter combination is disallowed.
Another example would be the way
interactive content cannot be nested. For example, a
button
element cannot contain a textarea
element. This is because the default behavior of such nesting
interactive elements would be highly confusing to users. Instead
of nesting these elements, they can be placed side by side.
Sometimes, something is disallowed because allowing it would likely cause author confusion.
For example, setting the disabled
attribute to the value
"false
" is disallowed, because despite the
appearance of meaning that the element is enabled, it in fact
means that the element is disabled (what matters for
implementations is the presence of the attribute, not its
value).
Some conformance errors simplify the language that authors need to learn.
For example, the area
element's
shape
attribute, despite
accepting both circ
and circle
values in
practice as synonyms, disallows the use of the circ
value, so as to
simplify tutorials and other learning aids. There would be no
benefit to allowing both, but it would cause extra confusion when
teaching the language.
Certain elements are parsed in somewhat eccentric ways (typically for historical reasons), and their content model restrictions are intended to avoid exposing the author to these issues.
For example, a form
element isn't allowed inside
phrasing content, because when parsed as HTML, a
form
element's start tag will imply a p
element's end tag. Thus, the following markup results in two
paragraphs, not one:
<p>Welcome. <form><label>Name:</label> <input></form>
It is parsed exactly like the following:
<p>Welcome. </p><form><label>Name:</label> <input></form>
Some errors are intended to help prevent script problems that would be hard to debug.
This is why, for instance, it is non-conforming
to have two id
attributes with the
same value. Duplicate IDs lead to the wrong element being
selected, with sometimes disastrous effects whose cause is hard to
determine.
Some constructs are disallowed because historically they have been the cause of a lot of wasted authoring time, and by encouraging authors to avoid making them, authors can save time in future efforts.
For example, a script
element's
src
attribute causes the
element's contents to be ignored. However, this isn't obvious,
especially if the element's contents appear to be executable
script — which can lead to authors spending a lot of time
trying to debug the inline script without realizing that it is not
executing. To reduce this problem, this specification makes it
non-conforming to have executable script in a script
element when the src
attribute is present. This means that authors who are validating
their documents are less likely to waste time with this kind of
mistake.
Some authors like to write files that can be interpreted as both XML and HTML with similar results. Though this practice is discouraged in general due to the myriad of subtle complications involved (especially when involving scripting, styling, or any kind of automated serialization), this specification has a few restrictions intended to at least somewhat mitigate the difficulties. This makes it easier for authors to use this as a transitionary step when migrating between HTML and XHTML.
For example, there are somewhat complicated
rules surrounding the lang
and
xml:lang
attributes intended
to keep the two synchronized.
Another example would be the restrictions on
the values of xmlns
attributes in the HTML
serialization, which are intended to ensure that elements in
conforming documents end up in the same namespaces whether
processed as HTML or XML.
As with the restrictions on the syntax intended to allow for new syntax in future revisions of the language, some restrictions on the content models of elements and values of attributes are intended to allow for future expansion of the HTML vocabulary.
For example, limiting the values of the target
attribute that start
with an U+005F LOW LINE character (_) to only specific predefined
values allows new predefined values to be introduced at a future
time without conflicting with author-defined values.
Certain restrictions are intended to support the restrictions made by other specifications.
For example, requiring that attributes that take media queries use only valid media queries reinforces the importance of following the conformance rules of that specification.
This section is non-normative.
The following documents might be of interest to readers of this specification.
This Architectural Specification provides authors of specifications, software developers, and content developers with a common reference for interoperable text manipulation on the World Wide Web, building on the Universal Character Set, defined jointly by the Unicode Standard and ISO/IEC 10646. Topics addressed include use of the terms 'character', 'encoding' and 'string', a reference processing model, choice and identification of character encodings, character escaping, and string indexing.
Because Unicode contains such a large number of characters and incorporates the varied writing systems of the world, incorrect usage can expose programs or systems to possible security attacks. This is especially important as more and more products are internationalized. This document describes some of the security considerations that programmers, system analysts, standards developers, and users should take into account, and provides specific recommendations to reduce the risk of problems.
Web Content Accessibility Guidelines (WCAG) 2.0 covers a wide range of recommendations for making Web content more accessible. Following these guidelines will make content accessible to a wider range of people with disabilities, including blindness and low vision, deafness and hearing loss, learning disabilities, cognitive limitations, limited movement, speech disabilities, photosensitivity and combinations of these. Following these guidelines will also often make your Web content more usable to users in general.
This specification provides guidelines for designing Web content authoring tools that are more accessible for people with disabilities. An authoring tool that conforms to these guidelines will promote accessibility by providing an accessible user interface to authors with disabilities as well as by enabling, supporting, and promoting the production of accessible Web content by all authors.
This document provides guidelines for designing user agents that lower barriers to Web accessibility for people with disabilities. User agents include browsers and other types of software that retrieve and render Web content. A user agent that conforms to these guidelines will promote accessibility through its own user interface and through other internal facilities, including its ability to communicate with other technologies (especially assistive technologies). Furthermore, all users, not just users with disabilities, should find conforming user agents to be more usable.
A document that uses polyglot markup is a document that is a stream of bytes that parses into identical document trees (with the exception of the xmlns attribute on the root element) when processed as HTML and when processed as XML. Polyglot markup that meets a well defined set of constraints is interpreted as compatible, regardless of whether they are processed as HTML or as XHTML, per the HTML5 specification. Polyglot markup uses a specific DOCTYPE, namespace declarations, and a specific case — normally lower case but occasionally camel case — for element and attribute names. Polyglot markup uses lower case for certain attribute values. Further constraints include those on empty elements, named entity references, and the use of scripts and style.
This is draft documentation mapping HTML elements and attributes to accessibility API Roles, States and Properties on a variety of platforms. It provides recommendations on deriving the accessible names and descriptions for HTML elements. It also provides accessible feature implementation examples.
This specification refers to both HTML and XML attributes and IDL attributes, often in the same context. When it is not clear which is being referred to, they are referred to as content attributes for HTML and XML attributes, and IDL attributes for those defined on IDL interfaces. Similarly, the term "properties" is used for both JavaScript object properties and CSS properties. When these are ambiguous they are qualified as object properties and CSS properties respectively.
Generally, when the specification states that a feature applies to the HTML syntax or the XHTML syntax, it also includes the other. When a feature specifically only applies to one of the two languages, it is called out by explicitly stating that it does not apply to the other format, as in "for HTML, ... (this does not apply to XHTML)".
This specification uses the term document to refer to any use of HTML, ranging from short static documents to long essays or reports with rich multimedia, as well as to fully-fledged interactive applications.
For simplicity, terms such as shown, displayed, and visible might sometimes be used when referring to the way a document is rendered to the user. These terms are not meant to imply a visual medium; they must be considered to apply to other media in equivalent ways.
When an algorithm B says to return to another algorithm A, it implies that A called B. Upon returning to A, the implementation must continue from where it left off in calling B.
The term "transparent black" refers to the color with red, green, blue, and alpha channels all set to zero.
The specification uses the term supported when referring to whether a user agent has an implementation capable of decoding the semantics of an external resource. A format or type is said to be supported if the implementation can process an external resource of that format or type without critical aspects of the resource being ignored. Whether a specific resource is supported can depend on what features of the resource's format are in use.
For example, a PNG image would be considered to be in a supported format if its pixel data could be decoded and rendered, even if, unbeknownst to the implementation, the image also contained animation data.
A MPEG4 video file would not be considered to be in a supported format if the compression format used was not supported, even if the implementation could determine the dimensions of the movie from the file's metadata.
What some specifications, in particular the HTTP and URI specifications, refer to as a representation is referred to in this specification as a resource. [HTTP] [RFC3986]
The term MIME type is used to refer to what is sometimes called an Internet media type in protocol literature. The term media type in this specification is used to refer to the type of media intended for presentation, as used by the CSS specifications. [RFC2046] [MQ]
A string is a valid MIME type if it matches the media-type
rule defined in section 3.7 "Media Types"
of RFC 2616. In particular, a valid MIME type may
include MIME type parameters. [HTTP]
A string is a valid MIME type with no parameters if it
matches the media-type
rule defined in section
3.7 "Media Types" of RFC 2616, but does not contain any U+003B
SEMICOLON characters (;). In other words, if it consists only of a
type and subtype, with no MIME Type parameters. [HTTP]
The term HTML MIME type is used to refer to the MIME types text/html
and
text/html-sandboxed
.
A resource's critical subresources are those that the
resource needs to have available to be correctly processed. Which
resources are considered critical or not is defined by the
specification that defines the resource's format. For CSS resources,
only @import
rules introduce critical
subresources; other resources, e.g. fonts or backgrounds, are
not.
The term data:
URL refers to URLs that use the data:
scheme. [RFC2397]
To ease migration from HTML to XHTML, UAs
conforming to this specification will place elements in HTML in the
http://www.w3.org/1999/xhtml
namespace, at least for
the purposes of the DOM and CSS. The term "HTML
elements", when used in this specification, refers to any
element in that namespace, and thus refers to both HTML and XHTML
elements.
Except where otherwise stated, all elements defined or mentioned
in this specification are in the
http://www.w3.org/1999/xhtml
namespace, and all
attributes defined or mentioned in this specification have no
namespace.
Attribute names are said to be XML-compatible if they
match the Name
production defined in XML, they contain no
U+003A COLON characters (:), and their first three characters are
not an ASCII case-insensitive match for the string
"xml
". [XML]
The term XML MIME type is used to refer to the MIME types text/xml
,
application/xml
, and any MIME
type whose subtype ends with the four characters "+xml
". [RFC3023]
The root element of a Document
object is
that Document
's first element child, if any. If it does
not have one then the Document
has no root element.
The term root element, when not referring to a
Document
object's root element, means the furthest
ancestor element node of whatever node is being discussed, or the
node itself if it has no ancestors. When the node is a part of the
document, then the node's root element is indeed the
document's root element; however, if the node is not currently part
of the document tree, the root element will be an orphaned node.
When an element's root element is the root
element of a Document
object, it is said to be
in a Document
. An element is said to have
been inserted into a
document when its root element changes and is now
the document's root element. Analogously, an element is
said to have been removed from a document when its root
element changes from being the document's root
element to being another element.
A node's home subtree is the subtree rooted at that
node's root element. When a node is in a
Document
, its home subtree is that
Document
's tree.
The Document
of a Node
(such as an
element) is the Document
that the Node
's
ownerDocument
IDL
attribute returns. When a Node
is in a
Document
then that Document
is
always the Node
's Document
, and the
Node
's ownerDocument
IDL attribute
thus always returns that Document
.
The term tree order means a pre-order, depth-first
traversal of DOM nodes involved (through the parentNode
/childNodes
relationship).
When it is stated that some element or attribute is ignored, or treated as some other value, or handled as if it was something else, this refers only to the processing of the node after it is in the DOM. A user agent must not mutate the DOM in such situations.
The term text node refers to any Text
node, including CDATASection
nodes; specifically, any
Node
with node type TEXT_NODE
(3)
or CDATA_SECTION_NODE
(4). [DOMCORE]
A content attribute is said to change value only if its new value is different than its previous value; setting an attribute to a value it already has does not change it.
The term empty, when used of an attribute value, text node, or string, means that the length of the text is zero (i.e. not even containing spaces or control characters).
Nodes can be cloned, as
described in the DOM Core specification. For example, the cloneNode()
and importNode()
methods of the
Node
interface both clone nodes, as do a number of
algorithms in this specification. Certain HTML elements
(in particular, input
and script
) apply
additional requirements on how they are cloned. [DOMCORE]
The construction "a Foo
object", where
Foo
is actually an interface, is sometimes used instead
of the more accurate "an object implementing the interface
Foo
".
An IDL attribute is said to be getting when its value is being retrieved (e.g. by author script), and is said to be setting when a new value is assigned to it.
If a DOM object is said to be live, then the attributes and methods on that object must operate on the actual underlying data, not a snapshot of the data.
The terms fire and dispatch are used interchangeably in the context of events, as in the DOM Events specifications. The term trusted event is used as defined by the DOM Events specification. [DOMEVENTS]
The term plugin refers to a user-agent defined set of
content handlers used by the user agent that can take part in the
user agent's rendering of a Document
object, but that
neither act as child browsing
contexts of the Document
nor introduce any
Node
objects to the Document
's DOM.
Typically such content handlers are provided by third parties, though a user agent can also designate built-in content handlers as plugins.
A user agent must not consider the types text/plain
and application/octet-stream
as having a registered
plugin.
One example of a plugin would be a PDF viewer that is instantiated in a browsing context when the user navigates to a PDF file. This would count as a plugin regardless of whether the party that implemented the PDF viewer component was the same as that which implemented the user agent itself. However, a PDF viewer application that launches separate from the user agent (as opposed to using the same interface) is not a plugin by this definition.
This specification does not define a mechanism for interacting with plugins, as it is expected to be user-agent- and platform-specific. Some UAs might opt to support a plugin mechanism such as the Netscape Plugin API; others might use remote content converters or have built-in support for certain types. Indeed, this specification doesn't require user agents to support plugins at all. [NPAPI]
Browsers should take extreme care when interacting with external content intended for plugins. When third-party software is run with the same privileges as the user agent itself, vulnerabilities in the third-party software become as dangerous as those in the user agent.
The preferred MIME name of a character encoding is the name or alias labeled as "preferred MIME name" in the IANA Character Sets registry, if there is one, or the encoding's name, if none of the aliases are so labeled. [IANACHARSET]
An ASCII-compatible character encoding is a single-byte or variable-length encoding in which the bytes 0x09, 0x0A, 0x0C, 0x0D, 0x20 - 0x22, 0x26, 0x27, 0x2C - 0x3F, 0x41 - 0x5A, and 0x61 - 0x7A, ignoring bytes that are the second and later bytes of multibyte sequences, all correspond to single-byte sequences that map to the same Unicode characters as those bytes in ANSI_X3.4-1968 (US-ASCII). [RFC1345]
This includes such encodings as Shift_JIS, HZ-GB-2312, and variants of ISO-2022, even though it is possible in these encodings for bytes like 0x70 to be part of longer sequences that are unrelated to their interpretation as ASCII. It excludes such encodings as UTF-7, UTF-16, GSM03.38, and EBCDIC variants.
The term Unicode character is used to mean a Unicode scalar value (i.e. any Unicode code point that is not a surrogate code point). [UNICODE]
All diagrams, examples, and notes in this specification are non-normative, as are all sections explicitly marked non-normative. Everything else in this specification is normative.
The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this document are to be interpreted as described in RFC2119. For readability, these words do not appear in all uppercase letters in this specification. [RFC2119]
Requirements phrased in the imperative as part of algorithms (such as "strip any leading space characters" or "return false and abort these steps") are to be interpreted with the meaning of the key word ("must", "should", "may", etc) used in introducing the algorithm.
Conformance requirements phrased as algorithms or specific steps may be implemented in any manner, so long as the end result is equivalent. (In particular, the algorithms defined in this specification are intended to be easy to follow, and not intended to be performant.)
This specification describes the conformance criteria for user agents (relevant to implementors) and documents (relevant to authors and authoring tool implementors).
Conforming HTML5 documents are those that comply with all the conformance criteria for documents. For readability, some of these conformance requirements are phrased as conformance requirements on authors; such requirements are implicitly requirements on documents: by definition, all documents are assumed to have had an author. (In some cases, that author may itself be a user agent — such user agents are subject to additional rules, as explained below.)
For example, if a requirement states that
"authors must not use the foobar
element", it
would imply that documents are not allowed to contain elements named
foobar
.
the conformance requirements for documents include syntax (the <table> element is conforming as a child of <body>, but not as a child ot <title>), and semantics (the <table> elements denotes a multi-dimensional data table, not a piece of furniture).
There is no implied relationship between document conformance requirements and implementation conformance requirements. User agents are not free to handle non-conformant documents as they please; the processing model described in this specification applies to implementations regardless of the conformity of the input documents.
User agents fall into several (overlapping) categories with different conformance requirements.
Web browsers that support the XHTML syntax must process elements and attributes from the HTML namespace found in XML documents as described in this specification, so that users can interact with them, unless the semantics of those elements have been overridden by other specifications.
A conforming XHTML processor would, upon
finding an XHTML script
element in an XML document,
execute the script contained in that element. However, if the
element is found within a transformation expressed in XSLT
(assuming the user agent also supports XSLT), then the processor
would instead treat the script
element as an opaque
element that forms part of the transform.
Web browsers that support the HTML syntax must process documents labeled with an HTML MIME type as described in this specification, so that users can interact with them.
User agents that support scripting must also be conforming implementations of the IDL fragments in this specification, as described in the Web IDL specification. [WEBIDL]
Unless explicitly stated, specifications that
override the semantics of HTML elements do not override the
requirements on DOM objects representing those elements. For
example, the script
element in the example above
would still implement the HTMLScriptElement
interface.
User agents that process HTML and XHTML documents purely to render non-interactive versions of them must comply to the same conformance criteria as Web browsers, except that they are exempt from requirements regarding user interaction.
Typical examples of non-interactive presentation user agents are printers (static UAs) and overhead displays (dynamic UAs). It is expected that most static non-interactive presentation user agents will also opt to lack scripting support.
A non-interactive but dynamic presentation UA would still execute scripts, allowing forms to be dynamically submitted, and so forth. However, since the concept of "focus" is irrelevant when the user cannot interact with the document, the UA would not need to support any of the focus-related DOM APIs.
User agents, whether interactive or not, may be designated (possibly as a user option) as supporting the suggested default rendering defined by this specification.
User agents that are designated as supporting the suggested default rendering must implement the rules in the rendering section that that section defines as the behavior that user agents are expected to implement.
Implementations that do not support scripting (or which have their scripting features disabled entirely) are exempt from supporting the events and DOM interfaces mentioned in this specification. For the parts of this specification that are defined in terms of an events model or in terms of the DOM, such user agents must still act as if events and the DOM were supported.
Scripting can form an integral part of an application. Web browsers that do not support scripting, or that have scripting disabled, might be unable to fully convey the author's intent.
Conformance checkers must verify that a document conforms to
the applicable conformance criteria described in this
specification. Automated conformance checkers are exempt from
detecting errors that require interpretation of the author's
intent (for example, while a document is non-conforming if the
content of a blockquote
element is not a quote,
conformance checkers running without the input of human judgement
do not have to check that blockquote
elements only
contain quoted material).
Conformance checkers must check that the input document conforms when parsed without a browsing context (meaning that no scripts are run, and that the parser's scripting flag is disabled), and should also check that the input document conforms when parsed with a browsing context in which scripts execute, and that the scripts never cause non-conforming states to occur other than transiently during script execution itself. (This is only a "SHOULD" and not a "MUST" requirement because it has been proven to be impossible. [COMPUTABLE])
The term "HTML5 validator" can be used to refer to a conformance checker that itself conforms to the applicable requirements of this specification.
XML DTDs cannot express all the conformance requirements of this specification. Therefore, a validating XML processor and a DTD cannot constitute a conformance checker. Also, since neither of the two authoring formats defined in this specification are applications of SGML, a validating SGML system cannot constitute a conformance checker either.
To put it another way, there are three types of conformance criteria:
A conformance checker must check for the first two. A simple DTD-based validator only checks for the first class of errors and is therefore not a conforming conformance checker according to this specification.
Applications and tools that process HTML and XHTML documents for reasons other than to either render the documents or check them for conformance should act in accordance with the semantics of the documents that they process.
A tool that generates document outlines but increases the nesting level for each paragraph and does not increase the nesting level for each section would not be conforming.
Authoring tools and markup generators must generate conforming HTML5 documents. Conformance criteria that apply to authors also apply to authoring tools, where appropriate.
Authoring tools are exempt from the strict requirements of using elements only for their specified purpose, but only to the extent that authoring tools are not yet able to determine author intent. However, authoring tools must not automatically misuse elements or encourage their users to do so.
For example, it is not conforming to use an
address
element for arbitrary contact information;
that element can only be used for marking up contact information
for the author of the document or section. However, since an
authoring tool is likely unable to determine the difference, an
authoring tool is exempt from that requirement. This does not
mean, though, that authoring tools can use address
elements for any block of italics text (for instance); it just
means that the authoring tool doesn't have to verify that when the
user uses a tool for inserting contact information for a section,
that the user really is doing that and not inserting something
else instead.
In terms of conformance checking, an editor has to output documents that conform to the same extent that a conformance checker will verify.
When an authoring tool is used to edit a non-conforming document, it may preserve the conformance errors in sections of the document that were not edited during the editing session (i.e. an editing tool is allowed to round-trip erroneous content). However, an authoring tool must not claim that the output is conformant if errors have been so preserved.
Authoring tools are expected to come in two broad varieties: tools that work from structure or semantic data, and tools that work on a What-You-See-Is-What-You-Get media-specific editing basis (WYSIWYG).
The former is the preferred mechanism for tools that author HTML, since the structure in the source information can be used to make informed choices regarding which HTML elements and attributes are most appropriate.
However, WYSIWYG tools are legitimate. WYSIWYG tools should use
elements they know are appropriate, and should not use elements
that they do not know to be appropriate. This might in certain
extreme cases mean limiting the use of flow elements to just a few
elements, like div
, b
, i
,
and span
and making liberal use of the style
attribute.
All authoring tools, whether WYSIWYG or not, should make a best effort attempt at enabling users to create well-structured, semantically rich, media-independent content.
User agents may impose implementation-specific limits on otherwise unconstrained inputs, e.g. to prevent denial of service attacks, to guard against running out of memory, or to work around platform-specific limitations.
For compatibility with existing content and prior specifications, this specification describes two authoring formats: one based on XML (referred to as the XHTML syntax), and one using a custom format inspired by SGML (referred to as the HTML syntax). Implementations must support at least one of these two formats, although supporting both is encouraged.
The language in this specification assumes that the user agent expands all entity references, and therefore does not include entity reference nodes in the DOM. If user agents do include entity reference nodes in the DOM, then user agents must handle them as if they were fully expanded when implementing this specification. For example, if a requirement talks about an element's child text nodes, then any text nodes that are children of an entity reference that is a child of that element would be used as well. Entity references to unknown entities must be treated as if they contained just an empty text node for the purposes of the algorithms defined in this specification.
Some conformance requirements are phrased as requirements on elements, attributes, methods or objects. Such requirements fall into two categories: those describing content model restrictions, and those describing implementation behavior. Those in the former category are requirements on documents and authoring tools. Those in the second category are requirements on user agents. Similarly, some conformance requirements are phrased as requirements on authors; such requirements are to be interpreted as conformance requirements on the documents that authors produce. (In other words, this specification does not distinguish between conformance criteria on authors and conformance criteria on documents.)
This specification relies on several other underlying specifications.
Implementations that support the XHTML syntax must support some version of XML, as well as its corresponding namespaces specification, because that syntax uses an XML serialization with namespaces. [XML] [XMLNS]
The Document Object Model (DOM) is a representation — a model — of a document and its content. The DOM is not just an API; the conformance criteria of HTML implementations are defined, in this specification, in terms of operations on the DOM. [DOMCORE]
Implementations must support some version of DOM Core and DOM Events, because this specification is defined in terms of the DOM, and some of the features are defined as extensions to the DOM Core interfaces. [DOMCORE] [DOMEVENTS]
In particular, the following features are defined in the DOM Core specification: [DOMCORE]
Attr
interfaceCDATASection
interfaceComment
interfaceDOMImplementation
interfaceDocument
interfaceDocumentFragment
interfaceDocumentType
interfaceDOMException
interfaceElement
interfaceNode
interfaceNodeList
interfaceProcessingInstruction
interfaceText
interfacecreateDocument()
methodcreateElement()
methodcreateElementNS()
methodgetElementById()
methodinsertBefore()
methodownerDocument
attributechildNodes
attributelocalName
attributeparentNode
attributenamespaceURI
attributetagName
attributetextContent
attributeThe following features are defined in the DOM Events specification: [DOMEVENTS]
Event
interfaceEventTarget
interfaceUIEvent
interfaceMouseEvent
interfaceclick
eventtarget
attributeThis specification uses the following interfaces defined in the File API specification: [FILEAPI]
The IDL fragments in this specification must be interpreted as required for conforming IDL fragments, as described in the Web IDL specification. [WEBIDL]
The terms supported property indices and supported property names are used as defined in the WebIDL specification.
Except where otherwise specified, if an IDL
attribute that is a floating point number type (double
) is assigned an Infinity or Not-a-Number
(NaN) value, a NOT_SUPPORTED_ERR
exception must be
raised.
Except where otherwise specified, if a method with an argument
that is a floating point number type (double
)
is passed an Infinity or Not-a-Number (NaN) value, a
NOT_SUPPORTED_ERR
exception must be raised.
Except where otherwise specified, if a method has an argument
of type DOMString
, or if an IDL attribute is assigned
a new value of type DOMString
, the user agent must
convert the
DOMString
to a sequence of Unicode characters
to obtain the string on which the algorithms in this specification
are to operate. [WEBIDL]
Some parts of the language described by this specification only support JavaScript as the underlying scripting language. [ECMA262]
The term "JavaScript" is used to refer to ECMA262,
rather than the official term ECMAScript, since the term
JavaScript is more widely known. Similarly, the MIME
type used to refer to JavaScript in this specification is
text/javascript
, since that is the most
commonly used type, despite it
being an officially obsoleted type according to RFC
4329. [RFC4329]
Implementations must support some version of the Media Queries language. [MQ]
Implementations must support the semantics of URLs defined in the URI and IRI specifications, as well as the semantics of IDNA domain names defined in the Internationalizing Domain Names in Applications (IDNA) specification. [RFC3986] [RFC3987] [RFC3490]
While support for CSS as a whole is not required of implementations of this specification (though it is encouraged, at least for Web browsers), some features are defined in terms of specific CSS requirements.
In particular, some features require that a string be parsed as a CSS <color> value. When parsing a CSS value, user agents are required by the CSS specifications to apply some error handling rules. These apply to this specification also. [CSSCOLOR] [CSS]
For example, user agents are required to close
all open constructs upon finding the end of a style sheet
unexpectedly. Thus, when parsing the string "rgb(0,0,0
" (with a missing close-parenthesis) for
a color value, the close parenthesis is implied by this error
handling rule, and a value is obtained (the color 'black').
However, the similar construct "rgb(0,0,
"
(with both a missing parenthesis and a missing "blue" value)
cannot be parsed, as closing the open construct does not result
in a viable value.
This specification does not require support of any particular network protocol, style sheet language, scripting language, or any of the DOM specifications beyond those described above. However, the language described by this specification is biased towards CSS as the styling language, JavaScript as the scripting language, and HTTP as the network protocol, and several features assume that those languages and protocols are in use.
This specification might have certain additional requirements on character encodings, image formats, audio formats, and video formats in the respective sections.
HTML has a wide number of extensibility mechanisms that can be used for adding semantics in a safe manner:
class
attribute to extend elements, effectively creating their own
elements, while using the most applicable existing "real" HTML
element, so that browsers and other tools that don't know of the
extension can still support it somewhat well. This is the tack used
by Microformats, for example.data-*=""
attributes. These are
guaranteed to never be touched by browsers, and allow scripts to
include data on HTML elements that scripts can then look for and
process.<meta name=""
content="">
mechanism to include page-wide metadata by
registering extensions to the
predefined set of metadata names.rel=""
mechanism to annotate
links with specific meanings by registering extensions to the predefined set of
link types. This is also used by Microformats.<script type="">
mechanism with a custom
type, for further handling by inline or server-side scripts.embed
element. This is how Flash
works.Vendor-specific proprietary user agent extensions to this specification are strongly discouraged. Documents must not use such extensions, as doing so reduces interoperability and fragments the user base, allowing only users of specific user agents to access the content in question.
If such extensions are nonetheless needed, e.g. for experimental purposes, then vendors are strongly urged to use one of the following extension mechanisms:
For markup-level features that can be limited to the XML serialization and need not be supported in the HTML serialization, vendors should use the namespace mechanism to define custom namespaces in which the non-standard elements and attributes are supported.
For markup-level features that are intended for use with
the HTML syntax, extensions should be limited to new
attributes of the form "x-vendor-feature
", where
vendor is a short string that identifies the
vendor responsible for the extension, and feature is the name of the feature. New element names
should not be created. Using attributes for such extensions
exclusively allows extensions from multiple vendors to co-exist on
the same element, which would not be possible with elements. Using
the "x-vendor-feature
" form allows extensions to be made
without risk of conflicting with future additions to the
specification.
For instance, a browser named "FerretBrowser" could use "ferret" as a vendor prefix, while a browser named "Mellblom Browser" could use "mb". If both of these browsers invented extensions that turned elements into scratch-and-sniff areas, an author experimenting with these features could write:
<p>This smells of lemons! <span x-ferret-smellovision x-ferret-smellcode="LEM01" x-mb-outputsmell x-mb-smell="lemon juice"></span></p>
Attribute names beginning with the two characters "x-
" are reserved for user agent use and are
guaranteed to never be formally added to the HTML language. For
flexibility, attributes names containing underscores (the U+005F LOW
LINE character) are also reserved for experimental purposes and are
guaranteed to never be formally added to the HTML language.
Pages that use such attributes are by definition non-conforming.
For DOM extensions, e.g. new methods and IDL attributes, the new members should be prefixed by vendor-specific strings to prevent clashes with future versions of this specification.
For events, experimental event names should be prefixed with vendor-specific strings.
For example, if a user agent called "Pleasold" were to
add an event to indicate when the user is going up in an elevator,
it could use the prefix "pleasold
" and thus
name the event "pleasoldgoingup
", possibly
with an event handler attribute named "onpleasoldgoingup
".
All extensions must be defined so that the use of extensions neither contradicts nor causes the non-conformance of functionality defined in the specification.
For example, while strongly discouraged from doing so, an
implementation "Foo Browser" could add a new IDL attribute "fooTypeTime
" to a control's DOM interface that
returned the time it took the user to select the current value of a
control (say). On the other hand, defining a new control that
appears in a form's elements
array would be in violation of the above requirement, as it would
violate the definition of elements
given in this
specification.
When adding new reflecting IDL
attributes corresponding to content attributes of the form "x-vendor-feature
", the IDL attribute should be named
"vendorFeature
" (i.e. the "x
"
is dropped from the IDL attribute's name).
When vendor-neutral extensions to this specification are needed, either this specification can be updated accordingly, or an extension specification can be written that overrides the requirements in this specification. When someone applying this specification to their activities decides that they will recognize the requirements of such an extension specification, it becomes an applicable specification.
The conformance terminology for documents depends on the nature of the changes introduced by such applicable specificactions, and on the content and intended interpretation of the document. Applicable specifications MAY define new document content (e.g. a foobar element), MAY prohibit certain otherwise conforming content (e.g. prohibit use of <table>s), or MAY change the semantics, DOM mappings, or other processing rules for content defined in this specification. Whether a document is or is not a conforming HTML5 document does not depend on the use of applicable specifications: if the syntax and semantics of a given conforming HTML5 document document is unchanged by the use of applicable specification(s), then that document remains a conforming HTML5 document. If the semantics or processing of a given (otherwise conforming) document is changed by use of applicable specification(s), then it is not a conforming HTML5 document. For such cases, the applicable specifications SHOULD define conformance terminology.
As a suggested but not required convention, such specifications might define conformance terminology such as: "Conforming HTML5+XXX document", where XXX is a short name for the applicable specification. (Example: "Conforming HTML5+AutomotiveExtensions document").
a consequence of the rule given above is that certain syntactically correct HTML5 documents may not be conforming HTML5 documents in the presence of applicable specifications. (Example: the applicable specification defines <table> to be a piece of furniture — a document written to that specification and containing a <table> element is NOT a conforming HTML5 document, even if the element happens to be syntactically correct HTML5.)
User agents must treat elements and attributes that they do not understand as semantically neutral; leaving them in the DOM (for DOM processors), and styling them according to CSS (for CSS processors), but not inferring any meaning from them.
When support for a feature is disabled (e.g. as an emergency measure to mitigate a security problem, or to aid in development, or for performance reasons), user agents must act as if they had no support for the feature whatsoever, and as if the feature was not mentioned in this specification. For example, if a particular feature is accessed via an attribute in a Web IDL interface, the attribute itself would be omitted from the objects that implement that interface — leaving the attribute on the object but making it return null or throw an exception is insufficient.
Comparing two strings in a case-sensitive manner means comparing them exactly, code point for code point.
Comparing two strings in an ASCII case-insensitive manner means comparing them exactly, code point for code point, except that the characters in the range U+0041 to U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z) and the corresponding characters in the range U+0061 to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z) are considered to also match.
Comparing two strings in a compatibility caseless manner means using the Unicode compatibility caseless match operation to compare the two strings. [UNICODE]
Except where otherwise stated, string comparisons must be performed in a case-sensitive manner.
Converting a string to ASCII uppercase means replacing all characters in the range U+0061 to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z) with the corresponding characters in the range U+0041 to U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z).
Converting a string to ASCII lowercase means replacing all characters in the range U+0041 to U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z) with the corresponding characters in the range U+0061 to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL LETTER Z).
A string pattern is a prefix match for a string s when pattern is not longer than s and truncating s to pattern's length leaves the two strings as matches of each other.
When a user agent is required to decode a byte string as UTF-8, with error handling, it means that the byte stream must be converted to a Unicode string by interpreting it as UTF-8, except that any errors must be handled as described in the following list. Bytes in the following list are represented in hexadecimal. [RFC3629]
For the purposes of the above requirements, an overlong form in UTF-8 is a sequence that encodes a code point using more bytes than the minimum needed to encode that code point in UTF-8.
For example, the byte string "41 98 BA 42 E2 98 43 E2 98 BA E2 98" would be converted to the string "A��B�C☺�".
There are various places in HTML that accept particular data types, such as dates or numbers. This section describes what the conformance criteria for content in those formats is, and how to parse them.
Implementors are strongly urged to carefully examine any third-party libraries they might consider using to implement the parsing of syntaxes described below. For example, date libraries are likely to implement error handling behavior that differs from what is required in this specification, since error-handling behavior is often not defined in specifications that describe date syntaxes similar to those used in this specification, and thus implementations tend to vary greatly in how they handle errors.
The space characters, for the purposes of this specification, are U+0020 SPACE, U+0009 CHARACTER TABULATION (tab), U+000A LINE FEED (LF), U+000C FORM FEED (FF), and U+000D CARRIAGE RETURN (CR).
The White_Space characters are
those that have the Unicode property "White_Space" in the Unicode
PropList.txt
data file. [UNICODE]
This should not be confused with the "White_Space"
value (abbreviated "WS") of the "Bidi_Class" property in the Unicode.txt
data file.
The alphanumeric ASCII characters are those in the ranges U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z, U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER Z.
Some of the micro-parsers described below follow the pattern of having an input variable that holds the string being parsed, and having a position variable pointing at the next character to parse in input.
For parsers based on this pattern, a step that requires the user agent to collect a sequence of characters means that the following algorithm must be run, with characters being the set of characters that can be collected:
Let input and position be the same variables as those of the same name in the algorithm that invoked these steps.
Let result be the empty string.
While position doesn't point past the end of input and the character at position is one of the characters, append that character to the end of result and advance position to the next character in input.
Return result.
The step skip whitespace means that the user agent must collect a sequence of characters that are space characters. The step skip White_Space characters means that the user agent must collect a sequence of characters that are White_Space characters. In both cases, the collected characters are not used. [UNICODE]
When a user agent is to strip line breaks from a string, the user agent must remove any U+000A LINE FEED (LF) and U+000D CARRIAGE RETURN (CR) characters from that string.
When a user agent is to strip leading and trailing whitespace from a string, the user agent must remove all space characters that are at the start or end of the string.
The code-point length of a string is the number of Unicode code points in that string.
A number of attributes are boolean attributes. The presence of a boolean attribute on an element represents the true value, and the absence of the attribute represents the false value.
If the attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace.
The values "true" and "false" are not allowed on boolean attributes. To represent a false value, the attribute has to be omitted altogether.
Here is an example of a checkbox that is checked and disabled.
The checked
and disabled
attributes are the
boolean attributes.
<label><input type=checkbox checked name=cheese disabled> Cheese</label>
This could be equivalently written as this:
<label><input type=checkbox checked=checked name=cheese disabled=disabled> Cheese</label>
You can also mix styles; the following is still equivalent:
<label><input type='checkbox' checked name=cheese disabled=""> Cheese</label>
Some attributes are defined as taking one of a finite set of keywords. Such attributes are called enumerated attributes. The keywords are each defined to map to a particular state (several keywords might map to the same state, in which case some of the keywords are synonyms of each other; additionally, some of the keywords can be said to be non-conforming, and are only in the specification for historical reasons). In addition, two default states can be given. The first is the invalid value default, the second is the missing value default.
If an enumerated attribute is specified, the attribute's value must be an ASCII case-insensitive match for one of the given keywords that are not said to be non-conforming, with no leading or trailing whitespace.
When the attribute is specified, if its value is an ASCII case-insensitive match for one of the given keywords then that keyword's state is the state that the attribute represents. If the attribute value matches none of the given keywords, but the attribute has an invalid value default, then the attribute represents that state. Otherwise, if the attribute value matches none of the keywords but there is a missing value default state defined, then that is the state represented by the attribute. Otherwise, there is no default, and invalid values must be ignored.
When the attribute is not specified, if there is a missing value default state defined, then that is the state represented by the (missing) attribute. Otherwise, the absence of the attribute means that there is no state represented.
The empty string can be a valid keyword.
A string is a valid non-negative integer if it consists of one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).
A valid non-negative integer represents the number that is represented in base ten by that string of digits.
The rules for parsing non-negative integers are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either zero, a positive integer, or an error.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
If position is past the end of input, return an error.
If the character indicated by position
is a U+002B PLUS SIGN character (+), advance position to the next character. (The "+
" is ignored, but it is not conforming.)
If position is past the end of input, return an error.
If the character indicated by position is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then return an error.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the resulting sequence as a base-ten integer. Let value be that integer.
Return value.
A string is a valid integer if it consists of one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), optionally prefixed with a U+002D HYPHEN-MINUS character (-).
A valid integer without a U+002D HYPHEN-MINUS (-) prefix represents the number that is represented in base ten by that string of digits. A valid integer with a U+002D HYPHEN-MINUS (-) prefix represents the number represented in base ten by the string of digits that follows the U+002D HYPHEN-MINUS, subtracted from zero.
The rules for parsing integers are similar to the rules for non-negative integers, and are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either an integer or an error.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Let sign have the value "positive".
If position is past the end of input, return an error.
If the character indicated by position (the first character) is a U+002D HYPHEN-MINUS character (-):
Otherwise, if the character indicated by position (the first character) is a U+002B PLUS SIGN character (+):
+
" is ignored, but it is
not conforming.)If the character indicated by position is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then return an error.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the resulting sequence as a base-ten integer. Let value be that integer.
If sign is "positive", return value, otherwise return the result of subtracting value from zero.
A string is a valid floating point number if it consists of:
A valid floating point number represents the number obtained by multiplying the significand by ten raised to the power of the exponent, where the significand is the first number, interpreted as base ten (including the decimal point and the number after the decimal point, if any, and interpreting the significand as a negative number if the whole string starts with a U+002D HYPHEN-MINUS character (-) and the number is not zero), and where the exponent is the number after the E, if any (interpreted as a negative number if there is a U+002D HYPHEN-MINUS character (-) between the E and the number and the number is not zero, or else ignoring a U+002B PLUS SIGN character (+) between the E and the number if there is one). If there is no E, then the exponent is treated as zero.
The Infinity and Not-a-Number (NaN) values are not valid floating point numbers.
The best representation of the number n as a floating point number is the string obtained from applying the JavaScript operator ToString to n. The JavaScript operator ToString is not uniquely determined. When there are multiple possible strings that could be obtained from the JavaScript operator ToString for a particular value, the user agent must always return the same string for that value (though it may differ from the value used by other user agents).
The rules for parsing floating point number values are as given in the following algorithm. This algorithm must be aborted at the first step that returns something. This algorithm will return either a number or an error.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Let value have the value 1.
Let divisor have the value 1.
Let exponent have the value 1.
If position is past the end of input, return an error.
If the character indicated by position is a U+002D HYPHEN-MINUS character (-):
Otherwise, if the character indicated by position (the first character) is a U+002B PLUS SIGN character (+):
+
" is ignored, but it is
not conforming.)If the character indicated by position is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then return an error.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the resulting sequence as a base-ten integer. Multiply value by that integer.
If the character indicated by position is a U+002E FULL STOP (.), run these substeps:
Advance position to the next character.
If position is past the end of input, or if the character indicated by position is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0065 LATIN SMALL LETTER E (e), or U+0045 LATIN CAPITAL LETTER E (E), then jump to the step labeled conversion.
If the character indicated by position is a U+0065 LATIN SMALL LETTER E character (e) or a U+0045 LATIN CAPITAL LETTER E character (E), skip the remainder of these substeps.
Fraction loop: Multiply divisor by ten.
Advance position to the next character.
If position is past the end of input, then jump to the step labeled conversion.
If the character indicated by position is one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), jump back to the step labeled fraction loop in these substeps.
If the character indicated by position is a U+0065 LATIN SMALL LETTER E character (e) or a U+0045 LATIN CAPITAL LETTER E character (E), run these substeps:
Advance position to the next character.
If position is past the end of input, then jump to the step labeled conversion.
If the character indicated by position is a U+002D HYPHEN-MINUS character (-):
If position is past the end of input, then jump to the step labeled conversion.
Otherwise, if the character indicated by position is a U+002B PLUS SIGN character (+):
If position is past the end of input, then jump to the step labeled conversion.
If the character indicated by position is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then jump to the step labeled conversion.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the resulting sequence as a base-ten integer. Multiply exponent by that integer.
Multiply value by ten raised to the exponentth power.
Conversion: Let S be the set of finite IEEE 754 double-precision floating point values except −0, but with two special values added: 21024 and −21024.
Let rounded-value be the number in S that is closest to value, selecting the number with an even significand if there are two equally close values. (The two special values 21024 and −21024 are considered to have even significands for this purpose.)
If rounded-value is 21024 or −21024, return an error.
Return rounded-value.
The rules for parsing dimension values are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either a number greater than or equal to 1.0, or an error; if a number is returned, then it is further categorized as either a percentage or a length.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
If position is past the end of input, return an error.
If the character indicated by position is a U+002B PLUS SIGN character (+), advance position to the next character.
Collect a sequence of characters that are U+0030 DIGIT ZERO (0) characters, and discard them.
If position is past the end of input, return an error.
If the character indicated by position is not one of U+0031 DIGIT ONE (1) to U+0039 DIGIT NINE (9), then return an error.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and interpret the resulting sequence as a base-ten integer. Let value be that number.
If position is past the end of input, return value as a length.
If the character indicated by position is a U+002E FULL STOP character (.):
Advance position to the next character.
If position is past the end of input, or if the character indicated by position is not one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then return value as a length.
Let divisor have the value 1.
Fraction loop: Multiply divisor by ten.
Advance position to the next character.
If position is past the end of input, then return value as a length.
If the character indicated by position is one of U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), return to the step labeled fraction loop in these substeps.
If position is past the end of input, return value as a length.
If the character indicated by position is a U+0025 PERCENT SIGN character (%), return value as a percentage.
Return value as a length.
A valid list of integers is a number of valid integers separated by U+002C COMMA characters, with no other characters (e.g. no space characters). In addition, there might be restrictions on the number of integers that can be given, or on the range of values allowed.
The rules for parsing a list of integers are as follows:
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Let numbers be an initially empty list of integers. This list will be the result of this algorithm.
If there is a character in the string input at position position, and it is either a U+0020 SPACE, U+002C COMMA, or U+003B SEMICOLON character, then advance position to the next character in input, or to beyond the end of the string if there are no more characters.
If position points to beyond the end of input, return numbers and abort.
If the character in the string input at position position is a U+0020 SPACE, U+002C COMMA, or U+003B SEMICOLON character, then return to step 4.
Let negated be false.
Let value be 0.
Let started be false. This variable is set to true when the parser sees a number or a U+002D HYPHEN-MINUS character (-).
Let got number be false. This variable is set to true when the parser sees a number.
Let finished be false. This variable is set to true to switch parser into a mode where it ignores characters until the next separator.
Let bogus be false.
Parser: If the character in the string input at position position is:
Follow these substeps:
Follow these substeps:
Follow these substeps:
1,2,x,4
".Follow these substeps:
Follow these substeps:
Advance position to the next character in input, or to beyond the end of the string if there are no more characters.
If position points to a character (and not to beyond the end of input), jump to the big Parser step above.
If negated is true, then negate value.
If got number is true, then append value to the numbers list.
Return the numbers list and abort.
The rules for parsing a list of dimensions are as follows. These rules return a list of zero or more pairs consisting of a number and a unit, the unit being one of percentage, relative, and absolute.
Let raw input be the string being parsed.
If the last character in raw input is a U+002C COMMA character (,), then remove that character from raw input.
Split the string raw input on commas. Let raw tokens be the resulting list of tokens.
Let result be an empty list of number/unit pairs.
For each token in raw tokens, run the following substeps:
Let input be the token.
Let position be a pointer into input, initially pointing at the start of the string.
Let value be the number 0.
Let unit be absolute.
If position is past the end of input, set unit to relative and jump to the last substep.
If the character at position is a character in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), interpret the resulting sequence as an integer in base ten, and increment value by that integer.
If the character at position is a U+002E FULL STOP character (.), run these substeps:
Collect a sequence of characters consisting of space characters and characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). Let s be the resulting sequence.
Remove all space characters in s.
If s is not the empty string, run these subsubsteps:
Let length be the number of characters in s (after the spaces were removed).
Let fraction be the result of interpreting s as a base-ten integer, and then dividing that number by 10length.
Increment value by fraction.
If the character at position is a U+0025 PERCENT SIGN character (%), then set unit to percentage.
Otherwise, if the character at position is a U+002A ASTERISK character (*), then set unit to relative.
Add an entry to result consisting of the number given by value and the unit given by unit.
Return the list result.
In the algorithms below, the number of days in month month of year year is: 31 if month is 1, 3, 5, 7, 8, 10, or 12; 30 if month is 4, 6, 9, or 11; 29 if month is 2 and year is a number divisible by 400, or if year is a number divisible by 4 but not by 100; and 28 otherwise. This takes into account leap years in the Gregorian calendar. [GREGORIAN]
The digits in the date and time syntaxes defined in this section must be characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), used to express numbers in base ten.
While the formats described here are intended to be subsets of the corresponding ISO8601 formats, this specification defines parsing rules in much more detail than ISO8601. Implementors are therefore encouraged to carefully examine any date parsing libraries before using them to implement the parsing rules described below; ISO8601 libraries might not parse dates and times in exactly the same manner. [ISO8601]
A month consists of a specific proleptic Gregorian date with no time-zone information and no date information beyond a year and a month. [GREGORIAN]
A string is a valid month string representing a year year and month month if it consists of the following components in the given order:
The rules to parse a month string are as follows. This will return either a year and month, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Parse a month component to obtain year and month. If this returns nothing, then fail.
If position is not beyond the end of input, then fail.
Return year and month.
The rules to parse a month component, given an input string and a position, are as follows. This will return either a year and a month, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not at least four characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the year.
If year is not a number greater than zero, then fail.
If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail. Otherwise, move position forwards one character.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the month.
If month is not a number in the range 1 ≤ month ≤ 12, then fail.
Return year and month.
A date consists of a specific proleptic Gregorian date with no time-zone information, consisting of a year, a month, and a day. [GREGORIAN]
A string is a valid date string representing a year year, month month, and day day if it consists of the following components in the given order:
The rules to parse a date string are as follows. This will return either a date, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Parse a date component to obtain year, month, and day. If this returns nothing, then fail.
If position is not beyond the end of input, then fail.
Let date be the date with year year, month month, and day day.
Return date.
The rules to parse a date component, given an input string and a position, are as follows. This will return either a year, a month, and a day, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Parse a month component to obtain year and month. If this returns nothing, then fail.
Let maxday be the number of days in month month of year year.
If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail. Otherwise, move position forwards one character.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the day.
If day is not a number in the range 1 ≤ day ≤ maxday, then fail.
Return year, month, and day.
A time consists of a specific time with no time-zone information, consisting of an hour, a minute, a second, and a fraction of a second.
A string is a valid time string representing an hour hour, a minute minute, and a second second if it consists of the following components in the given order:
The second component cannot be 60 or 61; leap seconds cannot be represented.
The rules to parse a time string are as follows. This will return either a time, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
If position is not beyond the end of input, then fail.
Let time be the time with hour hour, minute minute, and second second.
Return time.
The rules to parse a time component, given an input string and a position, are as follows. This will return either an hour, a minute, and a second, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the hour.
If position is beyond the end of input or if the character at position is not a U+003A COLON character, then fail. Otherwise, move position forwards one character.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the minute.
Let second be a string with the value "0".
If position is not beyond the end of input and the character at position is a U+003A COLON, then run these substeps:
Advance position to the next character in input.
If position is beyond the end of input, or at the last character in input, or if the next two characters in input starting at position are not two characters both in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then fail.
Collect a sequence of characters that are either characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) or U+002E FULL STOP characters. If the collected sequence has more than one U+002E FULL STOP characters, or if the last character in the sequence is a U+002E FULL STOP character, then fail. Otherwise, let the collected string be second instead of its previous value.
Interpret second as a base-ten number (possibly with a fractional part). Let second be that number instead of the string version.
If second is not a number in the range 0 ≤ second < 60, then fail.
Return hour, minute, and second.
A local date and time consists of a specific proleptic Gregorian date, consisting of a year, a month, and a day, and a time, consisting of an hour, a minute, a second, and a fraction of a second, but expressed without a time zone. [GREGORIAN]
A string is a valid local date and time string representing a date and time if it consists of the following components in the given order:
The rules to parse a local date and time string are as follows. This will return either a date and time, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Parse a date component to obtain year, month, and day. If this returns nothing, then fail.
If position is beyond the end of input or if the character at position is not a U+0054 LATIN CAPITAL LETTER T character (T) then fail. Otherwise, move position forwards one character.
Parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
If position is not beyond the end of input, then fail.
Let date be the date with year year, month month, and day day.
Let time be the time with hour hour, minute minute, and second second.
Return date and time.
A global date and time consists of a specific proleptic Gregorian date, consisting of a year, a month, and a day, and a time, consisting of an hour, a minute, a second, and a fraction of a second, expressed with a time-zone offset, consisting of a signed number of hours and minutes. [GREGORIAN]
A string is a valid global date and time string representing a date, time, and a time-zone offset if it consists of the following components in the given order:
This format allows for time-zone offsets from -23:59 to +23:59. In practice, however, the range of offsets of actual time zones is -12:00 to +14:00, and the minutes component of offsets of actual time zones is always either 00, 30, or 45.
Times in dates before the formation of UTC in the mid twentieth century must be expressed and interpreted in terms of UT1 (contemporary Earth solar time at the 0° longitude), not UTC (the approximation of UT1 that ticks in SI seconds). Time before the formation of time zones must be expressed and interpeted as UT1 times with explicit time zones that approximate the contemporary difference between the appropriate local time and the time observed at the location of Greenwich, London.
The following are some examples of dates written as valid global date and time strings.
0037-12-13T00:00Z
"1979-10-14T12:00:00.001-04:00
"8592-01-01T02:09+02:09
"Several things are notable about these dates:
The best representation of the global date and time string datetime is the valid global date and time string representing datetime, with the valid time string component being given in its shortest possible form, with the last character of the string not being a U+005A LATIN CAPITAL LETTER Z character (Z), even if the time zone is UTC, and with a U+002B PLUS SIGN character (+) representing the sign of the time-zone offset when the time zone is UTC.
The rules to parse a global date and time string are as follows. This will return either a time in UTC, with associated time-zone offset information for round-tripping or display purposes, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Parse a date component to obtain year, month, and day. If this returns nothing, then fail.
If position is beyond the end of input or if the character at position is not a U+0054 LATIN CAPITAL LETTER T character (T) then fail. Otherwise, move position forwards one character.
Parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
If position is beyond the end of input, then fail.
Parse a time-zone offset component to obtain timezonehours and timezoneminutes. If this returns nothing, then fail.
If position is not beyond the end of input, then fail.
Let time be the moment in time at year year, month month, day day, hours hour, minute minute, second second, subtracting timezonehours hours and timezoneminutes minutes. That moment in time is a moment in the UTC time zone.
Let timezone be timezonehours hours and timezoneminutes minutes from UTC.
Return time and timezone.
The rules to parse a time-zone offset component, given an input string and a position, are as follows. This will return either time-zone hours and time-zone minutes, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
If the character at position is a U+005A LATIN CAPITAL LETTER Z character (Z), then:
Let timezonehours be 0.
Let timezoneminutes be 0.
Advance position to the next character in input.
Otherwise, if the character at position is either a U+002B PLUS SIGN (+) or a U+002D HYPHEN-MINUS (-), then:
If the character at position is a U+002B PLUS SIGN (+), let sign be "positive". Otherwise, it's a U+002D HYPHEN-MINUS (-); let sign be "negative".
Advance position to the next character in input.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the timezonehours.
If position is beyond the end of input or if the character at position is not a U+003A COLON character, then fail. Otherwise, move position forwards one character.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the timezoneminutes.
Otherwise, fail.
Return timezonehours and timezoneminutes.
A week consists of a week-year number and a week number representing a seven-day period starting on a Monday. Each week-year in this calendaring system has either 52 or 53 such seven-day periods, as defined below. The seven-day period starting on the Gregorian date Monday December 29th 1969 (1969-12-29) is defined as week number 1 in week-year 1970. Consecutive weeks are numbered sequentially. The week before the number 1 week in a week-year is the last week in the previous week-year, and vice versa. [GREGORIAN]
A week-year with a number year has 53 weeks if it corresponds to either a year year in the proleptic Gregorian calendar that has a Thursday as its first day (January 1st), or a year year in the proleptic Gregorian calendar that has a Wednesday as its first day (January 1st) and where year is a number divisible by 400, or a number divisible by 4 but not by 100. All other week-years have 52 weeks.
The week number of the last day of a week-year with 53 weeks is 53; the week number of the last day of a week-year with 52 weeks is 52.
The week-year number of a particular day can be different than the number of the year that contains that day in the proleptic Gregorian calendar. The first week in a week-year y is the week that contains the first Thursday of the Gregorian year y.
A string is a valid week string representing a week-year year and week week if it consists of the following components in the given order:
The rules to parse a week string are as follows. This will return either a week-year number and week number, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not at least four characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the year.
If year is not a number greater than zero, then fail.
If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail. Otherwise, move position forwards one character.
If position is beyond the end of input or if the character at position is not a U+0057 LATIN CAPITAL LETTER W character (W), then fail. Otherwise, move position forwards one character.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9). If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the week.
Let maxweek be the week number of the last day of year year.
If week is not a number in the range 1 ≤ week ≤ maxweek, then fail.
If position is not beyond the end of input, then fail.
Return the week-year number year and the week number week.
A string is a valid date or time string if it is also one of the following:
A string is a valid date or time string in content if it consists of zero or more White_Space characters, followed by a valid date or time string, followed by zero or more further White_Space characters.
A string is a valid date string with optional time if it is also one of the following:
A string is a valid date string in content with optional time if it consists of zero or more White_Space characters, followed by a valid date string with optional time, followed by zero or more further White_Space characters.
The rules to parse a date or time string are as follows. The algorithm is invoked with a flag indicating if the in attribute variant or the in content variant is to be used. The algorithm will return either a date, a time, a global date and time, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
For the in content variant: skip White_Space characters.
Set start position to the same position as position.
Set the date present and time present flags to true.
Parse a date component to obtain year, month, and day. If this fails, then set the date present flag to false.
If date present is true, and position is not beyond the end of input, and the character at position is a U+0054 LATIN CAPITAL LETTER T character (T), then advance position to the next character in input.
Otherwise, if date present is true, and either position is beyond the end of input or the character at position is not a U+0054 LATIN CAPITAL LETTER T character (T), then set time present to false.
Otherwise, if date present is false, set position back to the same position as start position.
If the time present flag is true, then parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.
If the date present and time present flags are both true, but position is beyond the end of input, then fail.
If the date present and time present flags are both true, parse a time-zone offset component to obtain timezonehours and timezoneminutes. If this returns nothing, then fail.
For the in content variant: skip White_Space characters.
If position is not beyond the end of input, then fail.
If the date present flag is true and the time present flag is false, then let date be the date with year year, month month, and day day, and return date.
Otherwise, if the time present flag is true and the date present flag is false, then let time be the time with hour hour, minute minute, and second second, and return time.
Otherwise, let time be the moment in time at year year, month month, day day, hours hour, minute minute, second second, subtracting timezonehours hours and timezoneminutes minutes, that moment in time being a moment in the UTC time zone; let timezone be timezonehours hours and timezoneminutes minutes from UTC; and return time and timezone.
A simple color consists of three 8-bit numbers in the range 0..255, representing the red, green, and blue components of the color respectively, in the sRGB color space. [SRGB]
A string is a valid simple color if it is exactly seven characters long, and the first character is a U+0023 NUMBER SIGN character (#), and the remaining six characters are all in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F, U+0061 LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F, with the first two digits representing the red component, the middle two digits representing the green component, and the last two digits representing the blue component, in hexadecimal.
A string is a valid lowercase simple color if it is a valid simple color and doesn't use any characters in the range U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F.
The rules for parsing simple color values are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either a simple color or an error.
Let input be the string being parsed.
If input is not exactly seven characters long, then return an error.
If the first character in input is not a U+0023 NUMBER SIGN character (#), then return an error.
If the last six characters of input are not all in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F, U+0061 LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F, then return an error.
Let result be a simple color.
Interpret the second and third characters as a hexadecimal number and let the result be the red component of result.
Interpret the fourth and fifth characters as a hexadecimal number and let the result be the green component of result.
Interpret the sixth and seventh characters as a hexadecimal number and let the result be the blue component of result.
Return result.
The rules for serializing simple color values given a simple color are as given in the following algorithm:
Let result be a string consisting of a single U+0023 NUMBER SIGN character (#).
Convert the red, green, and blue components in turn to two-digit hexadecimal numbers using the digits U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) and U+0061 LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F, zero-padding if necessary, and append these numbers to result, in the order red, green, blue.
Return result, which will be a valid lowercase simple color.
Some obsolete legacy attributes parse colors in a more complicated manner, using the rules for parsing a legacy color value, which are given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either a simple color or an error.
Let input be the string being parsed.
If input is the empty string, then return an error.
Strip leading and trailing whitespace from input.
If input is an ASCII
case-insensitive match for the string "transparent
", then return an error.
If input is an ASCII case-insensitive match for one of the keywords listed in the SVG color keywords section of the CSS3 Color specification, then return the simple color corresponding to that keyword. [CSSCOLOR]
CSS2 System Colors are not recognised.
If input is four characters long, and the first character in input is a U+0023 NUMBER SIGN character (#), and the last three characters of input are all in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F, and U+0061 LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F, then run these substeps:
Let result be a simple color.
Interpret the second character of input as a hexadecimal digit; let the red component of result be the resulting number multiplied by 17.
Interpret the third character of input as a hexadecimal digit; let the green component of result be the resulting number multiplied by 17.
Interpret the fourth character of input as a hexadecimal digit; let the blue component of result be the resulting number multiplied by 17.
Return result.
Replace any characters in input that
have a Unicode code point greater than U+FFFF (i.e. any characters
that are not in the basic multilingual plane) with the
two-character string "00
".
If input is longer than 128 characters, truncate input, leaving only the first 128 characters.
If the first character in input is a U+0023 NUMBER SIGN character (#), remove it.
Replace any character in input that is not in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F, and U+0061 LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F with the character U+0030 DIGIT ZERO (0).
While input's length is zero or not a multiple of three, append a U+0030 DIGIT ZERO (0) character to input.
Split input into three strings of equal length, to obtain three components. Let length be the length of those components (one third the length of input).
If length is greater than 8, then remove the leading length-8 characters in each component, and let length be 8.
While length is greater than two and the first character in each component is a U+0030 DIGIT ZERO (0) character, remove that character and reduce length by one.
If length is still greater than two, truncate each component, leaving only the first two characters in each.
Let result be a simple color.
Interpret the first component as a hexadecimal number; let the red component of result be the resulting number.
Interpret the second component as a hexadecimal number; let the green component of result be the resulting number.
Interpret the third component as a hexadecimal number; let the blue component of result be the resulting number.
Return result.
A set of space-separated tokens is a string containing zero or more words (known as tokens) separated by one or more space characters, where words consist of any string of one or more characters, none of which are space characters.
A string containing a set of space-separated tokens may have leading or trailing space characters.
An unordered set of unique space-separated tokens is a set of space-separated tokens where none of the tokens are duplicated.
An ordered set of unique space-separated tokens is a set of space-separated tokens where none of the tokens are duplicated but where the order of the tokens is meaningful.
Sets of space-separated tokens sometimes have a defined set of allowed values. When a set of allowed values is defined, the tokens must all be from that list of allowed values; other values are non-conforming. If no such set of allowed values is provided, then all values are conforming.
How tokens in a set of space-separated tokens are to be compared (e.g. case-sensitively or not) is defined on a per-set basis.
When a user agent has to split a string on spaces, it must use the following algorithm:
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Let tokens be a list of tokens, initially empty.
While position is not past the end of input:
Collect a sequence of characters that are not space characters.
Add the string collected in the previous step to tokens.
Return tokens.
When a user agent has to remove a token from a string, it must use the following algorithm:
Let input be the string being modified.
Let token be the token being removed. It will not contain any space characters.
Let output be the output string, initially empty.
Let position be a pointer into input, initially pointing at the start of the string.
Loop: If position is beyond the end of input, abort these steps.
If the character at position is a space character:
Append the character at position to the end of output.
Advance position so it points at the next character in input.
Return to the step labeled loop.
Otherwise, the character at position is the first character of a token. Collect a sequence of characters that are not space characters, and let that be s.
If s is exactly equal to token (this is a case-sensitive comparison), then:
Skip whitespace (in input).
Remove any space characters currently at the end of output.
If position is not past the end of input, and output is not the empty string, append a single U+0020 SPACE character at the end of output.
Otherwise, append s to the end of output.
Return to the step labeled loop.
This causes any occurrences of the token to be removed from the string, and any spaces that were surrounding the token to be collapsed to a single space, except at the start and end of the string, where such spaces are removed.
A set of comma-separated tokens is a string containing zero or more tokens each separated from the next by a single U+002C COMMA character (,), where tokens consist of any string of zero or more characters, neither beginning nor ending with space characters, nor containing any U+002C COMMA characters (,), and optionally surrounded by space characters.
For instance, the string " a ,b,,d d
" consists of four
tokens: "a", "b", the empty string, and "d d". Leading and
trailing whitespace around each token doesn't count as part of the
token, and the empty string can be a token.
Sets of comma-separated tokens sometimes have further restrictions on what consists a valid token. When such restrictions are defined, the tokens must all fit within those restrictions; other values are non-conforming. If no such restrictions are specified, then all values are conforming.
When a user agent has to split a string on commas, it must use the following algorithm:
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
Let tokens be a list of tokens, initially empty.
Token: If position is past the end of input, jump to the last step.
Collect a sequence of characters that are not U+002C COMMA characters (,). Let s be the resulting sequence (which might be the empty string).
Remove any leading or trailing sequence of space characters from s.
Add s to tokens.
If position is not past the end of input, then the character at position is a U+002C COMMA character (,); advance position past that character.
Jump back to the step labeled token.
Return tokens.
A valid hash-name reference to an element of type type is a string consisting of a U+0023 NUMBER SIGN
character (#) followed by a string which exactly matches the value
of the name
attribute of an element with type
type in the document.
The rules for parsing a hash-name reference to an element of type type are as follows:
If the string being parsed does not contain a U+0023 NUMBER SIGN character, or if the first such character in the string is the last character in the string, then return null and abort these steps.
Let s be the string from the character immediately after the first U+0023 NUMBER SIGN character in the string being parsed up to the end of that string.
Return the first element of type type
that has an id
attribute whose value
is a case-sensitive match for s or
a name
attribute whose value is a
compatibility caseless match for s.
A string is a valid media query if it matches the
media_query_list
production of the Media
Queries specification. [MQ]
A string matches the environment of the user if it is the empty string, a string consisting of only space characters, or is a media query that matches the user's environment according to the definitions given in the Media Queries specification. [MQ]
This specification defines the term URL, and defines various algorithms for dealing with URLs, because for historical reasons the rules defined by the URI and IRI specifications are not a complete description of what HTML user agents need to implement to be compatible with Web content.
The term "URL" in this specification is used in a manner distinct from the precise technical meaning it is given in RFC 3986. Readers familiar with that RFC will find it easier to read this specification if they pretend the term "URL" as used herein is really called something else altogether. This is a willful violation of RFC 3986. [RFC3986]
A URL is a string used to identify a resource.
A URL is a valid URL if at least one of the following conditions holds:
The URL is a valid IRI reference and it has no query component. [RFC3987]
The URL is a valid IRI reference and its query component contains no unescaped non-ASCII characters. [RFC3987]
The URL is a valid IRI reference and the character encoding of
the URL's Document
is UTF-8 or UTF-16. [RFC3987]
A string is a valid non-empty URL if it is a valid URL but it is not the empty string.
A string is a valid URL potentially surrounded by spaces if, after stripping leading and trailing whitespace from it, it is a valid URL.
A string is a valid non-empty URL potentially surrounded by spaces if, after stripping leading and trailing whitespace from it, it is a valid non-empty URL.
This specification defines the URL
about:legacy-compat
as a reserved, though
unresolvable, about:
URI, for use in DOCTYPEs in HTML
documents when needed for compatibility with XML tools. [ABOUT]
This specification defines the URL
about:srcdoc
as a reserved, though
unresolvable, about:
URI, that is used as
the document's address of iframe
srcdoc
documents. [ABOUT]
To parse a URL url into its component parts, the user agent must use the following steps:
Strip leading and trailing space characters from url.
Parse url in the manner defined by RFC 3986, with the following exceptions:
If url doesn't match the <URI-reference> production, even after the above changes are made to the ABNF definitions, then parsing the URL fails with an error. [RFC3986]
Otherwise, parsing url was successful; the components of the URL are substrings of url defined as follows:
The substring matched by the <scheme> production, if any.
The substring matched by the <host> production, if any.
The substring matched by the <port> production, if any.
If there is a <scheme> component and a <port> component and the port given by the <port> component is different than the default port defined for the protocol given by the <scheme> component, then <hostport> is the substring that starts with the substring matched by the <host> production and ends with the substring matched by the <port> production, and includes the colon in between the two. Otherwise, it is the same as the <host> component.
The substring matched by one of the following productions, if one of them was matched:
The substring matched by the <query> production, if any.
The substring matched by the <fragment> production, if any.
The substring that follows the substring matched by the <authority> production, or the whole string if the <authority> production wasn't matched.
These parsing rules are a willful violation of RFC 3986 and RFC 3987 (which do not define error handling), motivated by a desire to handle legacy content. [RFC3986] [RFC3987]
Resolving a URL is the process of taking a relative URL and obtaining the absolute URL that it implies.
To resolve a URL to an absolute URL relative to either another absolute URL or an element, the user agent must use the following steps. Resolving a URL can result in an error, in which case the URL is not resolvable.
Let url be the URL being resolved.
Let encoding be determined as follows:
Document
, and the URL character
encoding is the document's character encoding.If encoding is a UTF-16 encoding, then change the value of encoding to UTF-8.
If the algorithm was invoked with an absolute URL to use as the base URL, let base be that absolute URL.
Otherwise, let base be the base URI of
the element, as defined by the XML Base specification, with
the base URI of the document entity being defined as the
document base URL of the Document
that
owns the element. [XMLBASE]
For the purposes of the XML Base specification, user agents
must act as if all Document
objects represented XML
documents.
It is possible for xml:base
attributes to be present
even in HTML fragments, as such attributes can be added
dynamically using script. (Such scripts would not be conforming,
however, as xml:base
attributes
are not allowed in HTML documents.)
The document base URL of a Document
object is the absolute URL obtained by running these
substeps:
Let fallback base url be the document's address.
If fallback base url is
about:blank
, and the Document
's
browsing context has a creator browsing
context, then let fallback base url
be the document base URL of the creator
Document
instead.
If the Document
is an
iframe
srcdoc
document, then
let fallback base url be the document
base URL of the Document
's browsing
context's browsing context container's
Document
instead.
If there is no base
element that has an href
attribute, then the
document base URL is fallback base
url; abort these steps. Otherwise, let url be the value of the href
attribute of the first such
element.
Resolve url relative to fallback base
url (thus, the base
href
attribute isn't affected by
xml:base
attributes).
The document base URL is the result of the previous step if it was successful; otherwise it is fallback base url.
Parse url into its component parts.
If parsing url resulted in a <host> component, then replace the matching substring of url with the string that results from expanding any sequences of percent-encoded octets in that component that are valid UTF-8 sequences into Unicode characters as defined by UTF-8.
If any percent-encoded octets in that component are not valid UTF-8 sequences, then return an error and abort these steps.
Apply the IDNA ToASCII algorithm to the matching substring, with both the AllowUnassigned and UseSTD3ASCIIRules flags set. Replace the matching substring with the result of the ToASCII algorithm.
If ToASCII fails to convert one of the components of the string, e.g. because it is too long or because it contains invalid characters, then return an error and abort these steps. [RFC3490]
If parsing url resulted in a <path> component, then replace the matching substring of url with the string that results from applying the following steps to each character other than U+0025 PERCENT SIGN (%) that doesn't match the original <path> production defined in RFC 3986:
For instance if url was "//example.com/a^b☺c%FFd%z/?e
", then the
<path> component's substring
would be "/a^b☺c%FFd%z/
" and the two
characters that would have to be escaped would be "^
" and "☺
". The
result after this step was applied would therefore be that url now had the value "//example.com/a%5Eb%E2%98%BAc%FFd%z/?e
".
If parsing url resulted in a <query> component, then replace the matching substring of url with the string that results from applying the following steps to each character other than U+0025 PERCENT SIGN (%) that doesn't match the original <query> production defined in RFC 3986:
Apply the algorithm described in RFC 3986 section 5.2 Relative Resolution, using url as the potentially relative URI reference (R), and base as the base URI (Base). [RFC3986]
Apply any relevant conformance criteria of RFC 3986 and RFC 3987, returning an error and aborting these steps if appropriate. [RFC3986] [RFC3987]
For instance, if an absolute URI that would be
returned by the above algorithm violates the restrictions specific
to its scheme, e.g. a data:
URI using the
"//
" server-based naming authority syntax,
then user agents are to treat this as an error instead.
Let result be the target URI (T) returned by the Relative Resolution algorithm.
If result uses a scheme with a server-based naming authority, replace all U+005C REVERSE SOLIDUS (\) characters in result with U+002F SOLIDUS (/) characters.
Return result.
Some of the steps in these rules, for example the processing of U+005C REVERSE SOLIDUS (\) characters, are a willful violation of RFC 3986 and RFC 3987, motivated by a desire to handle legacy content. [RFC3986] [RFC3987]
A URL is an absolute URL if resolving it results in the same output regardless of what it is resolved relative to, and that output is not a failure.
An absolute URL is a hierarchical URL if, when resolved and then parsed, there is a character immediately after the <scheme> component and it is a U+002F SOLIDUS character (/).
An absolute URL is an authority-based URL if, when resolved and then parsed, there are two characters immediately after the <scheme> component and they are both U+002F SOLIDUS characters (//).
To fragment-escape a string input, a user agent must run the following steps:
Let input be the string to be escaped.
Let position point at the first character of input.
Let output be an empty string.
Loop: If position is past the end of input, then jump to the step labeled end.
If the character in input pointed to by position is in the range U+0000 to U+0020 or is one of the following characters:
...then append the percent-encoded form of the character to output. [RFC3986]
Otherwise, append the character itself to output.
This escapes any ASCII characters that are not valid in the URI <fragment> production without being escaped.
Advance position to the next character in input.
Return to the step labeled loop.
End: Return output.
When an xml:base
attribute
changes, the attribute's element, and all descendant elements, are
affected by a base URL change.
When a document's document base URL changes, all elements in that document are affected by a base URL change.
When an element is moved from one document to another, if the two documents have different base URLs, then that element and all its descendants are affected by a base URL change.
When an element is affected by a base URL change, it must act as described in the following list:
If the absolute URL identified by the hyperlink is
being shown to the user, or if any data derived from that URL is
affecting the display, then the href
attribute should be re-resolved relative to the element
and the UI updated appropriately.
For example, the CSS :link
/:visited
pseudo-classes might have
been affected.
q
, blockquote
,
section
, article
, ins
, or
del
element with a cite
attributeIf the absolute URL identified by the cite
attribute is being shown to the user, or if
any data derived from that URL is affecting the display, then the
URL should be re-resolved relative to the element and the UI updated
appropriately.
The element is not directly affected.
Changing the base URL doesn't affect the image
displayed by img
elements, although subsequent
accesses of the src
IDL attribute
from script will return a new absolute URL that might
no longer correspond to the image being shown.
An interface that has a complement of URL decomposition IDL attributes has seven attributes with the following definitions:
attribute DOMString protocol; attribute DOMString host; attribute DOMString hostname; attribute DOMString port; attribute DOMString pathname; attribute DOMString search; attribute DOMString hash;
protocol
[ = value ]Returns the current scheme of the underlying URL.
Can be set, to change the underlying URL's scheme.
host
[ = value ]Returns the current host and port (if it's not the default port) in the underlying URL.
Can be set, to change the underlying URL's host and port.
The host and the port are separated by a colon. The port part, if omitted, will be assumed to be the current scheme's default port.
hostname
[ = value ]Returns the current host in the underlying URL.
Can be set, to change the underlying URL's host.
port
[ = value ]Returns the current port in the underlying URL.
Can be set, to change the underlying URL's port.
pathname
[ = value ]Returns the current path in the underlying URL.
Can be set, to change the underlying URL's path.
search
[ = value ]Returns the current query component in the underlying URL.
Can be set, to change the underlying URL's query component.
hash
[ = value ]Returns the current fragment identifier in the underlying URL.
Can be set, to change the underlying URL's fragment identifier.
The attributes defined to be URL decomposition IDL attributes must act as described for the attributes with the same corresponding names in this section.
In addition, an interface with a complement of URL decomposition IDL attributes defines an input, which is a URL that the attributes act on, and a common setter action, which is a set of steps invoked when any of the attributes' setters are invoked.
The seven URL decomposition IDL attributes have similar requirements.
On getting, if the input is an absolute URL that fulfills the condition given in the "getter condition" column corresponding to the attribute in the table below, the user agent must return the part of the input URL given in the "component" column, with any prefixes specified in the "prefix" column appropriately added to the start of the string and any suffixes specified in the "suffix" column appropriately added to the end of the string. Otherwise, the attribute must return the empty string.
On setting, the new value must first be mutated as described by the "setter preprocessor" column, then mutated by %-escaping any characters in the new value that are not valid in the relevant component as given by the "component" column. Then, if the input is an absolute URL and the resulting new value fulfills the condition given in the "setter condition" column, the user agent must make a new string output by replacing the component of the URL given by the "component" column in the input URL with the new value; otherwise, the user agent must let output be equal to the input. Finally, the user agent must invoke the common setter action with the value of output.
When replacing a component in the URL, if the component is part of an optional group in the URL syntax consisting of a character followed by the component, the component (including its prefix character) must be included even if the new value is the empty string.
The previous paragraph applies in particular to the
":
" before a <port> component, the "?
" before a <query> component, and the "#
" before a <fragment> component.
For the purposes of the above definitions, URLs must be parsed using the URL parsing rules defined in this specification.
Attribute | Component | Getter Condition | Prefix | Suffix | Setter Preprocessor | Setter Condition |
---|---|---|---|---|---|---|
protocol
| <scheme> | — | — | U+003A COLON (:) | Remove all trailing U+003A COLON characters (:) | The new value is not the empty string |
host
| <hostport> | input is an authority-based URL | — | — | — | The new value is not the empty string and input is an authority-based URL |
hostname
| <host> | input is an authority-based URL | — | — | Remove all leading U+002F SOLIDUS characters (/) | The new value is not the empty string and input is an authority-based URL |
port
| <port> | input is an authority-based URL, and contained a <port> component (possibly an empty one) | — | — | Remove all characters in the new value from the first that is not in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), if any. Remove any leading U+0030 DIGIT ZERO characters (0) in the new value. If the resulting string is empty, set it to a single U+0030 DIGIT ZERO character (0). | input is an authority-based URL, and the new value, when interpreted as a base-ten integer, is less than or equal to 65535 |
pathname
| <path> | input is a hierarchical URL | — | — | If it has no leading U+002F SOLIDUS character (/), prepend a U+002F SOLIDUS character (/) to the new value | input is hierarchical |
search
| <query> | input is a hierarchical URL, and contained a <query> component (possibly an empty one) | U+003F QUESTION MARK (?) | — | Remove one leading U+003F QUESTION MARK character (?), if any | input is a hierarchical URL |
hash
| <fragment> | input contained a non-empty <fragment> component | U+0023 NUMBER SIGN (#) | — | Remove one leading U+0023 NUMBER SIGN character (#), if any | — |
The table below demonstrates how the getter condition for search
results in different results
depending on the exact original syntax of the URL:
Input URL | search value
| Explanation |
---|---|---|
http://example.com/
| empty string | No <query> component in input URL. |
http://example.com/?
| ?
| There is a <query> component, but it is empty. The question mark in the resulting value is the prefix. |
http://example.com/?test
| ?test
| The <query> component has the value "test ".
|
http://example.com/?test#
| ?test
| The (empty) <fragment> component is not part of the <query> component. |
The following table is similar; it provides a list of what each of the URL decomposition IDL attributes returns for a given input URL.
Input | protocol
| host
| hostname
| port
| pathname
| search
| hash
|
---|---|---|---|---|---|---|---|
http://example.com/carrot#question%3f
| http:
| example.com
| example.com
| (empty string) | /carrot
| (empty string) | #question%3f
|
https://www.example.com:4443?
| https:
| www.example.com:4443
| www.example.com
| 4443
| /
| ?
| (empty string) |
When a user agent is to fetch a resource or URL, optionally from an origin origin, and optionally with a synchronous flag, a manual redirect flag, a force same-origin flag, and/or a block cookies flag, the following steps must be run. (When a URL is to be fetched, the URL identifies a resource to be obtained.)
Let document be the appropriate
Document
as given by the following list:
Document
.While document is an
iframe
srcdoc
document, let document be document's browsing context's
browsing context container's Document
instead.
Generate the address of the resource from which Request-URIs
are obtained as required by HTTP for the Referer
(sic) header from the
document's current address of document.
[HTTP]
Remove any <fragment> component from the generated address of the resource from which Request-URIs are obtained.
If the origin of the appropriate
Document
is not a scheme/host/port tuple, then the
Referer
(sic) header must be
omitted, regardless of its value.
If the algorithm was not invoked with the synchronous flag, perform the remaining steps asynchronously.
This is the main step.
If the resource is identified by an absolute URL,
and the resource is to be obtained using an idempotent action
(such as an HTTP GET or
equivalent), and it is already being downloaded for other
reasons (e.g. another invocation of this algorithm), and this
request would be identical to the previous one (e.g. same Accept
and Origin
headers), and the user agent is
configured such that it is to reuse the data from the existing
download instead of initiating a new one, then use the results of
the existing download instead of starting a new one.
Otherwise, if the resource is identified by an absolute
URL with a scheme that does not define a mechanism to
obtain the resource (e.g. it is a mailto:
URL) or that the user agent does not support, then act as if the
resource was an HTTP 204 No Content response with no other
metadata.
Otherwise, if the resource is identified by the
URL about:blank
, then the
resource is immediately available and consists of the empty
string, with no metadata.
Otherwise, at a time convenient to the user and the user agent,
download (or otherwise obtain) the resource, applying the
semantics of the relevant specifications (e.g. performing an HTTP
GET or POST operation, or reading the file from disk, dereferencing javascript:
URLs,
etc).
For the purposes of the Referer
(sic) header, use the
address of the resource from which Request-URIs are
obtained generated in the earlier step.
For the purposes of the Origin
header, if the fetching algorithm was
explicitly initiated from an origin, then the origin that initiated the HTTP request is origin. Otherwise, this is a request from
a "privacy-sensitive" context. [ORIGIN]
If the algorithm was not invoked with the block cookies flag, and there are cookies to be set, then the user agent must run the following substeps:
Wait until ownership of the storage mutex can be taken by this instance of the fetching algorithm.
Take ownership of the storage mutex.
Update the cookies. [COOKIES]
Release the storage mutex so that it is once again free.
If the fetched resource is an HTTP redirect or equivalent, then:
Abort these steps and return failure from this algorithm, as if the remote host could not be contacted.
Continue, using the fetched resource (the redirect) as the result of the algorithm.
First, apply any relevant requirements for redirects (such as showing any appropriate prompts). Then, redo main step, but using the target of the redirect as the resource to fetch, rather than the original resource.
The HTTP specification requires that 301, 302, and 307 redirects, when applied to methods other than the safe methods, not be followed without user confirmation. That would be an appropriate prompt for the purposes of the requirement in the paragraph above. [HTTP]
If the algorithm was not invoked with the synchronous flag: When the resource is available, or if there is an error of some description, queue a task that uses the resource as appropriate. If the resource can be processed incrementally, as, for instance, with a progressively interlaced JPEG or an HTML file, additional tasks may be queued to process the data as it is downloaded. The task source for these tasks is the networking task source.
Otherwise, return the resource or error information to the calling algorithm.
If the user agent can determine the actual length of the resource
being fetched for an instance of this
algorithm, and if that length is finite, then that length is the
file's size. Otherwise, the
subject of the algorithm (that is, the resource being fetched) has
no known size. (For
example, the HTTP Content-Length
header might
provide this information.)
The user agent must also keep track of the number of bytes downloaded for each instance of this algorithm. This number must exclude any out-of-band metadata, such as HTTP headers.
The application cache processing model introduces some changes to the networking model to handle the returning of cached resources.
The navigation processing model handles redirects itself, overriding the redirection handling that would be done by the fetching algorithm.
Whether the type sniffing rules apply to the fetched resource depends on the algorithm that invokes the rules — they are not always applicable.
User agents can implement a variety of transfer protocols, but this specification mostly defines behavior in terms of HTTP. [HTTP]
The HTTP GET method is equivalent to the default retrieval action of the protocol. For example, RETR in FTP. Such actions are idempotent and safe, in HTTP terms.
The HTTP response codes are equivalent to statuses in other protocols that have the same basic meanings. For example, a "file not found" error is equivalent to a 404 code, a server error is equivalent to a 5xx code, and so on.
The HTTP headers are equivalent to fields in other protocols that have the same basic meaning. For example, the HTTP authentication headers are equivalent to the authentication aspects of the FTP protocol.
Anything in this specification that refers to HTTP also applies
to HTTP-over-TLS, as represented by URLs
representing the https
scheme.
User agents should report certificate errors to the user and must either refuse to download resources sent with erroneous certificates or must act as if such resources were in fact served with no encryption.
User agents should warn the user that there is a potential problem whenever the user visits a page that the user has previously visited, if the page uses less secure encryption on the second visit.
Not doing so can result in users not noticing man-in-the-middle attacks.
If a user connects to a server with a self-signed certificate, the user agent could allow the connection but just act as if there had been no encryption. If the user agent instead allowed the user to override the problem and then displayed the page as if it was fully and safely encrypted, the user could be easily tricked into accepting man-in-the-middle connections.
If a user connects to a server with full encryption, but the page then refers to an external resource that has an expired certificate, then the user agent will act as if the resource was unavailable, possibly also reporting the problem to the user. If the user agent instead allowed the resource to be used, then an attacker could just look for "secure" sites that used resources from a different host and only apply man-in-the-middle attacks to that host, for example taking over scripts in the page.
If a user bookmarks a site that uses a CA-signed certificate, and then later revisits that site directly but the site has started using a self-signed certificate, the user agent could warn the user that a man-in-the-middle attack is likely underway, instead of simply acting as if the page was not encrypted.
The Content-Type metadata of a resource must be obtained and interpreted in a manner consistent with the requirements of the Media Type Sniffing specification. [MIMESNIFF]
The sniffed type of a resource must be found in a manner consistent with the requirements given in the Media Type Sniffing specification for finding the sniffed-type of the relevant sequence of octets. [MIMESNIFF]
The rules for sniffing images specifically and the rules for distinguishing if a resource is text or binary are also defined in the Media Type Sniffing specification. Both sets of rules return a MIME type as their result. [MIMESNIFF]
It is imperative that the rules in the Media Type Sniffing specification be followed exactly. When a user agent uses different heuristics for content type detection than the server expects, security problems can occur. For more details, see the Media Type Sniffing specification. [MIMESNIFF]
meta
elementsThe algorithm for extracting an encoding from a
meta
element, given a string s, is as follows. It either returns an encoding or
nothing.
Let position be a pointer into s, initially pointing at the start of the string.
Loop: Find the first seven characters in s after position that are an
ASCII case-insensitive match for the word "charset
". If no such match is found, return nothing
and abort these steps.
Skip any U+0009, U+000A, U+000C, U+000D, or U+0020
characters that immediately follow the word "charset
" (there might not be any).
If the next character is not a U+003D EQUALS SIGN ('='), then move position to point just before that next character, and jump back to the step labeled loop.
Skip any U+0009, U+000A, U+000C, U+000D, or U+0020 characters that immediately follow the equals sign (there might not be any).
Process the next character as follows:
This algorithm is distinct from those in the HTTP specification (for example, HTTP doesn't allow the use of single quotes and requires supporting a backslash-escape mechanism that is not supported by this algorithm). While the algorithm is used in contexts that, historically, were related to HTTP, the syntax as supported by implementations diverged some time ago. [HTTP]
Some IDL attributes are defined to reflect a particular content attribute. This means that on getting, the IDL attribute returns the current value of the content attribute, and on setting, the IDL attribute changes the value of the content attribute to the given value.
In general, on getting, if the content attribute is not present, the IDL attribute must act as if the content attribute's value is the empty string; and on setting, if the content attribute is not present, it must first be added.
If a reflecting IDL attribute is a DOMString
attribute whose content attribute is defined to contain a
URL, then on getting, the IDL attribute must resolve the value of the content
attribute relative to the element and return the resulting
absolute URL if that was successful, or the empty
string otherwise; and on setting, must set the content attribute to
the specified literal value. If the content attribute is absent, the
IDL attribute must return the default value, if the content
attribute has one, or else the empty string.
If a reflecting IDL attribute is a DOMString
attribute whose content attribute is defined to contain one or more
URLs, then on getting, the IDL attribute
must split the content
attribute on spaces and return the concatenation of resolving each token URL to an
absolute URL relative to the element, with a single
U+0020 SPACE character between each URL, ignoring any tokens that
did not resolve successfully. If the content attribute is absent,
the IDL attribute must return the default value, if the content
attribute has one, or else the empty string. On setting, the IDL
attribute must set the content attribute to the specified literal
value.
If a reflecting IDL attribute is a DOMString
attribute whose content attribute is an enumerated
attribute, and the IDL attribute is limited to only
known values, then, on getting, the IDL attribute must return
the conforming value associated with the state the attribute is in
(in its canonical case), or the empty string if the attribute is in
a state that has no associated keyword value; and on setting, the
content attribute must be set to the specified new value.
If a reflecting IDL attribute is a DOMString
attribute but doesn't fall into any of the above categories, then
the getting and setting must be done in a transparent,
case-preserving manner.
If a reflecting IDL attribute is a boolean
attribute, then on getting the IDL attribute must return true if the
content attribute is set, and false if it is absent. On setting, the
content attribute must be removed if the IDL attribute is set to
false, and must be set to the empty string if the IDL attribute is
set to true. (This corresponds to the rules for boolean content attributes.)
If a reflecting IDL attribute has a signed integer type
(long
) then, on getting, the content attribute must be
parsed according to the rules for parsing signed integers, and if that is
successful, and the value is in the range of the IDL attribute's
type, the resulting value must be returned. If, on the other hand,
it fails or returns an out of range value, or if the attribute is
absent, then the default value must be returned instead, or 0 if
there is no default value. On setting, the given value must be
converted to the shortest possible string representing the number as
a valid integer and then that string must be used as
the new content attribute value.
If a reflecting IDL attribute has a signed integer type
(long
) that is limited to only non-negative
numbers then, on getting, the content attribute must be parsed
according to the rules for parsing non-negative
integers, and if that is successful, and the value is in the
range of the IDL attribute's type, the resulting value must be
returned. If, on the other hand, it fails or returns an out of range
value, or if the attribute is absent, the default value must be
returned instead, or −1 if there is no default value. On
setting, if the value is negative, the user agent must fire an
INDEX_SIZE_ERR
exception. Otherwise, the given value
must be converted to the shortest possible string representing the
number as a valid non-negative integer and then that
string must be used as the new content attribute value.
If a reflecting IDL attribute has an unsigned integer
type (unsigned long
) then, on getting, the content
attribute must be parsed according to the rules for parsing
non-negative integers, and if that is successful, and the
value is in the range 0 to 2147483647 inclusive, the resulting value
must be returned. If, on the other hand, it fails or returns an out
of range value, or if the attribute is absent, the default value
must be returned instead, or 0 if there is no default value. On
setting, the given value must be converted to the shortest possible
string representing the number as a valid non-negative
integer and then that string must be used as the new content
attribute value.
If a reflecting IDL attribute has an unsigned integer type
(unsigned long
) that is limited to only
non-negative numbers greater than zero, then the behavior is
similar to the previous case, but zero is not allowed. On getting,
the content attribute must first be parsed according to the
rules for parsing non-negative integers, and if that is
successful, and the value is in the range 1 to 2147483647 inclusive,
the resulting value must be returned. If, on the other hand, it
fails or returns an out of range value, or if the attribute is
absent, the default value must be returned instead, or 1 if there is
no default value. On setting, if the value is zero, the user agent
must fire an INDEX_SIZE_ERR
exception. Otherwise, the
given value must be converted to the shortest possible string
representing the number as a valid non-negative integer
and then that string must be used as the new content attribute
value.
If a reflecting IDL attribute has a floating point number type
(double
), then, on getting, the content attribute must
be parsed according to the rules for parsing floating point
number values, and if that is successful, the resulting value
must be returned. If, on the other hand, it fails, or if the
attribute is absent, the default value must be returned instead, or
0.0 if there is no default value. On setting, the given value must
be converted to the best representation of the number as a
floating point number and then that string must be used as
the new content attribute value.
The values Infinity and Not-a-Number (NaN) values throw an exception on setting, as defined earlier.
If a reflecting IDL attribute has the type
DOMTokenList
or DOMSettableTokenList
, then
on getting it must return a DOMTokenList
or
DOMSettableTokenList
object (as appropriate) whose
underlying string is the element's corresponding content attribute.
When the object mutates its underlying string, the content attribute
must itself be immediately mutated. When the attribute is absent,
then the string represented by the object is the empty string; when
the object mutates this empty string, the user agent must add the
corresponding content attribute, with its value set to the value it
would have been set to after mutating the empty string. The same
DOMTokenList
or DOMSettableTokenList
object must be returned every time for each attribute.
If an element with no attributes has its element.classList.remove()
method invoked, the underlying string won't be changed, since the
result of removing any token from the empty string is still the
empty string. However, if the element.classList.add()
method is
then invoked, a class
attribute
will be added to the element with the value of the token to be
added.
If a reflecting IDL attribute has the type
HTMLElement
, or an interface that descends from
HTMLElement
, then, on getting, it must run the
following algorithm (stopping at the first point where a value is
returned):
document.getElementById()
method
would find when called on the content attribute's document if it
was passed as its argument the current value of the corresponding
content attribute.On setting, if the given element has an id
attribute, then the content attribute must
be set to the value of that id
attribute. Otherwise, the IDL attribute must be set to the empty
string.
The HTMLCollection
, HTMLAllCollection
,
HTMLFormControlsCollection
,
HTMLOptionsCollection
,
interfaces represent various
lists of DOM nodes. Collectively, objects implementing these
interfaces are called collections.
When a collection is created, a filter and a root are associated with the collection.
For example, when the HTMLCollection
object for the document.images
attribute is
created, it is associated with a filter that selects only
img
elements, and rooted at the root of the
document.
The collection then represents a live view of the subtree rooted at the collection's root, containing only nodes that match the given filter. The view is linear. In the absence of specific requirements to the contrary, the nodes within the collection must be sorted in tree order.
The rows
list is
not in tree order.
An attribute that returns a collection must return the same object every time it is retrieved.
The HTMLCollection
interface represents a generic
collection of elements.
interface HTMLCollection { readonly attribute unsigned long length; caller getter Element item(in unsigned long index); caller getter object namedItem(in DOMString name); // only returns Element };
length
Returns the number of elements in the collection.
item
(index)Returns the item with index index from the collection. The items are sorted in tree order.
Returns null if index is out of range.
namedItem
(name)Returns the first item with ID or name name from the collection.
Returns null if no element with that ID or name could be found.
Only a
, applet
, area
,
embed
, form
, frame
,
frameset
, iframe
, img
, and
object
elements can have a name for the purpose of
this method; their name is given by the value of their name
attribute.
The object's supported property indices are the numbers in the range zero to one less than the number of nodes represented by the collection. If there are no such elements, then there are no supported property indices.
The length
attribute must return the number of nodes represented by the
collection.
The item(index)
method must return the indexth node in the collection. If there is no indexth node in the collection, then the method must
return null.
The supported property names consist
of the values of the name
attributes of each
a
, applet
, area
,
embed
, form
, frame
,
frameset
, iframe
, img
, and
object
element represented by the
collection with a name
attribute, plus
the list of IDs that the elements represented by the
collection have.
The namedItem(key)
method must return the first node
in the collection that matches either of the following
requirements:
a
, applet
,
area
, embed
, form
,
frame
, frameset
, iframe
,
img
, or object
element with a name
attribute equal to key,
or,If no such elements are found, then the method must return null.
The HTMLAllCollection
interface represents a generic
collection of elements just like
HTMLCollection
, with the exception that its namedItem()
method
returns an HTMLAllCollection
object when there are
multiple matching elements.
interface HTMLAllCollection : HTMLCollection { // inherits length and item() caller getter object namedItem(in DOMString name); // overrides inherited namedItem() HTMLAllCollection tags(in DOMString tagName); };
length
Returns the number of elements in the collection.
item
(index)Returns the item with index index from the collection. The items are sorted in tree order.
Returns null if index is out of range.
namedItem
(name)namedItem
(name)Returns the item with ID or name name from the collection.
If there are multiple matching items, then an HTMLAllCollection
object containing all those elements is returned.
Returns null if no element with that ID or name could be found.
Only a
, applet
, area
,
embed
, form
, frame
,
frameset
, iframe
, img
, and
object
elements can have a name for the purpose of
this method; their name is given by the value of their name
attribute.
tags
(tagName)Returns a collection that is a filtered view of the current collection, containing only elements with the given tag name.
The object's supported property indices and
supported property names are as defined for
HTMLCollection
objects.
The namedItem(key)
method must act according to the
following algorithm:
Let collection be an
HTMLAllCollection
object rooted at the same node as
the HTMLAllCollection
object on which the method was
invoked, whose filter matches only elements that already
match the filter of the HTMLAllCollection
object on
which the method was invoked and that are either:
The tags(tagName)
method must return an
HTMLAllCollection
rooted at the same node as the
HTMLAllCollection
object on which the method was
invoked, whose filter matches only HTML elements whose
local name is the tagName argument and that
already match the filter of the HTMLAllCollection
object on which the method was invoked. In HTML
documents, the argument must first be converted to
ASCII lowercase.
The HTMLFormControlsCollection
interface represents
a collection of listed elements in form
and fieldset
elements.
interface HTMLFormControlsCollection : HTMLCollection { // inherits length and item() caller getter object namedItem(in DOMString name); // overrides inherited namedItem() }; interface RadioNodeList : NodeList { attribute DOMString value; };
length
Returns the number of elements in the collection.
item
(index)Returns the item with index index from the collection. The items are sorted in tree order.
Returns null if index is out of range.
namedItem
(name)namedItem
(name)Returns the item with ID or name
name from the collection.
If there are multiple matching items, then a RadioNodeList
object containing all those elements is returned.
Returns null if no element with that ID or name
could be found.
Returns the value of the first checked radio button represented by the object.
Can be set, to check the first radio button with the given value represented by the object.
The object's supported property indices are as
defined for HTMLCollection
objects.
The supported property names consist of the values
of all the id
and name
attributes of all the elements
represented by the collection.
The namedItem(name)
method must act according to the
following algorithm:
id
attribute or a name
attribute equal to name, then return that node and stop the
algorithm.id
attribute or a name
attribute equal to name, then return null and stop the algorithm.RadioNodeList
object
representing a live view of the
HTMLFormControlsCollection
object, further filtered so
that the only nodes in the RadioNodeList
object are
those that have either an id
attribute
or a name
attribute equal to name. The nodes in the RadioNodeList
object must be sorted in tree order.RadioNodeList
object.Members of the RadioNodeList
interface inherited
from the NodeList
interface must behave as they would
on a NodeList
object.
The value
IDL attribute on the RadioNodeList
object, on getting,
must return the value returned by running the following steps:
Let element be the first element in
tree order represented by the
RadioNodeList
object that is an input
element whose type
attribute
is in the Radio Button
state and whose checkedness
is true. Otherwise, let it be null.
If element is null, or if it is an
element with no value
attribute, return the empty string.
Otherwise, return the value of element's
value
attribute.
On setting, the value
IDL attribute must run
the following steps:
Let element be the first element in
tree order represented by the
RadioNodeList
object that is an input
element whose type
attribute
is in the Radio Button
state and whose value
content
attribute is present and equal to the new value, if any. Otherwise,
let it be null.
If element is not null, then set its checkedness to true.
The HTMLOptionsCollection
interface represents a
list of option
elements. It is always rooted on a
select
element and has attributes and methods that
manipulate that element's descendants.
interface HTMLOptionsCollection : HTMLCollection { // inherits item() attribute unsigned long length; // overrides inherited length caller getter object namedItem(in DOMString name); // overrides inherited namedItem() void add(in HTMLElement element, in optional HTMLElement before); void add(in HTMLElement element, in long before); void remove(in long index); attribute long selectedIndex; };
length
[ = value ]Returns the number of elements in the collection.
When set to a smaller number, truncates the number of option
elements in the corresponding container.
When set to a greater number, adds new blank option
elements to that container.
item
(index)Returns the item with index index from the collection. The items are sorted in tree order.
Returns null if index is out of range.
namedItem
(name)namedItem
(name)Returns the item with ID or name
name from the collection.
If there are multiple matching items, then a NodeList
object containing all those elements is returned.
Returns null if no element with that ID could be found.
add
(element [, before ] )Inserts element before the node given by before.
The before argument can be a number, in which case element is inserted before the item with that number, or an element from the collection, in which case element is inserted before that element.
If before is omitted, null, or a number out of range, then element will be added at the end of the list.
This method will throw a HIERARCHY_REQUEST_ERR
exception if element is an ancestor of the
element into which it is to be inserted. If element is not an option
or
optgroup
element, then the method does nothing.
selectedIndex
[ = value ]Returns the index of the first selected item, if any, or −1 if there is no selected item.
Can be set, to change the selection.
The object's supported property indices are as
defined for HTMLCollection
objects.
On getting, the length
attribute must return the number of nodes represented by the
collection.
On setting, the behavior depends on whether the new value is
equal to, greater than, or less than the number of nodes
represented by the collection at that time. If the
number is the same, then setting the attribute must do nothing. If
the new value is greater, then n new
option
elements with no attributes and no child nodes
must be appended to the select
element on which the
HTMLOptionsCollection
is rooted, where n is the difference between the two numbers (new
value minus old value). Mutation events must be fired as if a
DocumentFragment
containing the new option
elements had been inserted. If the new value is lower, then the
last n nodes in the collection must be removed
from their parent nodes, where n is the
difference between the two numbers (old value minus new value).
Setting length
never removes
or adds any optgroup
elements, and never adds new
children to existing optgroup
elements (though it can
remove children from them).
The supported property names consist of the values
of all the id
and name
attributes of all the elements
represented by the collection.
The namedItem(name)
method must act according to the
following algorithm:
id
attribute or a name
attribute equal to name, then return that node and stop the
algorithm.id
attribute or a name
attribute equal to name, then return null and stop the algorithm.NodeList
object
representing a live view of the
HTMLOptionsCollection
object, further filtered so that
the only nodes in the NodeList
object are those that
have either an id
attribute or a name
attribute equal to name. The nodes in the NodeList
object
must be sorted in tree order.NodeList
object.The add(element, before)
method must act according to the following algorithm:
If element is not an option
or optgroup
element, then return and abort these
steps.
If element is an ancestor of the
select
element on which the
HTMLOptionsCollection
is rooted, then throw a
HIERARCHY_REQUEST_ERR
exception.
If before is an element, but that
element isn't a descendant of the select
element on
which the HTMLOptionsCollection
is rooted, then throw
a NOT_FOUND_ERR
exception.
If element and before are the same element, then return and abort these steps.
If before is a node, then let reference be that node. Otherwise, if before is an integer, and there is a beforeth node in the collection, let reference be that node. Otherwise, let reference be null.
If reference is not null, let parent be the parent node of reference. Otherwise, let parent
be the select
element on which the
HTMLOptionsCollection
is rooted.
Act as if the DOM Core insertBefore()
method was
invoked on the parent node, with element as the first argument and reference as the second argument.
The remove(index)
method must act according to
the following algorithm:
If the number of nodes represented by the collection is zero, abort these steps.
If index is not a number greater than or equal to 0 and less than the number of nodes represented by the collection, let element be the first element in the collection. Otherwise, let element be the indexth element in the collection.
Remove element from its parent node.
The selectedIndex
IDL attribute must act like the identically named attribute on the
select
element on which the
HTMLOptionsCollection
is rooted
The DOMTokenList
interface represents an interface
to an underlying string that consists of a set of
space-separated tokens.
DOMTokenList
objects are always
case-sensitive, even when the underlying string might
ordinarily be treated in a case-insensitive manner.
interface DOMTokenList { readonly attribute unsigned long length; getter DOMString item(in unsigned long index); boolean contains(in DOMString token); void add(in DOMString token); void remove(in DOMString token); boolean toggle(in DOMString token); stringifier DOMString (); };
length
Returns the number of tokens in the string.
item
(index)Returns the token with index index. The tokens are returned in the order they are found in the underlying string.
Returns null if index is out of range.
contains
(token)Returns true if the token is present; false otherwise.
Throws a SYNTAX_ERR
exception if token is empty.
Throws an INVALID_CHARACTER_ERR
exception if token contains any spaces.
add
(token)Adds token, unless it is already present.
Throws a SYNTAX_ERR
exception if token is empty.
Throws an INVALID_CHARACTER_ERR
exception if token contains any spaces.
remove
(token)Removes token if it is present.
Throws a SYNTAX_ERR
exception if token is empty.
Throws an INVALID_CHARACTER_ERR
exception if token contains any spaces.
toggle
(token)Adds token if it is not present, or removes it if it is. Returns true if token is now present (it was added); returns false if it is not (it was removed).
Throws a SYNTAX_ERR
exception if token is empty.
Throws an INVALID_CHARACTER_ERR
exception if token contains any spaces.
The length
attribute must return the number of tokens that result from splitting the underlying string on
spaces. This is the length.
The object's supported property indices are the numbers in the range zero to length-1, unless the length is zero, in which case there are no supported property indices.
The item(index)
method must split the underlying string on spaces,
preserving the order of the tokens as found in the underlying
string, and then return the indexth item in this
list. If index is equal to or greater than the
number of tokens, then the method must return null.
For example, if the string is "a b
a c
" then there are four tokens: the token with index 0 is
"a
", the token with index 1 is "b
", the token with index 2 is "a
", and the token with index 3 is "c
".
The contains(token)
method must run the following
algorithm:
SYNTAX_ERR
exception and stop the
algorithm.INVALID_CHARACTER_ERR
exception and stop the
algorithm.DOMTokenList
object's underlying string.DOMTokenList
object's underlying string then return
true and stop this algorithm.The add(token)
method must run the following
algorithm:
SYNTAX_ERR
exception and stop the
algorithm.INVALID_CHARACTER_ERR
exception and stop the
algorithm.DOMTokenList
object's underlying string.DOMTokenList
object's underlying string then stop the
algorithm.DOMTokenList
object's underlying
string is not the empty string and the last character of that
string is not a space character, then append a U+0020
SPACE character to the end of that string.DOMTokenList
object's underlying string.The remove(token)
method must run the following
algorithm:
SYNTAX_ERR
exception and stop the
algorithm.INVALID_CHARACTER_ERR
exception and stop the
algorithm.The toggle(token)
method must run the following
algorithm:
SYNTAX_ERR
exception and stop the
algorithm.INVALID_CHARACTER_ERR
exception and stop the
algorithm.DOMTokenList
object's underlying string.DOMTokenList
object's underlying string then remove the given token from the underlying string and stop the
algorithm, returning false.DOMTokenList
object's underlying
string is not the empty string and the last character of that
string is not a space character, then append a U+0020
SPACE character to the end of that string.DOMTokenList
object's underlying string.A DOMTokenList
object must stringify to the value of the
DOMTokenList
object's underlying string.
The DOMSettableTokenList
interface is the same as the
DOMTokenList
interface, except that it allows the
underlying string to be directly changed.
interface DOMSettableTokenList : DOMTokenList { attribute DOMString value; };
value
Returns the underlying string.
Can be set, to change the underlying string.
An object implementing the DOMSettableTokenList
interface must act as defined for the DOMTokenList
interface, except for the value
attribute defined
here.
The value
attribute must return the underlying string on getting, and must
replace the underlying string with the new value on setting.
When a user agent is required to obtain a structured clone of a value, it must run the following algorithm, which either returns a separate value, or throws an exception.
Let input be the value being cloned.
Let memory be an association list of pairs of objects, initially empty. This is used to handle duplicate references. In each pair of objects, one is called the source object and the other the destination object.
Let output be the value resulting from calling the internal structured cloning algorithm with input and memory.
Return output.
The internal structured cloning algorithm is always called with two arguments, input and memory, and its behavior is as follows:
If input is the source object of a pair of objects in memory, then return the destination object in that pair of objects and abort these steps.
If input is a primitive value, then return that value and abort these steps.
The input value is an object. Jump to the appropriate step below:
Let output be a newly constructed Boolean object with the same value as input.
Let output be a newly constructed Number object with the same value as input.
Let output be a newly constructed String object with the same value as input.
Date
objectLet output be a newly constructed Date
object with the same value as input.
RegExp
objectLet output be a newly constructed RegExp
object with the same pattern and flags as input.
The value of the lastIndex
property is not copied.
ImageData
objectLet output be a newly constructed ImageData
object
with the same width
and
height
as input, and with a newly constructed
CanvasPixelArray
for its data
attribute, with the same
length
and pixel
values as the input's.
File
objectLet output be a newly constructed File
object corresponding to the same underlying data.
Blob
objectLet output be a newly constructed Blob
object corresponding to the same underlying data.
FileList
objectLet output be a newly constructed FileList
object containing a list of newly constructed File
objects corresponding to the same underlying data as those in input, maintaining their relative order.
Let output be a newly constructed empty Array
object.
Let output be a newly constructed empty Object
object.
Error
, Function
)Throw a DATA_CLONE_ERR
exception and abort
the overall structured clone algorithm.
Add a mapping from input (the source object) to output (the destination object) to memory.
If input is an Array object or an Object object, then, for each enumerable property in input, add a new property to output having the same name, and having a value created from invoking the internal structured cloning algorithm recursively with the value of the property as the "input" argument and memory as the "memory" argument. The order of the properties in the input and output objects must be the same.
This does not walk the prototype chain.
Property descriptors, setters, getters, and analogous features are not copied in this process. For example, the property in the input could be marked as read-only, but in the output it would just have the default state (typically read-write, though that could depend on the scripting environment).
Return output.
This algorithm preserves cycles and preserves the identity of duplicate objects in graphs.
The DOMStringMap
interface represents a set of
name-value pairs. It exposes these using the scripting language's
native mechanisms for property access.
When a DOMStringMap
object is instantiated, it is
associated with three algorithms, one for getting the list of
name-value pairs, one for setting names to certain values, and one
for deleting names.
interface DOMStringMap { getter DOMString (in DOMString name); setter void (in DOMString name, in DOMString value); creator void (in DOMString name, in DOMString value); deleter void (in DOMString name); };
The supported property names on a
DOMStringMap
object at any instant are the names of
each pair returned from the algorithm for getting the list of
name-value pairs at that instant.
To determine the value of
a named property name in a
DOMStringMap
, the user agent must return the value
component of the name-value pair whose name component is name in the list returned by the algorithm for
getting the list of name-value pairs.
To set the value of a new or existing named property name to value value, the
algorithm for setting names to certain values must be run, passing
name as the name and the result of converting
value to a DOMString
as the
value.
To delete an existing named property name, the algorithm for deleting names must be run, passing name as the name.
The DOMStringMap
interface definition
here is only intended for JavaScript environments. Other language
bindings will need to define how DOMStringMap
is to be
implemented for those languages.
The dataset
attribute on
elements exposes the data-*
attributes on the element.
Given the following fragment and elements with similar constructions:
<img class="tower" id="tower5" data-x="12" data-y="5" data-ai="robotarget" data-hp="46" data-ability="flames" src="towers/rocket.png alt="Rocket Tower">
...one could imagine a function splashDamage()
that takes some arguments, the first
of which is the element to process:
function splashDamage(node, x, y, damage) { if (node.classList.contains('tower') && // checking the 'class' attribute node.dataset.x == x && // reading the 'data-x' attribute node.dataset.y == y) { // reading the 'data-y' attribute var hp = parseInt(node.dataset.hp); // reading the 'data-hp' attribute hp = hp - damage; if (hp < 0) { hp = 0; node.dataset.ai = 'dead'; // setting the 'data-ai' attribute delete node.dataset.ability; // removing the 'data-ability' attribute } node.dataset.hp = hp; // setting the 'data-hp' attribute } }
DOM3 Core defines mechanisms for checking for interface support, and for obtaining implementations of interfaces, using feature strings. [DOMCORE]
Authors are strongly discouraged from using these, as they are notoriously unreliable and imprecise. Authors are encouraged to rely on explicit feature testing or the graceful degradation behavior intrinsic to some of the features in this specification.
For historical reasons, user agents should return the true value
when the hasFeature(feature, version)
method of the DOMImplementation
interface is invoked
with feature set to either "HTML
" or "XHTML
" and version set to either "1.0
" or
"2.0
".
The following are DOMException
codes. [DOMCORE]
INDEX_SIZE_ERR
DOMSTRING_SIZE_ERR
HIERARCHY_REQUEST_ERR
WRONG_DOCUMENT_ERR
INVALID_CHARACTER_ERR
NO_DATA_ALLOWED_ERR
NO_MODIFICATION_ALLOWED_ERR
NOT_FOUND_ERR
NOT_SUPPORTED_ERR
INUSE_ATTRIBUTE_ERR
INVALID_STATE_ERR
SYNTAX_ERR
INVALID_MODIFICATION_ERR
NAMESPACE_ERR
INVALID_ACCESS_ERR
VALIDATION_ERR
TYPE_MISMATCH_ERR
SECURITY_ERR
NETWORK_ERR
ABORT_ERR
URL_MISMATCH_ERR
QUOTA_EXCEEDED_ERR
TIMEOUT_ERR
DATA_CLONE_ERR
[Supplemental] exception DOMException { const unsigned short URL_MISMATCH_ERR = 21; const unsigned short QUOTA_EXCEEDED_ERR = 22; const unsigned short DATA_CLONE_ERR = 25; };
There is an implied strong reference from any IDL attribute that returns a pre-existing object to that object.
The HTML namespace is: http://www.w3.org/1999/xhtml
The MathML namespace is: http://www.w3.org/1998/Math/MathML
The SVG namespace is: http://www.w3.org/2000/svg
The XLink namespace is: http://www.w3.org/1999/xlink
The XML namespace is: http://www.w3.org/XML/1998/namespace
The XMLNS namespace is: http://www.w3.org/2000/xmlns/
Data mining tools and other user agents that perform operations on content without running scripts, evaluating CSS or XPath expressions, or otherwise exposing the resulting DOM to arbitrary content, may "support namespaces" by just asserting that their DOM node analogues are in certain namespaces, without actually exposing the above strings.
In the HTML syntax, namespace prefixes and namespace declarations do not have the same effect as in XML. For instance, the colon has no special meaning in HTML element names.
Every XML and HTML document in an HTML UA is represented by a
Document
object. [DOMCORE]
The document's address is an absolute URL
that is set when the Document
is created. The
document's current address is an absolute URL
that can change during the lifetime of the Document
,
for example when the user navigates to
a fragment identifier on the
page or when the pushState()
method is called
with a new URL. The document's
current address must be set to the document's
address when the Document
is created.
Interactive user agents typically expose the document's current address in their user interface.
When a Document
is created by a script using the createDocument()
or createHTMLDocument()
APIs, the document's address is the same as the
document's address of the script's document.
Document
objects are assumed to be XML
documents unless they are flagged as being HTML
documents when they are created. Whether a document is an
HTML document or an XML document affects the behavior of
certain APIs and the case-sensitivity of some selectors.
Each Document
object has a reload override
flag that is originally unset. The flag is set by the document.open()
and document.write()
methods in certain
situations. When the flag is set, the Document
also has
a reload override buffer which is a Unicode string that
is used as the source of the document when it is reloaded.
When the user agent is to perform an overridden reload, it must act as follows:
Let source be the value of the browsing context's active document's reload override buffer.
Navigate the
browsing context to a resource whose source is source, with replacement enabled. When
the navigate algorithm creates a Document
object for this purpose, set that Document
's
reload override flag and set its reload override
buffer to source.
All Document
objects (in user agents implementing
this specification) must also implement
the HTMLDocument
interface, available using
binding-specific methods. (This is the case whether or not the
document in question is an HTML
document or indeed whether it contains any HTML
elements at all.) Document
objects must also implement the document-level interface
of any other namespaces that the UA supports.
For example, if an HTML implementation also
supports SVG, then the Document
object implements both
HTMLDocument
and SVGDocument
.
Because the HTMLDocument
interface is
now obtained using binding-specific casting methods instead of
simply being the primary interface of the document object, it is no
longer defined as inheriting from Document
.
[OverrideBuiltins] interface HTMLDocument { // resource metadata management [PutForwards=href] readonly attribute Location location; readonly attribute DOMString URL; attribute DOMString domain; readonly attribute DOMString referrer; attribute DOMString cookie; readonly attribute DOMString lastModified; readonly attribute DOMString compatMode; attribute DOMString charset; readonly attribute DOMString characterSet; readonly attribute DOMString defaultCharset; readonly attribute DOMString readyState; // DOM tree accessors getter any (in DOMString name); attribute DOMString title; attribute DOMString dir; attribute HTMLElement body; readonly attribute HTMLHeadElement head; readonly attribute HTMLCollection images; readonly attribute HTMLCollection embeds; readonly attribute HTMLCollection plugins; readonly attribute HTMLCollection links; readonly attribute HTMLCollection forms; readonly attribute HTMLCollection scripts; NodeList getElementsByName(in DOMString elementName); NodeList getElementsByClassName(in DOMString classNames); // dynamic markup insertion attribute DOMString innerHTML; HTMLDocument open(in optional DOMString type, in optional DOMString replace); WindowProxy open(in DOMString url, in DOMString name, in DOMString features, in optional boolean replace); void close(); void write(in DOMString... text); void writeln(in DOMString... text); // user interaction readonly attribute WindowProxy defaultView; readonly attribute Element activeElement; boolean hasFocus(); attribute DOMString designMode; boolean execCommand(in DOMString commandId); boolean execCommand(in DOMString commandId, in boolean showUI); boolean execCommand(in DOMString commandId, in boolean showUI, in DOMString value); boolean queryCommandEnabled(in DOMString commandId); boolean queryCommandIndeterm(in DOMString commandId); boolean queryCommandState(in DOMString commandId); boolean queryCommandSupported(in DOMString commandId); DOMString queryCommandValue(in DOMString commandId); readonly attribute HTMLCollection commands; // event handler IDL attributes attribute Function onabort; attribute Function onblur; attribute Function oncanplay; attribute Function oncanplaythrough; attribute Function onchange; attribute Function onclick; attribute Function oncontextmenu; attribute Function oncuechange; attribute Function ondblclick; attribute Function ondrag; attribute Function ondragend; attribute Function ondragenter; attribute Function ondragleave; attribute Function ondragover; attribute Function ondragstart; attribute Function ondrop; attribute Function ondurationchange; attribute Function onemptied; attribute Function onended; attribute Function onerror; attribute Function onfocus; attribute Function oninput; attribute Function oninvalid; attribute Function onkeydown; attribute Function onkeypress; attribute Function onkeyup; attribute Function onload; attribute Function onloadeddata; attribute Function onloadedmetadata; attribute Function onloadstart; attribute Function onmousedown; attribute Function onmousemove; attribute Function onmouseout; attribute Function onmouseover; attribute Function onmouseup; attribute Function onmousewheel; attribute Function onpause; attribute Function onplay; attribute Function onplaying; attribute Function onprogress; attribute Function onratechange; attribute Function onreadystatechange; attribute Function onreset; attribute Function onscroll; attribute Function onseeked; attribute Function onseeking; attribute Function onselect; attribute Function onshow; attribute Function onstalled; attribute Function onsubmit; attribute Function onsuspend; attribute Function ontimeupdate; attribute Function onvolumechange; attribute Function onwaiting; }; Document implements HTMLDocument;
Since the HTMLDocument
interface holds methods and
attributes related to a number of disparate features, the members of
this interface are described in various different sections.
User agents must raise a
SECURITY_ERR
exception whenever any of the members of
an HTMLDocument
object are accessed by scripts whose
effective script origin is not the same as the Document
's effective
script origin.
URL
Returns the document's address.
referrer
Returns the
address of the Document
from which the user
navigated to this one, unless it was blocked or there was no such
document, in which case it returns the empty string.
The noreferrer
link
type can be used to block the referrer.
The URL
attribute must return the document's address.
The referrer
attribute
must return either the current address of the active document
of the source browsing context at the time the
navigation was started (that is, the page which navigated the browsing context
to the current document), with any <fragment> component removed; or
the empty string if there is no such originating page, or if the UA
has been configured not to report referrers in this case, or if the
navigation was initiated for a hyperlink with a noreferrer
keyword.
In the case of HTTP, the referrer
IDL attribute will
match the Referer
(sic) header
that was sent when fetching the current
page.
Typically user agents are configured to not report
referrers in the case where the referrer uses an encrypted protocol
and the current page does not (e.g. when navigating from an https:
page to an http:
page).
cookie
[ = value ]Returns the HTTP cookies that apply to the
Document
. If there are no cookies or cookies can't be
applied to this resource, the empty string will be returned.
Can be set, to add a new cookie to the element's set of HTTP cookies.
If the contents are sandboxed into a unique origin (in an
iframe
with the sandbox
attribute) or the
resource was labeled as text/html-sandboxed
, a
SECURITY_ERR
exception will be thrown on getting and
setting.
The cookie
attribute represents the cookies of the resource from which the
Document
was created.
A Document
object that falls into one of the
following conditions is a cookie-free Document
object:
Document
that has no browsing
context.Document
whose address does not use a server-based naming
authority.On getting, if the document is a
cookie-free Document
object, then the user
agent must return the empty string. Otherwise, if the
Document
's origin is not a
scheme/host/port tuple, the user agent must raise a
SECURITY_ERR
exception. Otherwise, the user agent must
first obtain the storage mutex and then return the
cookie-string for the document's address for a
"non-HTTP" API, decoded as UTF-8, with error handling.
[COOKIES]
On setting, if the document is a cookie-free
Document
object, then the user agent must do
nothing. Otherwise, if the Document
's
origin is not a scheme/host/port tuple, the user agent
must raise a SECURITY_ERR
exception. Otherwise, the
user agent must obtain the storage mutex and then act
as it would when receiving a set-cookie-string for
the document's address via a "non-HTTP" API, consisting
of the new value encoded as UTF-8. [COOKIES] [RFC3629]
Since the cookie
attribute is accessible
across frames, the path restrictions on cookies are only a tool to
help manage which cookies are sent to which parts of the site, and
are not in any way a security feature.
lastModified
Returns the date of the last modification to the document, as
reported by the server, in the form "MM/DD/YYYY hh:mm:ss
", in the user's local
time zone.
If the last modification date is not known, the current time is returned instead.
The lastModified
attribute, on getting, must return the date and time of the
Document
's source file's last modification, in the
user's local time zone, in the following format:
All the numeric components above, other than the year, must be given as two digits in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) representing the number in base ten, zero-padded if necessary. The year must be given as the shortest possible string of four or more digits in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) representing the number in base ten, zero-padded if necessary.
The Document
's source file's last modification date
and time must be derived from relevant features of the networking
protocols used, e.g. from the value of the HTTP Last-Modified
header of the
document, or from metadata in the file system for local files. If
the last modification date and time are not known, the attribute
must return the current date and time in the above format.
compatMode
In a conforming document, returns the string "CSS1Compat
". (In quirks mode
documents, returns the string "BackCompat
",
but a conforming document can never trigger quirks
mode.)
A Document
is always set to one of three modes:
no-quirks mode, the default; quirks mode, used
typically for legacy documents; and limited-quirks mode,
also known as "almost standards" mode. The mode is only ever changed
from the default by the HTML parser, based on the
presence, absence, or value of the DOCTYPE string.
The compatMode
IDL
attribute must return the literal string "CSS1Compat
" unless the document has been set to
quirks mode by the HTML parser, in which
case it must instead return the literal string "BackCompat
".
charset
[ = value ]Returns the document's character encoding.
Can be set, to dynamically change the document's character encoding.
New values that are not IANA-registered aliases supported by the user agent are ignored.
characterSet
Returns the document's character encoding.
defaultCharset
Returns what might be the user agent's default character encoding. (The user agent might return another character encoding altogether, e.g. to protect the user's privacy, or if the user agent doesn't use a single default encoding.)
Documents have an associated character encoding. When a Document
object is created, the document's character encoding
must be initialized to UTF-16. Various algorithms during page
loading affect this value, as does the charset
setter. [IANACHARSET]
The charset
IDL attribute must, on getting, return the preferred MIME
name of the document's character encoding. On
setting, if the new value is an IANA-registered alias for a
character encoding supported by the user agent, the document's
character encoding must be set to that character
encoding. (Otherwise, nothing happens.)
The characterSet
IDL attribute must, on getting, return the preferred MIME
name of the document's character encoding.
The defaultCharset
IDL attribute must, on getting, return the preferred MIME
name of a character encoding, possibly the user's default
encoding, or an encoding associated with the user's current
geographical location, or any arbitrary encoding name.
readyState
Returns "loading" while the Document
is loading, "interactive" once it is finished parsing but still loading sub-resources, and "complete" once it has loaded.
The readystatechange
event fires on the Document
object when this value changes.
Each document has a current document readiness. When a
Document
object is created, it must have its
current document readiness set to the string "loading"
if the document is associated with an HTML parser or an
XML parser, or to the string "complete" otherwise.
Various algorithms during page loading affect this value. When the
value is set, the user agent must fire a simple event
named readystatechange
at the Document
object.
A Document
is said to have an active
parser if it is associated with an HTML parser or
an XML parser that has not yet been stopped or aborted.
The readyState
IDL
attribute must, on getting, return the current document
readiness.
The html
element of a document is the
document's root element, if there is one and it's an
html
element, or null otherwise.
head
Returns the head
element.
The head
element of a document is the
first head
element that is a child of the
html
element, if there is one, or null
otherwise.
The head
attribute, on getting, must return the head
element of the document (a head
element or
null).
title
[ = value ]Returns the document's title, as given by the
title
element.
Can be set, to update the document's title. If there is no
head
element,
the new value is ignored.
In SVG documents, the SVGDocument
interface's
title
attribute takes
precedence.
The title
element of a document is the
first title
element in the document (in tree order), if
there is one, or null otherwise.
The title
attribute must,
on getting, run the following algorithm:
If the root element is an svg
element in the "http://www.w3.org/2000/svg
"
namespace, and the user agent supports SVG, then return the value
that would have been returned by the IDL attribute of the same name
on the SVGDocument
interface. [SVG]
Otherwise, let value be a concatenation
of the data of all the child text
nodes of the title
element, in
tree order, or the empty string if the
title
element is null.
Replace any sequence of one or more consecutive space characters in value with a single U+0020 SPACE character.
Remove any leading or trailing space characters in value.
Return value.
On setting, the following algorithm must be run. Mutation events must be fired as appropriate.
If the root element is an svg
element in the "http://www.w3.org/2000/svg
"
namespace, and the user agent supports SVG, then the setter must
defer to the setter for the IDL attribute of the same name on the
SVGDocument
interface (if it is readonly, then this
will raise an exception). Stop the algorithm here. [SVG]
title
element is null and
the head
element is null, then the
attribute must do nothing. Stop the algorithm here.title
element is null, then a
new title
element must be created and appended to
the head
element. Let element be that element. Otherwise, let element be the title
element.Text
node whose data is the new value
being assigned must be appended to element.The title
attribute on
the HTMLDocument
interface should shadow the attribute
of the same name on the SVGDocument
interface when the
user agent supports both HTML and SVG. [SVG]
body
[ = value ]Returns the body element.
Can be set, to replace the body element.
If the new value is not a body
or frameset
element, this will throw a HIERARCHY_REQUEST_ERR
exception.
The body element of a document is the first child of
the html
element that is either a
body
element or a frameset
element. If
there is no such element, it is null. If the body
element is null, then when the specification requires that events be
fired at "the body element", they must instead be fired at the
Document
object.
The body
attribute, on getting, must return the body element of
the document (either a body
element, a
frameset
element, or null). On setting, the following
algorithm must be run:
body
or
frameset
element, then raise a
HIERARCHY_REQUEST_ERR
exception and abort these
steps.replaceChild()
method had been
called with the new value and the
incumbent body element as its two arguments respectively,
then abort these steps.images
Returns an HTMLCollection
of the img
elements in the Document
.
embeds
plugins
Return an HTMLCollection
of the embed
elements in the Document
.
links
Returns an HTMLCollection
of the a
and area
elements in the Document
that have href
attributes.
forms
Return an HTMLCollection
of the form
elements in the Document
.
scripts
Return an HTMLCollection
of the script
elements in the Document
.
The images
attribute must return an HTMLCollection
rooted at the
Document
node, whose filter matches only
img
elements.
The embeds
attribute must return an HTMLCollection
rooted at the
Document
node, whose filter matches only
embed
elements.
The plugins
attribute must return the same object as that returned by the embeds
attribute.
The links
attribute must return an HTMLCollection
rooted at the
Document
node, whose filter matches only a
elements with href
attributes and area
elements with href
attributes.
The forms
attribute must return an HTMLCollection
rooted at the
Document
node, whose filter matches only
form
elements.
The scripts
attribute must return an HTMLCollection
rooted at the
Document
node, whose filter matches only
script
elements.
getElementsByName
(name)Returns a NodeList
of elements in the
Document
that have a name
attribute with the value name.
getElementsByClassName(classes)
getElementsByClassName(classes)
Returns a NodeList
of the elements in the object
on which the method was invoked (a Document
or an
Element
) that have all the classes given by classes.
The classes argument is interpreted as a space-separated list of classes.
The getElementsByName(name)
method takes a string name, and must return a live
NodeList
containing all the HTML elements
in that document that have a name
attribute
whose value is equal to the name argument (in a
case-sensitive manner), in tree order.
When the method is invoked on a Document
object again
with the same argument, the user agent may return the same as the
object returned by the earlier call. In other cases, a new
NodeList
object must be returned.
The getElementsByClassName(classNames)
method takes a string that
contains a set of space-separated tokens representing
classes. When called, the method must return a live
NodeList
object containing all the elements in the
document, in tree order, that have all the classes
specified in that argument, having obtained the classes by splitting a string on
spaces. (Duplicates are ignored.) If there are no tokens
specified in the argument, then the method must return an empty
NodeList
. If the document is in quirks
mode, then the comparisons for the classes must be done in an
ASCII case-insensitive manner, otherwise, the
comparisons must be done in a case-sensitive manner.
When the method is invoked on a Document
object again
with the same argument, the user agent may return the same object as
the object returned by the earlier call. In other cases, a new
NodeList
object must be returned.
The getElementsByClassName(classNames)
method on the
HTMLElement
interface must return a live
NodeList
with the nodes that the
HTMLDocument
getElementsByClassName()
method would return when passed the same argument(s), excluding any
elements that are not descendants of the HTMLElement
object on which the method was invoked.
When the method is invoked on an HTMLElement
object
again with the same argument, the user agent may return the same
object as the object returned by the earlier call. In other cases, a
new NodeList
object must be returned.
HTML, SVG, and MathML elements define which classes they are in
by having an attribute with no namespace with the name class
containing a space-separated list of classes
to which the element belongs. Other specifications may also allow
elements in their namespaces to be labeled as being in specific
classes.
Given the following XHTML fragment:
<div id="example"> <p id="p1" class="aaa bbb"/> <p id="p2" class="aaa ccc"/> <p id="p3" class="bbb ccc"/> </div>
A call to document.getElementById('example').getElementsByClassName('aaa')
would return a NodeList
with the two paragraphs p1
and p2
in it.
A call to getElementsByClassName('ccc bbb')
would only
return one node, however, namely p3
. A call
to document.getElementById('example').getElementsByClassName('bbb ccc ')
would return the same thing.
A call to getElementsByClassName('aaa,bbb')
would return no
nodes; none of the elements above are in the "aaa,bbb" class.
The HTMLDocument
interface supports named properties. The
supported property names at any moment consist of the
values of the name
content attributes
of all the
applet
,
exposed embed
,
form
,
iframe
,
img
, and
exposed object
elements in the Document
that have name
content attributes, and the values of
the id
content attributes of all the
applet
and
exposed object
elements in the Document
that have id
content attributes, and the values of the
id
content attributes of all the
img
elements in the Document
that have both name
content attributes and id
content attributes.
When the
HTMLDocument
object is indexed for property
retrieval using a name name, then the user
agent must return the value obtained using the following steps:
Let elements be the list of named elements with
the name name in the Document
.
There will be at least one such element, by definition.
If elements has only one element, and that
element is an iframe
element, then return the
WindowProxy
object of the nested browsing
context represented by that iframe
element,
and abort these steps.
Otherwise, if elements has only one element, return that element and abort these steps.
Otherwise return an HTMLCollection
rooted at the
Document
node, whose filter matches only named elements with
the name name.
Named elements with the name name, for the purposes of the above algorithm, are those that are either:
applet
, exposed embed
,
form
, iframe
, img
, or
exposed object
elements that have a name
content attribute whose value is name, orapplet
or exposed object
elements that have an id
content
attribute whose value is name, orimg
elements that have an id
content attribute whose value is name, and that have a name
content attribute present also.An embed
or object
element is said to
be exposed if it has no exposed
object
ancestor, and, for object
elements,
is additionally either not showing its fallback content
or has no object
or embed
descendants.
The dir
attribute on the HTMLDocument
interface is defined
along with the dir
content
attribute.
XML documents can be created from script using the
createDocument()
method on the DOMImplementation
interface.
HTML documents can be created using the createHTMLDocument()
method:
[Supplemental, NoInterfaceObject] interface DOMHTMLImplementation { Document createHTMLDocument(in DOMString title); }; DOMImplementation implements DOMHTMLImplementation;
implementation
. createHTMLDocument
( title )Returns a new Document
, with a basic DOM already
constructed with an appropriate title
element.
The createHTMLDocument(title)
method, when invoked, must run the
following steps:
Let doc be a newly created
Document
object.
Mark doc as being an HTML document.
Create a DocumentType
node with the name
attribute set to the string "html
", and the other attributes specific to
DocumentType
objects set to the empty string, null,
and empty lists, as appropriate. Append the newly created node to
doc.
Create an html
element, and append it to doc.
Create a head
element, and append it to the
html
element created in the previous step.
Create a title
element, and append it to the
head
element created in the previous step.
Create a Text
node, and set its data
attribute to the string given by the method's
argument (which could be the empty string). Append it to the
title
element created in the previous step.
Create a body
element, and append it to the
html
element created in the earlier step.
Return doc.
A Document
object that is an XML document that was created by the DOMImplementation.createDocument()
factory method must also implement the
XMLDocumentLoader
interface:
[Supplemental, NoInterfaceObject] interface XMLDocumentLoader { boolean load(in DOMString url); };
The load(url)
method must run the following
steps:
Let document be the Document
object on which the method was invoked.
Resolve the method's
first argument, relative to the entry script's base URL. If this is not
successful, throw a SYNTAX_ERR
exception and abort
these steps. Otherwise, let url be the
resulting absolute URL.
If the origin of url is not
the same as the origin of document, throw a SECURITY_ERR
exception and abort these steps.
Remove all child nodes of document, without firing any mutation events.
Set the current document readiness of document to "loading".
Run the remainder of these steps asynchronously, and return true from the method.
Let result be an Document
object.
Let success be false.
Fetch url from the origin of document, with the synchronous flag set and the force same-origin flag set.
If the fetch attempt was successful, and the resource's Content-Type metadata is an XML MIME type, then run these substeps:
Create a new XML parser associated with the result document.
Pass this parser the fetched document.
If there is an XML well-formedness or XML namespace well-formedness error, then remove all child nodes from result. Otherwise let success be true.
Queue a task to run the following steps.
Set the current document readiness of document to "complete".
Replace all the children of document
by the children of result (even if it has no
children), firing mutation events as if a
DocumentFragment
containing the new children had
been inserted.
Fire a simple event named load
at document.
Elements, attributes, and attribute values in HTML are defined
(by this specification) to have certain meanings (semantics). For
example, the ol
element represents an ordered list, and
the lang
attribute represents the
language of the content.
Authors must not use elements, attributes, or attribute values for purposes other than their appropriate intended semantic purpose. Authors must not use elements, attributes, or attribute values that are not permitted by this specification or other applicable specifications.
For example, the following document is non-conforming, despite being syntactically correct:
<!DOCTYPE HTML> <html lang="en-GB"> <head> <title> Demonstration </title> </head> <body> <table> <tr> <td> My favourite animal is the cat. </td> </tr> <tr> <td> —<a href="http://example.org/~ernest/"><cite>Ernest</cite></a>, in an essay from 1992 </td> </tr> </table> </body> </html>
...because the data placed in the cells is clearly not tabular
data (and the cite
element mis-used). A corrected
version of this document might be:
<!DOCTYPE HTML> <html lang="en-GB"> <head> <title> Demonstration </title> </head> <body> <blockquote> <p> My favourite animal is the cat. </p> </blockquote> <p> —<a href="http://example.org/~ernest/">Ernest</a>, in an essay from 1992 </p> </body> </html>
This next document fragment, intended to represent the heading of a corporate site, is similarly non-conforming because the second line is not intended to be a heading of a subsection, but merely a subheading or subtitle (a subordinate heading for the same section).
<body> <h1>ABC Company</h1> <h2>Leading the way in widget design since 1432</h2> ...
The hgroup
element is intended for these kinds of
situations:
<body> <hgroup> <h1>ABC Company</h1> <h2>Leading the way in widget design since 1432</h2> </hgroup> ...
In the next example, there is a non-conforming attribute value ("carpet") and a non-conforming attribute ("texture"), which is not permitted by this specification:
<label>Carpet: <input type="carpet" name="c" texture="deep pile"></label>
Here would be an alternative and correct way to mark this up:
<label>Carpet: <input type="text" class="carpet" name="c" data-texture="deep pile"></label>
Through scripting and using other mechanisms, the values of attributes, text, and indeed the entire structure of the document may change dynamically while a user agent is processing it. The semantics of a document at an instant in time are those represented by the state of the document at that instant in time, and the semantics of a document can therefore change over time. User agents must update their presentation of the document as this occurs.
HTML has a progress
element that
describes a progress bar. If its "value" attribute is dynamically
updated by a script, the UA would update the rendering to show the
progress changing.
The nodes representing HTML elements in the DOM must implement, and expose to scripts, the interfaces listed for them in the relevant sections of this specification. This includes HTML elements in XML documents, even when those documents are in another context (e.g. inside an XSLT transform).
Elements in the DOM represent things; that is, they have intrinsic meaning, also known as semantics.
For example, an ol
element
represents an ordered list.
The basic interface, from which all the HTML
elements' interfaces inherit, and which
must be used by elements that have no additional
requirements, is the HTMLElement
interface.
interface HTMLElement : Element { // DOM tree accessors NodeList getElementsByClassName(in DOMString classNames); // dynamic markup insertion attribute DOMString innerHTML; attribute DOMString outerHTML; void insertAdjacentHTML(in DOMString position, in DOMString text); // metadata attributes attribute DOMString id; attribute DOMString title; attribute DOMString lang; attribute DOMString dir; attribute DOMString className; readonly attribute DOMTokenList classList; readonly attribute DOMStringMap dataset; // user interaction attribute boolean hidden; void click(); attribute long tabIndex; void focus(); void blur(); attribute DOMString accessKey; readonly attribute DOMString accessKeyLabel; attribute boolean draggable; [PutForwards=value] attribute DOMSettableTokenList dropzone; attribute DOMString contentEditable; readonly attribute boolean isContentEditable; attribute HTMLMenuElement contextMenu; attribute boolean spellcheck; // command API readonly attribute DOMString commandType; readonly attribute DOMString label; readonly attribute DOMString icon; readonly attribute boolean disabled; readonly attribute boolean checked; // styling readonly attribute CSSStyleDeclaration style; // event handler IDL attributes attribute Function onabort; attribute Function onblur; attribute Function oncanplay; attribute Function oncanplaythrough; attribute Function onchange; attribute Function onclick; attribute Function oncontextmenu; attribute Function oncuechange; attribute Function ondblclick; attribute Function ondrag; attribute Function ondragend; attribute Function ondragenter; attribute Function ondragleave; attribute Function ondragover; attribute Function ondragstart; attribute Function ondrop; attribute Function ondurationchange; attribute Function onemptied; attribute Function onended; attribute Function onerror; attribute Function onfocus; attribute Function oninput; attribute Function oninvalid; attribute Function onkeydown; attribute Function onkeypress; attribute Function onkeyup; attribute Function onload; attribute Function onloadeddata; attribute Function onloadedmetadata; attribute Function onloadstart; attribute Function onmousedown; attribute Function onmousemove; attribute Function onmouseout; attribute Function onmouseover; attribute Function onmouseup; attribute Function onmousewheel; attribute Function onpause; attribute Function onplay; attribute Function onplaying; attribute Function onprogress; attribute Function onratechange; attribute Function onreadystatechange; attribute Function onreset; attribute Function onscroll; attribute Function onseeked; attribute Function onseeking; attribute Function onselect; attribute Function onshow; attribute Function onstalled; attribute Function onsubmit; attribute Function onsuspend; attribute Function ontimeupdate; attribute Function onvolumechange; attribute Function onwaiting; }; interface HTMLUnknownElement : HTMLElement { };
The HTMLElement
interface holds methods and
attributes related to a number of disparate features, and the
members of this interface are therefore described in various
different sections of this specification.
The HTMLUnknownElement
interface must be used for
HTML elements that are not defined by this
specification (or other applicable specifications).
The following attributes are common to and may be specified on all HTML elements (even those not defined in this specification):
accesskey
class
contenteditable
contextmenu
dir
draggable
dropzone
hidden
id
lang
spellcheck
style
tabindex
title
The following event handler content attributes may be specified on any HTML element:
onabort
onblur
*oncanplay
oncanplaythrough
onchange
onclick
oncontextmenu
oncuechange
ondblclick
ondrag
ondragend
ondragenter
ondragleave
ondragover
ondragstart
ondrop
ondurationchange
onemptied
onended
onerror
*onfocus
*oninput
oninvalid
onkeydown
onkeypress
onkeyup
onload
*onloadeddata
onloadedmetadata
onloadstart
onmousedown
onmousemove
onmouseout
onmouseover
onmouseup
onmousewheel
onpause
onplay
onplaying
onprogress
onratechange
onreadystatechange
onreset
onscroll
*onseeked
onseeking
onselect
onshow
onstalled
onsubmit
onsuspend
ontimeupdate
onvolumechange
onwaiting
The attributes marked with an asterisk have a
different meaning when specified on body
elements as
those elements expose event handlers of the
Window
object with the same names.
While these attributes apply to all elements, they
are not useful on all elements. For example, only media elements will ever receive a volumechange
event fired by
the user agent.
Custom data attributes
(e.g. data-foldername
or data-msgid
) can be specified on any HTML element, to store custom data
specific to the page.
In HTML documents, elements in the HTML
namespace may have an xmlns
attribute
specified, if, and only if, it has the exact value
"http://www.w3.org/1999/xhtml
". This does not apply to
XML documents.
In HTML, the xmlns
attribute
has absolutely no effect. It is basically a talisman. It is allowed
merely to make migration to and from XHTML mildly easier. When
parsed by an HTML parser, the attribute ends up in no
namespace, not the "http://www.w3.org/2000/xmlns/
"
namespace like namespace declaration attributes in XML do.
In XML, an xmlns
attribute is
part of the namespace declaration mechanism, and an element cannot
actually have an xmlns
attribute in no
namespace specified.
The XML specification also allows the use of the xml:space
attribute in the XML
namespace on any element in an XML document. This attribute has no effect on
HTML elements, as the default behavior in HTML is to
preserve whitespace. [XML]
There is no way to serialize the xml:space
attribute on HTML
elements in the text/html
syntax.
To enable assistive technology products to expose a more
fine-grained interface than is otherwise possible with HTML elements
and attributes, a set of annotations for
assistive technology products can be specified (the ARIA
role
and aria-*
attributes).
id
attributeThe id
attribute specifies its
element's unique identifier (ID). The
value must be unique amongst all the IDs in the element's home
subtree and must contain at least one character. The value
must not contain any space
characters.
An element's unique identifier can be used for a variety of purposes, most notably as a way to link to specific parts of a document using fragment identifiers, as a way to target an element when scripting, and as a way to style a specific element from CSS.
If the value is not the empty string, user agents must associate
the element with the given value (exactly, including any space
characters) for the purposes of ID matching within the element's
home subtree (e.g. for selectors in CSS or for the
getElementById()
method in the DOM).
Identifiers are opaque strings. Particular meanings should not be
derived from the value of the id
attribute.
This specification doesn't preclude an element having multiple
IDs, if other mechanisms (e.g. DOM Core methods) can set an
element's ID in a way that doesn't conflict with the id
attribute.
title
attributeThe title
attribute
represents advisory information for the element, such
as would be appropriate for a tooltip. On a link, this could be the
title or a description of the target resource; on an image, it could
be the image credit or a description of the image; on a paragraph,
it could be a footnote or commentary on the text; on a citation, it
could be further information about the source; and so forth. The
value is text.
If this attribute is omitted from an element, then it implies
that the title
attribute of the
nearest ancestor HTML element
with a title
attribute set is also
relevant to this element. Setting the attribute overrides this,
explicitly stating that the advisory information of any ancestors is
not relevant to this element. Setting the attribute to the empty
string indicates that the element has no advisory information.
If the title
attribute's value
contains U+000A LINE FEED (LF) characters, the content is split into
multiple lines. Each U+000A LINE FEED (LF) character represents a
line break.
Caution is advised with respect to the use of newlines in title
attributes.
For instance, the following snippet actually defines an abbreviation's expansion with a line break in it:
<p>My logs show that there was some interest in <abbr title="Hypertext Transport Protocol">HTTP</abbr> today.</p>
Some elements, such as link
, abbr
, and
input
, define additional semantics for the title
attribute beyond the semantics
described above.
lang
and xml:lang
attributesThe lang
attribute (in
no namespace) specifies the primary language for the element's
contents and for any of the element's attributes that contain
text. Its value must be a valid BCP 47 language tag, or the empty
string. Setting the attribute to the empty string indicates that the
primary language is unknown. [BCP47]
The lang
attribute in the XML namespace is defined in XML. [XML]
If these attributes are omitted from an element, then the language of this element is the same as the language of its parent element, if any.
The lang
attribute in no namespace
may be used on any HTML
element.
The lang
attribute in the XML namespace may be used on
HTML elements in XML documents, as well as
elements in other namespaces if the relevant specifications allow it
(in particular, MathML and SVG allow lang
attributes in the
XML namespace to be specified on their
elements). If both the lang
attribute
in no namespace and the lang
attribute in the XML
namespace are specified on the same element, they must
have exactly the same value when compared in an ASCII
case-insensitive manner.
Authors must not use the lang
attribute in the XML
namespace on HTML elements in HTML
documents. To ease migration to and from XHTML, authors may
specify an attribute in no namespace with no prefix and with the
literal localname "xml:lang
" on HTML
elements in HTML documents, but such attributes
must only be specified if a lang
attribute in no namespace is also specified, and both attributes
must have the same value when compared in an ASCII
case-insensitive manner.
The attribute in no namespace with no prefix and
with the literal localname "xml:lang
" has no
effect on language processing.
To determine the language of a node, user agents must
look at the nearest ancestor element (including the element itself
if the node is an element) that has a lang
attribute in the
XML namespace set or is an HTML element and has a lang
in no namespace attribute set. That
attribute specifies the language of the node (regardless of its
value).
If both the lang
attribute in no
namespace and the lang
attribute in the XML
namespace are set on an element, user agents must use
the lang
attribute
in the XML namespace, and the lang
attribute in no namespace must be
ignored for the purposes of determining
the element's language.
If none of the node's ancestors, including the root element, have either attribute set, but there is a pragma-set default language set, then that is the language of the node. If there is no pragma-set default language set, then language information from a higher-level protocol (such as HTTP), if any, must be used as the final fallback language instead. In the absence of any such language information, and in cases where the higher-level protocol reports multiple languages, the language of the node is unknown, and the corresponding language tag is the empty string.
If the resulting value is not a recognized language tag, then it must be treated as an unknown language having the given language tag, distinct from all other languages. For the purposes of round-tripping or communicating with other services that expect language tags, user agents should pass unknown language tags through unmodified.
Thus, for instance, an element with lang="xyzzy"
would be matched by the selector :lang(xyzzy)
(e.g. in CSS), but it would not be
matched by :lang(abcde)
, even though both are
equally invalid. Similarly, if a Web browser and screen reader
working in unison communicated about the language of the element,
the browser would tell the screen reader that the language was
"xyzzy", even if it knew it was invalid, just in case the screen
reader actually supported a language with that tag after all.
If the resulting value is the empty string, then it must be interpreted as meaning that the language of the node is explicitly unknown.
User agents may use the element's language to determine proper processing or rendering (e.g. in the selection of appropriate fonts or pronunciations, or for dictionary selection).
The lang
IDL attribute
must reflect the lang
content attribute in no namespace.
xml:base
attribute (XML only)The xml:base
attribute is
defined in XML Base. [XMLBASE]
The xml:base
attribute may be
used on elements of XML documents. Authors must not
use the xml:base
attribute in
HTML documents.
dir
attributeThe dir
attribute specifies the
element's text directionality. The attribute is an enumerated
attribute with the following keywords and states:
ltr
keyword, which maps to the ltr stateIndicates that the contents of the element are explicitly directionally embedded left-to-right text.
rtl
keyword, which maps to the rtl stateIndicates that the contents of the element are explicitly directionally embedded right-to-left text.
auto
keyword, which maps to the auto stateIndicates that the contents of the element are explicitly embedded text, but that the direction is to be determined programmatically using the contents of the element (as described below).
The heuristic used by this state is very crude (it just looks at the first character with a strong directionality, in a manner analogous to the Paragraph Level determination in the bidirectional algorithm). Authors are urged to only use this value as a last resort when the direction of the text is truly unknown and no better server-side heuristic can be applied.
For textarea
and pre
elements, the heuristic is applied on a per-paragraph level.
The attribute has no invalid value default and no missing value default.
The directionality of an element is either 'ltr' or 'rtl', and is determined as per the first appropriate set of steps from the following list:
dir
attribute is
in the ltr stateThe directionality of the element is 'ltr'.
dir
attribute is
in the rtl stateThe directionality of the element is 'rtl'.
dir
attribute is
in the auto statebdi
element and the dir
attribute is not in a defined state
(i.e. it is not present or has an invalid value)Find the first character in tree order that matches the following criteria:
The character is from a text node that is a descendant of the element whose directionality is being determined.
The character is of bidirectional character type L, AL, or R. [BIDI]
The character is not in a text node that has an ancestor element that is a descendant of the element whose directionality is being determined and that is either:
If such a character is found and it is of bidirectional character type AL or R, the directionality of the element is 'rtl'.
Otherwise, the directionality of the element is 'ltr'.
dir
attribute is not in a defined state
(i.e. it is not present or has an invalid value)The directionality of the element is 'ltr'.
dir
attribute is not in a defined state
(i.e. it is not present or has an invalid value)The directionality of the element is the same as the element's parent element's directionality.
The effect of this attribute is primarily on the presentation layer. For example, the rendering section in this specification defines a mapping from this attribute to the CSS 'direction' and 'unicode-bidi' properties, and CSS defines rendering in terms of those properties.
dir
[ = value ]Returns the html
element's dir
attribute's value, if any.
Can be set, to either "ltr
", "rtl
", or "auto
" to replace the html
element's dir
attribute's value.
If there is no html
element, returns the empty string and ignores new values.
The dir
IDL attribute on
an element must reflect the dir
content attribute of that element,
limited to only known values.
The dir
IDL
attribute on HTMLDocument
objects must
reflect the dir
content
attribute of the html
element, if any,
limited to only known values. If there is no such
element, then the attribute must return the empty string and do
nothing on setting.
Authors are strongly encouraged to use the dir
attribute to indicate text direction
rather than using CSS, since that way their documents will continue
to render correctly even in the absence of CSS (e.g. as interpreted
by search engines).
This markup fragment is of an IM conversation.
<p dir=auto class="u1"><b><bdi>Student</bdi>:</b> How do you write "What's your name?" in Arabic?</p> <p dir=auto class="u2"><b><bdi>Teacher</bdi>:</b> ما اسمك؟</p> <p dir=auto class="u1"><b><bdi>Student</bdi>:</b> Thanks.</p> <p dir=auto class="u2"><b><bdi>Teacher</bdi>:</b> That's written "شكرًا".</p> <p dir=auto class="u2"><b><bdi>Teacher</bdi>:</b> Do you know how to write "Please"?</p> <p dir=auto class="u1"><b><bdi>Student</bdi>:</b> "من فضلك", right?</p>
Given a suitable style sheet and the default alignment styles
for the p
element, namely to align the text to the
start edge of the paragraph, the resulting rendering could
be as follows:
As noted earlier, the auto
value is not a panacea. The final paragraph in this example is
misinterpreted as being right-to-left text, since it begins with an
Arabic character, which causes the "right?" to be to the left of
the Arabic text.
class
attributeEvery HTML element may have a
class
attribute specified.
The attribute, if specified, must have a value that is a set of space-separated tokens representing the various classes that the element belongs to.
The classes that an HTML
element has assigned to it consists of all the classes
returned when the value of the class
attribute is split on
spaces. (Duplicates are ignored.)
Assigning classes to an element affects class
matching in selectors in CSS, the getElementsByClassName()
method in the DOM, and other such features.
There are no additional restrictions on the tokens authors can
use in the class
attribute, but
authors are encouraged to use values that describe the nature of the
content, rather than values that describe the desired presentation
of the content.
style
attributeAll HTML elements may have the style
content attribute set. This is a
CSS styling attribute as defined by the CSS Styling
Attribute Syntax specification. [CSSATTR]
In user agents that support CSS, the attribute's value must be parsed when the attribute is added or has its value changed, according to the rules given for CSS styling attributes. [CSSATTR]
Documents that use style
attributes on any of their elements must still be comprehensible and
usable if those attributes were removed.
In particular, using the style
attribute to hide and show content,
or to convey meaning that is otherwise not included in the document,
is non-conforming. (To hide and show content, use the hidden
attribute.)
style
Returns a CSSStyleDeclaration
object for the element's style
attribute.
The style
IDL attribute
must return a CSSStyleDeclaration
whose value
represents the declarations specified in the attribute, if
present. Mutating the CSSStyleDeclaration
object must
create a style
attribute on the
element (if there isn't one already) and then change its value to be
a value representing the serialized form of the
CSSStyleDeclaration
object. The same object must be
returned each time. [CSSOM]
In the following example, the words that refer to colors are
marked up using the span
element and the style
attribute to make those words show
up in the relevant colors in visual media.
<p>My sweat suit is <span style="color: green; background: transparent">green</span> and my eyes are <span style="color: blue; background: transparent">blue</span>.</p>
data-*
attributesA custom data attribute is an attribute in no
namespace whose name starts with the string "data-
", has at least one
character after the hyphen, is XML-compatible, and
contains no characters in the range U+0041 to U+005A (LATIN CAPITAL
LETTER A to LATIN CAPITAL LETTER Z).
All attributes on HTML elements in HTML documents get ASCII-lowercased automatically, so the restriction on ASCII uppercase letters doesn't affect such documents.
Custom data attributes are intended to store custom data private to the page or application, for which there are no more appropriate attributes or elements.
These attributes are not intended for use by software that is independent of the site that uses the attributes.
For instance, a site about music could annotate list items representing tracks in an album with custom data attributes containing the length of each track. This information could then be used by the site itself to allow the user to sort the list by track length, or to filter the list for tracks of certain lengths.
<ol> <li data-length="2m11s">Beyond The Sea</li> ... </ol>
It would be inappropriate, however, for the user to use generic software not associated with that music site to search for tracks of a certain length by looking at this data.
This is because these attributes are intended for use by the site's own scripts, and are not a generic extension mechanism for publicly-usable metadata.
Every HTML element may have any number of custom data attributes specified, with any value.
dataset
Returns a DOMStringMap
object for the element's data-*
attributes.
Hyphenated names become camel-cased. For example, data-foo-bar=""
becomes element.dataset.fooBar
.
The dataset
IDL
attribute provides convenient accessors for all the data-*
attributes on an element. On
getting, the dataset
IDL attribute
must return a DOMStringMap
object, associated with the
following algorithms, which expose these attributes on their
element:
data-
" and whose
remaining characters (if any) do not include any characters in
the range U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN
CAPITAL LETTER Z), add a name-value pair to list whose name is the attribute's name with the
first five characters removed and whose value is the attribute's
value.SYNTAX_ERR
exception and abort these
steps.data-
at the front of
name.setAttribute()
would have raised an
exception when setting an attribute with the name name, then this must raise the same
exception.data-
at the front of
name.The same object must be returned each time.
If a Web page wanted an element to represent a space ship,
e.g. as part of a game, it would have to use the class
attribute along with data-*
attributes:
<div class="spaceship" data-ship-id="92432" data-weapons="laser 2" data-shields="50%" data-x="30" data-y="10" data-z="90"> <button class="fire" onclick="spaceships[this.parentNode.dataset.shipId].fire()"> Fire </button> </div>
Notice how the hyphenated attribute name becomes camel-cased in the API.
Authors should carefully design such extensions so that when the attributes are ignored and any associated CSS dropped, the page is still usable.
User agents must not derive any implementation behavior from these attributes or values. Specifications intended for user agents must not define these attributes to have any meaningful values.
JavaScript libraries may use the custom data attributes, as they are considered to be part of the page on which they are used. Authors of libraries that are reused by many authors are encouraged to include their name in the attribute names, to reduce the risk of clashes. Where it makes sense, library authors are also encouraged to make the exact name used in the attribute names customizable, so that libraries whose authors unknowingly picked the same name can be used on the same page, and so that multiple versions of a particular library can be used on the same page even when those versions are not mutually compatible.
For example, a library called "DoQuery" could use attribute
names like data-doquery-range
, and a library
called "jJo" could use attributes names like data-jjo-range
. The jJo library could also provide
an API to set which prefix to use (e.g. J.setDataPrefix('j2')
, making the attributes have
names like data-j2-range
).
Each element in this specification has a definition that includes the following information:
A list of categories to which the element belongs. These are used when defining the content models for each element.
A non-normative description of where the element can be used. This information is redundant with the content models of elements that allow this one as a child, and is provided only as a convenience.
For simplicity, only the most specific expectations are listed. For example, an element that is both flow content and phrasing content can be used anywhere that either flow content or phrasing content is expected, but since anywhere that flow content is expected, phrasing content is also expected (since all phrasing content is flow content), only "where phrasing content is expected" will be listed.
A normative description of what content must be included as children and descendants of the element.
A normative list of attributes that may be specified on the element (except where otherwise disallowed).
A normative definition of a DOM interface that such elements must implement.
This is then followed by a description of what the element represents, along with any additional normative conformance criteria that may apply to authors and implementations. Examples are sometimes also included.
Except where otherwise specified, attributes on HTML elements may have any string value, including the empty string. Except where explicitly stated, there is no restriction on what text can be specified in such attributes.
Each element defined in this specification has a content model: a description of the element's expected contents. An HTML element must have contents that match the requirements described in the element's content model.
As noted in the conformance and terminology
sections, for the purposes of determining if an element matches its
content model or not, CDATASection
nodes in the DOM are treated as
equivalent to Text
nodes, and entity reference nodes are treated as if
they were expanded in place.
The space characters are always allowed between elements. User agents represent these characters between elements in the source markup as text nodes in the DOM. Empty text nodes and text nodes consisting of just sequences of those characters are considered inter-element whitespace.
Inter-element whitespace, comment nodes, and processing instruction nodes must be ignored when establishing whether an element's contents match the element's content model or not, and must be ignored when following algorithms that define document and element semantics.
Thus, an element A is said to be preceded or followed by a second element B if A and B have the same parent node and there are no other element nodes or text nodes (other than inter-element whitespace) between them. Similarly, a node is the only child of an element if that element contains no other nodes other than inter-element whitespace, comment nodes, and processing instruction nodes.
Authors must not use HTML elements anywhere except where they are explicitly allowed, as defined for each element, or as explicitly required by other specifications. For XML compound documents, these contexts could be inside elements from other namespaces, if those elements are defined as providing the relevant contexts.
For example, the Atom specification defines a content
element. When its type
attribute has the value xhtml
, the Atom specification requires that it
contain a single HTML div
element. Thus, a
div
element is allowed in that context, even though
this is not explicitly normatively stated by this specification. [ATOM]
In addition, HTML elements may be orphan nodes (i.e. without a parent node).
For example, creating a td
element and storing it
in a global variable in a script is conforming, even though
td
elements are otherwise only supposed to be used
inside tr
elements.
var data = { name: "Banana", cell: document.createElement('td'), };
Each element in HTML falls into zero or more categories that group elements with similar characteristics together. The following broad categories are used in this specification:
Some elements also fall into other categories, which are defined in other parts of this specification.
These categories are related as follows:
In addition, certain elements are categorized as form-associated elements and further subcategorized to define their role in various form-related processing models.
Some elements have unique requirements and do not fit into any particular category.
Metadata content is content that sets up the presentation or behavior of the rest of the content, or that sets up the relationship of the document with other documents, or that conveys other "out of band" information.
Elements from other namespaces whose semantics are primarily metadata-related (e.g. RDF) are also metadata content.
Thus, in the XML serialization, one can use RDF, like this:
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:r="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> <head> <title>Hedral's Home Page</title> <r:RDF> <Person xmlns="http://www.w3.org/2000/10/swap/pim/contact#" r:about="http://hedral.example.com/#"> <fullName>Cat Hedral</fullName> <mailbox r:resource="mailto:hedral@damowmow.com"/> <personalTitle>Sir</personalTitle> </Person> </r:RDF> </head> <body> <h1>My home page</h1> <p>I like playing with string, I guess. Sister says squirrels are fun too so sometimes I follow her to play with them.</p> </body> </html>
This isn't possible in the HTML serialization, however.
Most elements that are used in the body of documents and applications are categorized as flow content.
a
abbr
address
area
(if it is a descendant of a map
element)article
aside
audio
b
bdi
bdo
blockquote
br
button
canvas
cite
code
command
datalist
del
details
dfn
div
dl
em
embed
fieldset
figure
footer
form
h1
h2
h3
h4
h5
h6
header
hgroup
hr
i
iframe
img
input
ins
kbd
keygen
label
map
mark
math
menu
meter
nav
noscript
object
ol
output
p
pre
progress
q
ruby
s
samp
script
section
select
small
span
strong
style
(if the scoped
attribute is present)sub
sup
svg
table
textarea
time
u
ul
var
video
wbr
As a general rule, elements whose content model allows any
flow content should have either at least one descendant
text node that is not inter-element
whitespace, or at least one descendant element node that is
embedded content. For the purposes of this requirement,
del
elements and their descendants must not be counted
as contributing to the ancestors of the del
element.
This requirement is not a hard requirement, however, as there are many cases where an element can be empty legitimately, for example when it is used as a placeholder which will later be filled in by a script, or when the element is part of a template and would on most pages be filled in but on some pages is not relevant.
Sectioning content is content that defines the scope of headings and footers.
Each sectioning content element potentially has a heading and an outline. See the section on headings and sections for further details.
There are also certain elements that are sectioning roots. These are distinct from sectioning content, but they can also have an outline.
Heading content defines the header of a section (whether explicitly marked up using sectioning content elements, or implied by the heading content itself).
Phrasing content is the text of the document, as well as elements that mark up that text at the intra-paragraph level. Runs of phrasing content form paragraphs.
a
(if it contains only phrasing content)abbr
area
(if it is a descendant of a map
element)audio
b
bdi
bdo
br
button
canvas
cite
code
command
datalist
del
(if it contains only phrasing content)dfn
em
embed
i
iframe
img
input
ins
(if it contains only phrasing content)kbd
keygen
label
map
(if it contains only phrasing content)mark
math
meter
noscript
object
output
progress
q
ruby
s
samp
script
select
small
span
strong
sub
sup
svg
textarea
time
u
var
video
wbr
As a general rule, elements whose content model allows any
phrasing content should have either at least one
descendant text node that is not inter-element
whitespace, or at least one descendant element node that is
embedded content. For the purposes of this requirement,
nodes that are descendants of del
elements must not be
counted as contributing to the ancestors of the del
element.
Most elements that are categorized as phrasing content can only contain elements that are themselves categorized as phrasing content, not any flow content.
Text, in the context of content models, means text nodes. Text is sometimes used as a content model on its own, but is also phrasing content, and can be inter-element whitespace (if the text nodes are empty or contain just space characters).
Embedded content is content that imports another resource into the document, or content from another vocabulary that is inserted into the document.
Elements that are from namespaces other than the HTML namespace and that convey content but not metadata, are embedded content for the purposes of the content models defined in this specification. (For example, MathML, or SVG.)
Some embedded content elements can have fallback content: content that is to be used when the external resource cannot be used (e.g. because it is of an unsupported format). The element definitions state what the fallback is, if any.
Interactive content is content that is specifically intended for user interaction.
a
audio
(if the controls
attribute is present)button
details
embed
iframe
img
(if the usemap
attribute is present)input
(if the type
attribute is not in the Hidden state)keygen
label
menu
(if the type
attribute is in the toolbar state)object
(if the usemap
attribute is present)select
textarea
video
(if the controls
attribute is present)Certain elements in HTML have an activation
behavior, which means that the user can activate them. This
triggers a sequence of events dependent on the activation mechanism,
and normally culminating in a click
event, as described below.
The user agent should allow the user to manually trigger elements that have an activation behavior, for instance using keyboard or voice input, or through mouse clicks. When the user triggers an element with a defined activation behavior in a manner other than clicking it, the default action of the interaction event must be to run synthetic click activation steps on the element.
When a user agent is to run synthetic click activation
steps on an element, the user agent must run pre-click
activation steps on the element, then fire a click
event at the element. The
default action of this click
event
must be to run post-click activation steps on the
element. If the event is canceled, the user agent must run
canceled activation steps on the element instead.
When a pointing device is clicked, the user agent must run these steps:
Let e be the nearest activatable element of the element designated by the user (defined below), if any.
If there is an element e, run pre-click activation steps on it.
Dispatch the required click
event.
If there is an element e, then the default
action of the click
event must be
to run post-click activation steps on element e.
If there is an element e but the event is canceled, the user agent must run canceled activation steps on element e.
The above doesn't happen for arbitrary synthetic
events dispatched by author script. However, the click()
method can be used to make it
happen programmatically.
Given an element target, the nearest activatable element is the element returned by the following algorithm:
If target has a defined activation behavior, then return target and abort these steps.
If target has a parent element, then set target to that parent element and return to the first step.
Otherwise, there is no nearest activatable element.
When a user agent is to run pre-click activation steps on an element, it must run the pre-click activation steps defined for that element, if any.
When a user agent is to run canceled activation steps on an element, it must run the canceled activation steps defined for that element, if any.
When a user agent is to run post-click activation
steps on an element, it must run the activation
behavior defined for that element. Activation behaviors can
refer to the click
event that was
fired by the steps above leading up to this point.
Some elements are described as transparent; they have "transparent" in the description of their content model. The content model of a transparent element is derived from the content model of its parent element: the elements required in the part of the content model that is "transparent" are the same elements as required in the part of the content model of the parent of the transparent element in which the transparent element finds itself.
For instance, an ins
element inside a
ruby
element cannot contain an rt
element, because the part of the ruby
element's
content model that allows ins
elements is the part
that allows phrasing content, and the rt
element is not phrasing content.
In some cases, where transparent elements are nested in each other, the process has to be applied iteratively.
Consider the following markup fragment:
<p><object><param><ins><map><a href="/">Apples</a></map></ins></object></p>
To check whether "Apples" is allowed inside the a
element, the content models are examined. The a
element's content model is transparent, as is the map
element's, as is the ins
element's, as is the part of
the object
element's in which the ins
element is found. The object
element is found in the
p
element, whose content model is phrasing
content. Thus, "Apples" is allowed, as text is phrasing
content.
When a transparent element has no parent, then the part of its content model that is "transparent" must instead be treated as accepting any flow content.
The term paragraph as defined in this
section is distinct from (though related to) the p
element defined later. The paragraph concept defined
here is used to describe how to interpret documents.
A paragraph is typically a run of phrasing content that forms a block of text with one or more sentences that discuss a particular topic, as in typography, but can also be used for more general thematic grouping. For instance, an address is also a paragraph, as is a part of a form, a byline, or a stanza in a poem.
In the following example, there are two paragraphs in a section. There is also a heading, which contains phrasing content that is not a paragraph. Note how the comments and inter-element whitespace do not form paragraphs.
<section> <h1>Example of paragraphs</h1> This is the <em>first</em> paragraph in this example. <p>This is the second.</p> <!-- This is not a paragraph. --> </section>
Paragraphs in flow content are defined relative to
what the document looks like without the a
,
ins
, del
, and map
elements
complicating matters, since those elements, with their hybrid
content models, can straddle paragraph boundaries, as shown in the
first two examples below.
Generally, having elements straddle paragraph boundaries is best avoided. Maintaining such markup can be difficult.
The following example takes the markup from the earlier example
and puts ins
and del
elements around some
of the markup to show that the text was changed (though in this
case, the changes admittedly don't make much sense). Notice how
this example has exactly the same paragraphs as the previous one,
despite the ins
and del
elements —
the ins
element straddles the heading and the first
paragraph, and the del
element straddles the boundary
between the two paragraphs.
<section> <ins><h1>Example of paragraphs</h1> This is the <em>first</em> paragraph in</ins> this example<del>. <p>This is the second.</p></del> <!-- This is not a paragraph. --> </section>
Let view be a view of the DOM that replaces
all a
, ins
, del
, and
map
elements in the document with their contents. Then,
in view, for each run of sibling phrasing
content nodes uninterrupted by other types of content, in an
element that accepts content other than phrasing
content as well as phrasing content, let first be the first node of the run, and let last be the last node of the run. For each such run
that consists of at least one node that is neither embedded
content nor inter-element whitespace, a
paragraph exists in the original DOM from immediately before first to immediately after last. (Paragraphs can thus span across
a
, ins
, del
, and
map
elements.)
Conformance checkers may warn authors of cases where they have
paragraphs that overlap each other (this can happen with
object
, video
, audio
, and
canvas
elements, and indirectly through elements in
other namespaces that allow HTML to be further embedded therein,
like svg
or math
).
A paragraph is also formed explicitly by
p
elements.
The p
element can be used to wrap
individual paragraphs when there would otherwise not be any content
other than phrasing content to separate the paragraphs from each
other.
In the following example, the link spans half of the first paragraph, all of the heading separating the two paragraphs, and half of the second paragraph. It straddles the paragraphs and the heading.
<aside> Welcome! <a href="about.html"> This is home of... <h1>The Falcons!</h1> The Lockheed Martin multirole jet fighter aircraft! </a> This page discusses the F-16 Fighting Falcon's innermost secrets. </aside>
Here is another way of marking this up, this time showing the paragraphs explicitly, and splitting the one link element into three:
<aside> <p>Welcome! <a href="about.html">This is home of...</a></p> <h1><a href="about.html">The Falcons!</a></h1> <p><a href="about.html">The Lockheed Martin multirole jet fighter aircraft!</a> This page discusses the F-16 Fighting Falcon's innermost secrets.</p> </aside>
It is possible for paragraphs to overlap when using certain elements that define fallback content. For example, in the following section:
<section> <h1>My Cats</h1> You can play with my cat simulator. <object data="cats.sim"> To see the cat simulator, use one of the following links: <ul> <li><a href="cats.sim">Download simulator file</a> <li><a href="http://sims.example.com/watch?v=LYds5xY4INU">Use online simulator</a> </ul> Alternatively, upgrade to the Mellblom Browser. </object> I'm quite proud of it. </section>
There are five paragraphs:
object
element.The first paragraph is overlapped by the other four. A user agent that supports the "cats.sim" resource will only show the first one, but a user agent that shows the fallback will confusingly show the first sentence of the first paragraph as if it was in the same paragraph as the second one, and will show the last paragraph as if it was at the start of the second sentence of the first paragraph.
To avoid this confusion, explicit p
elements can be
used.
Text content in HTML elements with child text nodes, and text in attributes of HTML elements that allow free-form text, may contain characters in the range U+202A to U+202E (the bidirectional-algorithm formatting characters). However, the use of these characters is restricted so that any embedding or overrides generated by these characters do not start and end with different parent elements, and so that all such embeddings and overrides are explicitly terminated by a U+202C POP DIRECTIONAL FORMATTING character. This helps reduce incidences of text being reused in a manner that has unforeseen effects on the bidirectional algorithm.
The aforementioned restrictions are defined by specifying that certain parts of documents form bidirectional-algorithm formatting character ranges, and then imposing a requirement on such ranges.
The string resulting from the concatenation of the data of all of an HTML element's text nodes, if any, is a bidirectional-algorithm formatting character range.
The value of a namespace-less attribute of an HTML element is a bidirectional-algorithm formatting character range.
Any strings that, as described above, are
bidirectional-algorithm formatting character ranges must
match the string
production in the following
ABNF, the character set for which is Unicode. [ABNF]
string = *( plaintext ( embedding / override ) ) plaintext embedding = ( lre / rle ) string pdf override = ( lro / rlo ) string pdf lre = %x202A ; U+202A LEFT-TO-RIGHT EMBEDDING rle = %x202B ; U+202B RIGHT-TO-LEFT EMBEDDING lro = %x202D ; U+202D LEFT-TO-RIGHT OVERRIDE rlo = %x202E ; U+202E RIGHT-TO-LEFT OVERRIDE pdf = %x202C ; U+202C POP DIRECTIONAL FORMATTING plaintext = *( %x0000-2029 / %x202F-10FFFF ) ; any string with no bidirectional-algorithm formatting characters
For convenience, where possible authors will likely
prefer to use the dir
attribute, the
bdo
element, and the bdi
element, rather
than maintaining the bidirectional-algorithm formatting characters
manually.
Authors may use the ARIA role
and aria-*
attributes on HTML
elements, in accordance with the requirements described in
the ARIA specifications, except where these conflict with the
strong native semantics
described below. These exceptions are intended to prevent authors
from making assistive technology products report nonsensical states
that do not represent the actual state of the document. [ARIA]
User agents are required to implement ARIA semantics on all HTML elements, as defined in the ARIA specifications. The implicit ARIA semantics defined below must be recognized by implementations. [ARIAIMPL]
The following table defines the strong native semantics and corresponding default implicit ARIA semantics that apply to HTML elements. Each language feature (element or attribute) in a cell in the first column implies the ARIA semantics (role, states, and/or properties) given in the cell in the second column of the same row. When multiple rows apply to an element, the role from the last row to define a role must be applied, and the states and properties from all the rows must be combined.
Language feature | Strong native semantics and default implied ARIA semantics |
---|---|
area element that creates a hyperlink
| link role
|
base element
| No role |
datalist element
| listbox role, with the aria-multiselectable property set to "false"
|
details element
| aria-expanded state set to "true" if the element's open attribute is present, and set to "false" otherwise
|
head element
| No role |
hgroup element
| heading role, with the aria-level property set to the element's outline depth
|
hr element
| separator role
|
html element
| No role |
img element whose alt attribute's value is empty
| presentation role
|
input element with a type attribute in the Checkbox state
| aria-checked state set to "mixed" if the element's indeterminate IDL attribute is true, or "true" if the element's checkedness is true, or "false" otherwise
|
input element with a type attribute in the Color state
| No role |
input element with a type attribute in the Date state
| No role, with the aria-readonly state set to "true" if the element has a readonly attribute
|
input element with a type attribute in the Date and Time state
| No role, with the aria-readonly state set to "true" if the element has a readonly attribute
|
input element with a type attribute in the Local Date and Time state
| No role, with the aria-readonly state set to "true" if the element has a readonly attribute
|
input element with a type attribute in the E-mail state with no suggestions source element
| textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
|
input element with a type attribute in the File Upload state
| No role |
input element with a type attribute in the Hidden state
| No role |
input element with a type attribute in the Month state
| No role, with the aria-readonly state set to "true" if the element has a readonly attribute
|
input element with a type attribute in the Number state
| spinbutton role, with the aria-readonly state set to "true" if the element has a readonly attribute, the aria-valuemax property set to the element's maximum, the aria-valuemin property set to the element's minimum, and, if the result of applying the rules for parsing floating point number values to the element's value is a number, with the aria-valuenow property set to that number
|
input element with a type attribute in the Password state
| textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
|
input element with a type attribute in the Radio Button state
| aria-checked state set to "true" if the element's checkedness is true, or "false" otherwise
|
input element with a type attribute in the Range state
| slider role, with the aria-valuemax property set to the element's maximum, the aria-valuemin property set to the element's minimum, and the aria-valuenow property set to the result of applying the rules for parsing floating point number values to the element's value, if that results in a number, or the default value otherwise
|
input element with a type attribute in the Reset Button state
| button role
|
input element with a type attribute in the Search state with no suggestions source element
| textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
|
input element with a type attribute in the Submit Button state
| button role
|
input element with a type attribute in the Telephone state with no suggestions source element
| textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
|
input element with a type attribute in the Text state with no suggestions source element
| textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
|
input element with a type attribute in the Text, Search, Telephone, URL, or E-mail states with a suggestions source element
| combobox role, with the aria-owns property set to the same value as the list attribute, and the aria-readonly state set to "true" if the element has a readonly attribute
|
input element with a type attribute in the Time state
| No role, with the aria-readonly state set to "true" if the element has a readonly attribute
|
input element with a type attribute in the URL state with no suggestions source element
| textbox role, with the aria-readonly state set to "true" if the element has a readonly attribute
|
input element with a type attribute in the Week state
| No role, with the aria-readonly state set to "true" if the element has a readonly attribute
|
input element that is required
| The aria-required state set to "true"
|
keygen element
| No role |
label element
| No role |
link element that creates a hyperlink
| link role
|
menu element with a type attribute in the context menu state
| No role |
menu element with a type attribute in the list state
| menu role
|
menu element with a type attribute in the toolbar state
| toolbar role
|
meta element
| No role |
meter element
| No role |
nav element
| navigation role
|
noscript element
| No role |
optgroup element
| No role |
option element that is in a list of options or that represents a suggestion in a datalist element
| option role, with the aria-selected state set to "true" if the element's selectedness is true, or "false" otherwise.
|
param element
| No role |
progress element
| progressbar role, with, if the progress bar is determinate, the aria-valuemax property set to the maximum value of the progress bar, the aria-valuemin property set to zero, and the aria-valuenow property set to the current value of the progress bar
|
script element
| No role |
select element with a multiple attribute
| listbox role, with the aria-multiselectable property set to "true"
|
select element with no multiple attribute
| listbox role, with the aria-multiselectable property set to "false"
|
select element with a required attribute
| The aria-required state set to "true"
|
source element
| No role |
style element
| No role |
summary element
| No role |
textarea element
| textbox role, with the aria-multiline property set to "true", and the aria-readonly state set to "true" if the element has a readonly attribute
|
textarea element with a required attribute
| The aria-required state set to "true"
|
title element
| No role |
An element that defines a command, whose Type facet is "checkbox", and that is a descendant of a menu element whose type attribute in the list state
| menuitemcheckbox role, with the aria-checked state set to "true" if the command's Checked State facet is true, and "false" otherwise
|
An element that defines a command, whose Type facet is "command", and that is a descendant of a menu element whose type attribute in the list state
| menuitem role
|
An element that defines a command, whose Type facet is "radio", and that is a descendant of a menu element whose type attribute in the list state
| menuitemradio role, with the aria-checked state set to "true" if the command's Checked State facet is true, and "false" otherwise
|
Element that is disabled | The aria-disabled state set to "true"
|
Element with a hidden attribute
| The aria-hidden state set to "true"
|
Element that is a candidate for constraint validation but that does not satisfy its constraints | The aria-invalid state set to "true"
|
Some HTML elements have native semantics that can be
overridden. The following table lists these elements and their
default implicit ARIA semantics, along with the
restrictions that apply to those elements. Each language feature
(element or attribute) in a cell in the first column implies, unless
otherwise overridden, the ARIA semantic (role, state, or property)
given in the cell in the second column of the same row, but this
semantic may be overridden under the conditions listed in the cell
in the third column of that row. In addition, any element may be
given the presentation
role,
regardless of the restrictions below.
Language feature | Default implied ARIA semantic | Restrictions |
---|---|---|
a element that creates a hyperlink
| link role
| Role must be either link , button , checkbox , menuitem , menuitemcheckbox , menuitemradio , tab , or treeitem
|
address element
| No role | If specified, role must be contentinfo
|
article element
| article role
| Role must be either article , document , application , or main
|
aside element
| note role
| Role must be either note , complementary , or search
|
audio element
| No role | If specified, role must be application
|
button element
| button role
| Role must be either button , link , menuitem , menuitemcheckbox , menuitemradio , radio
|
details element
| group role
| Role must be a role that supports aria-expanded
|
embed element
| No role | If specified, role must be either application , document , or img
|
footer element
| No role | If specified, role must be contentinfo
|
h1 element that does not have an hgroup ancestor
| heading role, with the aria-level property set to the element's outline depth
| Role must be either link , menuitem , menuitemcheckbox , menuitemradio , tab , or treeitem
|
h2 element that does not have an hgroup ancestor
| heading role, with the aria-level property set to the element's outline depth
| Role must be either link , menuitem , menuitemcheckbox , menuitemradio , tab , or treeitem
|
h3 element that does not have an hgroup ancestor
| heading role, with the aria-level property set to the element's outline depth
| Role must be either link , menuitem , menuitemcheckbox , menuitemradio , tab , or treeitem
|
h4 element that does not have an hgroup ancestor
| heading role, with the aria-level property set to the element's outline depth
| Role must be either link , menuitem , menuitemcheckbox , menuitemradio , tab , or treeitem
|
h5 element that does not have an hgroup ancestor
| heading role, with the aria-level property set to the element's outline depth
| Role must be either link , menuitem , menuitemcheckbox , menuitemradio , tab , or treeitem
|
h6 element that does not have an hgroup ancestor
| heading role, with the aria-level property set to the element's outline depth
| Role must be either link , menuitem , menuitemcheckbox , menuitemradio , tab , or treeitem
|
header element
| No role | If specified, role must be banner
|
iframe element
| No role | If specified, role must be either application , document , or img
|
img element whose alt attribute's value is absent
| img role
| No restrictions |
img element whose alt attribute's value is present and not empty
| img role
| No restrictions |
input element with a type attribute in the Button state
| button role
| Role must be either button , link , menuitem , menuitemcheckbox , menuitemradio , radio
|
input element with a type attribute in the Checkbox state
| checkbox role
| Role must be either checkbox or menuitemcheckbox
|
input element with a type attribute in the Image Button state
| button role
| Role must be either button , link , menuitem , menuitemcheckbox , menuitemradio , radio
|
input element with a type attribute in the Radio Button state
| radio role
| Role must be either radio or menuitemradio
|
li element whose parent is an ol or ul element
| listitem role
| Role must be either listitem , menuitemcheckbox , menuitemradio , option , tab , or treeitem
|
object element
| No role | If specified, role must be either application , document , or img
|
ol element
| list role
| Role must be either directory , list , listbox , menu , menubar , tablist , toolbar , tree
|
output element
| status role
| No restrictions |
section element
| region role
| Role must be either
alert ,
alertdialog ,
application ,
contentinfo ,
dialog ,
document ,
log ,
main ,
marquee ,
region ,
search , or
status
|
ul element
| list role
| Role must be either directory , list , listbox , menu , menubar , tablist , toolbar , tree
|
video element
| No role | If specified, role must be application
|
The body element | document role
| Role must be either document or application
|
The entry "no role", when
used as a strong native
semantic, means that no role other than presentation
can be used.
When used as a default
implied ARIA semantic, it means the user agent has no default
mapping to ARIA roles. (However, it probably will have its own
mappings to the accessibility layer.)
The WAI-ARIA specification neither requires or forbids user agents from enhancing native presentation and interaction behaviors on the basis of WAI- ARIA markup. Even mainstream user agents might choose to expose metadata or navigational features directly or via user-installed extensions; for example, exposing required form fields or landmark navigation. User agents are encouraged to maximize their usefulness to users, including users without disabilities.
Conformance checkers are encouraged to phrase errors such that
authors are encouraged to use more appropriate elements rather than
remove accessibility annotations. For example, if an a
element is marked as having the button
role, a conformance
checker could say "Use a more appropriate element to represent a
button, for example a button
element or an
input
element" rather than "The button
role cannot be used with
a
elements".
These features can be used to make accessibility tools render content to their users in more useful ways. For example, ASCII art, which is really an image, appears to be text, and in the absence of appropriate annotations would end up being rendered by screen readers as a very painful reading of lots of punctuation. Using the features described in this section, one can instead make the ATs skip the ASCII art and just read the caption:
<figure role="img" aria-labelledby="fish-caption"> <pre> o .'`/ ' / ( O .-'` ` `'-._ .') _/ (o) '. .' / ) ))) >< < `\ |_\ _.' '. \ '-._ _ .-' '.) jgs `\__\ </pre> <figcaption id="fish-caption"> Joan G. Stark, "<cite>fish</cite>". October 1997. ASCII on electrons. 28×8. </figcaption> </figure>
For HTML documents, and for HTML elements in HTML documents, certain APIs defined in DOM Core become case-insensitive or case-changing, as sometimes defined in DOM Core, and as summarized or required below. [DOMCORE]
This does not apply to XML documents or to elements that are not in the HTML namespace despite being in HTML documents.
Element.tagName
and Node.nodeName
These attributes must return element names converted to ASCII uppercase, regardless of the case with which they were created.
Document.createElement()
The canonical form of HTML markup is all-lowercase; thus, this method will lowercase the argument before creating the requisite element. Also, the element created must be in the HTML namespace.
This doesn't apply to Document.createElementNS()
.
Thus, it is possible, by passing this last method a tag name in
the wrong case, to create an element that appears to have the same
tag name as that of an element defined in this specification when
its tagName
attribute is
examined, but that doesn't support the corresponding interfaces.
The "real" element name (unaffected by case conversions) can be
obtained from the localName
attribute.
Element.setAttribute()
Element.setAttributeNode()
Attribute names are converted to ASCII lowercase.
Specifically: when an attribute is set on an HTML element using Element.setAttribute()
, the name argument must be
converted to ASCII lowercase before the element is
affected; and when an Attr
node is set on an HTML element using Element.setAttributeNode()
, it must have its name
converted to ASCII lowercase before the element is
affected.
This doesn't apply to Element.setAttributeNS()
and Element.setAttributeNodeNS()
.
Element.getAttribute()
Element.getAttributeNode()
Attribute names are converted to ASCII lowercase.
Specifically: When the Element.getAttribute()
method or the Element.getAttributeNode()
method is invoked on
an HTML element, the name
argument must be converted to ASCII lowercase before the
element's attributes are examined.
This doesn't apply to Element.getAttributeNS()
and Element.getAttributeNodeNS()
.
Document.getElementsByTagName()
Element.getElementsByTagName()
HTML elements match by lower-casing the argument before comparison, elements from other namespaces are treated as in XML (case-sensitively).
Specifically, these methods (but not their namespaced counterparts) must compare the given argument in a case-sensitive manner, but when looking at HTML elements, the argument must first be converted to ASCII lowercase.
Thus, in an HTML document with nodes in multiple namespaces, these methods will effectively be both case-sensitive and case-insensitive at the same time.
Implementations of XPath 1.0 that
operate on HTML documents parsed or created in the
manners described in this specification (e.g. as part of the document.evaluate()
API) must act as if the
following edit was applied to the XPath 1.0 specification.
First, remove this paragraph:
A QName in the node test is expanded into an expanded-name using the namespace declarations from the expression context. This is the same way expansion is done for element type names in start and end-tags except that the default namespace declared with
xmlns
is not used: if the QName does not have a prefix, then the namespace URI is null (this is the same way attribute names are expanded). It is an error if the QName has a prefix for which there is no namespace declaration in the expression context.
Then, insert in its place the following:
A QName in the node test is expanded into an expanded-name using the namespace declarations from the expression context. If the QName has a prefix, then there must be a namespace declaration for this prefix in the expression context, and the corresponding namespace URI is the one that is associated with this prefix. It is an error if the QName has a prefix for which there is no namespace declaration in the expression context.
If the QName has no prefix and the principal node type of the axis is element, then the default element namespace is used. Otherwise if the QName has no prefix, the namespace URI is null. The default element namespace is a member of the context for the XPath expression. The value of the default element namespace when executing an XPath expression through the DOM3 XPath API is determined in the following way:
- If the context node is from an HTML DOM, the default element namespace is "http://www.w3.org/1999/xhtml".
- Otherwise, the default element namespace URI is null.
This is equivalent to adding the default element namespace feature of XPath 2.0 to XPath 1.0, and using the HTML namespace as the default element namespace for HTML documents. It is motivated by the desire to have implementations be compatible with legacy HTML content while still supporting the changes that this specification introduces to HTML regarding the namespace used for HTML elements, and by the desire to use XPath 1.0 rather than XPath 2.0.
This change is a willful violation of the XPath 1.0 specification, motivated by desire to have implementations be compatible with legacy content while still supporting the changes that this specification introduces to HTML regarding which namespace is used for HTML elements. [XPATH10]
XSLT 1.0 processors outputting to a DOM when the output method is "html" (either explicitly or via the defaulting rule in XSLT 1.0) are affected as follows:
If the transformation program outputs an element in no namespace, the processor must, prior to constructing the corresponding DOM element node, change the namespace of the element to the HTML namespace, ASCII-lowercase the element's local name, and ASCII-lowercase the names of any non-namespaced attributes on the element.
This requirement is a willful violation of the XSLT 1.0 specification, required because this specification changes the namespaces and case-sensitivity rules of HTML in a manner that would otherwise be incompatible with DOM-based XSLT transformations. (Processors that serialize the output are unaffected.) [XSLT10]
There are also additional comments regarding the
interaction of XSLT and HTML in the
script
element section.
APIs for dynamically inserting markup into the document interact with the parser, and thus their behavior varies depending on whether they are used with HTML documents (and the HTML parser) or XHTML in XML documents (and the XML parser).
The open()
method comes in several variants with different numbers of
arguments.
open
( [ type [, replace ] ] )Causes the Document
to be replaced in-place, as if
it was a new Document
object, but reusing the
previous object, which is then returned.
If the type argument is omitted or has the
value "text/html
", then the resulting
Document
has an HTML parser associated with it, which
can be given data to parse using document.write()
. Otherwise, all
content passed to document.write()
will be parsed
as plain text.
If the replace argument is present and has
the value "replace
", the existing entries in
the session history for the Document
object are
removed.
The method has no effect if the Document
is still
being parsed.
Throws an INVALID_STATE_ERR
exception if the
Document
is an XML
document.
open
( url, name, features [, replace ] )Works like the window.open()
method.
When called with two or fewer arguments, the method must act as follows:
Document
object is not flagged as an HTML document, throw an
INVALID_STATE_ERR
exception and abort these
steps.Let type be the value of the first
argument, if there is one, or "text/html
"
otherwise.
Let replace be true if there is a second argument and it is an ASCII case-insensitive match for the value "replace", and false otherwise.
If the document has an active parser that isn't a
script-created parser, and the insertion
point associated with that parser's input
stream is not undefined (that is, it does point to
somewhere in the input stream), then the method does
nothing. Abort these steps and return the Document
object on which the method was invoked.
This basically causes document.open()
to be ignored
when it's called in an inline script found during the parsing of
data sent over the network, while still letting it have an effect
when called asynchronously or on a document that is itself being
spoon-fed using these APIs.
Release the storage mutex.
Prompt to
unload the Document
object. If the user
refused to allow the document to be unloaded, then
these steps must be aborted.
Unload the
Document
object, with the recycle
parameter set to true.
Unregister all event listeners registered on the
Document
node and its descendants.
Remove any tasks
associated with the Document
in any task
source.
Remove all child nodes of the document, without firing any mutation events.
Replace the Document
's singleton objects with
new instances of those objects. (This includes in particular the
Window
, Location
, History
,
ApplicationCache
,
and Navigator
, objects, the various
BarProp
objects, the two Storage
objects,
the various HTMLCollection
objects, and objects
defined by other specifications, like Selection
. It
also includes all the Web IDL prototypes in the JavaScript binding,
including the Document
object's prototype.)
Change the document's character encoding to UTF-8.
Set the Document
object's reload override
flag and set the Document
's reload
override buffer to the empty string.
Change the document's address to the entry script's document's address.
Create a new HTML parser and associate it with
the document. This is a script-created parser (meaning
that it can be closed by the document.open()
and document.close()
methods, and
that the tokenizer will wait for an explicit call to document.close()
before emitting
an end-of-file token). The encoding confidence is
irrelevant.
Set the current document readiness of the document to "loading".
If the type string contains a U+003B SEMICOLON character (;), remove the first such character and all characters from it up to the end of the string.
Strip all leading and trailing space characters from type.
If type is not now an ASCII
case-insensitive match for the string
"text/html
", then act as if the tokenizer had emitted
a start tag token with the tag name "pre" followed by a single
U+000A LINE FEED (LF) character, then
switch the HTML parser's tokenizer to the
PLAINTEXT state.
Remove all the entries in the browsing context's session history after the current entry. If the current entry is the last entry in the session history, then no entries are removed.
This doesn't necessarily have to affect the user agent's user interface.
Remove any tasks queued by the history traversal task source.
Document
.If replace is false, then add a new
entry, just before the last entry, and associate with the new entry
the text that was parsed by the previous parser associated with the
Document
object, as well as the state of the document
at the start of these steps. This allows the user to step backwards
in the session history to see the page before it was blown away by
the document.open()
call.
This new entry does not have a Document
object, so a
new one will be created if the session history is traversed to that
entry.
Finally, set the insertion point to point at just before the end of the input stream (which at this point will be empty).
Return the Document
on which the method was
invoked.
When called with three or more arguments, the open()
method on the
HTMLDocument
object must call the open()
method on the Window
object of the HTMLDocument
object, with the same
arguments as the original call to the open()
method, and return whatever
that method returned. If the HTMLDocument
object has no
Window
object, then the method must raise an
INVALID_ACCESS_ERR
exception.
close
()Closes the input stream that was opened by the document.open()
method.
Throws an INVALID_STATE_ERR
exception if the
Document
is an XML
document.
The close()
method must run the following steps:
If the Document
object is not flagged as an
HTML document, throw an
INVALID_STATE_ERR
exception and abort these
steps.
If there is no script-created parser associated with the document, then abort these steps.
Insert an explicit "EOF" character at the end of the parser's input stream.
If there is a pending parsing-blocking script, then abort these steps.
Run the tokenizer, processing resulting tokens as they are emitted, and stopping when the tokenizer reaches the explicit "EOF" character or spins the event loop.
document.write()
write
(text...)In general, adds the given string(s) to the
Document
's input stream.
This method has very idiosyncratic behavior. In
some cases, this method can affect the state of the HTML
parser while the parser is running, resulting in a DOM that
does not correspond to the source of the document. In other cases,
the call can clear the current page first, as if document.open()
had been called.
In yet more cases, the method is simply ignored, or throws an
exception. To make matters worse, the exact behavior of this
method can in some cases be dependent on network latency, which
can lead to failures that are very hard to debug. For all
these reasons, use of this method is strongly
discouraged.
This method throws an INVALID_STATE_ERR
exception
when invoked on XML documents.
Document
objects have an
ignore-destructive-writes counter, which is used in
conjunction with the processing of script
elements to
prevent external scripts from being able to use document.write()
to blow away the
document by implicitly calling document.open()
. Initially, the
counter must be set to zero.
The document.write(...)
method must act as follows:
If the method was invoked on an XML
document, throw an INVALID_STATE_ERR
exception and abort these steps.
If the insertion point is undefined and the
Document
's ignore-destructive-writes
counter is greater than zero, then abort these steps.
If the insertion point is undefined, call the
open()
method on the document
object (with no arguments). If
the user refused to allow the document to be
unloaded, then abort these steps. Otherwise, the
insertion point will point at just before the end of
the (empty) input stream.
Insert the string consisting of the concatenation of all the arguments to the method into the input stream just before the insertion point.
If the Document
object's reload override
flag is set, then append the string consisting of the
concatenation of all the arguments to the method to the
Document
's reload override buffer.
If there is no pending parsing-blocking script,
have the tokenizer process the characters that were inserted, one
at a time, processing resulting tokens as they are emitted, and
stopping when the tokenizer reaches the insertion point or when
the processing of the tokenizer is aborted by the tree
construction stage (this can happen if a script
end
tag token is emitted by the tokenizer).
If the document.write()
method was
called from script executing inline (i.e. executing because the
parser parsed a set of script
tags), then this is a
reentrant invocation of the
parser.
Finally, return from the method.
document.writeln()
writeln
(text...)Adds the given string(s) to the Document
's input
stream, followed by a newline character. If necessary, calls the
open()
method implicitly
first.
This method throws an INVALID_STATE_ERR
exception
when invoked on XML documents.
The document.writeln(...)
method, when invoked, must act as if the document.write()
method had been
invoked with the same argument(s), plus an extra argument consisting
of a string containing a single line feed character (U+000A).
innerHTML
The innerHTML
IDL
attribute represents the markup of the node's contents.
innerHTML
[ = value ]Returns a fragment of HTML or XML that represents the
Document
.
Can be set, to replace the Document
's contents
with the result of parsing the given string.
In the case of XML documents, will throw an
INVALID_STATE_ERR
if the Document
cannot
be serialized to XML, and a SYNTAX_ERR
if the given
string is not well-formed.
innerHTML
[ = value ]Returns a fragment of HTML or XML that represents the element's contents.
Can be set, to replace the contents of the element with nodes parsed from the given string.
In the case of XML documents, will throw an
INVALID_STATE_ERR
if the element cannot be serialized
to XML, and a SYNTAX_ERR
if the given string is not
well-formed.
On getting, if the node's document is an HTML document, then the attribute must return the result of running the HTML fragment serialization algorithm on the node; otherwise, the node's document is an XML document, and the attribute must return the result of running the XML fragment serialization algorithm on the node instead (this might raise an exception instead of returning a string).
On setting, the following steps must be run:
If the node's document is an HTML document: Invoke the HTML fragment parsing algorithm.
If the node's document is an XML document: Invoke the XML fragment parsing algorithm.
In either case, the algorithm must be invoked with the string
being assigned into the innerHTML
attribute as the input. If the node is an Element
node, then, in addition, that element must be passed as the context element.
If this raises an exception, then abort these steps.
Otherwise, let new children be the nodes returned.
If the attribute is being set on a Document
node,
and that document has an active parser, then abort
that parser.
Remove the child nodes of the node whose innerHTML
attribute is being set,
firing appropriate mutation events.
If the attribute is being set on a Document
node,
let target document be that
Document
node. Otherwise, the attribute is being set
on an Element
node; let target
document be the ownerDocument
of that
Element
.
Set the ownerDocument
of all the
nodes in new children to the target document.
Append all the new children nodes to the
node whose innerHTML
attribute
is being set, preserving their order, and firing mutation events
as if a DocumentFragment
containing the new children had been inserted.
outerHTML
The outerHTML
IDL
attribute represents the markup of the element and its contents.
outerHTML
[ = value ]Returns a fragment of HTML or XML that represents the element and its contents.
Can be set, to replace the element with nodes parsed from the given string.
In the case of XML documents, will throw an
INVALID_STATE_ERR
if the element cannot be serialized
to XML, and a SYNTAX_ERR
if the given string is not
well-formed.
Throws a NO_MODIFICATION_ALLOWED_ERR
exception if
the parent of the element is the Document
node.
On getting, if the node's document is an HTML document, then the attribute must return the result of running the HTML fragment serialization algorithm on a fictional node whose only child is the node on which the attribute was invoked; otherwise, the node's document is an XML document, and the attribute must return the result of running the XML fragment serialization algorithm on that fictional node instead (this might raise an exception instead of returning a string).
On setting, the following steps must be run:
Let target be the element whose outerHTML
attribute is being
set.
If target has no parent node, then abort these steps. There would be no way to obtain a reference to the nodes created even if the remaining steps were run.
If target's parent node is a
Document
object, throw a
NO_MODIFICATION_ALLOWED_ERR
exception and abort these
steps.
Let parent be target's
parent node, unless that is a DocumentFragment
node,
in which case let parent be an arbitrary
body
element.
If target's document is an HTML document: Invoke the HTML fragment parsing algorithm.
If target's document is an XML document: Invoke the XML fragment parsing algorithm.
In either case, the algorithm must be invoked with the string
being assigned into the outerHTML
attribute as the input, and parent as the context element.
If this raises an exception, then abort these steps.
Otherwise, let new children be the nodes returned.
Set the ownerDocument
of all the
nodes in new children to target's document.
Remove target from its parent node, firing
mutation events as appropriate, and then insert in its place all
the new children nodes, preserving their
order, and again firing mutation events as if a
DocumentFragment
containing the new
children had been inserted.
insertAdjacentHTML()
insertAdjacentHTML
(position, text)Parses the given string text as HTML or XML and inserts the resulting nodes into the tree in the position given by the position argument, as follows:
Throws a SYNTAX_ERR
exception if the arguments
have invalid values (e.g., in the case of XML
documents, if the given string is not well-formed).
Throws a NO_MODIFICATION_ALLOWED_ERR
exception if
the given position isn't possible (e.g. inserting elements after
the root element of a Document
).
The insertAdjacentHTML(position, text)
method, when invoked, must run the following algorithm:
Let position and text be the method's first and second arguments, respectively.
Let target be the element on which the method was invoked.
Use the first matching item from this list:
If target has no parent node, then abort these steps.
If target's parent node is a
Document
object, then throw a
NO_MODIFICATION_ALLOWED_ERR
exception and abort
these steps.
Otherwise, let destination be the parent node of target.
Let destination be the same as target.
Throw a SYNTAX_ERR
exception.
If target's document is an HTML document: Invoke the HTML fragment parsing algorithm.
If target's document is an XML document: Invoke the XML fragment parsing algorithm.
In either case, the algorithm must be invoked with text as the input, and destination as the context element.
If this raises an exception, then abort these steps.
Otherwise, let new children be the nodes returned.
Set the ownerDocument
of all the
nodes in new children to target's document.
Use the first matching item from this list:
Insert all the new children nodes immediately before target.
Insert all the new children nodes before the first child of target, if there is one. If there is no such child, append them all to target.
Append all the new children nodes to target.
Insert all the new children nodes immediately after target.
The new children nodes must be inserted in
a manner that preserves their order and fires mutation events as
if a DocumentFragment
containing the new children had been inserted.
html
elementhead
element followed by a body
element.manifest
interface HTMLHtmlElement : HTMLElement {};
The html
element represents the root of
an HTML document.
The manifest
attribute gives the address of the document's application
cache manifest, if there is
one. If the attribute is present, the attribute's value must be a
valid non-empty URL potentially surrounded by
spaces.
The manifest
attribute
only has an effect during
the early stages of document load. Changing the attribute
dynamically thus has no effect (and thus, no DOM API is provided for
this attribute).
For the purposes of application cache selection,
later base
elements cannot affect the resolving of relative URLs in manifest
attributes, as the
attributes are processed before those elements are seen.
The window.applicationCache
IDL
attribute provides scripted access to the offline application
cache mechanism.
The html
element in the following example declares
that the document's language is English.
<!DOCTYPE html> <html lang="en"> <head> <title>Swapping Songs</title> </head> <body> <h1>Swapping Songs</h1> <p>Tonight I swapped some of the songs I wrote with some friends, who gave me some of the songs they wrote. I love sharing my music.</p> </body> </html>
head
elementhtml
element.iframe
srcdoc
document or if title information is available from a higher-level protocol: Zero or more elements of metadata content.title
element.interface HTMLHeadElement : HTMLElement {};
The head
element represents a
collection of metadata for the Document
.
The collection of metadata in a head
element can be
large or small. Here is an example of a very short one:
<!doctype html> <html> <head> <title>A document with a short head</title> </head> <body> ...
Here is an example of a longer one:
<!DOCTYPE HTML> <HTML> <HEAD> <META CHARSET="UTF-8"> <BASE HREF="http://www.example.com/"> <TITLE>An application with a long head</TITLE> <LINK REL="STYLESHEET" HREF="default.css"> <LINK REL="STYLESHEET ALTERNATE" HREF="big.css" TITLE="Big Text"> <SCRIPT SRC="support.js"></SCRIPT> <META NAME="APPLICATION-NAME" CONTENT="Long headed application"> </HEAD> <BODY> ...
The title
element is a required child
in most situations, but when a higher-level protocol provides title
information, e.g. in the Subject line of an e-mail when HTML is used
as an e-mail authoring format, the title
element can be
omitted.
title
elementhead
element containing no other title
elements.interface HTMLTitleElement : HTMLElement { attribute DOMString text; };
The title
element represents the
document's title or name. Authors should use titles that identify
their documents even when they are used out of context, for example
in a user's history or bookmarks, or in search results. The
document's title is often different from its first heading, since the
first heading does not have to stand alone when taken out of
context.
There must be no more than one title
element per
document.
text
[ = value ]Returns the contents of the element, ignoring child nodes that aren't text nodes.
Can be set, to replace the element's children with the given value.
The IDL attribute text
must return a
concatenation of the contents of all the text nodes that are direct children of the
title
element (ignoring any other nodes such as
comments or elements), in tree order. On setting, it must act the
same way as the textContent
IDL attribute.
Here are some examples of appropriate titles, contrasted with the top-level headings that might be used on those same pages.
<title>Introduction to The Mating Rituals of Bees</title> ... <h1>Introduction</h1> <p>This companion guide to the highly successful <cite>Introduction to Medieval Bee-Keeping</cite> book is...
The next page might be a part of the same site. Note how the title describes the subject matter unambiguously, while the first heading assumes the reader knows what the context is and therefore won't wonder if the dances are Salsa or Waltz:
<title>Dances used during bee mating rituals</title> ... <h1>The Dances</h1>
The string to use as the document's title is given by the document.title
IDL attribute.
User agents should use the document's title when referring to the
document in their user interface. When the contents of a
title
element are used in this way, the
directionality of that title
element should be
used to set the directionality of the document's title in the user
interface.
base
elementhead
element containing no other base
elements.href
target
interface HTMLBaseElement : HTMLElement { attribute DOMString href; attribute DOMString target; };
The base
element allows authors to specify the
document base URL for the purposes of resolving relative URLs, and the name
of the default browsing context for the purposes of
following hyperlinks. The element does not represent any content beyond this
information.
There must be no more than one base
element per
document.
A base
element must have either an href
attribute, a target
attribute, or both.
The href
content
attribute, if specified, must contain a valid URL potentially
surrounded by spaces.
A base
element, if it has an href
attribute, must come before any
other elements in the tree that have attributes defined as taking
URLs, except the html
element
(its manifest
attribute
isn't affected by base
elements).
The target
attribute, if specified, must contain a valid browsing context
name or keyword, which specifies which browsing
context is to be used as the default when hyperlinks and forms in the Document
cause navigation.
A base
element, if it has a target
attribute, must come before
any elements in the tree that represent hyperlinks.
If there are multiple base
elements
with target
attributes, all but
the first are ignored.
The href
IDL
attribute, on getting, must return the page's document base
URL, and on setting, it must set the href
content attribute to the given
new value.
The target
IDL
attribute must reflect the content attribute of the
same name.
In this example, a base
element is used to set the
document base URL:
<!DOCTYPE html> <html> <head> <title>This is an example for the <base> element</title> <base href="http://www.example.com/news/index.html"> </head> <body> <p>Visit the <a href="archives.html">archives</a>.</p> </body> </html>
The link in the above example would be a link to "http://www.example.com/news/archives.html
".
link
elementnoscript
element that is a child of a head
element.href
rel
media
hreflang
type
sizes
title
attribute has special semantics on this element.interface HTMLLinkElement : HTMLElement {
attribute boolean disabled;
attribute DOMString href;
attribute DOMString rel;
readonly attribute DOMTokenList relList;
attribute DOMString media;
attribute DOMString hreflang;
attribute DOMString type;
[PutForwards=value] readonly attribute DOMSettableTokenList sizes;
};
HTMLLinkElement implements LinkStyle;
The link
element allows authors to link their
document to other resources.
The destination of the link(s) is given by the href
attribute, which must
be present and must contain a valid non-empty URL potentially
surrounded by spaces. If the href
attribute is absent, then the
element does not define a link.
A link
element must have rel
attribute.
The types of link indicated (the relationships) are given by the
value of the rel
attribute, which, if present, must have a value that is a set
of space-separated tokens. The allowed
keywords and their meanings are defined in a later
section. If the rel
attribute is absent, has no
keywords, or if none of the keywords used are allowed according to
the definitions in this specification, then the element does not
create any links.
Two categories of links can be created using the
link
element: Links to external resources and hyperlinks. The link
types section defines whether a particular link type is an
external resource or a hyperlink. One link
element can
create multiple links (of which some might be external resource
links and some might be hyperlinks); exactly which and how many
links are created depends on the keywords given in the rel
attribute. User agents must process
the links on a per-link basis, not a per-element basis.
Each link created for a link
element is
handled separately. For instance, if there are two link
elements with rel="stylesheet"
, they each
count as a separate external resource, and each is affected by its
own attributes independently. Similarly, if a single
link
element has a rel
attribute with the value next stylesheet
, it creates both a
hyperlink (for the next
keyword) and an external resource link (for the stylesheet
keyword), and they are
affected by other attributes (such as media
or title
) differently.
The exact behavior for links to external resources depends on the exact relationship, as defined for the relevant link type. Some of the attributes control whether or not the external resource is to be applied (as defined below).
For external resources that are represented in the DOM (for example, style sheets), the DOM representation must be made available even if the resource is not applied. To obtain the resource, the user agent must run the following steps:
If the href
attribute's
value is the empty string, then abort these steps.
Resolve the
URL given by the href
attribute, relative to the
element.
If the previous step fails, then abort these steps.
Fetch the resulting absolute URL.
User agents may opt to only try to obtain such resources when they are needed, instead of pro-actively fetching all the external resources that are not applied.
The semantics of the protocol used (e.g. HTTP) must be followed when fetching external resources. (For example, redirects will be followed and 404 responses will cause the external resource to not be applied.)
Once the attempts to obtain the resource and its critical
subresources are complete, the user agent must, if the loads
were successful, queue a task to fire a simple
event named load
at the
link
element, or, if the resource or one of its
critical subresources failed to completely load for any
reason (e.g. DNS error, HTTP 404 response, a connection being
prematurely closed, unsupported Content-Type), queue a
task to fire a simple event named error
at the link
element. Non-network errors in processing the resource or its
subresources (e.g. CSS parse errors, PNG decoding errors) are not
failures for the purposes of this paragraph.
The task source for these tasks is the DOM manipulation task source.
The element must delay the load event of the element's document until all the attempts to obtain the resource and its critical subresources are complete. (Resources that the user agent has not yet attempted to obtain, e.g. because it is waiting for the resource to be needed, do not delay the load event.)
Interactive user agents may provide users with a
means to follow the
hyperlinks created using the link
element,
somewhere within their user interface. The exact interface is not
defined by this specification, but it could include the following
information (obtained from the element's attributes, again as
defined below), in some form or another (possibly simplified), for
each hyperlink created with each link
element in the
document:
rel
attribute)title
attribute).href
attribute).hreflang
attribute).media
attribute).User agents could also include other information, such as the
type of the resource (as given by the type
attribute).
Hyperlinks created with the link
element and its rel
attribute
apply to the whole page. This contrasts with the rel
attribute of a
and area
elements, which indicates the type of a link
whose context is given by the link's location within the
document.
The media
attribute says which media the resource applies to. The value must
be a valid media query.
If the link is a hyperlink then the media
attribute is purely advisory,
and describes for which media the document in question was
designed.
However, if the link is an external resource link,
then the media
attribute is
prescriptive. The user agent must apply the external resource when
the media
attribute's value
matches the environment and the other relevant
conditions apply, and must not apply it otherwise.
The external resource might have further
restrictions defined within that limit its applicability. For
example, a CSS style sheet might have some @media
blocks. This specification does not override
such further restrictions or requirements.
The default, if the media
attribute is omitted, is "all
", meaning that by default links apply to all
media.
The hreflang
attribute on the link
element has the same semantics as
the hreflang
attribute on a
and area
elements.
The type
attribute
gives the MIME type of the linked resource. It is
purely advisory. The value must be a valid MIME
type.
For external resource
links, the type
attribute
is used as a hint to user agents so that they can avoid fetching
resources they do not support. If the attribute
is present, then the user agent must assume that the resource is of
the given type (even if that is not a valid MIME type,
e.g. the empty string). If the attribute is omitted, but the
external resource link type has a default type defined, then the
user agent must assume that the resource is of that type. If the UA
does not support the given MIME type for the given link
relationship, then the UA should not obtain the resource; if the UA
does support the given MIME type for the given link
relationship, then the UA should obtain the resource at the
appropriate time as specified for the external resource
link's particular type. If the attribute is omitted, and the
external resource link type does not have a default type defined,
but the user agent would obtain the resource if the type
was known and supported, then the user agent should obtain the resource under the
assumption that it will be supported.
User agents must not consider the type
attribute authoritative —
upon fetching the resource, user agents must not use the type
attribute to determine its actual
type. Only the actual type (as defined in the next paragraph) is
used to determine whether to apply the resource, not the
aforementioned assumed type.
If the external resource link type defines rules for processing the resource's Content-Type metadata, then those rules apply. Otherwise, if the resource is expected to be an image, user agents may apply the image sniffing rules, with the official type being the type determined from the resource's Content-Type metadata, and use the resulting sniffed type of the resource as if it was the actual type. Otherwise, if neither of these conditions apply or if the user agent opts not to apply the image sniffing rules, then the user agent must use the resource's Content-Type metadata to determine the type of the resource. If there is no type metadata, but the external resource link type has a default type defined, then the user agent must assume that the resource is of that type.
The stylesheet
link type defines rules for processing the resource's Content-Type metadata.
Once the user agent has established the type of the resource, the user agent must apply the resource if it is of a supported type and the other relevant conditions apply, and must ignore the resource otherwise.
If a document contains style sheet links labeled as follows:
<link rel="stylesheet" href="A" type="text/plain"> <link rel="stylesheet" href="B" type="text/css"> <link rel="stylesheet" href="C">
...then a compliant UA that supported only CSS style sheets
would fetch the B and C files, and skip the A file (since
text/plain
is not the MIME type for CSS style
sheets).
For files B and C, it would then check the actual types returned
by the server. For those that are sent as text/css
, it
would apply the styles, but for those labeled as
text/plain
, or any other type, it would not.
If one of the two files was returned without a
Content-Type metadata, or with a syntactically
incorrect type like Content-Type: "null"
, then the default type
for stylesheet
links would kick
in. Since that default type is text/css
, the
style sheet would nonetheless be applied.
The title
attribute gives the title of the link. With one exception, it is
purely advisory. The value is text. The exception is for style sheet
links, where the title
attribute defines alternative style sheet sets.
The title
attribute on link
elements differs from the global
title
attribute of most other
elements in that a link without a title does not inherit the title
of the parent element: it merely has no title.
The sizes
attribute is used
with the icon
link type. The attribute
must not be specified on link
elements that do not have
a rel
attribute that specifies
the icon
keyword.
HTTP Link:
headers, if supported, must be
assumed to come before any links in the document, in the order that
they were given in the HTTP entity header. (URLs in these headers
are to be processed and resolved according to the rules given in the
relevant specification; the rules of this specification
don't apply.) [HTTP] [WEBLINK]
The IDL attributes href
, rel
, media
, hreflang
, and type
, and sizes
each must
reflect the respective content attributes of the same
name.
The IDL attribute relList
must reflect the rel
content attribute.
The IDL attribute disabled
only applies
to style sheet links. When the link
element defines a
style sheet link, then the disabled
attribute behaves as
defined for the alternative
style sheets DOM. For all other link
elements it
always return false and does nothing on setting.
The LinkStyle
interface is also implemented by
this element; the styling processing model defines
how. [CSSOM]
Here, a set of link
elements provide some style
sheets:
<!-- a persistent style sheet --> <link rel="stylesheet" href="default.css"> <!-- the preferred alternate style sheet --> <link rel="stylesheet" href="green.css" title="Green styles"> <!-- some alternate style sheets --> <link rel="alternate stylesheet" href="contrast.css" title="High contrast"> <link rel="alternate stylesheet" href="big.css" title="Big fonts"> <link rel="alternate stylesheet" href="wide.css" title="Wide screen">
The following example shows how you can specify versions of the page that use alternative formats, are aimed at other languages, and that are intended for other media:
<link rel=alternate href="/en/html" hreflang=en type=text/html title="English HTML"> <link rel=alternate href="/fr/html" hreflang=fr type=text/html title="French HTML"> <link rel=alternate href="/en/html/print" hreflang=en type=text/html media=print title="English HTML (for printing)"> <link rel=alternate href="/fr/html/print" hreflang=fr type=text/html media=print title="French HTML (for printing)"> <link rel=alternate href="/en/pdf" hreflang=en type=application/pdf title="English PDF"> <link rel=alternate href="/fr/pdf" hreflang=fr type=application/pdf title="French PDF">
meta
elementcharset
attribute is present, or if the element's http-equiv
attribute is in the Encoding declaration state: in a head
element.http-equiv
attribute is present but not in the Encoding declaration state: in a head
element.http-equiv
attribute is present but not in the Encoding declaration state: in a noscript
element that is a child of a head
element.name
attribute is present: where metadata content is expected.name
http-equiv
content
charset
interface HTMLMetaElement : HTMLElement { attribute DOMString name; attribute DOMString httpEquiv; attribute DOMString content; };
The meta
element represents various
kinds of metadata that cannot be expressed using the
title
, base
, link
,
style
, and script
elements.
The meta
element can represent document-level
metadata with the name
attribute, pragma directives with the http-equiv
attribute, and the
file's character encoding declaration when an HTML
document is serialized to string form (e.g. for transmission over
the network or for disk storage) with the charset
attribute.
Exactly one of the name
,
http-equiv
, and charset
attributes must be
specified.
If either name
or http-equiv
is specified, then
the content
attribute must
also be specified. Otherwise, it must be omitted.
The charset
attribute specifies the character encoding used by the
document. This is a character encoding declaration. If
the attribute is present in an XML
document, its value must be an ASCII
case-insensitive match for the string "UTF-8
" (and the document is therefore forced to use
UTF-8 as its encoding).
The charset
attribute on the meta
element has no effect in XML
documents, and is only allowed in order to facilitate migration to
and from XHTML.
There must not be more than one meta
element with a
charset
attribute per
document.
The content
attribute gives the value of the document metadata or pragma
directive when the element is used for those purposes. The allowed
values depend on the exact context, as described in subsequent
sections of this specification.
If a meta
element has a name
attribute, it sets
document metadata. Document metadata is expressed in terms of
name/value pairs, the name
attribute on the meta
element giving the name, and the
content
attribute on the same
element giving the value. The name specifies what aspect of metadata
is being set; valid names and the meaning of their values are
described in the following sections. If a meta
element
has no content
attribute,
then the value part of the metadata name/value pair is the empty
string.
The name
and content
IDL attributes
must reflect the respective content attributes of the
same name. The IDL attribute httpEquiv
must
reflect the content attribute http-equiv
.
This specification defines a few names for the name
attribute of the
meta
element.
Names are case-insensitive, and must be compared in an ASCII case-insensitive manner.
application-name
The value must be a short free-form string giving the name
of the Web application that the page represents. If the page is not
a Web application, the application-name
metadata name
must not be used. There must not be more than one meta
element with its name
attribute
set to the value application-name
per
document. User agents may use the application
name in UI in preference to the page's title
, since
the title might include status messages and the like relevant to
the status of the page at a particular moment in time instead of
just being the name of the application.
author
The value must be a free-form string giving the name of one of the page's authors.
description
The value must be a free-form string that describes the
page. The value must be appropriate for use in a directory of
pages, e.g. in a search engine. There must not be more than one
meta
element with its name
attribute set to the value description
per document.
generator
The value must be a free-form string that identifies one of the software packages used to generate the document. This value must not be used on hand-authored pages.
Here is what a tool called "Frontweaver" could include in its
output, in the page's head
element, to identify
itself as the tool used to generate the page:
<meta name=generator content="Frontweaver 8.2">
keywords
The value must be a set of comma-separated tokens, each of which is a keyword relevant to the page.
This page about typefaces on British motorways uses a
meta
element to specify some keywords that users
might use to look for the page:
<!DOCTYPE HTML> <html> <head> <title>Typefaces on UK motorways</title> <meta name="keywords" content="british,type face,font,fonts,highway,highways"> </head> <body> ...
Many search engines do not consider such keywords, because this feature has historically been used unreliably and even misleadingly as a way to spam search engine results in a way that is not helpful for users.
To obtain the list of keywords that the author has specified as applicable to the page, the user agent must run the following steps:
Let keywords be an empty list.
For each meta
element with a name
attribute and a content
attribute and whose
name
attribute's value is
keywords
, run the following
substeps:
Split the value
of the element's content
attribute on commas.
Add the resulting tokens, if any, to keywords.
Remove any duplicates from keywords.
Return keywords. This is the list of keywords that the author has specified as applicable to the page.
User agents should not use this information when there is insufficient confidence in the reliability of the value.
For instance, it would be reasonable for a content management system to use the keyword information of pages within the system to populate the index of a site-specific search engine, but a large-scale content aggregator that used this information would likely find that certain users would try to game its ranking mechanism through the use of inappropriate keywords.
Extensions to the predefined set of metadata names may be registered in the WHATWG Wiki MetaExtensions page. [WHATWGWIKI]
Anyone is free to edit the WHATWG Wiki MetaExtensions page at any time to add a type. These new names must be specified with the following information:
The actual name being defined. The name should not be confusingly similar to any other defined name (e.g. differing only in case).
A short non-normative description of what the metadata name's meaning is, including the format the value is required to be in.
A list of other names that have exactly the same processing requirements. Authors should not use the names defined to be synonyms, they are only intended to allow user agents to support legacy content. Anyone may remove synonyms that are not used in practice; only names that need to be processed as synonyms for compatibility with legacy content are to be registered in this way.
One of the following:
If a metadata name is found to be redundant with existing values, it should be removed and listed as a synonym for the existing value.
If a metadata name is registered in the "proposed" state for a period of a month or more without being used or specified, then it may be removed from the registry.
If a metadata name is added with the "proposed" status and found to be redundant with existing values, it should be removed and listed as a synonym for the existing value. If a metadata name is added with the "proposed" status and found to be harmful, then it should be changed to "discontinued" status.
Anyone can change the status at any time, but should only do so in accordance with the definitions above.
Conformance checkers must use the information given on the WHATWG Wiki MetaExtensions page to establish if a value is allowed or not: values defined in this specification or marked as "proposed" or "ratified" must be accepted, whereas values marked as "discontinued" or not listed in either this specification or on the aforementioned page must be rejected as invalid. Conformance checkers may cache this information (e.g. for performance reasons or to avoid the use of unreliable network connectivity).
When an author uses a new metadata name not defined by either this specification or the Wiki page, conformance checkers should offer to add the value to the Wiki, with the details described above, with the "proposed" status.
Metadata names whose values are to be URLs must not be proposed or accepted. Links must
be represented using the link
element, not the
meta
element.
When the http-equiv
attribute
is specified on a meta
element, the element is a pragma
directive.
The http-equiv
attribute is an enumerated attribute. The following
table lists the keywords defined for this attribute. The states
given in the first cell of the rows with keywords give the states to
which those keywords map. Some of the keywords
are non-conforming, as noted in the last column.
State | Keyword | Notes |
---|---|---|
Content Language | content-language
| Non-conforming |
Encoding declaration | content-type
| |
Default style | default-style
| |
Refresh | refresh
| |
Cookie setter | set-cookie
| Non-conforming |
When a meta
element is inserted into the document, if its
http-equiv
attribute is
present and represents one of the above states, then the user agent
must run the algorithm appropriate for that state, as described in
the following list:
http-equiv="content-language"
)
This feature is non-conforming. Authors are
encouraged to use the lang
attribute instead.
This pragma sets the pragma-set default language. Until the pragma is successfully processed, there is no pragma-set default language.
If another meta
element with an http-equiv
attribute in the
Content
Language state has already been successfully processed
(i.e. when it was inserted the user agent processed it and
reached the last step of this list of steps), then abort these
steps.
If the meta
element has no content
attribute, or if that
attribute's value is the empty string, then abort these
steps.
If the element's content
attribute contains a
U+002C COMMA character (,) then abort these steps.
Let input be the value of the
element's content
attribute.
Let position point at the first character of input.
Collect a sequence of characters that are not space characters.
Let the pragma-set default language be the string that resulted from the previous step.
This pragma is not exactly equivalent to the HTTP
Content-Language
header. [HTTP]
http-equiv="content-type"
)
The Encoding
declaration state is just an alternative form of setting
the charset
attribute: it is a
character encoding declaration. This state's user agent requirements are all handled
by the parsing section of the specification.
For meta
elements with an http-equiv
attribute in the
Encoding
declaration state, the content
attribute must have a
value that is an ASCII case-insensitive match for a
string that consists of: the literal string "text/html;
", optionally followed by any number of
space characters, followed by
the literal string "charset=
", followed by
the character encoding name of the character encoding
declaration.
A document must not contain both a meta
element
with an http-equiv
attribute in the Encoding declaration
state and a meta
element with the charset
attribute present.
The Encoding
declaration state may be used in HTML
documents, but elements with an http-equiv
attribute in that
state must not be used in XML documents.
http-equiv="default-style"
)
This pragma sets the name of the default alternative style sheet set.
http-equiv="refresh"
)
This pragma acts as timed redirect.
If another meta
element with an http-equiv
attribute in the
Refresh state
has already been successfully processed (i.e. when it was
inserted the user agent processed it and reached the last step of
this list of steps), then abort these steps.
If the meta
element has no content
attribute, or if that
attribute's value is the empty string, then abort these
steps.
Let input be the value of the
element's content
attribute.
Let position point at the first character of input.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and parse the resulting string using the rules for parsing non-negative integers. If the sequence of characters collected is the empty string, then no number will have been parsed; abort these steps. Otherwise, let time be the parsed number.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) and U+002E FULL STOP (.). Ignore any collected characters.
Let url be the address of the current page.
If the character in input pointed to
by position is a U+003B SEMICOLON (";
"), then advance position to
the next character. Otherwise, jump to the last step.
If the character in input pointed to by position is a U+0055 LATIN CAPITAL LETTER U character (U) or a U+0075 LATIN SMALL LETTER U character (u), then advance position to the next character. Otherwise, jump to the last step.
If the character in input pointed to by position is a U+0052 LATIN CAPITAL LETTER R character (R) or a U+0072 LATIN SMALL LETTER R character (r), then advance position to the next character. Otherwise, jump to the last step.
If the character in input pointed to by position is s U+004C LATIN CAPITAL LETTER L character (L) or a U+006C LATIN SMALL LETTER L character (l), then advance position to the next character. Otherwise, jump to the last step.
If the character in input pointed to
by position is a U+003D EQUALS SIGN ("=
"), then advance position to
the next character. Otherwise, jump to the last step.
If the character in input pointed to by position is either a U+0027 APOSTROPHE character (') or U+0022 QUOTATION MARK character ("), then let quote be that character, and advance position to the next character. Otherwise, let quote be the empty string.
Let url be equal to the substring of input from the character at position to the end of the string.
If quote is not the empty string, and there is a character in url equal to quote, then truncate url at that character, so that it and all subsequent characters are removed.
Strip any trailing space characters from the end of url.
Strip any U+0009 CHARACTER TABULATION (tab), U+000A LINE FEED (LF), and U+000D CARRIAGE RETURN (CR) characters from url.
Resolve the url value to an absolute URL,
relative to the meta
element. If this fails, abort
these steps.
Perform one or more of the following steps:
After the refresh has come due (as defined below), if the
user has not canceled the redirect and if the
meta
element's Document
's
browsing context did not have the sandboxed
automatic features browsing context flag set when the
Document
was created, navigate the
Document
's browsing context to url, with replacement enabled, and
with the Document
's browsing context
as the source browsing context.
For the purposes of the previous paragraph, a refresh is said to have come due as soon as the later of the following two conditions occurs:
meta
element was inserted into the
Document
, adjusted to take into account
user or user agent preferences.Provide the user with an interface that, when selected, navigates a browsing context to url, with the document's browsing context as the source browsing context.
Do nothing.
In addition, the user agent may, as with anything, inform the user of any and all aspects of its operation, including the state of any timers, the destinations of any timed redirects, and so forth.
For meta
elements with an http-equiv
attribute in the
Refresh state,
the content
attribute must
have a value consisting either of:
URL
", followed by a U+003D
EQUALS SIGN character (=), followed by a valid URL
that does not start with a literal U+0027 APOSTROPHE (') or
U+0022 QUOTATION MARK (") character.In the former case, the integer represents a number of seconds before the page is to be reloaded; in the latter case the integer represents a number of seconds before the page is to be replaced by the page at the given URL.
A news organization's front page could include the following
markup in the page's head
element, to ensure that
the page automatically reloads from the server every five
minutes:
<meta http-equiv="Refresh" content="300">
A sequence of pages could be used as an automated slide show by making each page refresh to the next page in the sequence, using markup such as the following:
<meta http-equiv="Refresh" content="20; URL=page4.html">
http-equiv="set-cookie"
)
This pragma sets an HTTP cookie. [COOKIES]
It is non-conforming. Real HTTP headers should be used instead.
If the meta
element has no content
attribute, or if that
attribute's value is the empty string, then abort these
steps.
Act as if receiving a set-cookie-string for
the document's address via a "non-HTTP" API,
consisting of the value of the element's content
attribute encoded as
UTF-8. [COOKIES] [RFC3629]
There must not be more than one meta
element with
any particular state in the document at a time.
Extensions to the predefined set of pragma directives may, under certain conditions, be registered in the WHATWG Wiki PragmaExtensions page. [WHATWGWIKI]
Such extensions must use a name that is identical to an HTTP header registered in the Permanent Message Header Field Registry, and must have behavior identical to that described for the HTTP header. [IANAPERMHEADERS]
Pragma directives corresponding to headers describing metadata, or not requiring specific user agent processing, must not be registered; instead, use metadata names. Pragma directives corresponding to headers that affect the HTTP processing model (e.g. caching) must not be registered, as they would result in HTTP-level behavior being different for user agents that implement HTML than for user agents that do not.
Anyone is free to edit the WHATWG Wiki PragmaExtensions page at any time to add a pragma directive satisfying these conditions. Such registrations must specify the following information:
The actual name being defined. The name must match a previously-registered HTTP name with the same requirements.
A short non-normative description of the purpose of the pragma directive.
Conformance checkers must use the information given on the WHATWG Wiki PragmaExtensions page to establish if a value is allowed or not: values defined in this specification or listed on the aforementioned page must be accepted, whereas values not listed in either this specification or on the aforementioned page must be rejected as invalid. Conformance checkers may cache this information (e.g. for performance reasons or to avoid the use of unreliable network connectivity).
A character encoding declaration is a mechanism by which the character encoding used to store or transmit a document is specified.
The following restrictions apply to character encoding declarations:
In addition, due to a number of restrictions on meta
elements, there can only be one meta
-based character
encoding declaration per document.
If an HTML document does not
start with a BOM, and if its encoding is not explicitly given by
Content-Type metadata, and the
document is not an iframe
srcdoc
document, then the
character encoding used must be an ASCII-compatible character
encoding, and, in addition, if that encoding isn't US-ASCII
itself, then the encoding must be specified using a
meta
element with a charset
attribute or a
meta
element with an http-equiv
attribute in the
Encoding declaration
state.
If the document is an iframe
srcdoc
document, the
document must not have a character encoding
declaration. (In this case, the source is already decoded,
since it is part of the document that contained the
iframe
.)
If an HTML document contains
a meta
element with a charset
attribute or a
meta
element with an http-equiv
attribute in the
Encoding declaration
state, then the character encoding used must be an
ASCII-compatible character encoding.
Authors are encouraged to use UTF-8. Conformance checkers may advise authors against using legacy encodings. [RFC3629]
Authoring tools should default to using UTF-8 for newly-created documents. [RFC3629]
Encodings in which a series of bytes in the range 0x20 to 0x7E
can encode characters other than the corresponding characters in the
range U+0020 to U+007E represent a potential security vulnerability:
a user agent that does not support the encoding (or does not support
the label used to declare the encoding, or does not use the same
mechanism to detect the encoding of unlabelled content as another
user agent) might end up interpreting technically benign plain text
content as HTML tags and JavaScript. For example, this applies to
encodings in which the bytes corresponding to "<script>
" in ASCII can encode a different
string. Authors should not use such encodings, which are known to
include JIS_C6226-1983,
JIS_X0212-1990, HZ-GB-2312, JOHAB (Windows code
page 1361), encodings based on ISO-2022, and encodings based on EBCDIC. Furthermore, authors must not
use the CESU-8, UTF-7, BOCU-1 and SCSU encodings, which also fall
into this category, because these encodings were never intended for
use for Web content.
[RFC1345]
[RFC1842]
[RFC1468]
[RFC2237]
[RFC1554]
[RFC1922]
[RFC1557]
[CESU8]
[UTF7]
[BOCU1]
[SCSU]
Authors should not use UTF-32, as the encoding detection algorithms described in this specification intentionally do not distinguish it from UTF-16. [UNICODE]
Using non-UTF-8 encodings can have unexpected results on form submission and URL encodings, which use the document's character encoding by default.
In XHTML, the XML declaration should be used for inline character encoding information, if necessary.
In HTML, to declare that the character encoding is UTF-8, the
author could include the following markup near the top of the
document (in the head
element):
<meta charset="utf-8">
In XML, the XML declaration would be used instead, at the very top of the markup:
<?xml version="1.0" encoding="utf-8"?>
style
elementscoped
attribute is present: flow content.scoped
attribute is absent: where metadata content is expected.scoped
attribute is absent: in a noscript
element that is a child of a head
element.scoped
attribute is present: where flow content is expected, but before any other flow content other than other style
elements and inter-element whitespace.type
attribute, but must match requirements described in prose below.media
type
scoped
title
attribute has special semantics on this element.interface HTMLStyleElement : HTMLElement {
attribute boolean disabled;
attribute DOMString media;
attribute DOMString type;
attribute boolean scoped;
};
HTMLStyleElement implements LinkStyle;
The style
element allows authors to embed style
information in their documents. The style
element is
one of several inputs to the styling processing
model. The element does not represent content for the user.
The type
attribute gives the styling language. If the attribute is present,
its value must be a valid MIME type that designates a
styling language. The charset
parameter must
not be specified. The default value for the type
attribute, which is used if the
attribute is absent, is "text/css
". [RFC2318]
When examining types to determine if they support the language,
user agents must not ignore unknown MIME parameters — types
with unknown parameters must be assumed to be unsupported. The charset
parameter must be treated as an unknown
parameter for the purpose of comparing MIME
types here.
The media
attribute says which media the styles apply to. The value must be a
valid media query. The user agent
must apply the styles when the media
attribute's value
matches the environment and the other relevant
conditions apply, and must not apply them otherwise.
The styles might be further limited in scope,
e.g. in CSS with the use of @media
blocks. This specification does not override such further
restrictions or requirements.
The default, if the media
attribute is omitted, is
"all
", meaning that by default styles apply to
all media.
The scoped
attribute is a boolean attribute. If set, it indicates
that the styles are intended just for the subtree rooted at the
style
element's parent element, as opposed to the whole
Document
.
If the scoped
attribute is
present, then the user agent must apply the specified style
information only to the style
element's parent element
(if any), and that element's child nodes. Otherwise, the specified
styles must, if applied, be applied to the entire document.
For scoped CSS resources, the effect of @-rules must be scoped to
the scoped sheet and its subresources, even if the @-rule in
question would ordinarily apply to all style sheets that affect the
Document
. Any '@page' rules in scoped CSS resources
must be ignored.
For example, an '@font-face' rule defined in a scoped style sheet would only define the font for the purposes of font rules in the scoped section; style sheets outside the scoped section using the same font name would not end up using that embedded font.
The title
attribute on
style
elements defines alternative style sheet
sets. If the style
element has no title
attribute, then it has no
title; the title
attribute of
ancestors does not apply to the style
element. [CSSOM]
The title
attribute on style
elements, like the title
attribute on link
elements, differs from the global title
attribute in that a
style
block without a title does not inherit the title
of the parent element: it merely has no title.
The textContent
of a style
element must
match the style
production in the following
ABNF, the character set for which is Unicode. [ABNF]
style = no-c-start *( c-start no-c-end c-end no-c-start ) no-c-start = <any string that doesn't contain a substring that matches c-start > c-start = "<!--" no-c-end = <any string that doesn't contain a substring that matches c-end > c-end = "-->"
All descendant elements must be processed, according to their
semantics, before the style
element itself is
evaluated. For styling languages that consist of pure text (as
opposed to XML), user agents must evaluate style
elements by passing the concatenation of the contents of all the
text nodes that are direct children
of the style
element (not any other nodes such as
comments or elements), in tree order, to the style
system. For XML-based styling languages, user agents must pass all
the child nodes of the style
element to the style
system.
All URLs found by the styling language's processor must be resolved, relative to the element (or as defined by the styling language), when the processor is invoked.
Once the attempts to obtain the style sheet's critical
subresources, if any, are complete, or, if the style sheet
has no critical subresources, once the style sheet has
been parsed and processed, the user agent must, if the loads were
successful or there were none, queue a task to
fire a simple event named load
at the style
element,
or, if one of the style sheet's critical subresources
failed to completely load for any reason (e.g. DNS error, HTTP 404
response, a connection being prematurely closed, unsupported
Content-Type), queue a task to fire a simple
event named error
at the
style
element. Non-network errors in processing the
style sheet or its subresources (e.g. CSS parse errors, PNG decoding
errors) are not failures for the purposes of this paragraph.
The task source for these tasks is the DOM manipulation task source.
The element must delay the load event of the element's document until all the attempts to obtain the style sheet's critical subresources, if any, are complete.
This specification does not specify a style system, but CSS is expected to be supported by most Web browsers. [CSS]
The media
, type
and scoped
IDL attributes
must reflect the respective content attributes of the
same name.
The disabled
IDL attribute behaves as defined for the alternative style sheets
DOM.
The LinkStyle
interface is also implemented by
this element; the styling processing model defines
how. [CSSOM]
The following document has its emphasis styled as bright red text rather than italics text, while leaving titles of works and Latin words in their default italics. It shows how using appropriate elements enables easier restyling of documents.
<!DOCTYPE html> <html lang="en-US"> <head> <title>My favorite book</title> <style> body { color: black; background: white; } em { font-style: normal; color: red; } </style> </head> <body> <p>My <em>favorite</em> book of all time has <em>got</em> to be <cite>A Cat's Life</cite>. It is a book by P. Rahmel that talks about the <i lang="la">Felis Catus</i> in modern human society.</p> </body> </html>
The link
and style
elements can provide
styling information for the user agent to use when rendering the
document. The DOM Styling specification specifies what styling
information is to be used by the user agent and how it is to be
used. [CSSOM]
The style
and link
elements implement
the LinkStyle
interface. [CSSOM]
For style
elements, if the user agent does not
support the specified styling language, then the sheet
attribute of the element's
LinkStyle
interface must return null. Similarly,
link
elements that do not represent external resource links that contribute to
the styling processing model (i.e. that do not have a stylesheet
keyword in their rel
attribute), and link
elements whose specified resource has not yet been fetched, or is
not in a supported styling language, must have their
LinkStyle
interface's sheet
attribute return null.
Otherwise, the LinkStyle
interface's sheet
attribute must return a
StyleSheet
object with the following properties: [CSSOM]
The style sheet type must be the same as the style's specified
type. For style
elements, this is the same as the
type
content attribute's
value, or text/css
if that is omitted. For
link
elements, this is the Content-Type metadata of the specified
resource.
For link
elements, the location must be the
result of resolving the
URL given by the element's href
content attribute, relative to
the element, or the empty string if that fails. For
style
elements, there is no location.
The media must be the same as the value of the element's
media
content attribute, or the empty string,
if the attribute is omitted.
The title must be the same as the value of the element's
title
content attribute, if the
attribute is present and has a non-empty value. If the attribute is
absent or its value is the empty string, then the style sheet does
not have a title (it is the empty string). The title is used for
defining alternative style sheet sets.
For link
elements, true if the link is an
alternative stylesheet. In all other cases, false.
The same object must be returned each time.
The disabled
IDL
attribute on link
and style
elements must
return false and do nothing on setting, if the sheet
attribute of their
LinkStyle
interface is null. Otherwise, it must return
the value of the StyleSheet
interface's disabled
attribute on
getting, and forward the new value to that same attribute on
setting.
The rules for handling alternative style sheets are defined in the CSS object model specification. [CSSOM]
Style sheets, whether added by a link
element, a
style
element, an <?xml-stylesheet>
PI,
an HTTP Link:
header, or some other
mechanism, have a style sheet ready flag, which is
initially unset.
When a style sheet is ready to be applied, its style sheet
ready flag must be set. If the style sheet referenced no
other resources (e.g. it was an internal style sheet given by a
style
element with no @import
rules), then the style rules must be synchronously made available to
script; otherwise, the style rules must only be made available to
script once the event loop reaches its "update the
rendering" step.
A style sheet in the context of the Document
of an
HTML parser or XML parser is said to be
a style sheet that is blocking scripts if the element was
created by that Document
's parser, and the element is
either a style
element or a link
element
that was an external resource link that
contributes to the styling processing model when the element
was created by the parser, and the element's style sheet was enabled
when the element was created by the parser, and the element's
style sheet ready flag is not yet set, and, the last
time the event loop reached step 1, the element was
in that Document
,
and the user agent hasn't given up on that particular style sheet
yet. A user agent may give up on a style sheet at any time.
A Document
has a style sheet that is blocking
scripts if there is either a style sheet that is
blocking scripts in the context of that
Document
, or if that Document
is in a
browsing context that has a parent browsing
context, and the active document of that
parent browsing context itself has a style sheet
that is blocking scripts.
A Document
has no style sheet that is blocking
scripts if it does not have a style sheet that is blocking scripts
as defined in the previous paragraph.
Scripts allow authors to add interactivity to their documents.
Authors are encouraged to use declarative alternatives to scripting where possible, as declarative mechanisms are often more maintainable, and many users disable scripting.
For example, instead of using script to show or hide a section
to show more details, the details
element could be
used.
Authors are also encouraged to make their applications degrade gracefully in the absence of scripting support.
For example, if an author provides a link in a table header to dynamically resort the table, the link could also be made to function without scripts by requesting the sorted table from the server.
script
elementsrc
attribute, depends on the value of the type
attribute, but must match
script content restrictions.src
attribute, the element must be either empty or contain only
script documentation that also matches script
content restrictions.src
async
defer
type
charset
interface HTMLScriptElement : HTMLElement { attribute DOMString src; attribute boolean async; attribute boolean defer; attribute DOMString type; attribute DOMString charset; attribute DOMString text; };
The script
element allows authors to include dynamic
script and data blocks in their documents. The element does not
represent content for the user.
When used to include dynamic scripts, the scripts may either be
embedded inline or may be imported from an external file using the
src
attribute. If the language
is not that described by "text/javascript
",
then the type
attribute must
be present, as described below. Whatever language is used, the
contents of the script
element must conform with the
requirements of that language's specification.
When used to include data blocks (as opposed to scripts), the
data must be embedded inline, the format of the data must be given
using the type
attribute, the
src
attribute must not be
specified, and the contents of the script
element must
conform to the requirements defined for the format used.
The type
attribute gives the language of the script or format of the data. If
the attribute is present, its value must be a valid MIME
type. The charset
parameter must not be
specified. The default, which is used if the attribute is absent,
is "text/javascript
".
The src
attribute, if specified, gives the address of the external script
resource to use. The value of the attribute must be a valid
non-empty URL potentially surrounded by spaces identifying a
script resource of the type given by the type
attribute, if the attribute is
present, or of the type "text/javascript
", if
the attribute is absent. A resource is a script resource of a given
type if that type identifies a scripting language and the resource
conforms with the requirements of that language's specification.
The charset
attribute gives the character encoding of the external script
resource. The attribute must not be specified if the src
attribute is not present. If the
attribute is set, its value must be a valid character encoding name,
must be an ASCII case-insensitive match for the
preferred MIME name for that encoding, and must match
the encoding given in the charset
parameter of
the Content-Type metadata of the
external file, if any. [IANACHARSET]
The async
and
defer
attributes
are boolean attributes that
indicate how the script should be executed. The defer
and async
attributes must not be
specified if the src
attribute
is not present.
There are three possible modes that can be selected using these
attributes. If the async
attribute is present, then the script will be executed
asynchronously, as soon as it is available. If the async
attribute is not present but
the defer
attribute is
present, then the script is executed when the page has finished
parsing. If neither attribute is present, then the script is
fetched and executed immediately, before the user agent continues
parsing the page.
The exact processing details for these attributes
are, for mostly historical reasons, somewhat non-trivial, involving
a number of aspects of HTML. The implementation requirements are
therefore by necessity scattered throughout the specification. The
algorithms below (in this section) describe the core of this
processing, but these algorithms reference and are referenced by the
parsing rules for script
start
and end tags in HTML, in foreign content, and in XML, the rules for the document.write()
method, the
handling of scripting, etc.
The defer
attribute may be
specified even if the async
attribute is specified, to cause legacy Web browsers that only
support defer
(and not async
) to fall back to the defer
behavior instead of the
synchronous blocking behavior that is the default.
Changing the src
, type
, charset
, async
, and defer
attributes dynamically has no
direct effect; these attribute are only used at specific times
described below.
A script
element has several associated pieces of
state.
The first is a flag indicating whether or not the script block
has been "already started". Initially,
script
elements must have this flag unset (script
blocks, when created, are not "already started"). When a
script
element is cloned, the "already started" flag, if
set, must be propagated to the clone when it is created.
The second is a flag indicating whether the element was
"parser-inserted". Initially, script
elements must have this flag unset. It is set by the HTML
parser and the XML parser on script
elements they insert and affects the processing of those
elements.
The third is a flag indicating whether the element will
"force-async". Initially, script
elements
must have this flag set. It is unset by the HTML parser
and the XML parser on script
elements they
insert. In addition, whenever a script
element whose
"force-async" flag is set has a async
content attribute added, the
element's "force-async" flag must be unset.
The fourth is a flag indicating whether or not the script block is
"ready to be parser-executed". Initially,
script
elements must have this flag unset (script
blocks, when created, are not "ready to be parser-executed"). This
flag is used only for elements that are also
"parser-inserted", to let the parser know when to
execute the script.
The last few pieces of state are the script block's
type, the script block's character
encoding, and the script block's fallback
character encoding. They are determined when the script
is prepared, based on the attributes on the element at that time,
and the Document
of the script
element.
When a script
element that is not marked as being
"parser-inserted" experiences one of the events listed
in the following list, the user agent must synchronously prepare the script
element:
script
element gets inserted into a document.script
element is in a
Document
and its child nodes are changed.script
element is in a
Document
and has a src
attribute set where previously
the element had no such attribute.To prepare a script, the user agent must act as follows:
If the script
element is marked as having
"already started", then the user agent must abort
these steps at this point. The script is not executed.
If the element has its "parser-inserted" flag set, then set was-parser-inserted to true and unset the element's "parser-inserted" flag. Otherwise, set was-parser-inserted to false.
This is done so that if parser-inserted
script
elements fail to run when the parser tries to
run them, e.g. because they are empty or specify an unsupported
scripting language, another script can later mutate them and cause
them to run again.
If was-parser-inserted is true and the
element does not have an async
attribute, then set the
element's "force-async" flag to true.
This is done so that if a parser-inserted
script
element fails to run when the parser tries to
run it, but it is later executed after a script dynamically
updates it, it will execute asynchronously even if the
async
attribute isn't
set.
If the element has no src
attribute, and its child nodes, if any, consist only of comment
nodes and empty text nodes, then
the user agent must abort these steps at this point. The script is
not executed.
If the element is not in a Document
,
then the user agent must abort these steps at this point. The
script is not executed.
If either:
script
element has a type
attribute and its value is
the empty string, orscript
element has no type
attribute but it has a language
attribute and
that attribute's value is the empty string, orscript
element has neither a type
attribute nor a language
attribute, then...let the script block's type for this
script
element be "text/javascript
".
Otherwise, if the script
element has a type
attribute, let the
script block's type for this script
element be
the value of that attribute with any leading or trailing sequences
of space characters
removed.
Otherwise, the element has a non-empty language
attribute; let
the script block's type for this script
element be the concatenation of the string "text/
" followed by the value of the language
attribute.
The language
attribute is never
conforming, and is always ignored if there is a type
attribute present.
If the user agent does not support the scripting
language given by the script block's type for
this script
element, then the user agent must abort
these steps at this point. The script is not executed.
If was-parser-inserted is true, then flag the element as "parser-inserted" again, and set the element's "force-async" flag to false.
The user agent must set the element's "already started" flag.
The state of the element at this moment is later used to determine the script source.
If the element is flagged as "parser-inserted",
but the element's Document
is not the
Document
of the parser that created the element, then
abort these steps.
If scripting is
disabled for the script
element, then the user
agent must abort these steps at this point. The script is not
executed.
The definition of scripting is disabled means
that, amongst others, the following scripts will not execute:
scripts in XMLHttpRequest
's responseXML
documents, scripts in DOMParser
-created documents,
scripts in documents created by XSLTProcessor
's transformToDocument
feature, and scripts that are first inserted by a script into a
Document
that was created using the createDocument()
API. [XHR] [DOMPARSER] [DOMCORE]
If the script
element has an event
attribute and a for
attribute, then run these
substeps:
Let for be the value of the for
attribute.
Let event be the value of the event
attribute.
Strip leading and trailing whitespace from event and for.
If for is not an ASCII
case-insensitive match for the string "window
", then the user agent must abort these
steps at this point. The script is not executed.
If event is not an ASCII
case-insensitive match for either the string "onload
" or the string "onload()
", then the user agent must abort these
steps at this point. The script is not executed.
If the script
element has a charset
attribute, then let
the script block's character encoding for this
script
element be the encoding given by the charset
attribute.
Otherwise, let the script block's fallback character
encoding for this script
element be the same as
the encoding of the
document itself.
Only one of these two pieces of state is set.
If the element has a src
attribute whose value is not the empty string, then the value of
that attribute must be resolved
relative to the element, and if that is successful, the specified
resource must then be fetched, from the
origin of the element's Document
.
If the src
attribute's
value is the empty string or if it could not be resolved, then the
user agent must queue a task to fire a simple
event named error
at the
element, and abort these steps.
For historical reasons, if the URL is a javascript:
URL, then the user agent must not, despite the requirements
in the definition of the fetching
algorithm, actually execute the script in the URL; instead the
user agent must act as if it had received an empty HTTP 400
response.
For performance reasons, user agents may start fetching the
script as soon as the attribute is set, instead, in the hope that
the element will be inserted into the document. Either way, once
the element is inserted into the document, the load must have
started. If the UA performs such prefetching, but the element is
never inserted in the document, or the src
attribute is dynamically
changed, then the
user agent will not execute the script, and the fetching process
will have been effectively wasted.
Then, the first of the following options that describes the situation must be followed:
src
attribute, and the element has
a defer
attribute, and the
element has been flagged as "parser-inserted", and
the element does not have an async
attributeThe element must be added to the end of the list of
scripts that will execute when the document has finished
parsing associated with the Document
of the
parser that created the element.
The task that the networking task source places on the task queue once the fetching algorithm has completed must set the element's "ready to be parser-executed" flag. The parser will handle executing the script.
src
attribute, and the
element has been flagged as "parser-inserted", and
the element does not have an async
attributeThe element is the pending parsing-blocking
script of the Document
of the parser that
created the element. (There can only be one such script per
Document
at a time.)
The task that the networking task source places on the task queue once the fetching algorithm has completed must set the element's "ready to be parser-executed" flag. The parser will handle executing the script.
src
attribute, and
the element has been flagged as "parser-inserted",
and the Document
of the HTML parser or
XML parser that created the script
element has a style sheet that is blocking
scriptsThe element is the pending parsing-blocking
script of the Document
of the parser that
created the element. (There can only be one such script per
Document
at a time.)
Set the element's "ready to be parser-executed" flag. The parser will handle executing the script.
src
attribute, does not have an
async
attribute, and does
not have the "force-async" flag setThe element must be added to the end of the list of
scripts that will execute in order as soon as possible
associated with the Document
of the
script
element at the time the prepare a
script algorithm started.
The task that the networking task source places on the task queue once the fetching algorithm has completed must run the following steps:
If the element is not now the first element in the list of scripts that will execute in order as soon as possible to which it was added above, then mark the element as ready but abort these steps without executing the script yet.
Execution: Execute the script block corresponding to the first script element in this list of scripts that will execute in order as soon as possible.
Remove the first element from this list of scripts that will execute in order as soon as possible.
If this list of scripts that will execute in order as soon as possible is still not empty and the first entry has already been marked as ready, then jump back to the step labeled execution.
src
attributeThe element must be added to the set of scripts that
will execute as soon as possible of the
Document
of the script
element at the
time the prepare a script algorithm started.
The task that the networking task source places on the task queue once the fetching algorithm has completed must execute the script block and then remove the element from the set of scripts that will execute as soon as possible.
Fetching an external script must delay the load event of the element's document until the task that is queued by the networking task source once the resource has been fetched (defined above) has been run.
The pending parsing-blocking script of a
Document
is used by the Document
's
parser(s).
If a script
element that blocks a
parser gets moved to another Document
before it would
normally have stopped blocking that parser, it nonetheless continues
blocking that parser until the condition that causes it to be
blocking the parser no longer applies (e.g. if the script is a
pending parsing-blocking script because there was
a style sheet that is blocking scripts when it was
parsed, but then the script is moved to another
Document
before the style sheet loads, the script still
blocks the parser until the style sheets are all loaded, at which
time the script executes and the parser is unblocked).
When the user agent is required to execute a script block, it must run the following steps:
If the element is flagged as "parser-inserted",
but the element's Document
is not the
Document
of the parser that created the element, then
abort these steps.
Jump to the appropriate set of steps from the list below:
Executing the script block must just consist of firing a simple event named
error
at the element.
Executing the script block must consist of running the
following steps. For the purposes of these steps, the script is
considered to be from an external file if, while the
prepare a script algorithm above was running for
this script, the script
element had a src
attribute specified.
Initialize the script block's source as follows:
The contents of that file, interpreted as string of Unicode characters, are the script source.
To obtain the string of Unicode characters, the user agent run the following steps:
If the resource's Content Type metadata, if any, specifies a character encoding, and the user agent supports that encoding, then let character encoding be that encoding, and jump to the bottom step in this series of steps.
If the algorithm above set the script block's character encoding, then let character encoding be that encoding, and jump to the bottom step in this series of steps.
For each of the rows in the following table, starting with the first one and going down, if the file has as many or more bytes available than the number of bytes in the first column, and the first bytes of the file match the bytes given in the first column, then set character encoding to the encoding given in the cell in the second column of that row, and jump to the bottom step in this series of steps:
Bytes in Hexadecimal | Encoding |
---|---|
FE FF | Big-endian UTF-16 |
FF FE | Little-endian UTF-16 |
EF BB BF | UTF-8 |
This step looks for Unicode Byte Order Marks (BOMs).
Let character encoding be the script block's fallback character encoding.
Convert the file to Unicode using character encoding, following the rules for doing so given by the specification for the script block's type.
The external file is the script source. When it is later executed, it must be interpreted in a manner consistent with the specification defining the language given by the script block's type.
The value of the text
IDL attribute at the
time the element's "already started" flag was
last set is the script source.
The child nodes of the script
element at the
time the element's "already started" flag was
last set are the script source.
If the script is from an external file, then increment the
ignore-destructive-writes counter of the
script
element's Document
. Let neutralized doc be that
Document
.
Create a
script from the script
element node, using
the script block's source and the script
block's type.
This is where the script is compiled and actually executed.
Decrement the ignore-destructive-writes counter of neutralized doc, if it was incremented in the earlier step.
If the script is from an external file, fire a simple
event named load
at the
script
element.
Otherwise, the script is internal; queue a
task to fire a simple event named load
at the script
element.
The IDL attributes src
, type
, charset
, and defer
, each must
reflect the respective content attributes of the same
name.
The async
IDL
attribute controls whether the element will execute asynchronously
or not. If the element's "force-async" flag is set,
then, on getting, the async
IDL attribute must return true, and on setting, the
"force-async" flag must first be unset, and then the
content attribute must be removed if the IDL attribute's new value
is false, and must be set to the empty string if the IDL attribute's
new value is true. If the element's "force-async" flag
is not set, the IDL attribute must reflect the
async
content attribute.
text
[ = value ]Returns the contents of the element, ignoring child nodes that aren't text nodes.
Can be set, to replace the element's children with the given value.
The IDL attribute text
must return a
concatenation of the contents of all the text nodes that are direct children of the
script
element (ignoring any other nodes such as
comments or elements), in tree order. On setting, it must act the
same way as the textContent
IDL attribute.
When inserted using the document.write()
method,
script
elements execute (typically synchronously), but
when inserted using innerHTML
and outerHTML
attributes, they do not
execute at all.
In this example, two script
elements are used. One
embeds an external script, and the other includes some data.
<script src="game-engine.js"></script> <script type="text/x-game-map"> ........U.........e o............A....e .....A.....AAA....e .A..AAA...AAAAA...e </script>
The data in this case might be used by the script to generate the map of a video game. The data doesn't have to be used that way, though; maybe the map data is actually embedded in other parts of the page's markup, and the data block here is just used by the site's search engine to help users who are looking for particular features in their game maps.
The following sample shows how a script element can be used to
define a function that is then used by other parts of the
document. It also shows how a script
element can be
used to invoke script while the document is being parsed, in this
case to initialize the form's output.
<script> function calculate(form) { var price = 52000; if (form.elements.brakes.checked) price += 1000; if (form.elements.radio.checked) price += 2500; if (form.elements.turbo.checked) price += 5000; if (form.elements.sticker.checked) price += 250; form.elements.result.value = price; } </script> <form name="pricecalc" onsubmit="return false" onchange="calculate(this)"> <fieldset> <legend>Work out the price of your car</legend> <p>Base cost: £52000.</p> <p>Select additional options:</p> <ul> <li><label><input type=checkbox name=brakes> Ceramic brakes (£1000)</label></li> <li><label><input type=checkbox name=radio> Satellite radio (£2500)</label></li> <li><label><input type=checkbox name=turbo> Turbo charger (£5000)</label></li> <li><label><input type=checkbox name=sticker> "XZ" sticker (£250)</label></li> </ul> <p>Total: £<output name=result></output></p> </fieldset> <script> calculate(document.forms.pricecalc); </script> </form>
A user agent is said to support the scripting language if the script block's type is an ASCII case-insensitive match for the MIME type string of a scripting language that the user agent implements.
The following lists some MIME type strings and the languages to which they refer:
application/ecmascript
"application/javascript
"application/x-ecmascript
"application/x-javascript
"text/ecmascript
"text/javascript
"text/javascript1.0
"text/javascript1.1
"text/javascript1.2
"text/javascript1.3
"text/javascript1.4
"text/javascript1.5
"text/jscript
"text/livescript
"text/x-ecmascript
"text/x-javascript
"text/javascript;e4x=1
"User agents may support other MIME types and other languages.
When examining types to determine if they support the language,
user agents must not ignore unknown MIME parameters — types
with unknown parameters must be assumed to be unsupported. The charset
parameter must be treated as an unknown
parameter for the purpose of comparing MIME
types here.
script
elementsThe textContent
of a script
element
must match the script
production in the
following ABNF, the character set for which is Unicode. [ABNF]
script = data1 *( escape [ script-start data3 ] "-->" data1 ) [ escape ] escape = "<!--" data2 *( script-start data3 script-end data2 ) data1 = <any string that doesn't contain a substring that matches not-data1> not-data1 = "<!--" data2 = <any string that doesn't contain a substring that matches not-data2> not-data2 = script-start / "-->" data3 = <any string that doesn't contain a substring that matches not-data3> not-data3 = script-end / "-->" script-start = lt s c r i p t tag-end script-end = lt slash s c r i p t tag-end lt = %x003C ; U+003C LESS-THAN SIGN character (<) slash = %x002F ; U+002F SOLIDUS character (/) s = %x0053 ; U+0053 LATIN CAPITAL LETTER S s =/ %x0073 ; U+0073 LATIN SMALL LETTER S c = %x0043 ; U+0043 LATIN CAPITAL LETTER C c =/ %x0063 ; U+0063 LATIN SMALL LETTER C r = %x0052 ; U+0052 LATIN CAPITAL LETTER R r =/ %x0072 ; U+0072 LATIN SMALL LETTER R i = %x0049 ; U+0049 LATIN CAPITAL LETTER I i =/ %x0069 ; U+0069 LATIN SMALL LETTER I p = %x0050 ; U+0050 LATIN CAPITAL LETTER P p =/ %x0070 ; U+0070 LATIN SMALL LETTER P t = %x0054 ; U+0054 LATIN CAPITAL LETTER T t =/ %x0074 ; U+0074 LATIN SMALL LETTER T tag-end = %x0009 ; U+0009 CHARACTER TABULATION (tab) tag-end =/ %x000A ; U+000A LINE FEED (LF) tag-end =/ %x000C ; U+000C FORM FEED (FF) tag-end =/ %x0020 ; U+0020 SPACE tag-end =/ %x002F ; U+002F SOLIDUS (/) tag-end =/ %x003E ; U+003E GREATER-THAN SIGN (>)
When a script
element contains script
documentation, there are further restrictions on the contents
of the element, as described in the section below.
If a script
element's src
attribute is specified, then the
contents of the script
element, if any, must be such
that the value of the text
IDL
attribute, which is derived from the element's contents, matches the
documentation
production in the following
ABNF, the character set for which is Unicode. [ABNF]
documentation = *( *( space / tab / comment ) [ line-comment ] newline ) comment = slash star *( not-star / star not-slash ) 1*star slash line-comment = slash slash *not-newline ; characters tab = %x0009 ; U+0009 CHARACTER TABULATION (tab) newline = %x000A ; U+000A LINE FEED (LF) space = %x0020 ; U+0020 SPACE star = %x002A ; U+002A ASTERISK (*) slash = %x002F ; U+002F SOLIDUS (/) not-newline = %x0000-0009 / %x000B-10FFFF ; a Unicode character other than U+000A LINE FEED (LF) not-star = %x0000-0029 / %x002B-10FFFF ; a Unicode character other than U+002A ASTERISK (*) not-slash = %x0000-002E / %x0030-10FFFF ; a Unicode character other than U+002F SOLIDUS (/)
This corresponds to putting the contents of the element in JavaScript comments.
This requirement is in addition to the earlier
restrictions on the syntax of contents of script
elements.
This allows authors to include documentation, such as license
information or API information, inside their documents while still
referring to external script files. The syntax is constrained so
that authors don't accidentally include what looks like valid
script while also providing a src
attribute.
<script src="cool-effects.js"> // create new instances using: // var e = new Effect(); // start the effect using .play, stop using .stop: // e.play(); // e.stop(); </script>
script
elements and XSLTThis section is non-normative.
This specification does not define how XSLT interacts with the
script
element (or, indeed, how XSLT processing
triggers the stop parsing steps, how it interacts with
the navigation algorithm, or how it
fits in with the event loop). However, in the absence
of another specification actually defining this, here are some
guidelines for implementors, based on existing implementations:
When an XSLT transformation program is triggered by an <?xml-stylesheet?>
processing instruction and
the browser implements a direct-to-DOM transformation,
script
elements created by the XSLT processor need to
be marked "parser-inserted" and run in document order
(modulo scripts marked defer
or async
), asynchronously
while the transformation is occurring.
The XSLTProcessor.transformToDocument()
method adds elements to a Document
that is not in a
browsing context, and, accordingly, any
script
elements they create need to have their
"already started" flag set in the prepare a
script algorithm and never get executed (scripting is disabled). Such
script
elements still need to be marked
"parser-inserted", though, such that their async
IDL attribute will return
false in the absence of an async
content attribute.
The XSLTProcessor.transformToFragment()
method needs to create a fragment that is equivalent to one built
manually by creating the elements using document.createElementNS()
.
For instance, it needs to create script
elements that
aren't "parser-inserted" and that don't have their
"already started" flag set, so that they will execute
when the fragment is inserted into a document.
The main distinction between the first two cases and the last
case is that the first two operate on Document
s and the
last operates on a fragment.
noscript
elementhead
element of an HTML document, if there are no ancestor noscript
elements.noscript
elements.head
element: in any order, zero or more link
elements, zero or more style
elements, and zero or more meta
elements.head
element: transparent, but there must be no noscript
element descendants.HTMLElement
.The noscript
element represents nothing
if scripting is enabled, and
represents its children if scripting is disabled. It is used
to present different markup to user agents that support scripting
and those that don't support scripting, by affecting how the
document is parsed.
When used in HTML documents, the allowed content model is as follows:
head
element, if scripting is disabled for the
noscript
elementThe noscript
element must contain only
link
, style
, and meta
elements.
head
element, if scripting is enabled for the
noscript
elementThe noscript
element must contain only text,
except that invoking the HTML fragment parsing
algorithm with
the noscript
element as the context element and the
text contents as the input must result in a
list of nodes that consists only of link
,
style
, and meta
elements that would be
conforming if they were children of the noscript
element, and no parse
errors.
head
elements, if scripting is disabled for the
noscript
elementThe noscript
element's content model is
transparent, with the additional restriction that a
noscript
element must not have a noscript
element as an ancestor (that is, noscript
can't be
nested).
head
elements, if scripting is enabled for the
noscript
elementThe noscript
element must contain only text,
except that the text must be such that running the following
algorithm results in a conforming document with no
noscript
elements and no script
elements, and such that no step in the algorithm causes an
HTML parser to flag a parse error:
script
element from the
document.noscript
element in the
document. For every noscript
element in that list,
perform the following steps:
noscript
element.noscript
element, and call these
elements the before children.noscript
element, and
call these elements the after children.noscript
element.innerHTML
attribute of the parent element to the value
of s. (This, as a side-effect, causes the
noscript
element to be removed from the
document.)All these contortions are required because, for
historical reasons, the noscript
element is handled
differently by the HTML parser based on whether scripting was enabled or not when the
parser was invoked.
The noscript
element must not be used in XML
documents.
The noscript
element is only
effective in the HTML syntax, it has no effect in
the XHTML syntax.
The noscript
element has no other requirements. In
particular, children of the noscript
element are not
exempt from form submission, scripting, and so forth,
even when scripting is enabled
for the element.
In the following example, a noscript
element is
used to provide fallback for a script.
<form action="calcSquare.php"> <p> <label for=x>Number</label>: <input id="x" name="x" type="number"> </p> <script> var x = document.getElementById('x'); var output = document.createElement('p'); output.textContent = 'Type a number; it will be squared right then!'; x.form.appendChild(output); x.form.onsubmit = function () { return false; } x.oninput = function () { var v = x.valueAsNumber; output.textContent = v + ' squared is ' + v * v; }; </script> <noscript> <input type=submit value="Calculate Square"> </noscript> </form>
When script is disabled, a button appears to do the calculation on the server side. When script is enabled, the value is computed on-the-fly instead.
The noscript
element is a blunt
instrument. Sometimes, scripts might be enabled, but for some
reason the page's script might fail. For this reason, it's
generally better to avoid using noscript
, and to
instead design the script to change the page from being a
scriptless page to a scripted page on the fly, as in the next
example:
<form action="calcSquare.php"> <p> <label for=x>Number</label>: <input id="x" name="x" type="number"> </p> <input id="submit" type=submit value="Calculate Square"> <script> var x = document.getElementById('x'); var output = document.createElement('p'); output.textContent = 'Type a number; it will be squared right then!'; x.form.appendChild(output); x.form.onsubmit = function () { return false; } x.oninput = function () { var v = x.valueAsNumber; output.textContent = v + ' squared is ' + v * v; }; var submit = document.getElementById('submit'); submit.parentNode.removeChild(submit); </script> </form>
The above technique is also useful in XHTML, since
noscript
is not supported in the XHTML
syntax.
body
elementhtml
element.onafterprint
onbeforeprint
onbeforeunload
onblur
onerror
onfocus
onhashchange
onload
onmessage
onoffline
ononline
onpagehide
onpageshow
onpopstate
onredo
onresize
onscroll
onstorage
onundo
onunload
interface HTMLBodyElement : HTMLElement { attribute Function onafterprint; attribute Function onbeforeprint; attribute Function onbeforeunload; attribute Function onblur; attribute Function onerror; attribute Function onfocus; attribute Function onhashchange; attribute Function onload; attribute Function onmessage; attribute Function onoffline; attribute Function ononline; attribute Function onpopstate; attribute Function onpagehide; attribute Function onpageshow; attribute Function onredo; attribute Function onresize; attribute Function onscroll; attribute Function onstorage; attribute Function onundo; attribute Function onunload; };
The body
element represents the main
content of the document.
In conforming documents, there is only one body
element. The document.body
IDL attribute provides scripts with easy access to a document's
body
element.
Some DOM operations (for example, parts of the
drag and drop model) are defined in terms of "the
body element". This refers to a particular element in the
DOM, as per the definition of the term, and not any arbitrary
body
element.
The body
element exposes as event handler
content attributes a number of the event
handlers of the Window
object. It also mirrors
their event handler IDL attributes.
The onblur
, onerror
, onfocus
, onload
, and onscroll
event
handlers of the Window
object, exposed on the
body
element, shadow the generic event
handlers with the same names normally supported by HTML
elements.
Thus, for example, a bubbling error
event fired on a child of the
body element of a Document
would first trigger
the onerror
event handler
content attributes of that element, then that of the root
html
element, and only then would it trigger
the onerror
event handler content
attribute on the body
element. This is because
the event would bubble from the target, to the body
, to
the html
, to the Document
, to the
Window
, and the event
handler on the body
is watching the
Window
not the body
. A regular event
listener attached to the body
using addEventListener()
, however, would fire when the
event bubbled through the body
and not when it reaches
the Window
object.
This page updates an indicator to show whether or not the user is online:
<!DOCTYPE HTML> <html> <head> <title>Online or offline?</title> <script> function update(online) { document.getElementById('status').textContent = online ? 'Online' : 'Offline'; } </script> </head> <body ononline="update(true)" onoffline="update(false)" onload="update(navigator.onLine)"> <p>You are: <span id="status">(Unknown)</span></p> </body> </html>
section
elementformatBlock
candidate.HTMLElement
.The section
element represents a
generic section of a document or application. A section, in this
context, is a thematic grouping of content, typically with a
heading.
Examples of sections would be chapters, the various tabbed pages in a tabbed dialog box, or the numbered sections of a thesis. A Web site's home page could be split into sections for an introduction, news items, and contact information.
Authors are encouraged to use the
article
element instead of the section
element when it would make sense to syndicate the contents of the
element.
The section
element is not a generic container element. When an element is
needed for styling purposes or as a convenience for scripting,
authors are encouraged to use the div
element
instead. A general rule is that the section
element is
appropriate only if the element's contents would be listed
explicitly in the document's outline.
In the following example, we see an article (part of a larger Web page) about apples, containing two short sections.
<article> <hgroup> <h1>Apples</h1> <h2>Tasty, delicious fruit!</h2> </hgroup> <p>The apple is the pomaceous fruit of the apple tree.</p> <section> <h1>Red Delicious</h1> <p>These bright red apples are the most common found in many supermarkets.</p> </section> <section> <h1>Granny Smith</h1> <p>These juicy, green apples make a great filling for apple pies.</p> </section> </article>
Notice how the use of section
means that the author
can use h1
elements throughout, without having to
worry about whether a particular section is at the top level, the
second level, the third level, and so on.
Here is a graduation programme with two sections, one for the list of people graduating, and one for the description of the ceremony.
<!DOCTYPE Html> <Html ><Head ><Title >Graduation Ceremony Summer 2022</Title ></Head ><Body ><H1 >Graduation</H1 ><Section ><H1 >Ceremony</H1 ><P >Opening Procession</P ><P >Speech by Validactorian</P ><P >Speech by Class President</P ><P >Presentation of Diplomas</P ><P >Closing Speech by Headmaster</P ></Section ><Section ><H1 >Graduates</H1 ><Ul ><Li >Molly Carpenter</Li ><Li >Anastasia Luccio</Li ><Li >Ebenezar McCoy</Li ><Li >Karrin Murphy</Li ><Li >Thomas Raith</Li ><Li >Susan Rodriguez</Li ></Ul ></Section ></Body ></Html>
nav
elementformatBlock
candidate.HTMLElement
.The nav
element represents a section of
a page that links to other pages or to parts within the page: a
section with navigation links.
Not all groups of links on a page need to be in a
nav
element — the element is primarily intended
for sections that consist of major navigation blocks. In particular,
it is common for footers to have a short list of links to various
pages of a site, such as the terms of service, the home page, and a
copyright page. The footer
element alone is sufficient
for such cases; while a nav
element can be used in such
cases, it is usually unnecessary.
User agents (such as screen readers) that are targeted at users who can benefit from navigation information being omitted in the initial rendering, or who can benefit from navigation information being immediately available, can use this element as a way to determine what content on the page to initially skip and/or provide on request.
In the following example, the page has several places where links are present, but only one of those places is considered a navigation section.
<body> <header> <h1>Wake up sheeple!</h1> <p><a href="news.html">News</a> - <a href="blog.html">Blog</a> - <a href="forums.html">Forums</a></p> <p>Last Modified: <time>2009-04-01</time></p> <nav> <h1>Navigation</h1> <ul> <li><a href="articles.html">Index of all articles</a></li> <li><a href="today.html">Things sheeple need to wake up for today</a></li> <li><a href="successes.html">Sheeple we have managed to wake</a></li> </ul> </nav> </header> <div> <article> <header> <h1>My Day at the Beach</h1> </header> <div> <p>Today I went to the beach and had a lot of fun.</p> ...more content... </div> <footer> <p>Posted <time pubdate="" datetime="2009-10-10T14:36-08:00">Thursday</time>.</p> </footer> </article> ...more blog posts... </div> <footer> <p>Copyright © 2006 The Example Company</p> <p><a href="about.html">About</a> - <a href="policy.html">Privacy Policy</a> - <a href="contact.html">Contact Us</a></p> </footer> </body>
Notice the div
elements being used to wrap all the
contents of the page other than the header and footer, and all the
contents of the blog entry other than its header and footer.
In the following example, there are two nav
elements, one for primary navigation around the site, and one for
secondary navigation around the page itself.
<body> <h1>The Wiki Center Of Exampland</h1> <nav> <ul> <li><a href="/">Home</a></li> <li><a href="/events">Current Events</a></li> ...more... </ul> </nav> <article> <header> <h1>Demos in Exampland</h1> <p>Written by A. N. Other.</p> </header> <nav> <ul> <li><a href="#public">Public demonstrations</a></li> <li><a href="#destroy">Demolitions</a></li> ...more... </ul> </nav> <div> <section id="public"> <h1>Public demonstrations</h1> <p>...more...</p> </section> <section id="destroy"> <h1>Demolitions</h1> <p>...more...</p> </section> ...more... </div> <footer> <p><a href="?edit">Edit</a> | <a href="?delete">Delete</a> | <a href="?Rename">Rename</a></p> </footer> </article> <footer> <p><small>© copyright 1998 Exampland Emperor</small></p> </footer> </body>
A nav
element doesn't have to contain a list, it
can contain other kinds of content as well. In this navigation
block, links are provided in prose:
<nav> <h1>Navigation</h1> <p>You are on my home page. To the north lies <a href="/blog">my blog</a>, from whence the sounds of battle can be heard. To the east you can see a large mountain, upon which many <a href="/school">school papers</a> are littered. Far up thus mountain you can spy a little figure who appears to be me, desperately scribbling a <a href="/school/thesis">thesis</a>.</p> <p>To the west are several exits. One fun-looking exit is labeled <a href="http://games.example.com/">"games"</a>. Another more boring-looking exit is labeled <a href="http://isp.example.net/">ISP™</a>.</p> <p>To the south lies a dark and dank <a href="/about">contacts page</a>. Cobwebs cover its disused entrance, and at one point you see a rat run quickly out of the page.</p> </nav>
article
elementformatBlock
candidate.HTMLElement
.The article
element represents a
self-contained composition in a document, page, application, or site
and that is, in principle, independently distributable or reusable,
e.g. in syndication. This could be a forum post, a magazine or
newspaper article, a blog entry, a user-submitted comment, an
interactive widget or gadget, or any other independent item of
content.
When article
elements are nested, the inner
article
elements represent articles that are in
principle related to the contents of the outer article. For
instance, a blog entry on a site that accepts user-submitted
comments could represent the comments as article
elements nested within the article
element for the blog
entry.
Author information associated with an article
element (q.v. the address
element) does not apply to
nested article
elements.
When used specifically with content to be
redistributed in syndication, the article
element is
similar in purpose to the entry
element in
Atom. [ATOM]
The time
element's pubdate
attribute can be used to
provide the publication date for an article
element.
This example shows a blog post using the article
element:
<article> <header> <h1>The Very First Rule of Life</h1> <p><time pubdate datetime="2009-10-09T14:28-08:00"></time></p> </header> <p>If there's a microphone anywhere near you, assume it's hot and sending whatever you're saying to the world. Seriously.</p> <p>...</p> <footer> <a href="?comments=1">Show comments...</a> </footer> </article>
Here is that same blog post, but showing some of the comments:
<article> <header> <h1>The Very First Rule of Life</h1> <p><time pubdate datetime="2009-10-09T14:28-08:00"></time></p> </header> <p>If there's a microphone anywhere near you, assume it's hot and sending whatever you're saying to the world. Seriously.</p> <p>...</p> <section> <h1>Comments</h1> <article> <footer> <p>Posted by: George Washington</p> <p><time pubdate datetime="2009-10-10T19:10-08:00"></time></p> </footer> <p>Yeah! Especially when talking about your lobbyist friends!</p> </article> <article> <footer> <p>Posted by: George Hammond</p> <p><time pubdate datetime="2009-10-10T19:15-08:00"></time></p> </footer> <p>Hey, you have the same first name as me.</p> </article> </section> </article>
Notice the use of footer
to give the information
for each comment (such as who wrote it and when): the
footer
element can appear at the start of its
section when appropriate, such as in this case. (Using
header
in this case wouldn't be wrong either; it's
mostly a matter of authoring preference.)
aside
elementformatBlock
candidate.HTMLElement
.The aside
element represents a section
of a page that consists of content that is tangentially related to
the content around the aside
element, and which could
be considered separate from that content. Such sections are often
represented as sidebars in printed typography.
The element can be used for typographical effects like pull
quotes or sidebars, for advertising, for groups of nav
elements, and for other content that is considered separate from the
main content of the page.
It's not appropriate to use the aside
element just for parentheticals, since those are part of the main
flow of the document.
The following example shows how an aside is used to mark up background material on Switzerland in a much longer news story on Europe.
<aside> <h1>Switzerland</h1> <p>Switzerland, a land-locked country in the middle of geographic Europe, has not joined the geopolitical European Union, though it is a signatory to a number of European treaties.</p> </aside>
The following example shows how an aside is used to mark up a pull quote in a longer article.
... <p>He later joined a large company, continuing on the same work. <q>I love my job. People ask me what I do for fun when I'm not at work. But I'm paid to do my hobby, so I never know what to answer. Some people wonder what they would do if they didn't have to work... but I know what I would do, because I was unemployed for a year, and I filled that time doing exactly what I do now.</q></p> <aside> <q> People ask me what I do for fun when I'm not at work. But I'm paid to do my hobby, so I never know what to answer. </q> </aside> <p>Of course his work — or should that be hobby? — isn't his only passion. He also enjoys other pleasures.</p> ...
The following extract shows how aside
can be used
for blogrolls and other side content on a blog:
<body> <header> <h1>My wonderful blog</h1> <p>My tagline</p> </header> <aside> <!-- this aside contains two sections that are tangentially related to the page, namely, links to other blogs, and links to blog posts from this blog --> <nav> <h1>My blogroll</h1> <ul> <li><a href="http://blog.example.com/">Example Blog</a> </ul> </nav> <nav> <h1>Archives</h1> <ol reversed> <li><a href="/last-post">My last post</a> <li><a href="/first-post">My first post</a> </ol> </nav> </aside> <aside> <!-- this aside is tangentially related to the page also, it contains twitter messages from the blog author --> <h1>Twitter Feed</h1> <blockquote cite="http://twitter.example.net/t31351234"> I'm on vacation, writing my blog. </blockquote> <blockquote cite="http://twitter.example.net/t31219752"> I'm going to go on vacation soon. </blockquote> </aside> <article> <!-- this is a blog post --> <h1>My last post</h1> <p>This is my last post.</p> <footer> <p><a href="/last-post" rel=bookmark>Permalink</a> </footer> </article> <article> <!-- this is also a blog post --> <h1>My first post</h1> <p>This is my first post.</p> <aside> <!-- this aside is about the blog post, since it's inside the <article> element; it would be wrong, for instance, to put the blogroll here, since the blogroll isn't really related to this post specifically, only to the page as a whole --> <h1>Posting</h1> <p>While I'm thinking about it, I wanted to say something about posting. Posting is fun!</p> </aside> <footer> <p><a href="/first-post" rel=bookmark>Permalink</a> </footer> </article> <footer> <nav> <a href="/archives">Archives</a> — <a href="/about">About me</a> — <a href="/copyright">Copyright</a> </nav> </footer> </body>
h1
, h2
, h3
, h4
, h5
, and h6
elementsformatBlock
candidate.hgroup
element.interface HTMLHeadingElement : HTMLElement {};
These elements represent headings for their sections.
The semantics and meaning of these elements are defined in the section on headings and sections.
These elements have a rank given by the number in
their name. The h1
element is said to have the highest
rank, the h6
element has the lowest rank, and two
elements with the same name have equal rank.
These two snippets are equivalent:
<body> <h1>Let's call it a draw(ing surface)</h1> <h2>Diving in</h2> <h2>Simple shapes</h2> <h2>Canvas coordinates</h2> <h3>Canvas coordinates diagram</h3> <h2>Paths</h2> </body>
<body> <h1>Let's call it a draw(ing surface)</h1> <section> <h1>Diving in</h1> </section> <section> <h1>Simple shapes</h1> </section> <section> <h1>Canvas coordinates</h1> <section> <h1>Canvas coordinates diagram</h1> </section> </section> <section> <h1>Paths</h1> </section> </body>
hgroup
elementformatBlock
candidate.h1
, h2
, h3
, h4
, h5
, and/or h6
elements.HTMLElement
.The hgroup
element represents the
heading of a section. The element is used to group a set of
h1
–h6
elements when the heading has
multiple levels, such as subheadings, alternative titles, or
taglines.
For the purposes of document summaries, outlines, and the like,
the text of hgroup
elements is defined to be the text
of the highest ranked
h1
–h6
element descendant of the
hgroup
element, if there are any such elements, and the
first such element if there are multiple elements with that
rank. If there are no such elements, then the text of
the hgroup
element is the empty string.
Other elements of heading content in the
hgroup
element indicate subheadings or subtitles.
The rank of an hgroup
element is the
rank of the highest-ranked h1
–h6
element descendant of the hgroup
element, if there are
any such elements, or otherwise the same as for an h1
element (the highest rank).
The section on headings and sections
defines how hgroup
elements are assigned to individual
sections.
Here are some examples of valid headings. In each case, the emphasized text represents the text that would be used as the heading in an application extracting heading data and ignoring subheadings.
<hgroup> <h1>The reality dysfunction</h1> <h2>Space is not the only void</h2> </hgroup>
<hgroup> <h1>Dr. Strangelove</h1> <h2>Or: How I Learned to Stop Worrying and Love the Bomb</h2> </hgroup>
The point of using hgroup
in these examples is to
mask the h2
element (which acts as a secondary title)
from the outline algorithm.
header
elementformatBlock
candidate.header
or
footer
element descendants.HTMLElement
.The header
element represents a group
of introductory or navigational aids.
A header
element is intended to usually
contain the section's heading (an
h1
–h6
element or an
hgroup
element), but this is not required. The
header
element can also be used to wrap a section's
table of contents, a search form, or any relevant logos.
Here are some sample headers. This first one is for a game:
<header> <p>Welcome to...</p> <h1>Voidwars!</h1> </header>
The following snippet shows how the element can be used to mark up a specification's header:
<header> <hgroup> <h1>Scalable Vector Graphics (SVG) 1.2</h1> <h2>W3C Working Draft 27 October 2004</h2> </hgroup> <dl> <dt>This version:</dt> <dd><a href="http://www.w3.org/TR/2004/WD-SVG12-20041027/">http://www.w3.org/TR/2004/WD-SVG12-20041027/</a></dd> <dt>Previous version:</dt> <dd><a href="http://www.w3.org/TR/2004/WD-SVG12-20040510/">http://www.w3.org/TR/2004/WD-SVG12-20040510/</a></dd> <dt>Latest version of SVG 1.2:</dt> <dd><a href="http://www.w3.org/TR/SVG12/">http://www.w3.org/TR/SVG12/</a></dd> <dt>Latest SVG Recommendation:</dt> <dd><a href="http://www.w3.org/TR/SVG/">http://www.w3.org/TR/SVG/</a></dd> <dt>Editor:</dt> <dd>Dean Jackson, W3C, <a href="mailto:dean@w3.org">dean@w3.org</a></dd> <dt>Authors:</dt> <dd>See <a href="#authors">Author List</a></dd> </dl> <p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notic ... </header>
The header
element is not
sectioning content; it doesn't introduce a new
section.
In this example, the page has a page heading given by the
h1
element, and two subsections whose headings are
given by h2
elements. The content after the
header
element is still part of the last subsection
started in the header
element, because the
header
element doesn't take part in the
outline algorithm.
<body> <header> <h1>Little Green Guys With Guns</h1> <nav> <ul> <li><a href="/games">Games</a> <li><a href="/forum">Forum</a> <li><a href="/download">Download</a> </ul> </nav> <h2>Important News</h2> <!-- this starts a second subsection --> <!-- this is part of the subsection entitled "Important News" --> <p>To play today's games you will need to update your client.</p> <h2>Games</h2> <!-- this starts a third subsection --> </header> <p>You have three active games:</p> <!-- this is still part of the subsection entitled "Games" --> ...
footer
elementformatBlock
candidate.header
or
footer
element descendants.HTMLElement
.The footer
element represents a footer
for its nearest ancestor sectioning content or
sectioning root element. A footer typically contains
information about its section such as who wrote it, links to related
documents, copyright data, and the like.
When the footer
element contains entire sections,
they represent appendices, indexes,
long colophons, verbose license agreements, and other such
content.
Contact information for the author or editor of a
section belongs in an address
element, possibly itself
inside a footer
.
Footers don't necessarily have to appear at the end of a section, though they usually do.
When the nearest ancestor sectioning content or sectioning root element is the body element, then it applies to the whole page.
The footer
element is not
sectioning content; it doesn't introduce a new
section.
Here is a page with two footers, one at the top and one at the bottom, with the same content:
<body> <footer><a href="../">Back to index...</a></footer> <hgroup> <h1>Lorem ipsum</h1> <h2>The ipsum of all lorems</h2> </hgroup> <p>A dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p> <footer><a href="../">Back to index...</a></footer> </body>
Here is an example which shows the footer
element
being used both for a site-wide footer and for a section
footer.
<!DOCTYPE HTML> <HTML><HEAD> <TITLE>The Ramblings of a Scientist</TITLE> <BODY> <H1>The Ramblings of a Scientist</H1> <ARTICLE> <H1>Episode 15</H1> <VIDEO SRC="/fm/015.ogv" CONTROLS PRELOAD> <P><A HREF="/fm/015.ogv">Download video</A>.</P> </VIDEO> <FOOTER> <!-- footer for article --> <P>Published <TIME PUBDATE DATETIME="2009-10-21T18:26-07:00"></TIME></P> </FOOTER> </ARTICLE> <ARTICLE> <H1>My Favorite Trains</H1> <P>I love my trains. My favorite train of all time is a Köf.</P> <P>It is fun to see them pull some coal cars because they look so dwarfed in comparison.</P> <FOOTER> <!-- footer for article --> <P>Published <TIME PUBDATE DATETIME="2009-09-15T14:54-07:00"></TIME></P> </FOOTER> </ARTICLE> <FOOTER> <!-- site wide footer --> <NAV> <P><A HREF="/credits.html">Credits</A> — <A HREF="/tos.html">Terms of Service</A> — <A HREF="/index.html">Blog Index</A></P> </NAV> <P>Copyright © 2009 Gordon Freeman</P> </FOOTER> </BODY> </HTML>
Some site designs have what is sometimes referred to as "fat footers" — footers that contain a lot of material, including images, links to other articles, links to pages for sending feedback, special offers... in some ways, a whole "front page" in the footer.
This fragment shows the bottom of a page on a site with a "fat footer":
... <footer> <nav> <section> <h1>Articles</h1> <p><img src="http://dev.w3.org/html5/spec/images/somersaults.jpeg" alt=""> Go to the gym with our somersaults class! Our teacher Jim takes you through the paces in this two-part article. <a href="articles/somersaults/1">Part 1</a> · <a href="articles/somersaults/1">Part 2</a></p> <p><img src="http://dev.w3.org/html5/spec/images/kindplus.jpeg"> Tired of walking on the edge of a clif<!-- sic -->? Our guest writer Lara shows you how to bumble your way through the bars. <a href="articles/kindplus/1">Read more...</a></p> <p><img src="http://dev.w3.org/html5/spec/images/crisps.jpeg"> The chips are down, now all that's left is a potato. What can you do with it? <a href="articles/crisps/1">Read more...</a></p> </section> <ul> <li> <a href="/about">About us...</a> <li> <a href="/feedback">Send feedback!</a> <li> <a href="/sitemap">Sitemap</a> </ul> </nav> <p><small>Copyright © 2015 The Snacker — <a href="/tos">Terms of Service</a></small></p> </footer> </body>
address
elementformatBlock
candidate.header
, footer
, or
address
element descendants.HTMLElement
.The address
element represents the
contact information for its nearest article
or
body
element ancestor. If that is the body
element, then the contact information applies to the document
as a whole.
For example, a page at the W3C Web site related to HTML might include the following contact information:
<ADDRESS> <A href="../People/Raggett/">Dave Raggett</A>, <A href="../People/Arnaud/">Arnaud Le Hors</A>, contact persons for the <A href="Activity">W3C HTML Activity</A> </ADDRESS>
The address
element must not be used to represent
arbitrary addresses (e.g. postal addresses), unless those addresses
are in fact the relevant contact information. (The p
element is the appropriate element for marking up postal addresses
in general.)
The address
element must not contain information
other than contact information.
For example, the following is non-conforming use of the
address
element:
<ADDRESS>Last Modified: 1999/12/24 23:37:50</ADDRESS>
Typically, the address
element would be included
along with other information in a footer
element.
The contact information for a node node is a
collection of address
elements defined by the first
applicable entry from the following list:
article
elementbody
elementThe contact information consists of all the
address
elements that have node
as an ancestor and do not have another body
or
article
element ancestor that is a descendant of node.
article
elementbody
elementThe contact information of node is the same
as the contact information of the nearest article
or
body
element ancestor, whichever is nearest.
Document
has a body elementThe contact information of node is the same
as the contact information of the body element of the
Document
.
There is no contact information for node.
User agents may expose the contact information of a node to the user, or use it for other purposes, such as indexing sections based on the sections' contact information.
In this example the footer contains contact information and a copyright notice.
<footer> <address> For more details, contact <a href="mailto:js@example.com">John Smith</a>. </address> <p><small>© copyright 2038 Example Corp.</small></p> </footer>
The h1
–h6
elements and the
hgroup
element are headings.
The first element of heading content in an element of sectioning content represents the heading for that section. Subsequent headings of equal or higher rank start new (implied) sections, headings of lower rank start implied subsections that are part of the previous one. In both cases, the element represents the heading of the implied section.
Certain elements are said to be sectioning roots, including blockquote
and
td
elements. These elements can have their own
outlines, but the sections and headings inside these elements do not
contribute to the outlines of their ancestors.
Sectioning content elements are always considered subsections of their nearest ancestor sectioning root or their nearest ancestor element of sectioning content, whichever is nearest, regardless of what implied sections other headings may have created.
For the following fragment:
<body> <h1>Foo</h1> <h2>Bar</h2> <blockquote> <h3>Bla</h3> </blockquote> <p>Baz</p> <h2>Quux</h2> <section> <h3>Thud</h3> </section> <p>Grunt</p> </body>
...the structure would be:
body
section, containing the "Grunt" paragraph)
section
section)
Notice how the section
ends the earlier implicit
section so that a later paragraph ("Grunt") is back at the top
level.
Sections may contain headings of any rank, but
authors are strongly encouraged to either use only h1
elements, or to use elements of the appropriate rank
for the section's nesting level.
Authors are also encouraged to explicitly wrap sections in elements of sectioning content, instead of relying on the implicit sections generated by having multiple headings in one element of sectioning content.
For example, the following is correct:
<body> <h4>Apples</h4> <p>Apples are fruit.</p> <section> <h2>Taste</h2> <p>They taste lovely.</p> <h6>Sweet</h6> <p>Red apples are sweeter than green ones.</p> <h1>Color</h1> <p>Apples come in various colors.</p> </section> </body>
However, the same document would be more clearly expressed as:
<body> <h1>Apples</h1> <p>Apples are fruit.</p> <section> <h2>Taste</h2> <p>They taste lovely.</p> <section> <h3>Sweet</h3> <p>Red apples are sweeter than green ones.</p> </section> </section> <section> <h2>Color</h2> <p>Apples come in various colors.</p> </section> </body>
Both of the documents above are semantically identical and would produce the same outline in compliant user agents.
This third example is also semantically identical, and might be easier to maintain (e.g. if sections are often moved around in editing):
<body> <h1>Apples</h1> <p>Apples are fruit.</p> <section> <h1>Taste</h1> <p>They taste lovely.</p> <section> <h1>Sweet</h1> <p>Red apples are sweeter than green ones.</p> </section> </section> <section> <h1>Color</h1> <p>Apples come in various colors.</p> </section> </body>
This section defines an algorithm for creating an outline for a sectioning content element or a sectioning root element. It is defined in terms of a walk over the nodes of a DOM tree, in tree order, with each node being visited when it is entered and when it is exited during the walk.
The outline for a sectioning content
element or a sectioning root element consists of a list
of one or more potentially nested sections. A section is a container that
corresponds to some nodes in the original DOM tree. Each section can
have one heading associated with it, and can contain any number of
further nested sections. The algorithm for the
outline also associates each node in the DOM tree with a particular
section and potentially a heading. (The sections in the
outline aren't section
elements, though some may
correspond to such elements — they are merely conceptual
sections.)
The following markup fragment:
<body> <h1>A</h1> <p>B</p> <h2>C</h2> <p>D</p> <h2>E</h2> <p>F</p> </body>
...results in the following outline being created for the
body
node (and thus the entire document):
Section created for body
node.
Associated with heading "A".
Also associated with paragraph "B".
Nested sections:
The algorithm that must be followed during a walk of a DOM subtree rooted at a sectioning content element or a sectioning root element to determine that element's outline is as follows:
Let current outlinee be null. (It holds the element whose outline is being created.)
Let current section be null. (It holds a pointer to a section, so that elements in the DOM can all be associated with a section.)
Create a stack to hold elements, which is used to handle nesting. Initialize this stack to empty.
As you walk over the DOM in tree order, trigger the first relevant step below for each element as you enter and exit it.
The element being exited is a heading content element.
Pop that element from the stack.
Do nothing.
If current outlinee is not null, and the current section has no heading, create an implied heading and let that be the heading for the current section.
If current outlinee is not null, push current outlinee onto the stack.
Let current outlinee be the element that is being entered.
Let current section be a newly created section for the current outlinee element.
Associate current outlinee with current section.
Let there be a new outline for the new current outlinee, initialized with just the new current section as the only section in the outline.
Pop the top element from the stack, and let the current outlinee be that element.
Let current section be the last section in the outline of the current outlinee element.
Append the outline of the sectioning content element being exited to the current section. (This does not change which section is the last section in the outline.)
Run these steps:
Pop the top element from the stack, and let the current outlinee be that element.
Let current section be the last section in the outline of the current outlinee element.
Finding the deepest child: If current section has no child sections, stop these steps.
Let current section be the last child section of the current current section.
Go back to the substep labeled finding the deepest child.
The current outlinee is the element being exited.
Let current section be the first section in the outline of the current outlinee element.
Skip to the next step in the overall set of steps. (The walk is over.)
Do nothing.
If the current section has no heading, let the element being entered be the heading for the current section.
Otherwise, if the element being entered has a rank equal to or greater than the heading of the last section of the outline of the current outlinee, then create a new section and append it to the outline of the current outlinee element, so that this new section is the new last section of that outline. Let current section be that new section. Let the element being entered be the new heading for the current section.
Otherwise, run these substeps:
Let candidate section be current section.
If the element being entered has a rank lower than the rank of the heading of the candidate section, then create a new section, and append it to candidate section. (This does not change which section is the last section in the outline.) Let current section be this new section. Let the element being entered be the new heading for the current section. Abort these substeps.
Let new candidate section be the section that contains candidate section in the outline of current outlinee.
Let candidate section be new candidate section.
Return to step 2.
Push the element being entered onto the stack. (This causes the algorithm to skip any descendants of the element.)
Recall that h1
has the
highest rank, and h6
has the lowest
rank.
Do nothing.
In addition, whenever you exit a node, after doing the steps above, if the node is not associated with a section yet and current section is not null, associate the node with the section current section.
If the current outlinee is null, then there was no sectioning content element or sectioning root element in the DOM. There is no outline. Abort these steps.
Associate any nodes that were not associated with a section in the steps above with current outlinee as their section.
Associate all nodes with the heading of the section with which they are associated, if any.
If current outlinee is the body element, then the outline created for that element is the outline of the entire document.
The tree of sections created by the algorithm above, or a proper subset thereof, must be used when generating document outlines, for example when generating tables of contents.
When creating an interactive table of contents, entries should jump the user to the relevant sectioning content element, if the section was created for a real element in the original document, or to the relevant heading content element, if the section in the tree was generated for a heading in the above process.
Selecting the first section of the document therefore
always takes the user to the top of the document, regardless of
where the first heading in the body
is to be found.
The outline depth of a heading content
element associated with a section section
is the number of sections that
are ancestors of section in the
outline that section finds itself
in when the outlines of its
Document
's elements are created, plus 1. The
outline depth of a heading content element
not associated with a section
is 1.
User agents should provide default headings for sections that do not have explicit section headings.
Consider the following snippet:
<body> <nav> <p><a href="/">Home</a></p> </nav> <p>Hello world.</p> <aside> <p>My cat is cute.</p> </aside> </body>
Although it contains no headings, this snippet has three
sections: a document (the body
) with two subsections
(a nav
and an aside
). A user agent could
present the outline as follows:
These default headings ("Untitled document", "Navigation", "Sidebar") are not specified by this specification, and might vary with the user's language, the page's language, the user's preferences, the user agent implementor's preferences, etc.
The following JavaScript function shows how the tree walk could be implemented. The root argument is the root of the tree to walk, and the enter and exit arguments are callbacks that are called with the nodes as they are entered and exited. [ECMA262]
function (root, enter, exit) { var node = root; start: while (node) { enter(node); if (node.firstChild) { node = node.firstChild; continue start; } while (node) { exit(node); if (node.nextSibling) { node = node.nextSibling; continue start; } if (node == root) node = null; else node = node.parentNode; } } }
p
elementformatBlock
candidate.interface HTMLParagraphElement : HTMLElement {};
The p
element represents a
paragraph.
While paragraphs are usually represented in visual media by blocks of text that are physically separated from adjacent blocks through blank lines, a style sheet or user agent would be equally justified in presenting paragraph breaks in a different manner, for instance using inline pilcrows (¶).
The following examples are conforming HTML fragments:
<p>The little kitten gently seated himself on a piece of carpet. Later in his life, this would be referred to as the time the cat sat on the mat.</p>
<fieldset> <legend>Personal information</legend> <p> <label>Name: <input name="n"></label> <label><input name="anon" type="checkbox"> Hide from other users</label> </p> <p><label>Address: <textarea name="a"></textarea></label></p> </fieldset>
<p>There was once an example from Femley,<br> Whose markup was of dubious quality.<br> The validator complained,<br> So the author was pained,<br> To move the error from the markup to the rhyming.</p>
The p
element should not be used when a more
specific element is more appropriate.
The following example is technically correct:
<section> <!-- ... --> <p>Last modified: 2001-04-23</p> <p>Author: fred@example.com</p> </section>
However, it would be better marked-up as:
<section> <!-- ... --> <footer>Last modified: 2001-04-23</footer> <address>Author: fred@example.com</address> </section>
Or:
<section> <!-- ... --> <footer> <p>Last modified: 2001-04-23</p> <address>Author: fred@example.com</address> </footer> </section>
hr
elementinterface HTMLHRElement : HTMLElement {};
The hr
element represents a
paragraph-level thematic break, e.g. a scene change in
a story, or a transition to another topic within a section of a
reference book.
The following fictional extract from a project manual shows two
sections that use the hr
element to separate topics
within the section.
<section> <h1>Communication</h1> <p>There are various methods of communication. This section covers a few of the important ones used by the project.</p> <hr> <p>Communication stones seem to come in pairs and have mysterious properties:</p> <ul> <li>They can transfer thoughts in two directions once activated if used alone.</li> <li>If used with another device, they can transfer one's consciousness to another body.</li> <li>If both stones are used with another device, the consciousnesses switch bodies.</li> </ul> <hr> <p>Radios use the electromagnetic spectrum in the meter range and longer.</p> <hr> <p>Signal flares use the electromagnetic spectrum in the nanometer range.</p> </section> <section> <h1>Food</h1> <p>All food at the project is rationed:</p> <dl> <dt>Potatoes</dt> <dd>Two per day</dd> <dt>Soup</dt> <dd>One bowl per day</dd> </dl> <hr> <p>Cooking is done by the chefs on a set rotation.</p> </section>
There is no need for an hr
element between the
sections themselves, since the section
elements and
the h1
elements imply thematic changes themselves.
The following extract from Pandora's Star by Peter
F. Hamilton shows two paragraphs that precede a scene change and
the paragraph that follows it. The scene change, represented in the
printed book by a gap containing a solitary centered star between
the second and third paragraphs, is here represented using the
hr
element.
<p>Dudley was ninety-two, in his second life, and fast approaching
time for another rejuvenation. Despite his body having the physical
age of a standard fifty-year-old, the prospect of a long degrading
campaign within academia was one he regarded with dread. For a
supposedly advanced civilization, the Intersolar Commonwearth could be
appallingly backward at times, not to mention cruel.</p>
<p><i>Maybe it won't be that bad</i>, he told himself. The lie was
comforting enough to get him through the rest of the night's
shift.</p>
<hr>
<p>The Carlton AllLander drove Dudley home just after dawn. Like the
astronomer, the vehicle was old and worn, but perfectly capable of
doing its job. It had a cheap diesel engine, common enough on a
semi-frontier world like Gralmond, although its drive array was a
thoroughly modern photoneural processor. With its high suspension and
deep-tread tyres it could plough along the dirt track to the
observatory in all weather and seasons, including the metre-deep snow
of Gralmond's winters.</p>
The hr
element does not affect the
document's outline.
pre
elementformatBlock
candidate.interface HTMLPreElement : HTMLElement {};
The pre
element represents a block of
preformatted text, in which structure is represented by typographic
conventions rather than by elements.
In the HTML syntax, a leading
newline character immediately following the pre
element
start tag is stripped.
Some examples of cases where the pre
element could
be used:
Authors are encouraged to consider how preformatted text will be experienced when the formatting is lost, as will be the case for users of speech synthesizers, braille displays, and the like. For cases like ASCII art, it is likely that an alternative presentation, such as a textual description, would be more universally accessible to the readers of the document.
To represent a block of computer code, the pre
element can be used with a code
element; to represent a
block of computer output the pre
element can be used
with a samp
element. Similarly, the kbd
element can be used within a pre
element to indicate
text that the user is to enter.
A newline in a pre
element should separate
paragraphs for the purposes of the Unicode bidirectional algorithm.
This requirement may be implemented indirectly through the style
layer. For example, an HTML+CSS user agent could implement these
requirements by implementing the CSS 'unicode-bidi' property. [BIDI] [CSS]
In the following snippet, a sample of computer code is presented.
<p>This is the <code>Panel</code> constructor:</p> <pre><code>function Panel(element, canClose, closeHandler) { this.element = element; this.canClose = canClose; this.closeHandler = function () { if (closeHandler) closeHandler() }; }</code></pre>
In the following snippet, samp
and kbd
elements are mixed in the contents of a pre
element to
show a session of Zork I.
<pre><samp>You are in an open field west of a big white house with a boarded front door. There is a small mailbox here. ></samp> <kbd>open mailbox</kbd> <samp>Opening the mailbox reveals: A leaflet. ></samp></pre>
The following shows a contemporary poem that uses the
pre
element to preserve its unusual formatting, which
forms an intrinsic part of the poem itself.
<pre> maxling it is with a heart heavy that i admit loss of a feline so loved a friend lost to the unknown (night) ~cdr 11dec07</pre>
blockquote
elementformatBlock
candidate.cite
interface HTMLQuoteElement : HTMLElement { attribute DOMString cite; };
The HTMLQuoteElement
interface is
also used by the q
element.
The blockquote
element represents a
section that is quoted from another source.
Content inside a blockquote
must be quoted from
another source, whose address, if it has one, may be cited in the
cite
attribute.
If the cite
attribute
is present, it must be a valid URL potentially surrounded by
spaces. To obtain the corresponding
citation link, the value of the attribute must be resolved relative to the element. User
agents should allow users to follow such citation links.
The cite
IDL
attribute must reflect the element's cite
content attribute.
This next example shows the use of cite
alongside
blockquote
:
<p>His next piece was the aptly named <cite>Sonnet 130</cite>:</p> <blockquote cite="http://quotes.example.org/s/sonnet130.html"> <p>My mistress' eyes are nothing like the sun,<br> Coral is far more red, than her lips red,<br> ...
This example shows how a forum post could use
blockquote
to show what post a user is replying
to. The article
element is used for each post, to mark
up the threading.
<article> <h1><a href="http://bacon.example.com/?blog=109431">Bacon on a crowbar</a></h1> <article> <header><strong>t3yw</strong> 12 points 1 hour ago</header> <p>I bet a narwhal would love that.</p> <footer><a href="?pid=29578">permalink</a></footer> <article> <header><strong>greg</strong> 8 points 1 hour ago</header> <blockquote><p>I bet a narwhal would love that.</p></blockquote> <p>Dude narwhals don't eat bacon.</p> <footer><a href="?pid=29579">permalink</a></footer> <article> <header><strong>t3yw</strong> 15 points 1 hour ago</header> <blockquote> <blockquote><p>I bet a narwhal would love that.</p></blockquote> <p>Dude narwhals don't eat bacon.</p> </blockquote> <p>Next thing you'll be saying they don't get capes and wizard hats either!</p> <footer><a href="?pid=29580">permalink</a></footer> <article> <article> <header><strong>boing</strong> -5 points 1 hour ago</header> <p>narwhals are worse than ceiling cat</p> <footer><a href="?pid=29581">permalink</a></footer> </article> </article> </article> </article> <article> <header><strong>fred</strong> 1 points 23 minutes ago</header> <blockquote><p>I bet a narwhal would love that.</p></blockquote> <p>I bet they'd love to peel a banana too.</p> <footer><a href="?pid=29582">permalink</a></footer> </article> </article> </article>
This example shows the use of a blockquote
for
short snippets, demonstrating that one does not have to use
p
elements inside blockquote
elements:
<p>He began his list of "lessons" with the following:</p> <blockquote>One should never assume that his side of the issue will be recognized, let alone that it will be conceded to have merits.</blockquote> <p>He continued with a number of similar points, ending with:</p> <blockquote>Finally, one should be prepared for the threat of breakdown in negotiations at any given moment and not be cowed by the possiblity.</blockquote> <p>We shall now discuss these points...
Examples of how to
represent a conversation are shown in a later section; it is not
appropriate to use the cite
and blockquote
elements for this purpose.
ol
elementli
elements.reversed
start
type
interface HTMLOListElement : HTMLElement { attribute boolean reversed; attribute long start; attribute DOMString type; };
The ol
element represents a list of
items, where the items have been intentionally ordered, such that
changing the order would change the meaning of the document.
The items of the list are the li
element child nodes
of the ol
element, in tree order.
The reversed
attribute is a boolean attribute. If present, it
indicates that the list is a descending list (..., 3, 2, 1). If the
attribute is omitted, the list is an ascending list (1, 2, 3,
...).
The start
attribute, if present, must be a valid integer giving
the ordinal value of the first list item.
If the start
attribute is
present, user agents must parse it as an integer, in order to determine the
attribute's value. The default value, used if the attribute is
missing or if the value cannot be converted to a number according to
the referenced algorithm, is 1 if the element has no reversed
attribute, and is the
number of child li
elements otherwise.
The first item in the list has the ordinal value
given by the ol
element's start
attribute, unless that
li
element has a value
attribute with a value that can
be successfully parsed, in which case it has the ordinal
value given by that value
attribute.
Each subsequent item in the list has the ordinal
value given by its value
attribute, if it has one, or, if it doesn't, the ordinal
value of the previous item, plus one if the reversed
is absent, or minus one if
it is present.
The type
attribute
can be used to specify the kind of marker to use in the list, in the
cases where that matters (e.g. because items are to be referenced by
their number/letter). The attribute, if specified, must have a value
that is a case-sensitive match for one of the
characters given in the first cell of one of the rows of the
following table. The type
attribute represents the state
given in the cell in the second column of the row whose first cell
matches the attribute's value; if none of the cells match, or if the
attribute is omitted, then the attribute represents the decimal state.
Keyword | State | Description | Examples for values 1-3 and 3999-4001 | |||||||
---|---|---|---|---|---|---|---|---|---|---|
1 (U+0031)
| decimal | Decimal numbers | 1. | 2. | 3. | ... | 3999. | 4000. | 4001. | ... |
a (U+0061)
| lower-alpha | Lowercase latin alphabet | a. | b. | c. | ... | ewu. | ewv. | eww. | ... |
A (U+0041)
| upper-alpha | Uppercase latin alphabet | A. | B. | C. | ... | EWU. | EWV. | EWW. | ... |
i (U+0069)
| lower-roman | Lowercase roman numerals | i. | ii. | iii. | ... | mmmcmxcix. | i̅v̅. | i̅v̅i. | ... |
I (U+0049)
| upper-roman | Uppercase roman numerals | I. | II. | III. | ... | MMMCMXCIX. | I̅V̅. | I̅V̅I. | ... |
User agents should render the items of the list in a manner
consistent with the state of the type
attribute of the ol
element. Numbers less than or equal to zero should always use the
decimal system regardless of the type
attribute.
For CSS user agents, a mapping for this attribute to the 'list-style-type' CSS property is given in the rendering section (the mapping is straightforward: the states above have the same names as their corresponding CSS values).
The reversed
,
start
, and type
IDL attributes must
reflect the respective content attributes of the same
name. The start
IDL attribute has
the same default as its content attribute.
The following markup shows a list where the order matters, and
where the ol
element is therefore appropriate. Compare
this list to the equivalent list in the ul
section to
see an example of the same items using the ul
element.
<p>I have lived in the following countries (given in the order of when I first lived there):</p> <ol> <li>Switzerland <li>United Kingdom <li>United States <li>Norway </ol>
Note how changing the order of the list changes the meaning of the document. In the following example, changing the relative order of the first two items has changed the birthplace of the author:
<p>I have lived in the following countries (given in the order of when I first lived there):</p> <ol> <li>United Kingdom <li>Switzerland <li>United States <li>Norway </ol>
ul
elementli
elements.interface HTMLUListElement : HTMLElement {};
The ul
element represents a list of
items, where the order of the items is not important — that
is, where changing the order would not materially change the meaning
of the document.
The items of the list are the li
element child nodes
of the ul
element.
The following markup shows a list where the order does not
matter, and where the ul
element is therefore
appropriate. Compare this list to the equivalent list in the
ol
section to see an example of the same items using
the ol
element.
<p>I have lived in the following countries:</p> <ul> <li>Norway <li>Switzerland <li>United Kingdom <li>United States </ul>
Note that changing the order of the list does not change the meaning of the document. The items in the snippet above are given in alphabetical order, but in the snippet below they are given in order of the size of their current account balance in 2007, without changing the meaning of the document whatsoever:
<p>I have lived in the following countries:</p> <ul> <li>Switzerland <li>Norway <li>United Kingdom <li>United States </ul>
li
elementol
elements.ul
elements.menu
elements.ol
element: value
interface HTMLLIElement : HTMLElement { attribute long value; };
The li
element represents a list
item. If its parent element is an ol
, ul
,
or menu
element, then the element is an item of the
parent element's list, as defined for those elements. Otherwise, the
list item has no defined list-related relationship to any other
li
element.
If the parent element is an ol
element, then the
li
element has an ordinal value.
The value
attribute, if present, must be a valid integer giving
the ordinal value of the list item.
If the value
attribute is
present, user agents must parse it as an integer, in order to determine the
attribute's value. If the attribute's value cannot be converted to a
number, the attribute must be treated as if it was absent. The
attribute has no default value.
The value
attribute is
processed relative to the element's parent ol
element
(q.v.), if there is one. If there is not, the attribute has no
effect.
The value
IDL
attribute must reflect the value of the value
content attribute.
The following example, the top ten movies are listed (in reverse
order). Note the way the list is given a title by using a
figure
element and its figcaption
element.
<figure> <figcaption>The top 10 movies of all time</figcaption> <ol> <li value="10"><cite>Josie and the Pussycats</cite>, 2001</li> <li value="9"><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li> <li value="8"><cite>A Bug's Life</cite>, 1998</li> <li value="7"><cite>Toy Story</cite>, 1995</li> <li value="6"><cite>Monsters, Inc</cite>, 2001</li> <li value="5"><cite>Cars</cite>, 2006</li> <li value="4"><cite>Toy Story 2</cite>, 1999</li> <li value="3"><cite>Finding Nemo</cite>, 2003</li> <li value="2"><cite>The Incredibles</cite>, 2004</li> <li value="1"><cite>Ratatouille</cite>, 2007</li> </ol> </figure>
The markup could also be written as follows, using the reversed
attribute on the
ol
element:
<figure> <figcaption>The top 10 movies of all time</figcaption> <ol reversed> <li><cite>Josie and the Pussycats</cite>, 2001</li> <li><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li> <li><cite>A Bug's Life</cite>, 1998</li> <li><cite>Toy Story</cite>, 1995</li> <li><cite>Monsters, Inc</cite>, 2001</li> <li><cite>Cars</cite>, 2006</li> <li><cite>Toy Story 2</cite>, 1999</li> <li><cite>Finding Nemo</cite>, 2003</li> <li><cite>The Incredibles</cite>, 2004</li> <li><cite>Ratatouille</cite>, 2007</li> </ol> </figure>
If the li
element is the child of a
menu
element and itself has a child that defines a
command, then the
li
element will match the :enabled
and :disabled
pseudo-classes in the
same way as the first such child element does.
dl
elementdt
elements followed by one or more dd
elements.interface HTMLDListElement : HTMLElement {};
The dl
element represents an
association list consisting of zero or more name-value groups (a
description list). Each group must consist of one or more names
(dt
elements) followed by one or more values
(dd
elements). Within a single dl
element,
there should not be more than one dt
element for each
name.
Name-value groups may be terms and definitions, metadata topics and values, questions and answers, or any other groups of name-value data.
The values within a group are alternatives; multiple paragraphs
forming part of the same value must all be given within the same
dd
element.
The order of the list of groups, and of the names and values within each group, may be significant.
If a dl
element is empty, it contains no groups.
If a dl
element contains non-whitespace text nodes, or elements other than dt
and
dd
, then those elements or text
nodes do not form part of any groups in that
dl
.
If a dl
element contains only dt
elements, then it consists of one group with names but no
values.
If a dl
element contains only dd
elements, then it consists of one group with values but no
names.
If a dl
element starts with one or more
dd
elements, then the first group has no associated
name.
If a dl
element ends with one or more
dt
elements, then the last group has no associated
value.
When a dl
element doesn't match its
content model, it is often due to accidentally using dd
elements in the place of dt
elements and vice
versa. Conformance checkers can spot such mistakes and might be able
to advise authors how to correctly use the markup.
In the following example, one entry ("Authors") is linked to two values ("John" and "Luke").
<dl> <dt> Authors <dd> John <dd> Luke <dt> Editor <dd> Frank </dl>
In the following example, one definition is linked to two terms.
<dl> <dt lang="en-US"> <dfn>color</dfn> </dt> <dt lang="en-GB"> <dfn>colour</dfn> </dt> <dd> A sensation which (in humans) derives from the ability of the fine structure of the eye to distinguish three differently filtered analyses of a view. </dd> </dl>
The following example illustrates the use of the dl
element to mark up metadata of sorts. At the end of the example,
one group has two metadata labels ("Authors" and "Editors") and two
values ("Robert Rothman" and "Daniel Jackson").
<dl> <dt> Last modified time </dt> <dd> 2004-12-23T23:33Z </dd> <dt> Recommended update interval </dt> <dd> 60s </dd> <dt> Authors </dt> <dt> Editors </dt> <dd> Robert Rothman </dd> <dd> Daniel Jackson </dd> </dl>
The following example shows the dl
element used to
give a set of instructions. The order of the instructions here is
important (in the other examples, the order of the blocks was not
important).
<p>Determine the victory points as follows (use the first matching case):</p> <dl> <dt> If you have exactly five gold coins </dt> <dd> You get five victory points </dd> <dt> If you have one or more gold coins, and you have one or more silver coins </dt> <dd> You get two victory points </dd> <dt> If you have one or more silver coins </dt> <dd> You get one victory point </dd> <dt> Otherwise </dt> <dd> You get no victory points </dd> </dl>
The following snippet shows a dl
element being used
as a glossary. Note the use of dfn
to indicate the
word being defined.
<dl> <dt><dfn>Apartment</dfn>, n.</dt> <dd>An execution context grouping one or more threads with one or more COM objects.</dd> <dt><dfn>Flat</dfn>, n.</dt> <dd>A deflated tire.</dd> <dt><dfn>Home</dfn>, n.</dt> <dd>The user's login directory.</dd> </dl>
The dl
element is inappropriate for
marking up dialogue. Examples of how to
mark up dialogue are shown below.
dt
elementdd
or dt
elements inside dl
elements.HTMLElement
.The dt
element represents the term, or
name, part of a term-description group in a description list
(dl
element).
The dt
element itself, when used in a
dl
element, does not indicate that its contents are a
term being defined, but this can be indicated using the
dfn
element.
This example shows a list of frequently asked questions (a FAQ)
marked up using the dt
element for questions and the
dd
element for answers.
<article> <h1>FAQ</h1> <dl> <dt>What do we want?</dt> <dd>Our data.</dd> <dt>When do we want it?</dt> <dd>Now.</dd> <dt>Where is it?</dt> <dd>We are not sure.</dd> </dl> </article>
dd
elementdt
or dd
elements inside dl
elements.HTMLElement
.The dd
element represents the
description, definition, or value, part of a term-description group
in a description list (dl
element).
A dl
can be used to define a vocabulary list, like
in a dictionary. In the following example, each entry, given by a
dt
with a dfn
, has several
dd
s, showing the various parts of the definition.
<dl> <dt><dfn>happiness</dfn></dt> <dd class="pronunciation">/'hæ p. nes/</dd> <dd class="part-of-speech"><i><abbr>n.</abbr></i></dd> <dd>The state of being happy.</dd> <dd>Good fortune; success. <q>Oh <b>happiness</b>! It worked!</q></dd> <dt><dfn>rejoice</dfn></dt> <dd class="pronunciation">/ri jois'/</dd> <dd><i class="part-of-speech"><abbr>v.intr.</abbr></i> To be delighted oneself.</dd> <dd><i class="part-of-speech"><abbr>v.tr.</abbr></i> To cause one to be delighted.</dd> </dl>
figure
elementfigcaption
element followed by flow content.figcaption
element.HTMLElement
.The figure
element represents some
flow content, optionally with a caption, that is
self-contained and is typically referenced as a single unit from the
main flow of the document.
The element can thus be used to annotate illustrations, diagrams, photos, code listings, etc, that are referred to from the main content of the document, but that could, without affecting the flow of the document, be moved away from that primary content, e.g. to the side of the page, to dedicated pages, or to an appendix.
The first figcaption
element child of the element, if any, represents the caption of the
figure
element's contents. If there is no child
figcaption
element, then there is no caption.
This example shows the figure
element to mark up a
code listing.
<p>In <a href="#l4">listing 4</a> we see the primary core interface API declaration.</p> <figure id="l4"> <figcaption>Listing 4. The primary core interface API declaration.</figcaption> <pre><code>interface PrimaryCore { boolean verifyDataLine(); void sendData(in sequence<byte> data); void initSelfDestruct(); }</code></pre> </figure> <p>The API is designed to use UTF-8.</p>
Here we see a figure
element to mark up a
photo.
<figure> <img src="bubbles-work.jpeg" alt="Bubbles, sitting in his office chair, works on his latest project intently."> <figcaption>Bubbles at work</figcaption> </figure>
In this example, we see an image that is not a figure, as well as an image and a video that are.
<h2>Malinko's comics</h2> <p>This case centered on some sort of "intellectual property" infringement related to a comic (see Exhibit A). The suit started after a trailer ending with these words: <blockquote> <img src="promblem-packed-action.png" alt="ROUGH COPY! Promblem-Packed Action!"> </blockquote> <p>...was aired. A lawyer, armed with a Bigger Notebook, launched a preemptive strike using snowballs. A complete copy of the trailer is included with Exhibit B. <figure> <img src="ex-a.png" alt="Two squiggles on a dirty piece of paper."> <figcaption>Exhibit A. The alleged <cite>rough copy</cite> comic.</figcaption> </figure> <figure> <video src="ex-b.mov"></video> <figcaption>Exhibit B. The <cite>Rough Copy</cite> trailer.</figcaption> </figure> <p>The case was resolved out of court.
Here, a part of a poem is marked up using
figure
.
<figure> <p>'Twas brillig, and the slithy toves<br> Did gyre and gimble in the wabe;<br> All mimsy were the borogoves,<br> And the mome raths outgrabe.</p> <figcaption><cite>Jabberwocky</cite> (first verse). Lewis Carroll, 1832-98</figcaption> </figure>
In this example, which could be part of a much larger work discussing a castle, the figure has three images in it.
<figure> <img src="castle1423.jpeg" title="Etching. Anonymous, ca. 1423." alt="The castle has one tower, and a tall wall around it."> <img src="castle1858.jpeg" title="Oil-based paint on canvas. Maria Towle, 1858." alt="The castle now has two towers and two walls."> <img src="castle1999.jpeg" title="Film photograph. Peter Jankle, 1999." alt="The castle lies in ruins, the original tower all that remains in one piece."> <figcaption>The castle through the ages: 1423, 1858, and 1999 respectively.</figcaption> </figure>
figcaption
elementfigure
element.HTMLElement
.The figcaption
element represents a
caption or legend for the rest of the contents of the
figcaption
element's parent figure
element, if any.
div
elementformatBlock
candidate.interface HTMLDivElement : HTMLElement {};
The div
element has no special meaning at all. It
represents its children. It can be used with the class
, lang
, and title
attributes to mark up semantics
common to a group of consecutive elements.
Authors are strongly encouraged to view the
div
element as an element of last resort, for when no
other element is suitable. Use of the div
element
instead of more appropriate elements leads to poor accessibility for
readers and poor maintainability for authors.
For example, a blog post would be marked up using
article
, a chapter using section
, a
page's navigation aids using nav
, and a group of form
controls using fieldset
.
On the other hand, div
elements can be useful for
stylistic purposes or to wrap multiple paragraphs within a section
that are all to be annotated in a similar way. In the following
example, we see div
elements used as a way to set the
language of two paragraphs at once, instead of setting the language
on the two paragraph elements separately:
<article lang="en-US"> <h1>My use of language and my cats</h1> <p>My cat's behavior hasn't changed much since her absence, except that she plays her new physique to the neighbors regularly, in an attempt to get pets.</p> <div lang="en-GB"> <p>My other cat, coloured black and white, is a sweetie. He followed us to the pool today, walking down the pavement with us. Yesterday he apparently visited our neighbours. I wonder if he recognises that their flat is a mirror image of ours.</p> <p>Hm, I just noticed that in the last paragraph I used British English. But I'm supposed to write in American English. So I shouldn't say "pavement" or "flat" or "colour"...</p> </div> <p>I should say "sidewalk" and "apartment" and "color"!</p> </article>
a
elementhref
target
rel
media
hreflang
type
interface HTMLAnchorElement : HTMLElement { stringifier attribute DOMString href; attribute DOMString target; attribute DOMString rel; readonly attribute DOMTokenList relList; attribute DOMString media; attribute DOMString hreflang; attribute DOMString type; attribute DOMString text; // URL decomposition IDL attributes attribute DOMString protocol; attribute DOMString host; attribute DOMString hostname; attribute DOMString port; attribute DOMString pathname; attribute DOMString search; attribute DOMString hash; };
If the a
element has an href
attribute, then it
represents a hyperlink (a hypertext
anchor).
If the a
element has no href
attribute, then the element
represents a placeholder for where a link might
otherwise have been placed, if it had been relevant.
The target
,
rel
, media
, hreflang
, and type
attributes must be omitted
if the href
attribute is
not present.
If a site uses a consistent navigation toolbar on every page,
then the link that would normally link to the page itself could be
marked up using an a
element:
<nav> <ul> <li> <a href="/">Home</a> </li> <li> <a href="/news">News</a> </li> <li> <a>Examples</a> </li> <li> <a href="/legal">Legal</a> </li> </ul> </nav>
The href
, target
attributes affect what
happens when users follow
hyperlinks created using the a
element. The
rel
, media
, hreflang
, and type
attributes may be used to
indicate to the user the likely nature of the target resource before
the user follows the link.
The activation behavior of a
elements
that create hyperlinks is to run the
following steps:
If the click
event in question is not trusted (i.e. a click()
method call was the reason for the
event being dispatched), and the a
element's target
attribute is such that
applying the rules for choosing a browsing context given a
browsing context name, using the value of the target
attribute as the
browsing context name, would result in there not being a chosen
browsing context, then raise an INVALID_ACCESS_ERR
exception and abort these steps.
If the target of the click
event is an img
element with an ismap
attribute specified, then
server-side image map processing must be performed, as follows:
click
event was a
real pointing-device-triggered click
event on the img
element, then let x be the distance in CSS
pixels from the left edge of the image's left border, if it has
one, or the left edge of the image otherwise, to the location of
the click, and let y be the distance in CSS
pixels from the top edge of the image's top border, if it has
one, or the top edge of the image otherwise, to the location of
the click. Otherwise, let x and y be zero.Finally, the user agent must follow the hyperlink created by the
a
element. If the steps above defined a hyperlink
suffix, then take that into account when following the
hyperlink.
text
Same as textContent
.
The IDL attributes href
,
target
, rel
, media
, hreflang
, and type
, must
reflect the respective content attributes of the same
name.
The IDL attribute relList
must
reflect the rel
content attribute.
The text
IDL
attribute, on getting, must return the same value as the
textContent
IDL attribute on the element, and on
setting, must act as if the textContent
IDL attribute
on the element had been set to the new value.
The a
element also supports the complement of
URL decomposition IDL attributes, protocol
, host
, port
, hostname
, pathname
, search
, and hash
. These must follow the
rules given for URL decomposition IDL attributes, with
the input being the result of
resolving the element's href
attribute relative to the
element, if there is such an attribute and resolving it is
successful, or the empty string otherwise; and the common setter action being the
same as setting the element's href
attribute to the new output
value.
The a
element may be wrapped around entire
paragraphs, lists, tables, and so forth, even entire sections, so
long as there is no interactive content within (e.g. buttons or
other links). This example shows how this can be used to make an
entire advertising block into a link:
<aside class="advertising"> <h1>Advertising</h1> <a href="http://ad.example.com/?adid=1929&pubid=1422"> <section> <h1>Mellblomatic 9000!</h1> <p>Turn all your widgets into mellbloms!</p> <p>Only $9.99 plus shipping and handling.</p> </section> </a> <a href="http://ad.example.com/?adid=375&pubid=1422"> <section> <h1>The Mellblom Browser</h1> <p>Web browsing at the speed of light.</p> <p>No other browser goes faster!</p> </section> </a> </aside>
em
elementHTMLElement
.The em
element represents stress
emphasis of its contents.
The level of emphasis that a particular piece of content has is
given by its number of ancestor em
elements.
The placement of emphasis changes the meaning of the sentence. The element thus forms an integral part of the content. The precise way in which emphasis is used in this way depends on the language.
These examples show how changing the emphasis changes the meaning. First, a general statement of fact, with no emphasis:
<p>Cats are cute animals.</p>
By emphasizing the first word, the statement implies that the kind of animal under discussion is in question (maybe someone is asserting that dogs are cute):
<p><em>Cats</em> are cute animals.</p>
Moving the emphasis to the verb, one highlights that the truth of the entire sentence is in question (maybe someone is saying cats are not cute):
<p>Cats <em>are</em> cute animals.</p>
By moving it to the adjective, the exact nature of the cats is reasserted (maybe someone suggested cats were mean animals):
<p>Cats are <em>cute</em> animals.</p>
Similarly, if someone asserted that cats were vegetables, someone correcting this might emphasize the last word:
<p>Cats are cute <em>animals</em>.</p>
By emphasizing the entire sentence, it becomes clear that the speaker is fighting hard to get the point across. This kind of emphasis also typically affects the punctuation, hence the exclamation mark here.
<p><em>Cats are cute animals!</em></p>
Anger mixed with emphasizing the cuteness could lead to markup such as:
<p><em>Cats are <em>cute</em> animals!</em></p>
The em
element isn't a generic "italics"
element. Sometimes, text is intended to stand out from the rest of
the paragraph, as if it was in a different mood or voice. For this,
the i
element is more appropriate.
The em
element also isn't intended to convey
importance; for that purpose, the strong
element is
more appropriate.
strong
elementHTMLElement
.The strong
element represents strong
importance for its contents.
The relative level of importance of a piece of content is given
by its number of ancestor strong
elements; each
strong
element increases the importance of its
contents.
Changing the importance of a piece of text with the
strong
element does not change the meaning of the
sentence.
Here is an example of a warning notice in a game, with the various parts marked up according to how important they are:
<p><strong>Warning.</strong> This dungeon is dangerous. <strong>Avoid the ducks.</strong> Take any gold you find. <strong><strong>Do not take any of the diamonds</strong>, they are explosive and <strong>will destroy anything within ten meters.</strong></strong> You have been warned.</p>
small
elementHTMLElement
.The small
element represents side
comments such as small print.
Small print typically features disclaimers, caveats, legal restrictions, or copyrights. Small print is also sometimes used for attribution, or for satisfying licensing requirements.
The small
element does not
"de-emphasize" or lower the importance of text emphasized by the
em
element or marked as important with the
strong
element. To mark text as not emphasized or
important, simply do not mark it up with the em
or
strong
elements respectively.
The small
element should not be used for extended
spans of text, such as multiple paragraphs, lists, or sections of
text. It is only intended for short runs of text. The text of a page
listing terms of use, for instance, would not be a suitable
candidate for the small
element: in such a case, the
text is not a side comment, it is the main content of the page.
In this example, the small
element is used to
indicate that value-added tax is not included in a price of a hotel
room:
<dl> <dt>Single room <dd>199 € <small>breakfast included, VAT not included</small> <dt>Double room <dd>239 € <small>breakfast included, VAT not included</small> </dl>
In this second example, the small
element is used
for a side comment in an article.
<p>Example Corp today announced record profits for the second quarter <small>(Full Disclosure: Foo News is a subsidiary of Example Corp)</small>, leading to speculation about a third quarter merger with Demo Group.</p>
This is distinct from a sidebar, which might be multiple paragraphs long and is removed from the main flow of text. In the following example, we see a sidebar from the same article. This sidebar also has small print, indicating the source of the information in the sidebar.
<aside> <h1>Example Corp</h1> <p>This company mostly creates small software and Web sites.</p> <p>The Example Corp company mission is "To provide entertainment and news on a sample basis".</p> <p><small>Information obtained from <a href="http://example.com/about.html">example.com</a> home page.</small></p> </aside>
In this last example, the small
element is marked
as being important small print.
<p><strong><small>Continued use of this service will result in a kiss.</small></strong></p>
s
elementHTMLElement
.The s
element represents contents that
are no longer accurate or no longer relevant.
The s
element is not appropriate when
indicating document edits; to mark a span of text as having been
removed from a document, use the del
element.
In this example a recommended retail price has been marked as no longer relevant as the product in question has a new sale price.
<p>Buy our Iced Tea and Lemonade!</p> <p><s>Recommended retail price: $3.99 per bottle</s></p> <p><strong>Now selling for just $2.99 a bottle!</strong></p>
cite
elementHTMLElement
.The cite
element represents the title
of a work (e.g.
a book,
a paper,
an essay,
a poem,
a score,
a song,
a script,
a film,
a TV show,
a game,
a sculpture,
a painting,
a theatre production,
a play,
an opera,
a musical,
an exhibition,
a legal case report,
etc). This can be a work that is being quoted or
referenced in detail (i.e. a citation), or it can just be a work
that is mentioned in passing.
A person's name is not the title of a work — even if people
call that person a piece of work — and the element must
therefore not be used to mark up people's names. (In some cases, the
b
element might be appropriate for names; e.g. in a
gossip article where the names of famous people are keywords
rendered with a different style to draw attention to them. In other
cases, if an element is really needed, the
span
element can be used.)
This next example shows a typical use of the cite
element:
<p>My favorite book is <cite>The Reality Dysfunction</cite> by Peter F. Hamilton. My favorite comic is <cite>Pearls Before Swine</cite> by Stephan Pastis. My favorite track is <cite>Jive Samba</cite> by the Cannonball Adderley Sextet.</p>
This is correct usage:
<p>According to the Wikipedia article <cite>HTML</cite>, as it stood in mid-February 2008, leaving attribute values unquoted is unsafe. This is obviously an over-simplification.</p>
The following, however, is incorrect usage, as the
cite
element here is containing far more than the
title of the work:
<!-- do not copy this example, it is an example of bad usage! --> <p>According to <cite>the Wikipedia article on HTML</cite>, as it stood in mid-February 2008, leaving attribute values unquoted is unsafe. This is obviously an over-simplification.</p>
The cite
element is obviously a key part of any
citation in a bibliography, but it is only used to mark the
title:
<p><cite>Universal Declaration of Human Rights</cite>, United Nations, December 1948. Adopted by General Assembly resolution 217 A (III).</p>
A citation is not a quote (for
which the q
element is appropriate).
This is incorrect usage, because cite
is not for
quotes:
<p><cite>This is wrong!</cite>, said Ian.</p>
This is also incorrect usage, because a person is not a work:
<p><q>This is still wrong!</q>, said <cite>Ian</cite>.</p>
The correct usage does not use a cite
element:
<p><q>This is correct</q>, said Ian.</p>
As mentioned above, the b
element might be relevant
for marking names as being keywords in certain kinds of
documents:
<p>And then <b>Ian</b> said <q>this might be right, in a gossip column, maybe!</q>.</p>
q
elementcite
HTMLQuoteElement
.The q
element represents some phrasing content quoted from another
source.
Quotation punctuation (such as quotation marks) that is quoting
the contents of the element must not appear immediately before,
after, or inside q
elements; they will be inserted into
the rendering by the user agent.
Content inside a q
element must be quoted from
another source, whose address, if it has one, may be cited in the
cite
attribute. The
source may be fictional, as when quoting characters in a novel or
screenplay.
If the cite
attribute is
present, it must be a valid URL potentially surrounded by
spaces. To obtain the corresponding
citation link, the value of the attribute must be resolved relative to the element. User
agents should allow users to follow such citation links.
The q
element must not be used in place of quotation
marks that do not represent quotes; for example, it is inappropriate
to use the q
element for marking up sarcastic
statements.
The use of q
elements to mark up quotations is
entirely optional; using explicit quotation punctuation without
q
elements is just as correct.
Here is a simple example of the use of the q
element:
<p>The man said <q>Things that are impossible just take longer</q>. I disagreed with him.</p>
Here is an example with both an explicit citation link in the
q
element, and an explicit citation outside:
<p>The W3C page <cite>About W3C</cite> says the W3C's mission is <q cite="http://www.w3.org/Consortium/">To lead the World Wide Web to its full potential by developing protocols and guidelines that ensure long-term growth for the Web</q>. I disagree with this mission.</p>
In the following example, the quotation itself contains a quotation:
<p>In <cite>Example One</cite>, he writes <q>The man said <q>Things that are impossible just take longer</q>. I disagreed with him</q>. Well, I disagree even more!</p>
In the following example, quotation marks are used instead of
the q
element:
<p>His best argument was ❝I disagree❞, which I thought was laughable.</p>
In the following example, there is no quote — the
quotation marks are used to name a word. Use of the q
element in this case would be inappropriate.
<p>The word "ineffable" could have been used to describe the disaster resulting from the campaign's mismanagement.</p>
dfn
elementdfn
element descendants.title
attribute has special semantics on this element.HTMLElement
.The dfn
element represents the defining
instance of a term. The paragraph,
description list group, or section that is the nearest
ancestor of the dfn
element must also contain the
definition(s) for the term given
by the dfn
element.
Defining term: If the dfn
element has a
title
attribute, then
the exact value of that attribute is the term being defined.
Otherwise, if it contains exactly one element child node and no
child text nodes, and that child
element is an abbr
element with a title
attribute, then the exact value
of that attribute is the term being defined. Otherwise, it
is the exact textContent
of the dfn
element that gives the term being defined.
If the title
attribute of the
dfn
element is present, then it must contain only the
term being defined.
The title
attribute
of ancestor elements does not affect dfn
elements.
An a
element that links to a dfn
element represents an instance of the term defined by the
dfn
element.
In the following fragment, the term "GDO" is first defined in the first paragraph, then used in the second.
<p>The <dfn><abbr title="Garage Door Opener">GDO</abbr></dfn> is a device that allows off-world teams to open the iris.</p> <!-- ... later in the document: --> <p>Teal'c activated his <abbr title="Garage Door Opener">GDO</abbr> and so Hammond ordered the iris to be opened.</p>
With the addition of an a
element, the reference
can be made explicit:
<p>The <dfn id=gdo><abbr title="Garage Door Opener">GDO</abbr></dfn> is a device that allows off-world teams to open the iris.</p> <!-- ... later in the document: --> <p>Teal'c activated his <a href=#gdo><abbr title="Garage Door Opener">GDO</abbr></a> and so Hammond ordered the iris to be opened.</p>
abbr
elementtitle
attribute has special semantics on this element.HTMLElement
.The abbr
element represents an
abbreviation or acronym, optionally with its expansion. The title
attribute may be
used to provide an expansion of the abbreviation. The attribute, if
specified, must contain an expansion of the abbreviation, and
nothing else.
The paragraph below contains an abbreviation marked up with the
abbr
element. This paragraph defines the term "Web Hypertext Application Technology
Working Group".
<p>The <dfn id=whatwg><abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr></dfn> is a loose unofficial collaboration of Web browser manufacturers and interested parties who wish to develop new technologies designed to allow authors to write and deploy Applications over the World Wide Web.</p>
An alternative way to write this would be:
<p>The <dfn id=whatwg>Web Hypertext Application Technology Working Group</dfn> (<abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr>) is a loose unofficial collaboration of Web browser manufacturers and interested parties who wish to develop new technologies designed to allow authors to write and deploy Applications over the World Wide Web.</p>
This paragraph has two abbreviations. Notice how only one is
defined; the other, with no expansion associated with it, does not
use the abbr
element.
<p>The <abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr> started working on HTML5 in 2004.</p>
This paragraph links an abbreviation to its definition.
<p>The <a href="#whatwg"><abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr></a> community does not have much representation from Asia.</p>
This paragraph marks up an abbreviation without giving an expansion, possibly as a hook to apply styles for abbreviations (e.g. smallcaps).
<p>Philip` and Dashiva both denied that they were going to get the issue counts from past revisions of the specification to backfill the <abbr>WHATWG</abbr> issue graph.</p>
If an abbreviation is pluralized, the expansion's grammatical number (plural vs singular) must match the grammatical number of the contents of the element.
Here the plural is outside the element, so the expansion is in the singular:
<p>Two <abbr title="Working Group">WG</abbr>s worked on this specification: the <abbr>WHATWG</abbr> and the <abbr>HTMLWG</abbr>.</p>
Here the plural is inside the element, so the expansion is in the plural:
<p>Two <abbr title="Working Groups">WGs</abbr> worked on this specification: the <abbr>WHATWG</abbr> and the <abbr>HTMLWG</abbr>.</p>
Abbreviations do not have to be marked up using this element. It is expected to be useful in the following cases:
abbr
element with a title
attribute is an alternative to
including the expansion inline (e.g. in parentheses).abbr
element with a title
attribute or include the expansion
inline in the text the first time the abbreviation is used.abbr
element
can be used without a title
attribute.Providing an expansion in a title
attribute once will not necessarily
cause other abbr
elements in the same document with the
same contents but without a title
attribute to behave as if they had the same expansion. Every
abbr
element is independent.
time
elementtime
element descendants.datetime
pubdate
interface HTMLTimeElement : HTMLElement {
attribute DOMString dateTime;
attribute boolean pubDate;
readonly attribute Date valueAsDate;
};
The time
element represents either a
time on a 24 hour clock, or a precise date in the proleptic
Gregorian calendar, optionally with a time and a time-zone
offset. [GREGORIAN]
This element is intended as a way to encode modern dates and times in a machine-readable way so that, for example, user agents can offer to add birthday reminders or scheduled events to the user's calendar.
The time
element is not intended for encoding times
for which a precise date or time cannot be established. For
example, it would be inappropriate for encoding times like "one
millisecond after the big bang", "the early part of the Jurassic
period", or "a winter around 250 BCE".
For dates before the introduction of the Gregorian calendar,
authors are encouraged to not use the time
element, or
else to be very careful about converting dates and times from the
period to the Gregorian calendar. This is complicated by the manner
in which the Gregorian calendar was phased in, which occurred at
different times in different countries, ranging from partway
through the 16th century all the way to early in the 20th.
The pubdate
attribute is a boolean attribute. If specified, it
indicates that the date and time given by the element is the
publication date and time of the nearest ancestor
article
element, or, if the element has no ancestor
article
element, of the document as a whole. If the
element has a pubdate
attribute specified, then the element needs a date. For
each article
element, there must be no more than one
time
element with a pubdate
attribute whose nearest
ancestor is that article
element. Furthermore, for each
Document
, there must be no more than one
time
element with a pubdate
attribute that does not
have an ancestor article
element.
The datetime
attribute, if present, gives the date or time being
specified. Otherwise, the date or time is given by the element's
contents.
If the element needs a date, and the datetime
attribute is present,
then the attribute's value must be a valid date string with
optional time.
If the element needs a date, but the datetime
attribute is not present,
then the element's textContent
must be a valid
date string in content with optional time.
If the element does not need a date,
and the datetime
attribute
is present, then the attribute's value must be a valid date or
time string.
If the element does not need a date,
but the datetime
attribute
is not present, then the element's textContent
must be
a valid date or time string in content.
The date, if any, must be expressed using the Gregorian calendar.
If the datetime
attribute
is present, the user agent should convey the attribute's value to
the user when rendering the element.
The time
element can be used to encode dates, for
example in Microformats. The following shows a hypothetical way of
encoding an event using a variant on hCalendar that uses the
time
element:
<div class="vevent"> <a class="url" href="http://www.web2con.com/">http://www.web2con.com/</a> <span class="summary">Web 2.0 Conference</span>: <time class="dtstart" datetime="2007-10-05">October 5</time> - <time class="dtend" datetime="2007-10-20">19</time>, at the <span class="location">Argent Hotel, San Francisco, CA</span> </div>
(The end date is encoded as one day after the last date of the event because in the iCalendar format, end dates are exclusive, not inclusive.)
The time
element is not necessary for encoding
dates or times. In the following snippet, the time is encoded using
time
, so that it can be restyled (e.g. using XBL2) to
match local conventions, while the year is not marked up at all,
since marking it up would not be particularly useful, and doing so
is thus not allowed.
<p>I usually have a snack at <time>16:00</time>.</p> <p>I've liked model trains since at least 1983.</p>
Using a styling technology that supports restyling times, the first paragraph from the above snippet could be rendered as follows:
I usually have a snack at 4pm.
Or it could be rendered as follows:
I usually have a snack at 16h00.
The dateTime
IDL
attribute must reflect the datetime
content attribute.
The pubDate
IDL
attribute must reflect the pubdate
content attribute.
User agents, to obtain the date, time, and time-zone offset represented by
a time
element, must follow these steps:
datetime
attribute is present, then use the rules to parse a date or
time string with the flag in attribute from the value
of that attribute, and let the result be result.textContent
, and let the result be result.valueAsDate
Returns a Date
object representing the specified date and time.
The valueAsDate
IDL
attribute must return either null or a new Date
object
initialised to the relevant value as defined by the following
list:
When a Date
object is to be returned, a new one must
be constructed.
In the following snippet:
<p>Our first date was <time datetime="2006-09-23">a Saturday</time>.</p>
...the time
element's valueAsDate
attribute would
have the value 1,158,969,600,000ms.
In the following snippet:
<p>Many people get up at <time>08:00</time>.</p>
...the time
element's valueAsDate
attribute would
have the value 28,800,000ms.
In this example, an article's publication date is marked up
using time
:
<article> <h1>Small tasks</h1> <footer>Published <time pubdate>2009-08-30</time>.</footer> <p>I put a bike bell on his bike.</p> </article>
Here is another way that could be marked up. In this example, legacy user agents would say "today", while newer user agents would render the time in a locale-specific manner based on the value of the attribute.
<article> <h1>Small tasks</h1> <footer>Published <time pubdate datetime="2009-08-30">today</time>.</footer> <p>I put a bike bell on his bike.</p> </article>
Here is the same thing but with the time included only. Because the element is empty, legacy user agents will not show anything useful; user agents that implement this specification, on the other hand, would show the date and time in a locale-specific manner.
<article> <h1>Small tasks</h1> <footer>Published <time pubdate datetime="2009-08-30T07:13Z"></time>.</footer> <p>I put a bike bell on his bike.</p> </article>
code
elementHTMLElement
.The code
element represents a fragment
of computer code. This could be an XML element name, a filename, a
computer program, or any other string that a computer would
recognize.
Although there is no formal way to indicate the language of
computer code being marked up, authors who wish to mark
code
elements with the language used, e.g. so that
syntax highlighting scripts can use the right rules, may do so by
adding a class prefixed with "language-
" to
the element.
The following example shows how the element can be used in a paragraph to mark up element names and computer code, including punctuation.
<p>The <code>code</code> element represents a fragment of computer code.</p> <p>When you call the <code>activate()</code> method on the <code>robotSnowman</code> object, the eyes glow.</p> <p>The example below uses the <code>begin</code> keyword to indicate the start of a statement block. It is paired with an <code>end</code> keyword, which is followed by the <code>.</code> punctuation character (full stop) to indicate the end of the program.</p>
The following example shows how a block of code could be marked
up using the pre
and code
elements.
<pre><code class="language-pascal">var i: Integer; begin i := 1; end.</code></pre>
A class is used in that example to indicate the language used.
See the pre
element for more details.
var
elementHTMLElement
.The var
element represents a
variable. This could be an actual variable in a mathematical
expression or programming context, or it could just be a term used
as a placeholder in prose.
In the paragraph below, the letter "n" is being used as a variable in prose:
<p>If there are <var>n</var> pipes leading to the ice cream factory then I expect at <em>least</em> <var>n</var> flavors of ice cream to be available for purchase!</p>
For mathematics, in particular for anything beyond the simplest
of expressions, MathML is more appropriate. However, the
var
element can still be used to refer to specific
variables that are then mentioned in MathML expressions.
In this example, an equation is shown, with a legend that
references the variables in the equation. The expression itself is
marked up with MathML, but the variables are mentioned in the
figure's legend using var
.
<figure> <math> <mi>a</mi> <mo>=</mo> <msqrt> <msup><mi>b</mi><mn>2</mn></msup> <mi>+</mi> <msup><mi>c</mi><mn>2</mn></msup> </msqrt> </math> <figcaption> Using Pythagoras' theorem to solve for the hypotenuse <var>a</var> of a triangle with sides <var>b</var> and <var>c</var> </figcaption> </figure>
samp
elementHTMLElement
.The samp
element represents (sample)
output from a program or computing system.
See the pre
and kbd
elements for more details.
This example shows the samp
element being used
inline:
<p>The computer said <samp>Too much cheese in tray two</samp> but I didn't know what that meant.</p>
This second example shows a block of sample output. Nested
samp
and kbd
elements allow for the
styling of specific elements of the sample output using a
style sheet.
<pre><samp><span class="prompt">jdoe@mowmow:~$</span> <kbd>ssh demo.example.com</kbd> Last login: Tue Apr 12 09:10:17 2005 from mowmow.example.com on pts/1 Linux demo 2.6.10-grsec+gg3+e+fhs6b+nfs+gr0501+++p3+c4a+gr2b-reslog-v6.189 #1 SMP Tue Feb 1 11:22:36 PST 2005 i686 unknown <span class="prompt">jdoe@demo:~$</span> <span class="cursor">_</span></samp></pre>
kbd
elementHTMLElement
.The kbd
element represents user input
(typically keyboard input, although it may also be used to represent
other input, such as voice commands).
When the kbd
element is nested inside a
samp
element, it represents the input as it was echoed
by the system.
When the kbd
element contains a
samp
element, it represents input based on system
output, for example invoking a menu item.
When the kbd
element is nested inside another
kbd
element, it represents an actual key or other
single unit of input as appropriate for the input mechanism.
Here the kbd
element is used to indicate keys to press:
<p>To make George eat an apple, press <kbd><kbd>Shift</kbd>+<kbd>F3</kbd></kbd></p>
In this second example, the user is told to pick a particular
menu item. The outer kbd
element marks up a block of
input, with the inner kbd
elements representing each
individual step of the input, and the samp
elements
inside them indicating that the steps are input based on something
being displayed by the system, in this case menu labels:
<p>To make George eat an apple, select <kbd><kbd><samp>File</samp></kbd>|<kbd><samp>Eat Apple...</samp></kbd></kbd> </p>
Such precision isn't necessary; the following is equally fine:
<p>To make George eat an apple, select <kbd>File | Eat Apple...</kbd></p>
sub
and sup
elementsHTMLElement
.The sup
element represents a
superscript and the sub
element represents
a subscript.
These elements must be used only to mark up typographical
conventions with specific meanings, not for typographical
presentation for presentation's sake. For example, it would be
inappropriate for the sub
and sup
elements
to be used in the name of the LaTeX document preparation system. In
general, authors should use these elements only if the
absence of those elements would change the meaning of the
content.
In certain languages, superscripts are part of the typographical conventions for some abbreviations.
<p>The most beautiful women are <span lang="fr"><abbr>M<sup>lle</sup></abbr> Gwendoline</span> and <span lang="fr"><abbr>M<sup>me</sup></abbr> Denise</span>.</p>
The sub
element can be used inside a
var
element, for variables that have subscripts.
Here, the sub
element is used to represents the
subscript that identifies the variable in a family of
variables:
<p>The coordinate of the <var>i</var>th point is (<var>x<sub><var>i</var></sub></var>, <var>y<sub><var>i</var></sub></var>). For example, the 10th point has coordinate (<var>x<sub>10</sub></var>, <var>y<sub>10</sub></var>).</p>
Mathematical expressions often use subscripts and superscripts.
Authors are encouraged to use MathML for marking up mathematics, but
authors may opt to use sub
and sup
if
detailed mathematical markup is not desired. [MATHML]
<var>E</var>=<var>m</var><var>c</var><sup>2</sup>
f(<var>x</var>, <var>n</var>) = log<sub>4</sub><var>x</var><sup><var>n</var></sup>
i
elementHTMLElement
.The i
element represents a span of text
in an alternate voice or mood, or otherwise offset from the normal
prose in a manner indicating a different quality of text, such as a
taxonomic designation, a technical term, an idiomatic phrase from
another language, a thought, or a ship name in Western texts.
Terms in languages different from the main text should be
annotated with lang
attributes (or,
in XML, lang
attributes in the XML namespace).
The examples below show uses of the i
element:
<p>The <i class="taxonomy">Felis silvestris catus</i> is cute.</p> <p>The term <i>prose content</i> is defined above.</p> <p>There is a certain <i lang="fr">je ne sais quoi</i> in the air.</p>
In the following example, a dream sequence is marked up using
i
elements.
<p>Raymond tried to sleep.</p> <p><i>The ship sailed away on Thursday</i>, he dreamt. <i>The ship had many people aboard, including a beautiful princess called Carey. He watched her, day-in, day-out, hoping she would notice him, but she never did.</i></p> <p><i>Finally one night he picked up the courage to speak with her—</i></p> <p>Raymond woke with a start as the fire alarm rang out.</p>
Authors can use the class
attribute on the i
element to identify why the element
is being used, so that if the style of a particular use (e.g. dream
sequences as opposed to taxonomic terms) is to be changed at a later
date, the author doesn't have to go through the entire document (or
series of related documents) annotating each use.
Authors are encouraged to consider whether other elements might
be more applicable than the i
element, for instance the
em
element for marking up stress emphasis, or the
dfn
element to mark up the defining instance of a
term.
Style sheets can be used to format i
elements, just like any other element can be restyled. Thus, it is
not the case that content in i
elements will
necessarily be italicized.
b
elementHTMLElement
.The b
element represents a span of text
to which attention is being drawn for utilitarian purposes without
conveying any extra importance and with no implication of an
alternate voice or mood, such as key words in a document abstract,
product names in a review, actionable words in interactive
text-driven software, or an article lede.
The following example shows a use of the b
element
to highlight key words without marking them up as important:
<p>The <b>frobonitor</b> and <b>barbinator</b> components are fried.</p>
In the following example, objects in a text adventure are
highlighted as being special by use of the b
element.
<p>You enter a small room. Your <b>sword</b> glows brighter. A <b>rat</b> scurries past the corner wall.</p>
Another case where the b
element is appropriate is
in marking up the lede (or lead) sentence or paragraph. The
following example shows how a BBC
article about kittens adopting a rabbit as their own could be
marked up:
<article> <h2>Kittens 'adopted' by pet rabbit</h2> <p><b class="lede">Six abandoned kittens have found an unexpected new mother figure — a pet rabbit.</b></p> <p>Veterinary nurse Melanie Humble took the three-week-old kittens to her Aberdeen home.</p> [...]
As with the i
element, authors can use the class
attribute on the b
element to identify why the element is being used, so that if the
style of a particular use is to be changed at a later date, the
author doesn't have to go through annotating each use.
The b
element should be used as a last resort when
no other element is more appropriate. In particular, headings should
use the h1
to h6
elements, stress emphasis
should use the em
element, importance should be denoted
with the strong
element, and text marked or highlighted
should use the mark
element.
The following would be incorrect usage:
<p><b>WARNING!</b> Do not frob the barbinator!</p>
In the previous example, the correct element to use would have
been strong
, not b
.
Style sheets can be used to format b
elements, just like any other element can be restyled. Thus, it is
not the case that content in b
elements will
necessarily be boldened.
u
elementHTMLElement
.The u
element represents a span of text
with an unarticulated, though explicitly rendered, non-textual
annotation, such as labeling the text as being a proper name in
Chinese text (a Chinese proper name mark), or labeling the text as
being misspelt.
In most cases, another element is likely to be more appropriate:
for marking stress emphasis, the em
element should be
used; for marking key words or phrases either the b
element or the mark
element should be used, depending
on the context; for marking book titles, the cite
element should be used; for labeling text with explicit textual
annotations, the ruby
element should be used; for
labeling ship names in Western texts, the i
element
should be used.
The default rendering of the u
element
in visual presentations clashes with the conventional rendering of
hyperlinks (underlining). Authors are encouraged to avoid using the
u
element where it could be confused for a
hyperlink.
mark
elementHTMLElement
.The mark
element represents a run of
text in one document marked or highlighted for reference purposes,
due to its relevance in another context. When used in a quotation or
other block of text referred to from the prose, it indicates a
highlight that was not originally present but which has been added
to bring the reader's attention to a part of the text that might not
have been considered important by the original author when the block
was originally written, but which is now under previously unexpected
scrutiny. When used in the main prose of a document, it indicates a
part of the document that has been highlighted due to its likely
relevance to the user's current activity.
This example shows how the mark
element can be used
to bring attention to a particular part of a quotation:
<p lang="en-US">Consider the following quote:</p> <blockquote lang="en-GB"> <p>Look around and you will find, no-one's really <mark>colour</mark> blind.</p> </blockquote> <p lang="en-US">As we can tell from the <em>spelling</em> of the word, the person writing this quote is clearly not American.</p>
(If the goal was to mark the element as misspelt, however, the
u
element, possibly with a class, would be more
appropriate.
Another example of the mark
element is highlighting
parts of a document that are matching some search string. If
someone looked at a document, and the server knew that the user was
searching for the word "kitten", then the server might return the
document with one paragraph modified as follows:
<p>I also have some <mark>kitten</mark>s who are visiting me these days. They're really cute. I think they like my garden! Maybe I should adopt a <mark>kitten</mark>.</p>
In the following snippet, a paragraph of text refers to a specific part of a code fragment.
<p>The highlighted part below is where the error lies:</p> <pre><code>var i: Integer; begin i := <mark>1.1</mark>; end.</code></pre>
This is separate from syntax highlighting, for which
span
is more appropriate. Combining both, one would
get:
<p>The highlighted part below is where the error lies:</p> <pre><code><span class=keyword>var</span> <span class=ident>i</span>: <span class=type>Integer</span>; <span class=keyword>begin</span> <span class=ident>i</span> := <span class=literal><mark>1.1</mark></span>; <span class=keyword>end</span>.</code></pre>
This is another example showing the use of mark
to
highlight a part of quoted text that was originally not
emphasized. In this example, common typographic conventions have
led the author to explicitly style mark
elements in
quotes to render in italics.
<article> <style scoped> blockquote mark, q mark { font: inherit; font-style: italic; text-decoration: none; background: transparent; color: inherit; } .bubble em { font: inherit; font-size: larger; text-decoration: underline; } </style> <h1>She knew</h1> <p>Did you notice the subtle joke in the joke on panel 4?</p> <blockquote> <p class="bubble">I didn't <em>want</em> to believe. <mark>Of course on some level I realized it was a known-plaintext attack.</mark> But I couldn't admit it until I saw for myself.</p> </blockquote> <p>(Emphasis mine.) I thought that was great. It's so pedantic, yet it explains everything neatly.</p> </article>
Note, incidentally, the distinction between the em
element in this example, which is part of the original text being
quoted, and the mark
element, which is highlighting a
part for comment.
The following example shows the difference between denoting the
importance of a span of text (strong
) as
opposed to denoting the relevance of a span of text
(mark
). It is an extract from a textbook, where the
extract has had the parts relevant to the exam highlighted. The
safety warnings, important though they may be, are apparently not
relevant to the exam.
<h3>Wormhole Physics Introduction</h3> <p><mark>A wormhole in normal conditions can be held open for a maximum of just under 39 minutes.</mark> Conditions that can increase the time include a powerful energy source coupled to one or both of the gates connecting the wormhole, and a large gravity well (such as a black hole).</p> <p><mark>Momentum is preserved across the wormhole. Electromagnetic radiation can travel in both directions through a wormhole, but matter cannot.</mark></p> <p>When a wormhole is created, a vortex normally forms. <strong>Warning: The vortex caused by the wormhole opening will annihilate anything in its path.</strong> Vortexes can be avoided when using sufficiently advanced dialing technology.</p> <p><mark>An obstruction in a gate will prevent it from accepting a wormhole connection.</mark></p>
ruby
elementrt
element, or an rp
element, an rt
element, and another rp
element.HTMLElement
.The ruby
element allows one or more spans of
phrasing content to be marked with ruby annotations. Ruby
annotations are short runs of text presented alongside base text,
primarily used in East Asian typography as a guide for
pronunciation or to include other annotations. In Japanese, this
form of typography is also known as furigana.
A ruby
element represents the spans of
phrasing content it contains, ignoring all the child rt
and rp
elements and their descendants. Those spans of
phrasing content have associated annotations created using the
rt
element.
In this example, each ideograph in the Japanese text 漢字 is annotated with its reading in hiragana.
...
<ruby>漢<rt>かん</rt>字<rt>じ </rt></ruby>
...
This might be rendered as:
In this example, each ideograph in the traditional Chinese text 漢字 is annotated with its bopomofo reading.
<ruby>漢<rt>ㄏㄢˋ</rt>字<rt>ㄗˋ </rt></ruby>
This might be rendered as:
In this example, each ideograph in the simplified Chinese text 汉字 is annotated with its pinyin reading.
...<ruby>汉<rt>hàn</rt>字<rt>zì </rt></ruby>...
This might be rendered as:
rt
elementruby
element.HTMLElement
.The rt
element marks the ruby text component of a
ruby annotation.
An rt
element that is a child of
a ruby
element represents an
annotation (given by its children) for the zero or more nodes of
phrasing content that immediately precedes it in the
ruby
element, ignoring rp
elements.
rp
elementruby
element, either immediately before or immediately after an rt
element.HTMLElement
.The rp
element can be used to provide parentheses
around a ruby text component of a ruby annotation, to be shown by
user agents that don't support ruby annotations.
An rp
element that is a child of
a ruby
element represents
nothing and its contents must be
ignored. An rp
element whose
parent element is not a ruby
element
represents its children.
The example above, in which each ideograph in the text 漢字 is annotated with its
phonetic reading, could be expanded to use rp
so that in
legacy user agents the readings are in parentheses:
...
<ruby>
漢 <rp>(</rp><rt>かん</rt><rp>)</rp>
字 <rp>(</rp><rt>じ</rt><rp>)</rp>
</ruby>
...
In conforming user agents the rendering would be as above, but in user agents that do not support ruby, the rendering would be:
... 漢 (かん) 字 (じ) ...
bdi
elementdir
global attribute has special semantics on this element.HTMLElement
.The bdi
element represents a span of
text that is to be isolated from its surroundings for the purposes
of bidirectional text formatting. [BIDI]
The dir
global
attribute defaults to auto
on
this element (it never inherits from the parent element like with
other elements).
For the purposes of applying the bidirectional algorithm to the
contents of a bdi
element, user agents must treat the
element as a paragraph-level container.
For the purposes of applying the bidirectional algorithm to the
paragraph-level container that a bdi
element finds
itself within, the bdi
element must be treated like a
U+FFFC OBJECT REPLACEMENT CHARACTER (in the same manner that an
image or other inline object is handled).
The requirements on handling the bdi
element for the
bidirectional algorithm may be implemented indirectly through the
style layer. For example, an HTML+CSS user agent could implement
these requirements by implementing the CSS 'unicode-bidi' property.
[CSS]
This element is especially useful when embedding user-generated content with an unknown directionality.
In this example, usernames are shown along with the number of
posts that the user has submitted. If the bdi
element
were not used, the username of the Arabic user would end up
confusing the text (the bidirectional algorithm would put the colon
and the number "3" next to the word "User" rather than next to the
word "posts").
<ul> <li>User <bdi>jcranmer</bdi>: 12 posts. <li>User <bdi>hober</bdi>: 5 posts. <li>User <bdi>إيان</bdi>: 3 posts. </ul>
bdo
elementdir
global attribute has special semantics on this element.HTMLElement
.The bdo
element represents explicit
text directionality formatting control for its children. It allows
authors to override the Unicode bidirectional algorithm by
explicitly specifying a direction override. [BIDI]
Authors must specify the dir
attribute on this element, with the value ltr
to
specify a left-to-right override and with the value rtl
to specify a right-to-left override.
If the element's dir
attribute is
in the rtl state, then for the
purposes of the bidirectional algorithm, the user agent must act as
if there was a U+202D LEFT-TO-RIGHT OVERRIDE character at the start
of the element, and a U+202C POP DIRECTIONAL FORMATTING at the end
of the element.
If the element's dir
attribute is
in the ltr, then for the purposes
of the bidirectional algorithm, the user agent must act as if there
was a U+202E RIGHT-TO-LEFT OVERRIDE character at the start of the
element, and a U+202C POP DIRECTIONAL FORMATTING at the end of the
element.
The requirements on handling the bdo
element for the
bidirectional algorithm may be implemented indirectly through the
style layer. For example, an HTML+CSS user agent could implement
these requirements by implementing the CSS 'unicode-bidi' property.
[CSS]
span
elementinterface HTMLSpanElement : HTMLElement {};
The span
element doesn't mean anything on its own,
but can be useful when used together with the global
attributes, e.g. class
, lang
, or dir
.
It represents its children.
In this example, a code fragment is marked up using
span
elements and class
attributes so that its keywords and
identifiers can be color-coded from CSS:
<pre><code class="lang-c"><span class="keyword">for</span> (<span class="ident">j</span> = 0; <span class="ident">j</span> < 256; <span class="ident">j</span>++) { <span class="ident">i_t3</span> = (<span class="ident">i_t3</span> & 0x1ffff) | (<span class="ident">j</span> << 17); <span class="ident">i_t6</span> = (((((((<span class="ident">i_t3</span> >> 3) ^ <span class="ident">i_t3</span>) >> 1) ^ <span class="ident">i_t3</span>) >> 8) ^ <span class="ident">i_t3</span>) >> 5) & 0xff; <span class="keyword">if</span> (<span class="ident">i_t6</span> == <span class="ident">i_t1</span>) <span class="keyword">break</span>; }</code></pre>
br
elementinterface HTMLBRElement : HTMLElement {};
The br
element represents a line
break.
While line breaks are usually represented in visual media by physically moving subsequent text to a new line, a style sheet or user agent would be equally justified in causing line breaks to be rendered in a different manner, for instance as green dots, or as extra spacing.
br
elements must be used only for line breaks that
are actually part of the content, as in poems or addresses.
The following example is correct usage of the br
element:
<p>P. Sherman<br> 42 Wallaby Way<br> Sydney</p>
br
elements must not be used for separating thematic
groups in a paragraph.
The following examples are non-conforming, as they abuse the
br
element:
<p><a ...>34 comments.</a><br> <a ...>Add a comment.</a></p>
<p><label>Name: <input name="name"></label><br> <label>Address: <input name="address"></label></p>
Here are alternatives to the above, which are correct:
<p><a ...>34 comments.</a></p> <p><a ...>Add a comment.</a></p>
<p><label>Name: <input name="name"></label></p> <p><label>Address: <input name="address"></label></p>
If a paragraph consists of nothing but a single
br
element, it represents a placeholder blank line
(e.g. as in a template). Such blank lines must not be used for
presentation purposes.
Any content inside br
elements must not be
considered part of the surrounding text.
A br
element should separate paragraphs for the
purposes of the Unicode bidirectional algorithm. This requirement
may be implemented indirectly through the style layer. For example,
an HTML+CSS user agent could implement these requirements by
implementing the CSS 'unicode-bidi' property. [BIDI] [CSS]
wbr
elementHTMLElement
.The wbr
element represents a line break
opportunity.
In the following example, someone is quoted as saying something
which, for effect, is written as one long word. However, to ensure
that the text can be wrapped in a readable fashion, the individual
words in the quote are separated using a wbr
element.
<p>So then he pointed at the tiger and screamed "there<wbr>is<wbr>no<wbr>way<wbr>you<wbr>are<wbr>ever<wbr>going<wbr>to<wbr>catch<wbr>me"!</p>
Any content inside wbr
elements must not be
considered part of the surrounding text.
This section is non-normative.
Element | Purpose | Example |
---|---|---|
a
| Hyperlinks | Visit my <a href="drinks.html">drinks</a> page. |
em
| Stress emphasis | I must say I <em>adore</em> lemonade. |
strong
| Importance | This tea is <strong>very hot</strong>. |
small
| Side comments | These grapes are made into wine. <small>Alcohol is addictive.</small> |
s
| Inaccurate text | Price: <s>£4.50</s> £2.00! |
cite
| Titles of works | The case <cite>Hugo v. Danielle</cite> is relevant here. |
q
| Quotations | The judge said <q>You can drink water from the fish tank</q> but advised against it. |
dfn
| Defining instance | The term <dfn>organic food</dfn> refers to food produced without synthetic chemicals. |
abbr
| Abbreviations | Organic food in Ireland is certified by the <abbr title="Irish Organic Farmers and Growers Association">IOFGA</abbr>. |
time
| Date and/or time | Published <time>2009-10-21</time>. |
code
| Computer code | The <code>fruitdb</code> program can be used for tracking fruit production. |
var
| Variables | If there are <var>n</var> fruit in the bowl, at least <var>n</var>÷2 will be ripe. |
samp
| Computer output | The computer said <samp>Unknown error -3</samp>. |
kbd
| User input | Hit <kbd>F1</kbd> to continue. |
sub
| Subscripts | Water is H<sub>2</sub>O. |
sup
| Superscripts | The Hydrogen in heavy water is usually <sup>2</sup>H. |
i
| Alternative voice | Lemonade consists primarily of <i>Citrus limon</i>. |
b
| Keywords | Take a <b>lemon</b> and squeeze it with a <b>juicer</b>. |
u
| Annotations | The mixture of apple juice and <u class="spelling">eldeflower</u> juice is very pleasant. |
mark
| Highlight | Elderflower cordial, with one <mark>part</mark> cordial to ten <mark>part</mark>s water, stands a<mark>part</mark> from the rest. |
ruby , rt , rp
| Ruby annotations | <ruby> OJ <rp>(<rt>Orange Juice<rp>)</ruby> |
bdi
| Text directionality isolation | The recommended restaurant is <bdi lang="">My Juice Café (At The Beach)</bdi>. |
bdo
| Text directionality formatting | The proposal is to write English, but in reverse order. "Juice" would become "<bdo dir=rtl>Juice</bdo>" |
span
| Other | In French we call it <span lang="fr">sirop de sureau</span>. |
br
| Line break | Simply Orange Juice Company<br>Apopka, FL 32703<br>U.S.A. |
wbr
| Line breaking opportunity | www.simply<wbr>orange<wbr>juice.com |
The ins
and del
elements represent
edits to the document.
ins
elementcite
datetime
HTMLModElement
interface.The ins
element represents an addition
to the document.
The following represents the addition of a single paragraph:
<aside> <ins> <p> I like fruit. </p> </ins> </aside>
As does this, because everything in the aside
element here counts as phrasing content and therefore
there is just one paragraph:
<aside> <ins> Apples are <em>tasty</em>. </ins> <ins> So are pears. </ins> </aside>
ins
elements should not cross implied paragraph boundaries.
The following example represents the addition of two paragraphs,
the second of which was inserted in two parts. The first
ins
element in this example thus crosses a paragraph
boundary, which is considered poor form.
<aside> <!-- don't do this --> <ins datetime="2005-03-16T00:00Z"> <p> I like fruit. </p> Apples are <em>tasty</em>. </ins> <ins datetime="2007-12-19T00:00Z"> So are pears. </ins> </aside>
Here is a better way of marking this up. It uses more elements, but none of the elements cross implied paragraph boundaries.
<aside> <ins datetime="2005-03-16T00:00Z"> <p> I like fruit. </p> </ins> <ins datetime="2005-03-16T00:00Z"> Apples are <em>tasty</em>. </ins> <ins datetime="2007-12-19T00:00Z"> So are pears. </ins> </aside>
del
elementcite
datetime
HTMLModElement
interface.The del
element represents a removal
from the document.
del
elements should not cross implied paragraph boundaries.
The following shows a "to do" list where items that have been done are crossed-off with the date and time of their completion.
<h1>To Do</h1> <ul> <li>Empty the dishwasher</li> <li><del datetime="2009-10-11T01:25-07:00">Watch Walter Lewin's lectures</del></li> <li><del datetime="2009-10-10T23:38-07:00">Download more tracks</del></li> <li>Buy a printer</li> </ul>
ins
and del
elementsThe cite
attribute
may be used to specify the address of a document that explains the
change. When that document is long, for instance the minutes of a
meeting, authors are encouraged to include a fragment identifier
pointing to the specific part of that document that discusses the
change.
If the cite
attribute is
present, it must be a valid URL potentially surrounded by
spaces that explains the change. To obtain
the corresponding citation link, the value of the attribute must be
resolved relative to the
element. User agents should allow users to follow such citation
links.
The datetime
attribute may be used to specify the time and date of the change.
If present, the datetime
attribute's value must be a valid date string with optional
time.
User agents must parse the datetime
attribute according to the
parse a date or time string algorithm. If that doesn't
return a date or a global date and time, then the
modification has no associated timestamp (the value is
non-conforming; it is not a valid date string with optional
time). Otherwise, the modification is marked as having been
made at the given date or global date and time. If the given
value is a global date and
time then user agents should use the associated time-zone
offset information to determine which time zone to present the given
datetime in.
The ins
and del
elements must implement the HTMLModElement
interface:
interface HTMLModElement : HTMLElement { attribute DOMString cite; attribute DOMString dateTime; };
The cite
IDL
attribute must reflect the element's cite
content attribute. The dateTime
IDL attribute
must reflect the element's datetime
content attribute.
This section is non-normative.
Since the ins
and del
elements do not
affect paragraphing, it is possible,
in some cases where paragraphs are implied (without explicit p
elements), for an ins
or del
element to
span both an entire paragraph or other non-phrasing
content elements and part of another paragraph. For
example:
<section> <ins> <p> This is a paragraph that was inserted. </p> This is another paragraph whose first sentence was inserted at the same time as the paragraph above. </ins> This is a second sentence, which was there all along. </section>
By only wrapping some paragraphs in p
elements, one
can even get the end of one paragraph, a whole second paragraph,
and the start of a third paragraph to be covered by the same
ins
or del
element (though this is very
confusing, and not considered good practice):
<section> This is the first paragraph. <ins>This sentence was inserted. <p>This second paragraph was inserted.</p> This sentence was inserted too.</ins> This is the third paragraph in this example. <!-- (don't do this) --> </section>
However, due to the way implied
paragraphs are defined, it is not possible to mark up the
end of one paragraph and the start of the very next one using the
same ins
or del
element. You instead have
to use one (or two) p
element(s) and two
ins
or del
elements, as for example:
<section> <p>This is the first paragraph. <del>This sentence was deleted.</del></p> <p><del>This sentence was deleted too.</del> That sentence needed a separate <del> element.</p> </section>
Partly because of the confusion described above, authors are
strongly encouraged to always mark up all paragraphs with the
p
element, instead of having ins
or
del
elements that cross implied
paragraphs boundaries.
This section is non-normative.
The content models of the ol
and ul
elements do not allow ins
and del
elements
as children. Lists always represent all their items, including items
that would otherwise have been marked as deleted.
To indicate that an item is inserted or deleted, an
ins
or del
element can be wrapped around
the contents of the li
element. To indicate that an
item has been replaced by another, a single li
element
can have one or more del
elements followed by one or
more ins
elements.
In the following example, a list that started empty had items added and removed from it over time. The bits in the example that have been emphasized show the parts that are the "current" state of the list. The list item numbers don't take into account the edits, though.
<h1>Stop-ship bugs</h1> <ol> <li><ins datetime="2008-02-12T15:20Z">Bug 225: Rain detector doesn't work in snow</ins></li> <li><del datetime="2008-03-01T20:22Z"><ins datetime="2008-02-14T12:02Z">Bug 228: Water buffer overflows in April</ins></del></li> <li><ins datetime="2008-02-16T13:50Z">Bug 230: Water heater doesn't use renewable fuels</ins></li> <li><del datetime="2008-02-20T21:15Z"><ins datetime="2008-02-16T14:25Z">Bug 232: Carbon dioxide emissions detected after startup</ins></del></li> </ol>
In the following example, a list that started with just fruit was replaced by a list with just colors.
<h1>List of <del>fruits</del><ins>colors</ins></h1> <ul> <li><del>Lime</del><ins>Green</ins></li> <li><del>Apple</del></li> <li>Orange</li> <li><del>Pear</del></li> <li><ins>Teal</ins></li> <li><del>Lemon</del><ins>Yellow</ins></li> <li>Olive</li> <li><ins>Purple</ins></li> </ul>
img
elementISSUE-30 (longdesc) blocks progress to Last Call
usemap
attribute: Interactive content.alt
src
usemap
ismap
width
height
[NamedConstructor=Image(), NamedConstructor=Image(in unsigned long width), NamedConstructor=Image(in unsigned long width, in unsigned long height)] interface HTMLImageElement : HTMLElement { attribute DOMString alt; attribute DOMString src; attribute DOMString useMap; attribute boolean isMap; attribute unsigned long width; attribute unsigned long height; readonly attribute unsigned long naturalWidth; readonly attribute unsigned long naturalHeight; readonly attribute boolean complete; };
An img
element represents an image.
The image given by the src
attribute is the
embedded content; the value of the alt
attribute provides
equivalent content for those who cannot process images or who have
image loading disabled.
The src
attribute must be
present, and must contain a valid non-empty URL potentially
surrounded by spaces referencing a non-interactive,
optionally animated, image resource that is neither paged nor
scripted.
Images can thus be static bitmaps (e.g. PNGs, GIFs, JPEGs), single-page vector documents (single-page PDFs, XML files with an SVG root element), animated bitmaps (APNGs, animated GIFs), animated vector graphics (XML files with an SVG root element that use declarative SMIL animation), and so forth. However, this also precludes SVG files with script, multipage PDF files, interactive MNG files, HTML documents, plain text documents, and so forth.
The requirements on the alt
attribute's value are described in the next
section.
The img
element must not be used as a layout tool.
In particular, img
elements should not be used to
display transparent images, as they rarely convey meaning and rarely
add anything useful to the document.
An img
is always in one of the following states:
When an img
element is either in the partially available state or in the completely available state, it is said to be
available.
An img
element is initially unavailable.
User agents may obtain images immediately or on demand.
A user agent that obtains images immediately must synchronously
update the image data of an img
element
whenever that element is either created with a src
attribute, or has its src
attribute set, changed, or
removed.
A user agent that obtains images on demand must update the
image data of an img
element whenever it needs
the image data (i.e. on demand), but only if the img
element has a src
attribute, and
if it has not updated the image
data since the last time the src
attribute was set. When an
img
element's src
attribute is changed or removed, if the user agent only obtains
images on demand, the img
element must return to the
unavailable state.
When the user agent is to update the image data of an
img
element, it must run the following steps:
Return the img
element to the unavailable state.
If an instance of the fetching algorithm is still running for this element, then abort that algorithm, discarding any pending tasks generated by that algorithm.
Forget the img
element's current image data, if
any.
If the user agent cannot support images, or its support for images has been disabled, then abort these steps.
If the element's src
attribute's value is the empty string, then set the element to the
broken state, queue a
task to fire a simple event named error
at the img
element,
and abort these steps.
Otherwise, resolve the value
of the element's src
attribute,
relative to the element, and, if that is successful,
fetch that resource.
The resouce obtained in this fashion is the img
element's image data.
Fetching the image must delay the load event of the element's document until the task that is queued by the networking task source once the resource has been fetched (defined below) has been run.
This, unfortunately, can be used to perform a rudimentary port scan of the user's local network (especially in conjunction with scripting, though scripting isn't actually necessary to carry out such an attack). User agents may implement cross-origin access control policies that mitigate this attack, but unfortunately such policies are typically not compatible with existing Web content.
Each task that is queued by the networking task
source while the image is being fetched must set the img
element's
state to partially available and update
the presentation of the image appropriately.
The task that is queued by the networking task source once the resource has been fetched must act as appropriate given the following alternatives:
img
element to the completely available state, update the
presentation of the image appropriately, and queue a
task to fire a simple event named load
at the img
element.img
element to the broken state, and queue a
task to fire a simple event named error
at the img
element.If at any point the user agent discovers that the image data is
corrupted in some fatal way, or that the image is not in a supported
file format, then the user agent must set the img
element to the broken state. If the
fetching algorithm is still running for
this element, then the user agent must also abort that algorithm,
discarding any pending tasks
generated by that algorithm, and then queue a task to
fire a simple event named error
at the img
element.
When an img
element is in the completely available state and the
user agent can completely decode the media data without errors, then
the img
element is said to be fully decodable.
Whether the image is fetched successfully or not (e.g. whether the response code was a 2xx code or equivalent) must be ignored when determining the image's type and whether it is a valid image.
This allows servers to return images with error responses, and have them displayed.
The user agents should apply the image sniffing rules to determine the type of the image, with the image's associated Content-Type headers giving the official type. If these rules are not applied, then the type of the image must be the type given by the image's associated Content-Type headers.
User agents must not support non-image resources with the
img
element (e.g. XML files whose root element is an
HTML element). User agents must not run executable code
(e.g. scripts) embedded in the image resource. User agents must only
display the first page of a multipage resource (e.g. a PDF
file). User agents must not allow the resource to act in an
interactive fashion, but should honor any animation in the
resource.
This specification does not specify which image types are to be supported.
The task source for these tasks is the DOM manipulation task source.
What an img
element represents depends on the src
attribute and the alt
attribute.
src
attribute is set
and the alt
attribute is set to
the empty stringThe image is either decorative or supplemental to the rest of the content, redundant with some other information in the document.
If the image is available and the user agent is configured to display that image, then the element represents the element's image data.
Otherwise, the element represents nothing, and may be omitted completely from the rendering. User agents may provide the user with a notification that an image is present but has been omitted from the rendering.
src
attribute is set
and the alt
attribute is set to a
value that isn't emptyThe image is a key part of the content; the alt
attribute gives a textual
equivalent or replacement for the image.
If the image is available and the user agent is configured to display that image, then the element represents the element's image data.
Otherwise, the element represents the text given
by the alt
attribute. User
agents may provide the user with a notification that an image is
present but has been omitted from the rendering.
src
attribute is set
and the alt
attribute is notThe image might be a key part of the content, and there is no textual equivalent of the image available.
In a conforming document, the absence of the alt
attribute indicates that the image
is a key part of the content but that a textual replacement for
the image was not available when the image was generated.
If the image is available and the user agent is configured to display that image, then the element represents the element's image data.
Otherwise, the user agent should display some sort of indicator that there is an image that is not being rendered, and may, if requested by the user, or if so configured, or when required to provide contextual information in response to navigation, provide caption information for the image, derived as follows:
If the image has a title
attribute whose value is not the empty string, then the value of
that attribute is the caption information; abort these
steps.
If the image is a descendant of a figure
element that has a child figcaption
element, and,
ignoring the figcaption
element and its descendants,
the figure
element has no text node descendants
other than inter-element whitespace, and no
embedded content descendant other than the
img
element, then the contents of the first such
figcaption
element are the caption information;
abort these steps.
src
attribute is not
set and either the alt
attribute
is set to the empty string or the alt
attribute is not set at allThe element represents nothing.
The element represents the text given by the alt
attribute.
The alt
attribute does not
represent advisory information. User agents must not present the
contents of the alt
attribute in
the same way as content of the title
attribute.
User agents may always provide the user with the option to display any image, or to prevent any image from being displayed.
While user agents are encouraged to repair cases
of missing alt
attributes, authors
must not rely on such behavior. Requirements for
providing text to act as an alternative for images are described
in detail below.
The contents of img
elements, if any, are
ignored for the purposes of rendering.
The usemap
attribute,
if present, can indicate that the image has an associated
image map.
The ismap
attribute, when used on an element that is a descendant of an
a
element with an href
attribute, indicates by its
presence that the element provides access to a server-side image
map. This affects how events are handled on the corresponding
a
element.
The ismap
attribute is a
boolean attribute. The attribute must not be specified
on an element that does not have an ancestor a
element
with an href
attribute.
The img
element supports dimension
attributes.
The IDL attributes alt
, src
, useMap
, and isMap
each must
reflect the respective content attributes of the same
name.
width
[ = value ]height
[ = value ]These attributes return the actual rendered dimensions of the image, or zero if the dimensions are not known.
They can be set, to change the corresponding content attributes.
naturalWidth
naturalHeight
These attributes return the intrinsic dimensions of the image, or zero if the dimensions are not known.
complete
Returns true if the image has been completely downloaded or if no image is specified; otherwise, returns false.
Image
( [ width [, height ] ] )Returns a new img
element, with the width
and height
attributes set to the values
passed in the relevant arguments, if applicable.
The IDL attributes width
and height
must return the
rendered width and height of the image, in CSS pixels, if the image
is being rendered, and is being rendered to a visual
medium; or else the intrinsic width and height of the image, in CSS
pixels, if the image is available but
not being rendered to a visual medium; or else 0, if the image is
not available. [CSS]
On setting, they must act as if they reflected the respective content attributes of the same name.
The IDL attributes naturalWidth
and
naturalHeight
must return the intrinsic width and height of the image, in CSS
pixels, if the image is available, or
else 0. [CSS]
The IDL attribute complete
must return
true if any of the following conditions is true:
src
attribute is omitted.
src
attribute's value is the empty string.
img
element is not in the broken state.
img
element is completely available.
Otherwise, the attribute must return false.
The value of complete
can thus change while a
script is executing.
Three constructors are provided for creating
HTMLImageElement
objects (in addition to the factory
methods from DOM Core such as createElement()
): Image()
, Image(width)
, and Image(width, height)
. When invoked as constructors,
these must return a new HTMLImageElement
object (a new
img
element). If the width argument
is present, the new object's width
content attribute must be set to
width. If the height
argument is also present, the new object's height
content attribute must be set
to height. The element's document must be the
active document of the browsing context of
the Window
object on which the interface object of the
invoked constructor is found.
A single image can have different appropriate alternative text depending on the context.
In each of the following cases, the same image is used, yet the
alt
text is different each
time. The image is the coat of arms of the Carouge municipality in
the canton Geneva in Switzerland.
Here it is used as a supplementary icon:
<p>I lived in <img src="carouge.svg" alt=""> Carouge.</p>
Here it is used as an icon representing the town:
<p>Home town: <img src="carouge.svg" alt="Carouge"></p>
Here it is used as part of a text on the town:
<p>Carouge has a coat of arms.</p> <p><img src="carouge.svg" alt="The coat of arms depicts a lion, sitting in front of a tree."></p> <p>It is used as decoration all over the town.</p>
Here it is used as a way to support a similar text where the description is given as well as, instead of as an alternative to, the image:
<p>Carouge has a coat of arms.</p> <p><img src="carouge.svg" alt=""></p> <p>The coat of arms depicts a lion, sitting in front of a tree. It is used as decoration all over the town.</p>
Here it is used as part of a story:
<p>He picked up the folder and a piece of paper fell out.</p> <p><img src="carouge.svg" alt="Shaped like a shield, the paper had a red background, a green tree, and a yellow lion with its tongue hanging out and whose tail was shaped like an S."></p> <p>He stared at the folder. S! The answer he had been looking for all this time was simply the letter S! How had he not seen that before? It all came together now. The phone call where Hector had referred to a lion's tail, the time Marco had stuck his tongue out...</p>
Here it is not known at the time of publication what the image
will be, only that it will be a coat of arms of some kind, and thus
no replacement text can be provided, and instead only a brief
caption for the image is provided, in the title
attribute:
<p>The last user to have uploaded a coat of arms uploaded this one:</p> <p><img src="last-uploaded-coat-of-arms.cgi" title="User-uploaded coat of arms."></p>
Ideally, the author would find a way to provide real replacement text even in this case, e.g. by asking the previous user. Not providing replacement text makes the document more difficult to use for people who are unable to view images, e.g. blind users, or users or very low-bandwidth connections or who pay by the byte, or users who are forced to use a text-only Web browser.
Here are some more examples showing the same picture used in different contexts, with different appropriate alternate texts each time.
<article> <h1>My cats</h1> <h2>Fluffy</h2> <p>Fluffy is my favorite.</p> <img src="fluffy.jpg" alt="She likes playing with a ball of yarn."> <p>She's just too cute.</p> <h2>Miles</h2> <p>My other cat, Miles just eats and sleeps.</p> </article>
<article> <h1>Photography</h1> <h2>Shooting moving targets indoors</h2> <p>The trick here is to know how to anticipate; to know at what speed and what distance the subject will pass by.</p> <img src="fluffy.jpg" alt="A cat flying by, chasing a ball of yarn, can be photographed quite nicely using this technique."> <h2>Nature by night</h2> <p>To achieve this, you'll need either an extremely sensitive film, or immense flash lights.</p> </article>
<article> <h1>About me</h1> <h2>My pets</h2> <p>I've got a cat named Fluffy and a dog named Miles.</p> <img src="fluffy.jpg" alt="Fluffy, my cat, tends to keep itself busy."> <p>My dog Miles and I like go on long walks together.</p> <h2>music</h2> <p>After our walks, having emptied my mind, I like listening to Bach.</p> </article>
<article> <h1>Fluffy and the Yarn</h1> <p>Fluffy was a cat who liked to play with yarn. He also liked to jump.</p> <aside><img src="fluffy.jpg" alt="" title="Fluffy"></aside> <p>He would play in the morning, he would play in the evening.</p> </article>
Except where otherwise specified, the alt
attribute must be specified and its
value must not be empty; the value must be an appropriate
replacement for the image. The specific requirements for the alt
attribute depend on what the image
is intended to represent, as described in the following
sections.
The most general rule to consider when writing alternative text
is the following: the intent is that replacing every image
with the text of its alt
attribute
not change the meaning of the page.
So, in general, alternative text can be written by considering what one would have written had one not been able to include the image.
A corollary to this is that the alt
attribute's value should never
contain text that could be considered the image's caption,
title, or legend. It is supposed to contain
replacement text that could be used by users instead of the
image; it is not meant to supplement the image. The title
attribute can be used for
supplemental information.
One way to think of alternative text is to think about how you would read the page containing the image to someone over the phone, without mentioning that there is an image present. Whatever you say instead of the image is typically a good start for writing the alternative text.
When an a element that creates a
hyperlink, or a button
element, has no
textual content but contains one or more images, the alt
attributes must contain text that
together convey the purpose of the link or button.
In this example, a user is asked to pick his preferred color from a list of three. Each color is given by an image, but for users who have configured their user agent not to display images, the color names are used instead:
<h1>Pick your color</h1> <ul> <li><a href="green.html"><img src="green.jpeg" alt="Green"></a></li> <li><a href="blue.html"><img src="blue.jpeg" alt="Blue"></a></li> <li><a href="red.html"><img src="red.jpeg" alt="Red"></a></li> </ul>
In this example, each button has a set of images to indicate the kind of color output desired by the user. The first image is used in each case to give the alternative text.
<button name="rgb"><img src="red" alt="RGB"><img src="green" alt=""><img src="blue" alt=""></button> <button name="cmyk"><img src="cyan" alt="CMYK"><img src="magenta" alt=""><img src="yellow" alt=""><img src="black" alt=""></button>
Since each image represents one part of the text, it could also be written like this:
<button name="rgb"><img src="red" alt="R"><img src="green" alt="G"><img src="blue" alt="B"></button> <button name="cmyk"><img src="cyan" alt="C"><img src="magenta" alt="M"><img src="yellow" alt="Y"><img src="black" alt="K"></button>
However, with other alternative text, this might not work, and putting all the alternative text into one image in each case might make more sense:
<button name="rgb"><img src="red" alt="sRGB profile"><img src="green" alt=""><img src="blue" alt=""></button> <button name="cmyk"><img src="cyan" alt="CMYK profile"><img src="magenta" alt=""><img src="yellow" alt=""><img src="black" alt=""></button>
Sometimes something can be more clearly stated in graphical
form, for example as a flowchart, a diagram, a graph, or a simple
map showing directions. In such cases, an image can be given using
the img
element, but the lesser textual version must
still be given, so that users who are unable to view the image
(e.g. because they have a very slow connection, or because they
are using a text-only browser, or because they are listening to
the page being read out by a hands-free automobile voice Web
browser, or simply because they are blind) are still able to
understand the message being conveyed.
The text must be given in the alt
attribute, and must convey the
same message as the image specified in the src
attribute.
It is important to realize that the alternative text is a replacement for the image, not a description of the image.
In the following example we have a flowchart in image
form, with text in the alt
attribute rephrasing the flowchart in prose form:
<p>In the common case, the data handled by the tokenization stage comes from the network, but it can also come from script.</p> <p><img src="http://dev.w3.org/html5/spec/images/parsing-model-overview.png" alt="The network passes data to the Tokenizer stage, which passes data to the Tree Construction stage. From there, data goes to both the DOM and to Script Execution. Script Execution is linked to the DOM, and, using document.write(), passes data to the Tokenizer."></p>
Here's another example, showing a good solution and a bad solution to the problem of including an image in a description.
First, here's the good solution. This sample shows how the alternative text should just be what you would have put in the prose if the image had never existed.
<!-- This is the correct way to do things. --> <p> You are standing in an open field west of a house. <img src="house.jpeg" alt="The house is white, with a boarded front door."> There is a small mailbox here. </p>
Second, here's the bad solution. In this incorrect way of doing things, the alternative text is simply a description of the image, instead of a textual replacement for the image. It's bad because when the image isn't shown, the text doesn't flow as well as in the first example.
<!-- This is the wrong way to do things. --> <p> You are standing in an open field west of a house. <img src="house.jpeg" alt="A white house, with a boarded front door."> There is a small mailbox here. </p>
Text such as "Photo of white house with boarded door" would be
equally bad alternative text (though it could be suitable for the
title
attribute or in the
figcaption
element of a figure
with this
image).
A document can contain information in iconic form. The icon is intended to help users of visual browsers to recognize features at a glance.
In some cases, the icon is supplemental to a text label
conveying the same meaning. In those cases, the alt
attribute must be present but must
be empty.
Here the icons are next to text that conveys the same meaning,
so they have an empty alt
attribute:
<nav> <p><a href="/help/"><img src="/icons/help.png" alt=""> Help</a></p> <p><a href="/configure/"><img src="/icons/configuration.png" alt=""> Configuration Tools</a></p> </nav>
In other cases, the icon has no text next to it describing what
it means; the icon is supposed to be self-explanatory. In those
cases, an equivalent textual label must be given in the alt
attribute.
Here, posts on a news site are labeled with an icon indicating their topic.
<body> <article> <header> <h1>Ratatouille wins <i>Best Movie of the Year</i> award</h1> <p><img src="movies.png" alt="Movies"></p> </header> <p>Pixar has won yet another <i>Best Movie of the Year</i> award, making this its 8th win in the last 12 years.</p> </article> <article> <header> <h1>Latest TWiT episode is online</h1> <p><img src="podcasts.png" alt="Podcasts"></p> </header> <p>The latest TWiT episode has been posted, in which we hear several tech news stories as well as learning much more about the iPhone. This week, the panelists compare how reflective their iPhones' Apple logos are.</p> </article> </body>
Many pages include logos, insignia, flags, or emblems, which stand for a particular entity such as a company, organization, project, band, software package, country, or some such.
If the logo is being used to represent the entity, e.g. as a page
heading, the alt
attribute must
contain the name of the entity being represented by the logo. The
alt
attribute must not
contain text like the word "logo", as it is not the fact that it is
a logo that is being conveyed, it's the entity itself.
If the logo is being used next to the name of the entity that
it represents, then the logo is supplemental, and its alt
attribute must instead be
empty.
If the logo is merely used as decorative material (as branding, or, for example, as a side image in an article that mentions the entity to which the logo belongs), then the entry below on purely decorative images applies. If the logo is actually being discussed, then it is being used as a phrase or paragraph (the description of the logo) with an alternative graphical representation (the logo itself), and the first entry above applies.
In the following snippets, all four of the above cases are present. First, we see a logo used to represent a company:
<h1><img src="XYZ.gif" alt="The XYZ company"></h1>
Next, we see a paragraph which uses a logo right next to the company name, and so doesn't have any alternative text:
<article> <h2>News</h2> <p>We have recently been looking at buying the <img src="alpha.gif" alt=""> ΑΒΓ company, a small Greek company specializing in our type of product.</p>
In this third snippet, we have a logo being used in an aside, as part of the larger article discussing the acquisition:
<aside><p><img src="alpha-large.gif" alt=""></p></aside> <p>The ΑΒΓ company has had a good quarter, and our pie chart studies of their accounts suggest a much bigger blue slice than its green and orange slices, which is always a good sign.</p> </article>
Finally, we have an opinion piece talking about a logo, and the logo is therefore described in detail in the alternative text.
<p>Consider for a moment their logo:</p> <p><img src="/images/logo" alt="It consists of a green circle with a green question mark centered inside it."></p> <p>How unoriginal can you get? I mean, oooooh, a question mark, how <em>revolutionary</em>, how utterly <em>ground-breaking</em>, I'm sure everyone will rush to adopt those specifications now! They could at least have tried for some sort of, I don't know, sequence of rounded squares with varying shades of green and bold white outlines, at least that would look good on the cover of a blue book.</p>
This example shows how the alternative text should be written such that if the image isn't available, and the text is used instead, the text flows seamlessly into the surrounding text, as if the image had never been there in the first place.
Sometimes, an image just consists of text, and the purpose of the image is not to highlight the actual typographic effects used to render the text, but just to convey the text itself.
In such cases, the alt
attribute must be present but must consist of the same text as
written in the image itself.
Consider a graphic containing the text "Earth Day", but with the letters all decorated with flowers and plants. If the text is merely being used as a heading, to spice up the page for graphical users, then the correct alternative text is just the same text "Earth Day", and no mention need be made of the decorations:
<h1><img src="earthdayheading.png" alt="Earth Day"></h1>
In many cases, the image is actually just supplementary, and
its presence merely reinforces the surrounding text. In these
cases, the alt
attribute must be
present but its value must be the empty string.
In general, an image falls into this category if removing the image doesn't make the page any less useful, but including the image makes it a lot easier for users of visual browsers to understand the concept.
A flowchart that repeats the previous paragraph in graphical form:
<p>The network passes data to the Tokenizer stage, which passes data to the Tree Construction stage. From there, data goes to both the DOM and to Script Execution. Script Execution is linked to the DOM, and, using document.write(), passes data to the Tokenizer.</p> <p><img src="http://dev.w3.org/html5/spec/images/parsing-model-overview.png" alt=""></p>
In these cases, it would be wrong to include alternative text
that consists of just a caption. If a caption is to be included,
then either the title
attribute can
be used, or the figure
and figcaption
elements can be used. In the latter case, the image would in fact
be a phrase or paragraph with an alternative graphical
representation, and would thus require alternative text.
<!-- Using the title="" attribute --> <p>The network passes data to the Tokenizer stage, which passes data to the Tree Construction stage. From there, data goes to both the DOM and to Script Execution. Script Execution is linked to the DOM, and, using document.write(), passes data to the Tokenizer.</p> <p><img src="http://dev.w3.org/html5/spec/images/parsing-model-overview.png" alt="" title="Flowchart representation of the parsing model."></p>
<!-- Using <figure> and <figcaption> --> <p>The network passes data to the Tokenizer stage, which passes data to the Tree Construction stage. From there, data goes to both the DOM and to Script Execution. Script Execution is linked to the DOM, and, using document.write(), passes data to the Tokenizer.</p> <figure> <img src="http://dev.w3.org/html5/spec/images/parsing-model-overview.png" alt="The Network leads to the Tokenizer, which leads to the Tree Construction. The Tree Construction leads to two items. The first is Script Execution, which leads via document.write() back to the Tokenizer. The second item from which Tree Construction leads is the DOM. The DOM is related to the Script Execution."> <figcaption>Flowchart representation of the parsing model.</figcaption> </figure>
<!-- This is WRONG. Do not do this. Instead, do what the above examples do. --> <p>The network passes data to the Tokenizer stage, which passes data to the Tree Construction stage. From there, data goes to both the DOM and to Script Execution. Script Execution is linked to the DOM, and, using document.write(), passes data to the Tokenizer.</p> <p><img src="http://dev.w3.org/html5/spec/images/parsing-model-overview.png" alt="Flowchart representation of the parsing model."></p> <!-- Never put the image's caption in the alt="" attribute! -->
A graph that repeats the previous paragraph in graphical form:
<p>According to a study covering several billion pages, about 62% of documents on the Web in 2007 triggered the Quirks rendering mode of Web browsers, about 30% triggered the Almost Standards mode, and about 9% triggered the Standards mode.</p> <p><img src="rendering-mode-pie-chart.png" alt=""></p>
If an image is decorative but isn't especially page-specific — for example an image that forms part of a site-wide design scheme — the image should be specified in the site's CSS, not in the markup of the document.
Exceptions to this rule, in cases where CSS cannot be used to display an entirely decorative image, are covered by the HTML5: Techniques for providing useful text alternatives. [HTMLALTTECHS] Authors are also encouraged to consult the Web Content Accessibility Guidelines 2.0 for more detailed information and acceptable techniques. [WCAG]
When a picture has been sliced into smaller image files that are
then displayed together to form the complete picture again, one of
the images must have its alt
attribute set as per the relevant rules that would be appropriate
for the picture as a whole, and then all the remaining images must
have their alt
attribute set to
the empty string.
In the following example, a picture representing a company logo for XYZ Corp has been split into two pieces, the first containing the letters "XYZ" and the second with the word "Corp". The alternative text ("XYZ Corp") is all in the first image.
<h1><img src="logo1.png" alt="XYZ Corp"><img src="logo2.png" alt=""></h1>
In the following example, a rating is shown as three filled stars and two empty stars. While the alternative text could have been "★★★☆☆", the author has instead decided to more helpfully give the rating in the form "3 out of 5". That is the alternative text of the first image, and the rest have blank alternative text.
<p>Rating: <meter max=5 value=3><img src="1" alt="3 out of 5" ><img src="1" alt=""><img src="1" alt=""><img src="0" alt="" ><img src="0" alt=""></meter></p>
Generally, image maps should be used instead of slicing an image for links.
However, if an image is indeed sliced and any of the components
of the sliced picture are the sole contents of links, then one image
per link must have alternative text in its alt
attribute representing the purpose
of the link.
In the following example, a picture representing the flying spaghetti monster emblem, with each of the left noodly appendages and the right noodly appendages in different images, so that the user can pick the left side or the right side in an adventure.
<h1>The Church</h1> <p>You come across a flying spaghetti monster. Which side of His Noodliness do you wish to reach out for?</p> <p><a href="?go=left" ><img src="fsm-left.png" alt="Left side. "></a ><img src="fsm-middle.png" alt="" ><a href="?go=right"><img src="fsm-right.png" alt="Right side."></a></p>
In some cases, the image is a critical part of the content. This could be the case, for instance, on a page that is part of a photo gallery. The image is the whole point of the page containing it.
How to provide alternative text for an image that is a key part of the content depends on the image's provenance.
When it is possible for detailed alternative text to be
provided, for example if the image is part of a series of
screenshots in a magazine review, or part of a comic strip, or is
a photograph in a blog entry about that photograph, text that can
serve as a substitute for the image must be given as the contents
of the alt
attribute.
A screenshot in a gallery of screenshots for a new OS, with some alternative text:
<figure> <img src="KDE%20Light%20desktop.png" alt="The desktop is blue, with icons along the left hand side in two columns, reading System, Home, K-Mail, etc. A window is open showing that menus wrap to a second line if they cannot fit in the window. The window has a list of icons along the top, with an address bar below it, a list of icons for tabs along the left edge, a status bar on the bottom, and two panes in the middle. The desktop has a bar at the bottom of the screen with a few buttons, a pager, a list of open applications, and a clock."> <figcaption>Screenshot of a KDE desktop.</figcaption> </figure>
A graph in a financial report:
<img src="sales.gif" title="Sales graph" alt="From 1998 to 2005, sales increased by the following percentages with each year: 624%, 75%, 138%, 40%, 35%, 9%, 21%">
Note that "sales graph" would be inadequate alternative text for a sales graph. Text that would be a good caption is not generally suitable as replacement text.
In certain cases, the nature of the image might be such that providing thorough alternative text is impractical. For example, the image could be indistinct, or could be a complex fractal, or could be a detailed topographical map.
In these cases, the alt
attribute must contain some suitable alternative text, but it may
be somewhat brief.
Sometimes there simply is no text that can do justice to an image. For example, there is little that can be said to usefully describe a Rorschach inkblot test. However, a description, even if brief, is still better than nothing:
<figure> <img src="/commons/a/a7/Rorschach1.jpg" alt="A shape with left-right symmetry with indistinct edges, with a small gap in the center, two larger gaps offset slightly from the center, with two similar gaps under them. The outline is wider in the top half than the bottom half, with the sides extending upwards higher than the center, and the center extending below the sides."> <figcaption>A black outline of the first of the ten cards in the Rorschach inkblot test.</figcaption> </figure>
Note that the following would be a very bad use of alternative text:
<!-- This example is wrong. Do not copy it. --> <figure> <img src="/commons/a/a7/Rorschach1.jpg" alt="A black outline of the first of the ten cards in the Rorschach inkblot test."> <figcaption>A black outline of the first of the ten cards in the Rorschach inkblot test.</figcaption> </figure>
Including the caption in the alternative text like this isn't useful because it effectively duplicates the caption for users who don't have images, taunting them twice yet not helping them any more than if they had only read or heard the caption once.
Another example of an image that defies full description is a fractal, which, by definition, is infinite in detail.
The following example shows one possible way of providing alternative text for the full view of an image of the Mandelbrot set.
<img src="ms1.jpeg" alt="The Mandelbrot set appears as a cardioid with its cusp on the real axis in the positive direction, with a smaller bulb aligned along the same center line, touching it in the negative direction, and with these two shapes being surrounded by smaller bulbs of various sizes.">
In some unfortunate cases, there might be no alternative text available at all, either because the image is obtained in some automated fashion without any associated alternative text (e.g. a Webcam), or because the page is being generated by a script using user-provided images where the user did not provide suitable or usable alternative text (e.g. photograph sharing sites), or because the author does not himself know what the images represent (e.g. a blind photographer sharing an image on his blog).
In such cases, the alt
attribute may be omitted, but one of the following conditions must
be met as well:
title
attribute is
present and has a non-empty value.Such cases are to be kept to an absolute
minimum. If there is even the slightest possibility of the author
having the ability to provide real alternative text, then it would
not be acceptable to omit the alt
attribute.
A photo on a photo-sharing site, if the site received the image with no metadata other than the caption, could be marked up as follows:
<figure> <img src="1100670787_6a7c664aef.jpg"> <figcaption>Bubbles traveled everywhere with us.</figcaption> </figure>
It would be better, however, if a detailed description of the important parts of the image obtained from the user and included on the page.
A blind user's blog in which a photo taken by the user is shown. Initially, the user might not have any idea what the photo he took shows:
<article> <h1>I took a photo</h1> <p>I went out today and took a photo!</p> <figure> <img src="photo2.jpeg"> <figcaption>A photograph taken blindly from my front porch.</figcaption> </figure> </article>
Eventually though, the user might obtain a description of the image from his friends and could then include alternative text:
<article> <h1>I took a photo</h1> <p>I went out today and took a photo!</p> <figure> <img src="photo2.jpeg" alt="The photograph shows my hummingbird feeder hanging from the edge of my roof. It is half full, but there are no birds around. In the background, out-of-focus trees fill the shot. The feeder is made of wood with a metal grate, and it contains peanuts. The edge of the roof is wooden too, and is painted white with light blue streaks."> <figcaption>A photograph taken blindly from my front porch.</figcaption> </figure> </article>
Sometimes the entire point of the image is that a textual
description is not available, and the user is to provide the
description. For instance, the point of a CAPTCHA image is to see
if the user can literally read the graphic. Here is one way to
mark up a CAPTCHA (note the title
attribute):
<p><label>What does this image say? <img src="captcha.cgi?id=8934" title="CAPTCHA"> <input type=text name=captcha></label> (If you cannot see the image, you can use an <a href="?audio">audio</a> test instead.)</p>
Another example would be software that displays images and asks for alternative text precisely for the purpose of then writing a page with correct alternative text. Such a page could have a table of images, like this:
<table> <thead> <tr> <th> Image <th> Description <tbody> <tr> <td> <img src="2421.png" title="Image 640 by 100, filename 'banner.gif'"> <td> <input name="alt2421"> <tr> <td> <img src="2422.png" title="Image 200 by 480, filename 'ad3.gif'"> <td> <input name="alt2422"> </table>
Notice that even in this example, as much useful information
as possible is still included in the title
attribute.
Since some users cannot use images at all
(e.g. because they have a very slow connection, or because they
are using a text-only browser, or because they are listening to
the page being read out by a hands-free automobile voice Web
browser, or simply because they are blind), the alt
attribute is only allowed to be
omitted rather than being provided with replacement text when no
alternative text is available and none can be made available, as
in the above examples. Lack of effort from the part of the author
is not an acceptable reason for omitting the alt
attribute.
Generally authors should avoid using img
elements
for purposes other than showing images.
If an img
element is being used for purposes other
than showing an image, e.g. as part of a service to count page
views, then the alt
attribute must
be the empty string.
In such cases, the width
and
height
attributes should both
be set to zero.
Markup generators (such as WYSIWYG authoring tools) should, wherever possible, obtain alternative text from their users. However, it is recognized that in many cases, this will not be possible.
For images that are the sole contents of links, markup generators should examine the link target to determine the title of the target, or the URL of the target, and use information obtained in this manner as the alternative text.
As a last resort, implementors should either set the alt
attribute to the empty string, under
the assumption that the image is a purely decorative image that
doesn't add any information but is still specific to the surrounding
content, or omit the alt
attribute
altogether, under the assumption that the image is a key part of the
content.
Markup generators should generally avoid using the image's own file name as the alternative text. Similarly, markup generators should avoid generating alternative text from any content that will be equally available to presentation user agents (e.g. Web browsers).
This is because once a page is generated, it will typically not be updated, whereas the browsers that later read the page can be updated by the user, therefore the browser is likely to have more up-to-date and finely-tuned heuristics than the markup generator did when generating the page.
A conformance checker must report the lack of an alt
attribute as an error unless one of
the conditions listed below applies:
title
attribute is present
and has a non-empty value (as described
above).img
element is in a figure
element that satisfies the
conditions described above.meta
element with a name
attribute whose value is an
ASCII case-insensitive match for the string "generator
". (This case does not
represent a case where the document is conforming, only that the
generator could not determine appropriate alternative text —
validators are required to not show an error in this case to
discourage markup generators from including bogus alternative text
purely in an attempt to silence validators.)iframe
elementsrc
srcdoc
name
sandbox
seamless
width
height
interface HTMLIFrameElement : HTMLElement { attribute DOMString src; attribute DOMString srcdoc; attribute DOMString name; [PutForwards=value] readonly attribute DOMSettableTokenList sandbox; attribute boolean seamless; attribute DOMString width; attribute DOMString height; readonly attribute Document contentDocument; readonly attribute WindowProxy contentWindow; };
The iframe
element represents a
nested browsing context.
The src
attribute
gives the address of a page that the nested browsing
context is to contain. The attribute, if present, must be a
valid non-empty URL potentially surrounded by
spaces.
The srcdoc
attribute gives the content of the page that the nested
browsing context is to contain. The value of the attribute is
the source of an iframe
srcdoc
document.
For iframe
elements in HTML documents,
the attribute, if present, must have a value using the HTML
syntax that consists of the following syntactic components,
in the given order:
html
element.For iframe
elements in XML documents,
the attribute, if present, must have a value that matches the
production labeled document
in the XML
specification. [XML]
If the src
attribute and the
srcdoc
attribute are both
specified together, the srcdoc
attribute takes priority. This allows authors to provide a fallback
URL for legacy user agents that do not support the
srcdoc
attribute.
When an iframe
element is first inserted into a document, the
user agent must create a nested browsing context, and
then process the iframe
attributes for the
first time.
Whenever an iframe
element with a nested
browsing context has its srcdoc
attribute set, changed, or
removed, the user agent must process the iframe
attributes.
Similarly, whenever an iframe
element with a
nested browsing context but with no srcdoc
attribute specified has its
src
attribute set, changed, or
removed, the user agent must process the iframe
attributes.
When the user agent is to process the iframe
attributes, it must run the first appropriate steps from the
following list:
srcdoc
attribute
is specifiedNavigate the element's
browsing context to a resource whose
Content-Type is text/html
, whose
URL is about:srcdoc
, and whose data
consists of the value of the attribute. The resulting
Document
must be considered an
iframe
srcdoc
document.
src
attribute is specified but the srcdoc
attribute is notIf the value of the src
attribute is the empty string,
jump to the empty step below.
Resolve the value of
the src
attribute, relative
to the iframe
element.
If that is not successful, then jump to the empty step below.
If the resulting absolute URL is an
ASCII case-insensitive match for the string
"about:blank
", and the user agent is processing this
iframe
's attributes for the first time, then jump to
the empty step below. (In cases other than the
first time, about:blank
is loaded
normally.)
Navigate the element's browsing context to the resulting absolute URL.
Empty: When the steps above require the user agent to
jump to the empty step, if the user agent is
processing this iframe
's attributes for the first
time, then the user agent must queue a task to
fire a simple event named load
at the iframe
element. (After jumping to this step, the above steps are not
resumed.)
Queue a task to fire a simple event
named load
at the
iframe
element.
Any navigation required of the user
agent in the process the iframe
attributes
algorithm must be completed with the iframe
element's
document's browsing context as the source
browsing context.
Furthermore, if the browsing context's session
history contained only one Document
when the
process the iframe
attributes algorithm
was invoked, and that was the about:blank
Document
created when the browsing context
was created, then any navigation
required of the user agent in that algorithm must be completed with
replacement enabled.
If, when the element is created, the srcdoc
attribute is not set, and
the src
attribute is either
also not set or set but its value cannot be resolved, the browsing context will remain at the
initial about:blank
page.
If the user navigates
away from this page, the iframe
's corresponding
WindowProxy
object will proxy new Window
objects for new Document
objects, but the src
attribute will not change.
Removing
an iframe
from a Document
does not cause
its browsing context to be discarded. Indeed, an
iframe
's browsing context can survive its
original parent Document
if its iframe
is
moved to another Document
.
On the other hand, if an iframe
is removed from a
Document
and is then subsequently garbage collected,
this will likely mean (in the absence of other references) that the
child browsing context's WindowProxy
object will become eligble for garbage collection, which will then
lead to that browsing context being discarded, which will then
lead to its Document
being discarded also. This happens without notice to any
scripts running in that Document
; for example, no
unload
events are fired (the
"unload a document" steps are not run).
Here a blog uses the srcdoc
attribute in conjunction
with the sandbox
and seamless
attributes described
below to provide users of user agents that support this feature
with an extra layer of protection from script injection in the blog
post comments:
<article> <h1>I got my own magazine!</h1> <p>After much effort, I've finally found a publisher, and so now I have my own magazine! Isn't that awesome?! The first issue will come out in September, and we have articles about getting food, and about getting in boxes, it's going to be great!</p> <footer> <p>Written by <a href="/users/cap">cap</a>. <time pubdate>2009-08-21T23:32Z</time></p> </footer> <article> <footer> At <time pubdate>2009-08-21T23:35Z</time>, <a href="/users/ch">ch</a> writes: </footer> <iframe seamless sandbox srcdoc="<p>did you get a cover picture yet?"></iframe> </article> <article> <footer> At <time pubdate>2009-08-21T23:44Z</time>, <a href="/users/cap">cap</a> writes: </footer> <iframe seamless sandbox srcdoc="<p>Yeah, you can see it <a href="/gallery?mode=cover&amp;page=1">in my gallery</a>."></iframe> </article> <article> <footer> At <time pubdate>2009-08-21T23:58Z</time>, <a href="/users/ch">ch</a> writes: </footer> <iframe seamless sandbox srcdoc="<p>hey that's earl's table. <p>you should get earl&amp;me on the next cover."></iframe> </article>
Notice the way that quotes have to be escaped (otherwise the
sandbox
attribute would
end prematurely), and the way raw ampersands (e.g. in URLs or in
prose) mentioned in the sandboxed content have to be
doubly escaped — once so that the ampersand is
preserved when originally parsing the sandbox
attribute, and once more
to prevent the ampersand from being misinterpreted when parsing the
sandboxed content.
In the HTML syntax, authors need only
remember to use U+0022 QUOTATION MARK characters (") to wrap the
attribute contents and then to escape all U+0022 QUOTATION MARK (")
and U+0026 AMPERSAND (&) characters, and to specify the sandbox
attribute, to ensure safe
embedding of content.
Due to restrictions of the XML syntax, in XML the U+003C LESS-THAN SIGN character (<) needs to be escaped as well. In order to prevent attribute-value normalization, some of XML's whitespace characters — specifically U+0009 CHARACTER TABULATION (tab), U+000A LINE FEED (LF), and U+000D CARRIAGE RETURN (CR) — also need to be escaped. [XML]
The name
attribute, if present, must be a valid browsing context
name. The given value is used to name the nested
browsing context. When the browsing
context is created, if the attribute is present, the browsing
context name must be set to the value of this attribute;
otherwise, the browsing context name must be set to the
empty string.
Whenever the name
attribute
is set, the nested browsing context's name must be changed to the new
value. If the attribute is removed, the browsing context
name must be set to the empty string.
When content loads in an iframe
, after any load
events are fired within the content
itself, the user agent must queue a task to fire
a simple event named load
at
the iframe
element. When content whose URL
has the same origin as the iframe
element's Document
fails to load (e.g. due to a DNS
error, network error, or if the server returned a 4xx or 5xx status
code or
equivalent), then the user agent must queue a
task to fire a simple event named error
at the element instead. (This event
does not fire for parse errors,
script errors, or any errors for cross-origin resources.)
The task source for these tasks is the DOM manipulation task source.
A load
event is also
fired at the iframe
element when it is created if no
other data is loaded in it.
When there is an active parser in the
iframe
, and when anything in the iframe
is
delaying the load event of
the iframe
's browsing context's
active document, the iframe
must
delay the load event of its document.
If, during the handling of the load
event, the browsing
context in the iframe
is again navigated, that will further delay the
load event.
The sandbox
attribute, when specified, enables a set of extra restrictions on
any content hosted by the iframe
. Its value must be an
unordered set of unique space-separated tokens that are
ASCII case-insensitive. The allowed values are allow-same-origin
,
allow-top-navigation
,
allow-forms
,
and allow-scripts
. When
the attribute is set, the content is treated as being from a unique
origin, forms and scripts are disabled, links are
prevented from targeting other browsing contexts, and plugins are disabled. The
allow-same-origin
keyword allows the content to be treated as being from the same
origin instead of forcing it into a unique origin, the allow-top-navigation
keyword allows the content to navigate its
top-level browsing context, and the allow-forms
and allow-scripts
keywords re-enable forms and scripts respectively (though scripts
are still prevented from creating popups).
Setting both the allow-scripts
and
allow-same-origin
keywords together when the embedded page has the same
origin as the page containing the iframe
allows
the embedded page to simply remove the sandbox
attribute.
Sandboxing hostile content is of minimal help if
an attacker can convince the user to just visit the hostile content
directly, rather than in the iframe
. To limit the
damage that can be caused by hostile HTML content, it should be
served using the text/html-sandboxed
MIME type.
While the sandbox
attribute is specified, the iframe
element's
nested browsing context must have the flags given in
the following list set. In addition, any browsing contexts nested within an
iframe
, either directly or indirectly, must have all
the flags set on them as were set on the iframe
's
Document
's browsing context when the
iframe
's Document
was created.
This flag prevents content from navigating browsing contexts other than the sandboxed browsing context itself (or browsing contexts further nested inside it), and the top-level browsing context (which is protected by the sandboxed top-level navigation browsing context flag defined next).
This flag also prevents content
from creating new auxiliary browsing contexts, e.g. using the
target
attribute or the
window.open()
method.
sandbox
attribute's value, when
split on spaces, is
found to have the allow-top-navigation
keyword setThis flag prevents content from navigating their top-level browsing context.
When the allow-top-navigation
is set, content can navigate its top-level browsing
context, but other browsing
contexts are still protected by the sandboxed
navigation browsing context flag defined above.
This flag prevents content from instantiating plugins, whether using the embed
element, the object
element,
the applet
element, or through navigation of a nested
browsing context.
This flag prevents content from using the seamless
attribute on
descendant iframe
elements.
This prevents a page inserted using the allow-same-origin
keyword from using a CSS-selector-based method of probing the DOM
of other pages on the same site (in particular, pages that contain
user-sensitive information).
sandbox
attribute's
value, when split on
spaces, is found to have the allow-same-origin
keyword setThis flag forces content into a unique origin, thus preventing it from accessing other content from the same origin.
This flag also prevents script from
reading from or writing to the document.cookie
IDL
attribute, and blocks access to localStorage
.
[WEBSTORAGE]
The allow-same-origin
attribute is intended for two cases.
First, it can be used to allow content from the same site to be sandboxed to disable scripting, while still allowing access to the DOM of the sandboxed content.
Second, it can be used to embed content from a third-party site, sandboxed to prevent that site from opening popup windows, etc, without preventing the embedded page from communicating back to its originating site, using the database APIs to store data, etc.
sandbox
attribute's
value, when split on
spaces, is found to have the allow-forms
keyword setThis flag blocks form submission.
sandbox
attribute's
value, when split on
spaces, is found to have the allow-scripts
keyword setThis flag blocks script execution.
sandbox
attribute's value, when
split on spaces, is
found to have the allow-scripts
keyword (defined above) setThis flag blocks features that trigger automatically, such as automatically playing a video or automatically focusing a form control. It is relaxed by the same flag as scripts, because when scripts are enabled these features are trivially possible anyway, and it would be unfortunate to force authors to use script to do them when sandboxed rather than allowing them to use the declarative features.
These flags must not be set unless the conditions listed above define them as being set.
These flags only take effect when the
nested browsing context of the iframe
is
navigated. Removing them, or removing
the entire sandbox
attribute, has no effect on an already-loaded page.
In this example, some completely-unknown, potentially hostile, user-provided HTML content is embedded in a page. Because it is sandboxed, it is treated by the user agent as being from a unique origin, despite the content being served from the same site. Thus it is affected by all the normal cross-site restrictions. In addition, the embedded page has scripting disabled, plugins disabled, forms disabled, and it cannot navigate any frames or windows other than itself (or any frames or windows it itself embeds).
<p>We're not scared of you! Here is your content, unedited:</p> <iframe sandbox src="getusercontent.cgi?id=12193"></iframe>
Note that cookies are still sent to the server in the getusercontent.cgi
request, though they are not
visible in the document.cookie
IDL
attribute.
It is important that the server serve the
user-provided HTML using the text/html-sandboxed
MIME
type so that if the attacker convinces the user to visit that page
directly, the page doesn't run in the context of the site's origin,
which would make the user vulnerable to any attack found in the
page.
In this example, a gadget from another site is embedded. The gadget has scripting and forms enabled, and the origin sandbox restrictions are lifted, allowing the gadget to communicate with its originating server. The sandbox is still useful, however, as it disables plugins and popups, thus reducing the risk of the user being exposed to malware and other annoyances.
<iframe sandbox="allow-same-origin allow-forms allow-scripts" src="http://maps.example.com/embedded.html"></iframe>
Suppose a file A contained the following fragment:
<iframe sandbox="allow-same-origin allow-forms" src=B></iframe>
Suppose that file B contained an iframe also:
<iframe sandbox="allow-scripts" src=C></iframe>
Further, suppose that file C contained a link:
<a href=D>Link</a>
For this example, suppose all the files were served as
text/html
.
Page C in this scenario has all the sandboxing flags
set. Scripts are disabled, because the iframe
in A has
scripts disabled, and this overrides the allow-scripts
keyword set on the iframe
in B. Forms are also
disabled, because the inner iframe
(in B) does not
have the allow-forms
keyword
set.
Suppose now that a script in A removes all the sandbox
attributes in A and
B. This would change nothing immediately. If the user clicked the
link in C, loading page D into the iframe
in B, page D
would now act as if the iframe
in B had the allow-same-origin
and allow-forms
keywords
set, because that was the state of the nested browsing
context in the iframe
in A when page B was
loaded.
Generally speaking, dynamically removing or changing the sandbox
attribute is
ill-advised, because it can make it quite hard to reason about what
will be allowed and what will not.
Potentially hostile files can be served from the
same server as the file containing the iframe
element
by labeling them as text/html-sandboxed
instead of
text/html
. This ensures that scripts in the files are
unable to attack the site (as if they were actually served from
another server), even if the user is tricked into visiting those
pages directly, without the protection of the sandbox
attribute.
If the allow-scripts
keyword is set along with allow-same-origin
keyword, and the file is from the same origin as the
iframe
's Document
, then a script in the
"sandboxed" iframe could just reach out, remove the sandbox
attribute, and then
reload itself, effectively breaking out of the sandbox
altogether.
The seamless
attribute is a boolean attribute. When specified, it
indicates that the iframe
element's browsing
context is to be rendered in a manner that makes it appear to
be part of the containing document (seamlessly included in the
parent document). Specifically, when the
attribute is set on an iframe
element whose owner
Document
's browsing context did not have
the sandboxed seamless iframes flag set when that
Document
was created, and while either the
browsing context's active document has the
same origin as the iframe
element's
document, or the browsing context's active
document's address has the same origin as the
iframe
element's document, or the browsing
context's active document is an
iframe
srcdoc
document, the following requirements apply:
The user agent must set the seamless browsing context
flag to true for that browsing context. This
will cause links to open in the parent
browsing context unless an explicit self-navigation
override is used (target="_self"
).
In a CSS-supporting user agent: the user agent must add all
the style sheets that apply to the iframe
element to
the cascade of the active document of the
iframe
element's nested browsing context,
at the appropriate cascade levels, before any style sheets
specified by the document itself.
In a CSS-supporting user agent: the user agent must, for the
purpose of CSS property inheritance only, treat the root element of
the active document of the iframe
element's nested browsing context as being a child of
the iframe
element. (Thus inherited properties on the
root element of the document in the iframe
will
inherit the computed values of those properties on the
iframe
element instead of taking their initial
values.)
In visual media, in a CSS-supporting user agent: the user agent
should set the intrinsic width of the iframe
to the
width that the element would have if it was a non-replaced
block-level element with 'width: auto'.
In visual media, in a CSS-supporting user agent: the user
agent should set the intrinsic height of the iframe
to
the height of the bounding box around the content rendered in the
iframe
at its current width (as given in the previous
bullet point), as it would be if the scrolling position was such
that the top of the viewport for the content rendered in the
iframe
was aligned with the origin of that content's
canvas.
In visual media, in a CSS-supporting user agent: the user agent
must force the height of the initial containing block of the
active document of the nested browsing
context of the iframe
to zero.
This is intended to get around the otherwise circular dependency of percentage dimensions that depend on the height of the containing block, thus affecting the height of the document's bounding box, thus affecting the height of the viewport, thus affecting the size of the initial containing block.
In speech media, the user agent should render the nested browsing context without announcing that it is a separate document.
User agents should, in general, act as if the active
document of the iframe
's nested browsing
context was part of the document that the
iframe
is in, if any.
For example if the user agent supports listing all the links in a document, links in "seamlessly" nested documents would be included in that list without being significantly distinguished from links in the document itself.
If the attribute is not specified, or if the origin conditions listed above are not met, then the user agent should render the nested browsing context in a manner that is clearly distinguishable as a separate browsing context, and the seamless browsing context flag must be set to false for that browsing context.
It is important that user agents recheck the
above conditions whenever the active document of the
nested browsing context of the iframe
changes, such that the seamless browsing context flag
gets unset if the nested browsing context is navigated to another origin.
The attribute can be set or removed dynamically, with the rendering updating in tandem.
In this example, the site's navigation is embedded using a
client-side include using an iframe
. Any links in the
iframe
will, in new user agents, be automatically
opened in the iframe
's parent browsing context; for
legacy user agents, the site could also include a base
element with a target
attribute with the value _parent
. Similarly,
in new user agents the styles of the parent page will be
automatically applied to the contents of the frame, but to support
legacy user agents authors might wish to include the styles
explicitly.
<nav><iframe seamless src="nav.include.html"></iframe></nav>
The iframe
element supports dimension
attributes for cases where the embedded content has specific
dimensions (e.g. ad units have well-defined dimensions).
An iframe
element never has fallback
content, as it will always create a nested browsing
context, regardless of whether the specified initial contents
are successfully used.
Descendants of iframe
elements represent
nothing. (In legacy user agents that do not support
iframe
elements, the contents would be parsed as markup
that could act as fallback content.)
When used in HTML
documents, the allowed content model of iframe
elements is text, except that invoking the HTML fragment
parsing algorithm with the iframe
element as the
context element and
the text contents as the input must result in a
list of nodes that are all phrasing content, with no
parse errors having occurred, with
no script
elements being anywhere in the list or as
descendants of elements in the list, and with all the elements in
the list (including their descendants) being themselves
conforming.
The iframe
element must be empty in XML
documents.
The HTML parser treats markup inside
iframe
elements as text.
The IDL attributes src
, srcdoc
, name
, sandbox
, and seamless
must
reflect the respective content attributes of the same
name.
The contentDocument
IDL attribute must return the Document
object of the
active document of the iframe
element's
nested browsing context.
The contentWindow
IDL attribute must return the WindowProxy
object of the
iframe
element's nested browsing
context.
Here is an example of a page using an iframe
to
include advertising from an advertising broker:
<iframe src="http://ads.example.com/?customerid=923513721&format=banner" width="468" height="60"></iframe>
embed
elementsrc
type
width
height
interface HTMLEmbedElement : HTMLElement { attribute DOMString src; attribute DOMString type; attribute DOMString width; attribute DOMString height; };
Depending on the type of content instantiated by the
embed
element, the node may also support other
interfaces.
The embed
element represents an
integration point for an external (typically non-HTML) application
or interactive content.
The src
attribute
gives the address of the resource being embedded. The attribute, if
present, must contain a valid non-empty URL potentially
surrounded by spaces.
The type
attribute, if present, gives the MIME type by which the
plugin to instantiate is selected. The value must be a valid
MIME type. If both the type
attribute and the src
attribute are present, then the
type
attribute must specify the
same type as the explicit Content-Type
metadata of the resource given by the src
attribute.
When the element is created with neither a src
attribute nor a type
attribute, and when attributes
are removed such that neither attribute is present on the element
anymore, and when the element has a media element
ancestor, and when the element has an ancestor object
element that is not showing its fallback
content, any plugins instantiated for the element must be
removed, and the embed
element represents nothing.
If either:
embed
element's Document
is the
active document when that Document
was
created, orembed
element's Document
was
parsed from a resource whose sniffed type as determined during navigation is
text/html-sandboxed
...then the user agent must render the embed
element
in a manner that conveys that the plugin was
disabled. The user agent may offer the user the option to override
the sandbox and instantiate the plugin anyway; if the
user invokes such an option, the user agent must act as if the
conditions above did not apply for the purposes of this element.
Plugins are disabled in sandboxed browsing contexts because they might not honor the restrictions imposed by the sandbox (e.g. they might allow scripting even when scripting in the sandbox is disabled). User agents should convey the danger of overriding the sandbox to the user if an option to do so is provided.
An embed
element is said to be potentially active when the
following conditions are all met simultaneously:
Document
.Document
is fully active.src
attribute set or a type
attribute set (or both).src
attribute is either absent or its value is the empty string.Document
whose browsing context had the sandboxed plugins browsing context flag set when the Document
was created (unless this has been overridden as described above).Document
was not parsed from a resource whose sniffed type as determined during navigation is text/html-sandboxed
(unless this has been overridden as described above).object
element that is not showing its fallback content.Whenever an embed
element that was not potentially active becomes potentially active, and whenever
a potentially active
embed
element's src
attribute is set, changed, or
removed, and whenever a potentially active
embed
element's type
attribute is set, changed, or
removed, the appropriate set of steps from the following is then
applied:
src
attribute setThe user agent must resolve
the value of the element's src
attribute, relative to the element. If that is successful, the
user agent should fetch the resulting absolute
URL, from the element's browsing context scope
origin if it has one. The task that is
queued by the networking
task source once the resource has been fetched must find and instantiate an
appropriate plugin based on the content's type, and hand that
plugin the content of the resource, replacing any
previously instantiated plugin for the element.
Fetching the resource must delay the load event of the element's document.
src
attribute setThe user agent should find and instantiate an appropriate
plugin based on the value of the type
attribute.
Whenever an embed
element that was potentially active stops being
potentially active, any
plugin that had been instantiated for that element must
be unloaded.
The embed
element is unaffected by the
CSS 'display' property. The selected plugin is instantiated even if
the element is hidden with a 'display:none' CSS style.
The type of the content being embedded is defined as follows:
If the element has a type
attribute, and that attribute's
value is a type that a plugin supports, then the value
of the type
attribute is the
content's type.
Otherwise, if the <path> component of the URL of the specified resource (after any redirects) matches a pattern that a plugin supports, then the content's type is the type that that plugin can handle.
For example, a plugin might say that it can
handle resources with <path>
components that end with the four character string ".swf
".
Otherwise, if the specified resource has explicit Content-Type metadata, then that is the content's type.
Otherwise, the content has no type and there can be no appropriate plugin for it.
The embed
element has no fallback
content. If the user agent can't find a suitable plugin, then
the user agent must use a default plugin. (This default could be as
simple as saying "Unsupported Format".)
Whether the resource is fetched successfully or not (e.g. whether the response code was a 2xx code or equivalent) must be ignored when determining the resource's type and when handing the resource to the plugin.
This allows servers to return data for plugins even with error responses (e.g. HTTP 500 Internal Server Error codes can still contain plugin data).
Any namespace-less attribute other than name
, align
, hspace
, and vspace
may be specified on the embed
element,
so long as its name is XML-compatible and contains no
characters in the range U+0041 to U+005A (LATIN CAPITAL LETTER A to
LATIN CAPITAL LETTER Z). These attributes are then passed as
parameters to the plugin.
All attributes in HTML documents get lowercased automatically, so the restriction on uppercase letters doesn't affect such documents.
The four exceptions are to exclude legacy attributes that have side-effects beyond just sending parameters to the plugin.
The user agent should pass the names and values of all the
attributes of the embed
element that have no namespace
to the plugin used, when it is instantiated.
If the plugin instantiated for the
embed
element supports a scriptable interface, the
HTMLEmbedElement
object representing the element should
expose that interface while the element is instantiated.
The embed
element supports dimension
attributes.
The IDL attributes src
and type
each must
reflect the respective content attributes of the same
name.
Here's a way to embed a resource that requires a proprietary plug-in, like Flash:
<embed src="catgame.swf">
If the user does not have the plug-in (for example if the plug-in vendor doesn't support the user's platform), then the user will be unable to use the resource.
To pass the plugin a parameter "quality" with the value "high", an attribute can be specified:
<embed src="catgame.swf" quality="high">
This would be equivalent to the following, when using an
object
element instead:
<object data="catgame.swf"> <param name="quality" value="high"> </object>
object
elementusemap
attribute: Interactive content.param
elements, then, transparent.data
type
name
usemap
form
width
height
interface HTMLObjectElement : HTMLElement { attribute DOMString data; attribute DOMString type; attribute DOMString name; attribute DOMString useMap; readonly attribute HTMLFormElement form; attribute DOMString width; attribute DOMString height; readonly attribute Document contentDocument; readonly attribute WindowProxy contentWindow; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); void setCustomValidity(in DOMString error); };
Depending on the type of content instantiated by the
object
element, the node also supports other
interfaces.
The object
element can represent an external
resource, which, depending on the type of the resource, will either
be treated as an image, as a nested browsing context,
or as an external resource to be processed by a
plugin.
The data
attribute, if present, specifies the address of the resource. If
present, the attribute must be a valid non-empty
URL potentially surrounded by spaces.
The type
attribute, if present, specifies the type of the resource. If
present, the attribute must be a valid MIME type.
At least one of either the data
attribute or the type
attribute must be present.
The name
attribute, if present, must be a valid browsing context
name. The given value is used to name the nested
browsing context, if applicable.
When the element is created, when it is popped off the
stack of open elements of an HTML parser
or XML parser, and subsequently whenever the element is
inserted into a
document or removed from a document; and whenever the element's
Document
changes whether it is fully
active; and whenever an ancestor object
element
changes to or from showing its fallback content; and
whenever the element's classid
attribute is set,
changed, or removed; and, when its classid
attribute is not present,
whenever its data
attribute is
set, changed, or removed; and, when neither its classid
attribute nor its data
attribute are present, whenever
its type
attribute is set,
changed, or removed: the user agent must queue a task
to run the following steps to (re)determine what the
object
element represents. The task source
for this task is the DOM
manipulation task source.
If the user has indicated a preference that this
object
element's fallback content be
shown instead of the element's usual behavior, then jump to the
last step in the overall set of steps (fallback).
For example, a user could ask for the element's fallback content to be shown because that content uses a format that the user finds more accessible.
If the element has an ancestor media element, or
has an ancestor object
element that is not
showing its fallback content, or if the element is
not in a Document
with a browsing context, or if the element's
Document
is not fully active, or if the
element is still in the stack of open elements of an
HTML parser or XML parser, then jump to
the last step in the overall set of steps (fallback).
If the classid
attribute is present, and has a value that isn't the empty string,
then: if the user agent can find a plugin suitable
according to the value of the classid
attribute, and plugins aren't being sandboxed,
then that plugin should be
used, and the value of the data
attribute, if any, should be
passed to the plugin. If no suitable
plugin can be found, or if the plugin
reports an error, jump to the last step in the overall set of
steps (fallback).
If the data
attribute
is present and its value is not the empty string, then:
If the type
attribute is present and its value is not a type that the user
agent supports, and is not a type that the user agent can find a
plugin for, then the user agent may jump to the last
step in the overall set of steps (fallback) without fetching the
content to examine its real type.
Resolve the
URL specified by the data
attribute, relative to the
element.
If that failed, fire a simple event named
error
at the element, then jump
to the last step in the overall set of steps (fallback).
Fetch the resulting absolute URL, from the element's browsing context scope origin if it has one.
Fetching the resource must delay the load event of the element's document until the task that is queued by the networking task source once the resource has been fetched (defined next) has been run.
For the purposes of the application cache networking model, this fetch operation is not for a child browsing context (though it might end up being used for one after all, as defined below).
If the resource is not yet available (e.g. because the resource was not available in the cache, so that loading the resource required making a request over the network), then jump to the last step in the overall set of steps (fallback). The task that is queued by the networking task source once the resource is available must restart this algorithm from this step. Resources can load incrementally; user agents may opt to consider a resource "available" whenever enough data has been obtained to begin processing the resource.
If the load failed (e.g. there was an HTTP 404 error,
there was a DNS error), fire a simple event named
error
at the element, then jump
to the last step in the overall set of steps (fallback).
Determine the resource type, as follows:
Let the resource type be unknown.
If the user agent is configured to strictly obey Content-Type headers for this resource, and the resource has associated Content-Type metadata, then let the resource type be the type specified in the resource's Content-Type metadata, and jump to the step below labeled handler.
If there is a type
attribute present on the object
element, and that
attribute's value is not a type that the user agent supports,
but it is a type that a plugin supports,
then let the resource type be the type
specified in that type
attribute, and jump to the step below labeled
handler.
Run the approprate set of steps from the following list:
Let binary be false.
If the type specified in the
resource's Content-Type metadata is
"text/plain
", and the result of applying the
rules
for distinguishing if a resource is text or binary
to the resource is that the resource is not
text/plain
, then set binary to true.
If the type specified in the
resource's Content-Type metadata is
"application/octet-stream
", then set binary to true.
If binary is false, then let the resource type be the type specified in the resource's Content-Type metadata, and jump to the step below labeled handler.
If there is a type
attribute present on
the object
element, and its value is not
application/octet-stream
, then run the
following steps:
If the attribute's value is a type that a plugin supports, or
the attribute's value is a type that starts with "image/
" that is not also an XML MIME type,
then let the resource type be the type specified in that type
attribute.
Jump to the step below labeled handler.
If there is a type
attribute present on
the object
element, then let the tentative type be the type specified in that
type
attribute.
Otherwise, let tentative type be the sniffed type of the resource.
If tentative type is not
application/octet-stream
, then let resource type be tentative
type and jump to the step below labeled
handler.
If the <path> component of the URL of the specified resource (after any redirects) matches a pattern that a plugin supports, then let resource type be the type that that plugin can handle.
For example, a plugin might say that it can
handle resources with <path> components that end with
the four character string ".swf
".
It is possible for this step to finish with resource type still being unknown, or for one of the substeps above to jump straight to the next step. In both cases, the next step will trigger fallback.
Handler: Handle the content as given by the first of the following cases that matches:
If plugins are being sandboxed, jump to the last step in the overall set of steps (fallback).
Otherwise, the user agent should use the plugin that supports resource type and pass the content of the resource to that plugin. If the plugin reports an error, then jump to the last step in the overall set of steps (fallback).
image/
"The object
element must be associated with a
newly created nested browsing context, if it does
not already have one.
If the URL of the given resource is not
about:blank
, the element's nested browsing
context must then be navigated to that
resource, with replacement enabled, and with the
object
element's document's browsing
context as the source browsing context.
(The data
attribute of
the object
element doesn't get updated if the
browsing context gets further navigated to other
locations.)
If the URL of the given resource is
about:blank
, then, instead, the user agent must
queue a task to fire a simple event
named load
at the
object
element.
The object
element represents the
nested browsing context.
If the name
attribute
is present, the browsing context name must be set
to the value of this attribute; otherwise, the browsing
context name must be set to the empty string.
In certain situations, e.g. if the resource
was fetched from an
application cache but it is an HTML file with a
manifest
attribute
that points to a different application cache
manifest, the navigation
of the browsing context will be restarted so as
to load the resource afresh from the network or a different
application cache. Even if the resource is then
found to have a different type, it is still used as part of a
nested browsing context: only the
navigate algorithm is restarted, not this
object
algorithm.
image/
", and support for images has not been
disabledApply the image sniffing rules to determine the type of the image.
The object
element represents the
specified image. The image is not a nested browsing
context.
If the image cannot be rendered, e.g. because it is malformed or in an unsupported format, jump to the last step in the overall set of steps (fallback).
The given resource type is not supported. Jump to the last step in the overall set of steps (fallback).
If the previous step ended with the resource type being unknown, this is the case that is triggered.
The element's contents are not part of what the
object
element represents.
Once the resource is completely loaded, queue a
task to fire a simple event named load
at the element.
The task source for this task is the DOM manipulation task source.
If the data
attribute
is absent but the type
attribute is present, plugins aren't
being sandboxed, and the user agent can find a
plugin suitable according to the value of the type
attribute, then that
plugin should be used. If
no suitable plugin can be found, or if the
plugin reports an error, jump to the next step
(fallback).
(Fallback.) The object
element
represents the element's children, ignoring any
leading param
element children. This is the element's
fallback content. If the element has an instantiated
plugin, then unload it.
When the algorithm above instantiates a
plugin, the user agent should pass to the
plugin used the names and values of all the attributes
on the element, in the order they were added to the element, with
the attributes added by the parser being ordered in source order,
followed by a parameter named "PARAM" whose value is null,
followed by all the names and values of parameters given by
param
elements that are children of the
object
element, in tree order. If the
plugin supports a scriptable interface, the
HTMLObjectElement
object representing the element
should expose that interface. The object
element
represents the plugin. The
plugin is not a nested browsing
context.
If either:
object
element's Document
's
browsing context when the Document
was
created, orobject
element's Document
was
parsed from a resource whose sniffed type as determined during navigation is
text/html-sandboxed
...then the steps above must always act as if they had failed to find a plugin, even if one would otherwise have been used.
The above algorithm is independent of CSS properties (including 'display', 'overflow', and 'visibility'). For example, it runs even if the element is hidden with a 'display:none' CSS style, and does not run again if the element's visibility changes.
Due to the algorithm above, the contents of object
elements act as fallback content, used only when
referenced resources can't be shown (e.g. because it returned a 404
error). This allows multiple object
elements to be
nested inside each other, targeting multiple user agents with
different capabilities, with the user agent picking the first one it
supports.
Whenever the name
attribute
is set, if the object
element has a nested
browsing context, its name must be changed to the new value. If the attribute
is removed, if the object
element has a browsing
context, the browsing context name must be set
to the empty string.
The usemap
attribute,
if present while the object
element represents an
image, can indicate that the object has an associated image
map. The attribute must be ignored if the
object
element doesn't represent an image.
The form
attribute is used to
explicitly associate the object
element with its
form owner.
Constraint validation: object
elements are always barred from constraint
validation.
The object
element supports dimension
attributes.
The IDL attributes data
, type
, name
, and useMap
each must
reflect the respective content attributes of the same
name.
The contentDocument
IDL attribute must return the Document
object of the
active document of the object
element's
nested browsing context, if it has one; otherwise, it
must return null.
The contentWindow
IDL attribute must return the WindowProxy
object of the
object
element's nested browsing context,
if it has one; otherwise, it must return null.
The willValidate
, validity
, and validationMessage
attributes, and the checkValidity()
and setCustomValidity()
methods, are part of the constraint validation API. The
form
IDL attribute is part of the
element's forms API.
In the following example, a Java applet is embedded in a page
using the object
element. (Generally speaking, it is
better to avoid using applets like these and instead use native
JavaScript and HTML to provide the functionality, since that way
the application will work on all Web browsers without requiring a
third-party plugin. Many devices, especially embedded devices, do
not support third-party technologies like Java.)
<figure> <object type="application/x-java-applet"> <param name="code" value="MyJavaClass"> <p>You do not have Java available, or it is disabled.</p> </object> <figcaption>My Java Clock</figcaption> </figure>
In this example, an HTML page is embedded in another using the
object
element.
<figure> <object data="clock.html"></object> <figcaption>My HTML Clock</figcaption> </figure>
The following example shows how a plugin can be used in HTML (in
this case the Flash plugin, to show a video file). Fallback is
provided for users who do not have Flash enabled, in this case
using the video
element to show the video for those
using user agents that support video
, and finally
providing a link to the video for those who have neither Flash nor
a video
-capable browser.
<p>Look at my video: <object type="application/x-shockwave-flash"> <param name=movie value="http://video.example.com/library/watch.swf"> <param name=allowfullscreen value=true> <param name=flashvars value="http://video.example.com/vids/315981"> <video controls src="http://video.example.com/vids/315981"> <a href="http://video.example.com/vids/315981">View video</a>. </video> </object> </p>
param
elementobject
element, before any flow content.name
value
interface HTMLParamElement : HTMLElement { attribute DOMString name; attribute DOMString value; };
The param
element defines parameters for plugins
invoked by object
elements. It does not represent anything on its own.
The name
attribute gives the name of the parameter.
The value
attribute gives the value of the parameter.
Both attributes must be present. They may have any value.
If both attributes are present, and if the parent element of the
param
is an object
element, then the
element defines a parameter with the given
name/value pair.
If either the name or value of a parameter defined by a
param
element that is the child of an
object
element that represents an
instantiated plugin changes, and if that
plugin is communicating with the user agent using an
API that features the ability to update the plugin when
the name or value of a parameter so changes, then
the user agent must appropriately exercise that ability to notify
the plugin of the change.
The IDL attributes name
and value
must both
reflect the respective content attributes of the same
name.
The following example shows how the param
element
can be used to pass a parameter to a plugin, in this case the O3D
plugin.
<!DOCTYPE HTML> <html lang="en"> <head> <title>O3D Utah Teapot</title> </head> <body> <p> <object type="application/vnd.o3d.auto"> <param name="o3d_features" value="FloatingPointTextures"> <img src="o3d-teapot.png" title="3D Utah Teapot illustration rendered using O3D." alt="When O3D renders the Utah Teapot, it appears as a squat teapot with a shiny metallic finish on which the surroundings are reflected, with a faint shadow caused by the lighting."> <p>To see the teapot actually rendered by O3D on your computer, please download and install the <a href="http://code.google.com/apis/o3d/docs/gettingstarted.html#install">O3D plugin</a>.</p> </object> <script src="o3d-teapot.js"></script> </p> </body> </html>
video
elementcontrols
attribute: Interactive content.src
attribute:
zero or more track
elements, then
transparent, but with no media element descendants.src
attribute: zero or more source
elements, then
zero or more track
elements, then
transparent, but with no media element descendants.src
poster
preload
autoplay
mediagroup
loop
muted
controls
width
height
interface HTMLVideoElement : HTMLMediaElement { attribute unsigned long width; attribute unsigned long height; readonly attribute unsigned long videoWidth; readonly attribute unsigned long videoHeight; attribute DOMString poster; };
A video
element is used for playing videos or
movies, and audio files with captions.
Content may be provided inside the video
element. User agents should not show this content
to the user; it is intended for older Web browsers which do
not support video
, so that legacy video plugins can be
tried, or to show text to the users of these older browsers informing
them of how to access the video contents.
In particular, this content is not intended to address accessibility concerns. To make video content accessible to the blind, deaf, and those with other physical or cognitive disabilities, authors are expected to provide alternative media streams and/or to embed accessibility aids (such as caption or subtitle tracks, audio description tracks, or sign-language overlays) into their media streams.
The video
element is a media element
whose media data is ostensibly video data, possibly
with associated audio data.
The src
, preload
, autoplay
,
mediagroup
,
loop
,
muted
, and controls
attributes are the attributes common to all media
elements.
The poster
attribute gives the address of an image file that the user agent can
show while no video data is available. The attribute, if present,
must contain a valid non-empty URL potentially surrounded by
spaces.
If the specified resource is to be used, then, when the element
is created or when the poster
attribute is set, changed, or removed, the user agent must run the
following steps to determine the element's poster
frame:
If there is an existing instance of this algorithm running
for this video
element, abort that instance of this
algorithm without changing the poster frame.
If the poster
attribute's value is the empty string or if the attribute is
absent, then there is no poster frame; abort these
steps.
Resolve the poster
attribute's value relative
to the element. If this fails, then there is no poster
frame; abort these steps.
Fetch the resulting absolute URL,
from the element's Document
's origin.
This must delay the load event of the element's
document.
If an image is thus obtained, the poster frame is that image. Otherwise, there is no poster frame.
The image given by the poster
attribute, the poster
frame, is intended to be a representative frame of the video
(typically one of the first non-blank frames) that gives the user an
idea of what the video is like.
When no video data is available (the element's readyState
attribute is either
HAVE_NOTHING
, or HAVE_METADATA
but no video
data has yet been obtained at all, or the element's readyState
attribute is any
subsequent value but the media resource does not have a
video channel), the video
element
represents either the poster frame, or
nothing.
When a video
element is paused and the current playback position is the first
frame of video, the element represents either the frame
of video corresponding to the current playback position or the poster
frame, at the discretion of the user agent.
Notwithstanding the above, the poster frame should be preferred over nothing, but the poster frame should not be shown again after a frame of video has been shown.
When a video
element is paused at any other position, and
the media resource has a video channel, the element
represents the frame of video corresponding to the
current playback
position, or, if that is not yet available (e.g. because the
video is seeking or buffering), the last frame of the video to have
been rendered.
When a video
element whose media
resource has a video channel is potentially
playing, it represents the frame of video at the
continuously increasing "current" position. When the current playback
position changes such that the last frame rendered is no
longer the frame corresponding to the current playback
position in the video, the new frame must be rendered.
Similarly, any audio associated with the media resource
must, if played, be played synchronized with the current
playback position, at the element's effective media
volume.
When a video
element whose media
resource has a video channel is neither potentially
playing nor paused
(e.g. when seeking or stalled), the element represents
the last frame of the video to have been rendered.
Which frame in a video stream corresponds to a particular playback position is defined by the video stream's format.
The video
element also represents any
text track cues whose
text track cue active flag is set and whose
text track is in the showing or showing by default modes.
In addition to the above, the user agent may provide messages to the user (such as "buffering", "no video loaded", "error", or more detailed information) by overlaying text or icons on the video or other areas of the element's playback area, or in another appropriate manner.
User agents that cannot render the video may instead make the element represent a link to an external video playback utility or to the video data itself.
videoWidth
videoHeight
These attributes return the intrinsic dimensions of the video, or zero if the dimensions are not known.
The intrinsic width and intrinsic height of the media resource are the dimensions of the resource in CSS pixels after taking into account the resource's dimensions, aspect ratio, clean aperture, resolution, and so forth, as defined for the format used by the resource. If an anamorphic format does not define how to apply the aspect ratio to the video data's dimensions to obtain the "correct" dimensions, then the user agent must apply the ratio by increasing one dimension and leaving the other unchanged.
The videoWidth
IDL
attribute must return the intrinsic width of the
video in CSS pixels. The videoHeight
IDL
attribute must return the intrinsic height of
the video in CSS pixels. If the element's readyState
attribute is HAVE_NOTHING
, then the
attributes must return 0.
The video
element supports dimension
attributes.
In the absence of style rules to the contrary, video content should be rendered inside the element's playback area such that the video content is shown centered in the playback area at the largest possible size that fits completely within it, with the video content's aspect ratio being preserved. Thus, if the aspect ratio of the playback area does not match the aspect ratio of the video, the video will be shown letterboxed or pillarboxed. Areas of the element's playback area that do not contain the video represent nothing.
In user agents that implement CSS, the above requirement can be implemented by using the style rule suggested in the rendering section.
The intrinsic width of a video
element's playback
area is the intrinsic
width of the video resource, if that is available; otherwise
it is the intrinsic width of the poster frame, if that
is available; otherwise it is 300 CSS pixels.
The intrinsic height of a video
element's playback
area is the intrinsic
height of the video resource, if that is available; otherwise
it is the intrinsic height of the poster frame, if that
is available; otherwise it is 150 CSS pixels.
User agents should provide controls to enable or disable the display of closed captions, audio description tracks, and other additional data associated with the video stream, though such features should, again, not interfere with the page's normal rendering.
User agents may allow users to view the video content in manners
more suitable to the user (e.g. full-screen or in an independent
resizable window). As for the other user interface features,
controls to enable this should not interfere with the page's normal
rendering unless the user agent is exposing a user interface. In such an
independent context, however, user agents may make full user
interfaces visible, with, e.g., play, pause, seeking, and volume
controls, even if the controls
attribute is absent.
User agents may allow video playback to affect system features that could interfere with the user's experience; for example, user agents could disable screensavers while video playback is in progress.
The poster
IDL
attribute must reflect the poster
content attribute.
This example shows how to detect when a video has failed to play correctly:
<script> function failed(e) { // video playback failed - show a message saying why switch (e.target.error.code) { case e.target.error.MEDIA_ERR_ABORTED: alert('You aborted the video playback.'); break; case e.target.error.MEDIA_ERR_NETWORK: alert('A network error caused the video download to fail part-way.'); break; case e.target.error.MEDIA_ERR_DECODE: alert('The video playback was aborted due to a corruption problem or because the video used features your browser did not support.'); break; case e.target.error.MEDIA_ERR_SRC_NOT_SUPPORTED: alert('The video could not be loaded, either because the server or network failed or because the format is not supported.'); break; default: alert('An unknown error occurred.'); break; } } </script> <p><video src="tgif.vid" autoplay controls onerror="failed(event)"></video></p> <p><a href="tgif.vid">Download the video file</a>.</p>
audio
elementcontrols
attribute: Interactive content.src
attribute:
zero or more track
elements, then
transparent, but with no media element descendants.src
attribute: one or more source
elements, then
zero or more track
elements, then
transparent, but with no media element descendants.src
preload
autoplay
mediagroup
loop
muted
controls
[NamedConstructor=Audio(), NamedConstructor=Audio(in DOMString src)] interface HTMLAudioElement : HTMLMediaElement {};
An audio
element represents a sound or
audio stream.
Content may be provided inside the audio
element. User agents should not show this content
to the user; it is intended for older Web browsers which do
not support audio
, so that legacy audio plugins can be
tried, or to show text to the users of these older browsers informing
them of how to access the audio contents.
In particular, this content is not intended to address accessibility concerns. To make audio content accessible to the deaf or to those with other physical or cognitive disabilities, authors are expected to provide alternative media streams and/or to embed accessibility aids (such as transcriptions) into their media streams.
The audio
element is a media element
whose media data is ostensibly audio data.
The src
, preload
, autoplay
,
mediagroup
,
loop
,
muted
, and controls
attributes are the attributes common to all media
elements.
When an audio
element is potentially
playing, it must have its audio data played synchronized with
the current playback position, at the element's
effective media volume.
When an audio
element is not potentially
playing, audio must not play for the element.
Audio
( [ url ] )Returns a new audio
element, with the src
attribute set to the value
passed in the argument, if applicable.
Two constructors are provided for creating
HTMLAudioElement
objects (in addition to the factory
methods from DOM Core such as createElement()
): Audio()
and Audio(src)
. When invoked as constructors,
these must return a new HTMLAudioElement
object (a new
audio
element). The element must have its preload
attribute set to the
literal value "auto
". If the src argument is present, the object created must have
its src
content attribute set to
the provided value, and the user agent must invoke the object's
resource selection
algorithm before returning. The element's document must be
the active document of the browsing
context of the Window
object on which the
interface object of the invoked constructor is found.
source
elementtrack
elements.src
type
media
interface HTMLSourceElement : HTMLElement { attribute DOMString src; attribute DOMString type; attribute DOMString media; };
The source
element allows authors to specify
multiple alternative media
resources for media
elements. It does not represent anything on its own.
The src
attribute
gives the address of the media resource. The value must
be a valid non-empty URL potentially surrounded by
spaces. This attribute must be present.
Dynamically modifying a source
element
and its attribute when the element is already inserted in a
video
or audio
element will have no
effect. To change what is playing, either just use the src
attribute on the media
element directly, or call the load()
method on the media
element after manipulating the source
elements.
The type
attribute gives the type of the media resource, to help
the user agent determine if it can play this media
resource before fetching it. If specified, its value must be
a valid MIME type. The codecs
parameter, which certain MIME types define, might be necessary to
specify exactly how the resource is encoded. [RFC4281]
The following list shows some examples of how to use the codecs=
MIME parameter in the type
attribute.
<source src='video.mp4' type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"'>
<source src='video.mp4' type='video/mp4; codecs="avc1.58A01E, mp4a.40.2"'>
<source src='video.mp4' type='video/mp4; codecs="avc1.4D401E, mp4a.40.2"'>
<source src='video.mp4' type='video/mp4; codecs="avc1.64001E, mp4a.40.2"'>
<source src='video.mp4' type='video/mp4; codecs="mp4v.20.8, mp4a.40.2"'>
<source src='video.mp4' type='video/mp4; codecs="mp4v.20.240, mp4a.40.2"'>
<source src='video.3gp' type='video/3gpp; codecs="mp4v.20.8, samr"'>
<source src='video.ogv' type='video/ogg; codecs="theora, vorbis"'>
<source src='video.ogv' type='video/ogg; codecs="theora, speex"'>
<source src='audio.ogg' type='audio/ogg; codecs=vorbis'>
<source src='audio.spx' type='audio/ogg; codecs=speex'>
<source src='audio.oga' type='audio/ogg; codecs=flac'>
<source src='video.ogv' type='video/ogg; codecs="dirac, vorbis"'>
The media
attribute gives the intended media type of the media
resource, to help the user agent determine if this
media resource is useful to the user before fetching
it. Its value must be a valid media query.
The default, if the media
attribute is omitted, is
"all
", meaning that by default the media
resource is suitable for all media.
If a source
element is inserted as a child of a
media element that has no src
attribute and whose networkState
has the value
NETWORK_EMPTY
, the user
agent must invoke the media element's resource selection
algorithm.
The IDL attributes src
, type
, and media
must
reflect the respective content attributes of the same
name.
If the author isn't sure if the user agents will all be able to
render the media resources provided, the author can listen to the
error
event on the last
source
element and trigger fallback behavior:
<script> function fallback(video) { // replace <video> with its contents while (video.hasChildNodes()) { if (video.firstChild instanceof HTMLSourceElement) video.removeChild(video.firstChild); else video.parentNode.insertBefore(video.firstChild, video); } video.parentNode.removeChild(video); } </script> <video controls autoplay> <source src='video.mp4' type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"'> <source src='video.ogv' type='video/ogg; codecs="theora, vorbis"' onerror="fallback(parentNode)"> ... </video>
track
elementkind
src
srclang
label
default
interface HTMLTrackElement : HTMLElement { attribute DOMString kind; attribute DOMString src; attribute DOMString srclang; attribute DOMString label; attribute boolean default; readonly attribute TextTrack track; };
The track
element allows authors to specify explicit
external timed text tracks for media elements. It does not represent anything on its own.
The kind
attribute is an enumerated attribute. The following
table lists the keywords defined for this attribute. The keyword
given in the first cell of each row maps to the state given in the
second cell.
Keyword | State | Brief description |
---|---|---|
subtitles
| Subtitles | Transcription or translation of the dialogue, suitable for when the sound is available but not understood (e.g. because the user does not understand the language of the media resource's soundtrack). Displayed over the video. |
captions
| Captions | Transcription or translation of the dialogue, sound effects, relevant musical cues, and other relevant audio information, suitable for when the soundtrack is unavailable (e.g. because it is muted or because the user is deaf). Displayed over the video; labeled as appropriate for the hard-of-hearing. |
descriptions
| Descriptions | Textual descriptions of the video component of the media resource, intended for audio synthesis when the visual component is unavailable (e.g. because the user is interacting with the application without a screen while driving, or because the user is blind). Synthesized as separate audio track. |
chapters
| Chapters | Chapter titles, intended to be used for navigating the media resource. Displayed as an interactive list in the user agent's interface. |
metadata
| Metadata | Tracks intended for use from script. Not displayed by the user agent. |
The attribute may be omitted. The missing value default is the subtitles state.
The src
attribute
gives the address of the text track data. The value must be a
valid non-empty URL potentially surrounded by
spaces. This attribute must be present.
If the element has a src
attribute whose value is not the empty string and whose value, when
the attribute was set, could be successfully resolved relative to the element, then the element's
track URL is the resulting absolute
URL. Otherwise, the element's track URL is the
empty string.
The srclang
attribute gives the language of the text track data. The value must
be a valid BCP 47 language tag. This attribute must be present if
the element's kind
attribute is
in the subtitles
state. [BCP47]
If the element has a srclang
attribute whose value is
not the empty string, then the element's track language
is the value of the attribute. Otherwise, the element has no
track language.
The label
attribute gives a user-readable title for the track. This title is
used by user agents when listing subtitle, caption, and audio description tracks
in their user interface.
The value of the label
attribute, if the attribute is present, must not be the empty
string. Furthermore, there must not be two track
element children of the same media element whose kind
attributes are in the same
state, whose srclang
attributes are both missing or have values that represent the same
language, and whose label
attributes are again both missing or both have the same value.
If the element has a label
attribute whose value is not the empty string, then the element's
track label is the value of the attribute. Otherwise, the
element's track label is a user-agent defined string
(e.g. the string "untitled" in the user's locale, or a value
automatically generated from the other attributes).
The default
attribute, if specified, indicates that the track is to be enabled
if the user's preferences do not indicate that another track would
be more appropriate. There must not be more than one
track
element with the same parent node with the default
attribute specified.
track
Returns the TextTrack
object corresponding to the text track of the track
element.
The track
IDL
attribute must, on getting, return the track
element's
text track's corresponding TextTrack
object.
The src
, srclang
, label
, and default
IDL attributes
must reflect the respective content attributes of the
same name. The kind
IDL attribute must reflect the content attribute of the
same name, limited to only known values.
This video has subtitles in several languages:
<video src="brave.webm"> <track kind=subtitles src=brave.en.vtt srclang=en label="English"> <track kind=captions src=brave.en.vtt srclang=en label="English for the Hard of Hearing"> <track kind=subtitles src=brave.fr.vtt srclang=fr label="Français"> <track kind=subtitles src=brave.de.vtt srclang=de label="Deutsch"> </video>
Media elements
(audio
and video
, in this specification)
implement the following interface:
interface HTMLMediaElement : HTMLElement { // error state readonly attribute MediaError error; // network state attribute DOMString src; readonly attribute DOMString currentSrc; const unsigned short NETWORK_EMPTY = 0; const unsigned short NETWORK_IDLE = 1; const unsigned short NETWORK_LOADING = 2; const unsigned short NETWORK_NO_SOURCE = 3; readonly attribute unsigned short networkState; attribute DOMString preload; readonly attribute TimeRanges buffered; void load(); DOMString canPlayType(in DOMString type); // ready state const unsigned short HAVE_NOTHING = 0; const unsigned short HAVE_METADATA = 1; const unsigned short HAVE_CURRENT_DATA = 2; const unsigned short HAVE_FUTURE_DATA = 3; const unsigned short HAVE_ENOUGH_DATA = 4; readonly attribute unsigned short readyState; readonly attribute boolean seeking; // playback state attribute double currentTime; readonly attribute double initialTime; readonly attribute double duration; readonly attribute Date startOffsetTime; readonly attribute boolean paused; attribute double defaultPlaybackRate; attribute double playbackRate; readonly attribute TimeRanges played; readonly attribute TimeRanges seekable; readonly attribute boolean ended; attribute boolean autoplay; attribute boolean loop; void play(); void pause(); // media controller attribute DOMString mediaGroup; attribute MediaController controller; // controls attribute boolean controls; attribute double volume; attribute boolean muted; attribute boolean defaultMuted; // tracks readonly attribute MultipleTrackList audioTracks; readonly attribute ExclusiveTrackList videoTracks; readonly attribute TextTrack[] textTracks; MutableTextTrack addTextTrack(in DOMString kind, in optional DOMString label, in optional DOMString language); };
The media element attributes, src
, preload
, autoplay
,
mediagroup
,
loop
,
muted
, and controls
, apply to all media elements. They are defined in
this section.
Media elements are used to present audio data, or video and audio data, to the user. This is referred to as media data in this section, since this section applies equally to media elements for audio or for video. The term media resource is used to refer to the complete set of media data, e.g. the complete video file, or complete audio file.
A media resource can have multiple audio and video
tracks. For the purposes of a media element, the video
data of the media resource is only that of the
currently selected track (if any) given by the element's videoTracks
attribute, and the
audio data of the media resource is the result of
mixing all the currently enabled tracks (if any) given by the
element's audioTracks
attribute.
Both audio
and video
elements can be used for both audio and video. The main difference
between the two is simply that the audio
element has no
playback area for visual content (such as video or captions),
whereas the video
element does.
Except where otherwise specified, the task source for all the tasks queued in this section and its subsections is the media element event task source.
error
Returns a MediaError
object representing the
current error state of the element.
Returns null if there is no error.
All media elements have an
associated error status, which records the last error the element
encountered since its resource selection
algorithm was last invoked. The error
attribute, on
getting, must return the MediaError
object created for
this last error, or null if there has not been an error.
interface MediaError { const unsigned short MEDIA_ERR_ABORTED = 1; const unsigned short MEDIA_ERR_NETWORK = 2; const unsigned short MEDIA_ERR_DECODE = 3; const unsigned short MEDIA_ERR_SRC_NOT_SUPPORTED = 4; readonly attribute unsigned short code; };
error
. code
Returns the current error's error code, from the list below.
The code
attribute of a MediaError
object must return the code
for the error, which must be one of the following:
MEDIA_ERR_ABORTED
(numeric value 1)MEDIA_ERR_NETWORK
(numeric value 2)MEDIA_ERR_DECODE
(numeric value 3)MEDIA_ERR_SRC_NOT_SUPPORTED
(numeric value 4)src
attribute was not suitable.The src
content
attribute on media elements gives
the address of the media resource (video, audio) to show. The
attribute, if present, must contain a valid non-empty
URL potentially surrounded by spaces.
If a src
attribute of a
media element is set or changed, the user agent must
invoke the media element's media element load
algorithm. (Removing the src
attribute does not do this, even
if there are source
elements present.)
The src
IDL
attribute on media elements must
reflect the content attribute of the same name.
currentSrc
Returns the address of the current media resource.
Returns the empty string when there is no media resource.
The currentSrc
IDL
attribute is initially the empty string. Its value is changed by the
resource selection
algorithm defined below.
There are two ways to specify a media
resource, the src
attribute, or source
elements. The attribute overrides
the elements.
A media resource can be described in terms of its
type, specifically a MIME type, in some cases
with a codecs
parameter. (Whether the codecs
parameter is allowed or not depends on the
MIME type.) [RFC4281]
Types are usually somewhat incomplete descriptions; for example
"video/mpeg
" doesn't say anything except what
the container type is, and even a type like "video/mp4; codecs="avc1.42E01E,
mp4a.40.2"
" doesn't include information like the actual
bitrate (only the maximum bitrate). Thus, given a type, a user agent
can often only know whether it might be able to play
media of that type (with varying levels of confidence), or whether
it definitely cannot play media of that type.
A type that the user agent knows it cannot render is one that describes a resource that the user agent definitely does not support, for example because it doesn't recognize the container type, or it doesn't support the listed codecs.
The MIME type
"application/octet-stream
" with no parameters is never
a type that the user agent knows it cannot render. User
agents must treat that type as equivalent to the lack of any
explicit Content-Type metadata
when it is used to label a potential media
resource.
"application/octet-stream
"
is special-cased here; if any parameter appears with it, it
should
be treated just like any other MIME type.
This is a deviation from the rule that unknown MIME type parameters
should be ignored.
canPlayType
(type)Returns the empty string (a negative response), "maybe", or "probably" based on how confident the user agent is that it can play media resources of the given type.
The canPlayType(type)
method must return the empty
string if type is a type that the user
agent knows it cannot render or is the type
"application/octet-stream
"; it must return "probably
" if the user agent is confident that the
type represents a media resource that it can render if
used in with this audio
or video
element;
and it must return "maybe
" otherwise.
Implementors are encouraged to return "maybe
"
unless the type can be confidently established as being supported or
not. Generally, a user agent should never return "probably
" for a type that allows the codecs
parameter if that parameter is not
present.
This script tests to see if the user agent supports a
(fictional) new format to dynamically decide whether to use a
video
element or a plugin:
<section id="video"> <p><a href="playing-cats.nfv">Download video</a></p> </section> <script> var videoSection = document.getElementById('video'); var videoElement = document.createElement('video'); var support = videoElement.canPlayType('video/x-new-fictional-format;codecs="kittens,bunnies"'); if (support != "probably" && "New Fictional Video Plug-in" in navigator.plugins) { // not confident of browser support // but we have a plugin // so use plugin instead videoElement = document.createElement("embed"); } else if (support == "") { // no support from browser and no plugin // do nothing videoElement = null; } if (videoElement) { while (videoSection.hasChildNodes()) videoSection.removeChild(videoSection.firstChild); videoElement.setAttribute("src", "playing-cats.nfv"); videoSection.appendChild(videoElement); } </script>
The type
attribute of the source
element allows the user agent
to avoid downloading resources that use formats it cannot
render.
networkState
Returns the current state of network activity for the element, from the codes in the list below.
As media elements interact
with the network, their current network activity is represented by
the networkState
attribute. On getting, it must return the current network state of
the element, which must be one of the following values:
NETWORK_EMPTY
(numeric value 0)NETWORK_IDLE
(numeric value 1)NETWORK_LOADING
(numeric value 2)NETWORK_NO_SOURCE
(numeric value 3)The resource selection
algorithm defined below describes exactly when the networkState
attribute changes
value and what events fire to indicate changes in this state.
load
()Causes the element to reset and start selecting and loading a new media resource from scratch.
All media elements have an autoplaying flag, which must begin in the true state, and a delaying-the-load-event flag, which must begin in the false state. While the delaying-the-load-event flag is true, the element must delay the load event of its document.
When the load()
method on a media element is invoked, the user agent
must run the media element load algorithm.
The media element load algorithm consists of the following steps.
Abort any already-running instance of the resource selection algorithm for this element.
If there are any tasks from the media element's media element event task source in one of the task queues, then remove those tasks.
Basically, pending events and callbacks for the media element are discarded when the media element starts loading a new resource.
If the media element's networkState
is set to NETWORK_LOADING
or NETWORK_IDLE
, queue a
task to fire a simple event named abort
at the media
element.
If the media element's networkState
is not set to
NETWORK_EMPTY
, then
run these substeps:
Queue a task to fire a simple
event named emptied
at the media
element.
If a fetching process is in progress for the media element, the user agent should stop it.
Set the networkState
attribute to
NETWORK_EMPTY
.
Forget the media element's media-resource-specific text tracks.
If readyState
is
not set to HAVE_NOTHING
, then set it
to that state.
If the paused
attribute is false, then set it to true.
If seeking
is true,
set it to false.
Set the current playback position to 0.
If this changed the current playback position,
then queue a task to fire a simple
event named timeupdate
at the
media element.
Set the initial playback position to 0.
Set the timeline offset to Not-a-Number (NaN).
Update the duration
attribute to Not-a-Number (NaN).
The user agent will
not fire a durationchange
event
for this particular change of the duration.
Set the playbackRate
attribute to the
value of the defaultPlaybackRate
attribute.
Set the error
attribute
to null and the autoplaying flag to true.
Invoke the media element's resource selection algorithm.
Playback of any previously playing media resource for this element stops.
The resource selection algorithm for a media element is as follows. This algorithm is always invoked synchronously, but one of the first steps in the algorithm is to return and continue running the remaining steps asynchronously, meaning that it runs in the background with scripts and other tasks running in parallel. In addition, this algorithm interacts closely with the event loop mechanism; in particular, it has synchronous sections (which are triggered as part of the event loop algorithm). Steps in such sections are marked with ⌛.
Set the networkState
to NETWORK_NO_SOURCE
.
Asynchronously await a stable state, allowing the task that invoked this algorithm to continue. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)
⌛ If the media element has a src
attribute, then let mode be attribute.
⌛ Otherwise, if the media element does not
have a src
attribute but has a
source
element child, then let mode be children and let candidate be the first such source
element child in tree order.
⌛ Otherwise the media element has neither a
src
attribute nor a
source
element child: set the networkState
to NETWORK_EMPTY
, and abort
these steps; the synchronous section ends.
⌛ Set the media element's
delaying-the-load-event flag to true (this delays the load event), and set
its networkState
to
NETWORK_LOADING
.
⌛ Queue a task to fire a simple
event named loadstart
at the media
element.
If mode is attribute, then run these substeps:
⌛ Process candidate: If the src
attribute's value is the empty
string, then end the synchronous section, and jump
down to the failed step below.
⌛ Let absolute URL be the
absolute URL that would have resulted from resolving the URL
specified by the src
attribute's value relative to the media element when
the src
attribute was last
changed.
⌛ If absolute URL was obtained
successfully, set the currentSrc
attribute to absolute URL.
End the synchronous section, continuing the remaining steps asynchronously.
If absolute URL was obtained successfully, run the resource fetch algorithm with absolute URL. If that algorithm returns without aborting this one, then the load failed.
Failed: Reaching this step indicates that the media resource failed to load or that the given URL could not be resolved. In one atomic operation, run the following steps:
Set the error
attribute to a new MediaError
object whose code
attribute is set to
MEDIA_ERR_SRC_NOT_SUPPORTED
.
Forget the media element's media-resource-specific text tracks.
Set the element's networkState
attribute to
the NETWORK_NO_SOURCE
value.
Queue a task to fire a simple
event named error
at the media element.
Set the element's delaying-the-load-event flag to false. This stops delaying the load event.
Abort these steps. Until the load()
method is invoked or the
src
attribute is changed, the
element won't attempt to load another resource.
Otherwise, the source
elements will be used; run
these substeps:
⌛ Let pointer be a position defined by two adjacent nodes in the media element's child list, treating the start of the list (before the first child in the list, if any) and end of the list (after the last child in the list, if any) as nodes in their own right. One node is the node before pointer, and the other node is the node after pointer. Initially, let pointer be the position between the candidate node and the next node, if there are any, or the end of the list, if it is the last node.
As nodes are inserted and removed into the media element, pointer must be updated as follows:
Other changes don't affect pointer.
⌛ Process candidate: If candidate does not have a src
attribute, or if its src
attribute's value is the empty
string, then end the synchronous section, and jump
down to the failed step below.
⌛ Let absolute URL be the
absolute URL that would have resulted from resolving the URL
specified by candidate's src
attribute's value relative to
the candidate when the src
attribute was last
changed.
⌛ If absolute URL was not obtained successfully, then end the synchronous section, and jump down to the failed step below.
⌛ If candidate has a type
attribute whose value, when
parsed as a MIME type (including any codecs
described by the codecs
parameter, for
types that define that parameter), represents a type that
the user agent knows it cannot render, then end the
synchronous section, and jump down to the failed step below.
⌛ If candidate has a media
attribute whose value does
not match the
environment, then end the synchronous
section, and jump down to the failed step
below.
⌛ Set the currentSrc
attribute to absolute URL.
End the synchronous section, continuing the remaining steps asynchronously.
Run the resource fetch algorithm with absolute URL. If that algorithm returns without aborting this one, then the load failed.
Failed: Queue a task to
fire a simple event named error
at the candidate element, in the context of the fetching process that was used to try to
obtain candidate's corresponding media
resource in the resource fetch
algorithm.
Asynchronously await a stable state. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)
⌛ Forget the media element's media-resource-specific text tracks.
⌛ Find next candidate: Let candidate be null.
⌛ Search loop: If the node after pointer is the end of the list, then jump to the waiting step below.
⌛ If the node after pointer is
a source
element, let candidate
be that element.
⌛ Advance pointer so that the node before pointer is now the node that was after pointer, and the node after pointer is the node after the node that used to be after pointer, if any.
⌛ If candidate is null, jump back to the search loop step. Otherwise, jump back to the process candidate step.
⌛ Waiting: Set the element's networkState
attribute to
the NETWORK_NO_SOURCE
value.
⌛ Set the element's delaying-the-load-event flag to false. This stops delaying the load event.
End the synchronous section, continuing the remaining steps asynchronously.
Wait until the node after pointer is a node other than the end of the list. (This step might wait forever.)
Asynchronously await a stable state. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)
⌛ Set the element's delaying-the-load-event flag back to true (this delays the load event again, in case it hasn't been fired yet).
⌛ Set the networkState
back to NETWORK_LOADING
.
⌛ Jump back to the find next candidate step above.
The resource fetch algorithm for a media element and a given absolute URL is as follows:
Let the current media resource be the resource given by the absolute URL passed to this algorithm. This is now the element's media resource.
Begin to fetch the current media
resource, from the media element's
Document
's origin, with the force
same-origin flag set.
Every 350ms (±200ms) or for every byte received, whichever
is least frequent, queue a task to
fire a simple event named progress
at the element.
The stall timeout is a user-agent defined length of
time, which should be about three seconds. When a media
element that is actively attempting to obtain media
data has failed to receive any data for a duration equal to
the stall timeout, the user agent must queue a
task to fire a simple event named stalled
at the element.
User agents may allow users to selectively block or slow media data downloads. When a media element's download has been blocked altogether, the user agent must act as if it was stalled (as opposed to acting as if the connection was closed). The rate of the download may also be throttled automatically by the user agent, e.g. to balance the download with other connections sharing the same bandwidth.
User agents may decide to not download more content at any
time, e.g. after buffering five minutes of a one hour media
resource, while waiting for the user to decide whether to play the
resource or not, or while waiting for user input in an interactive
resource. When a media element's download has been
suspended, the user agent must set the networkState
to NETWORK_IDLE
and queue
a task to fire a simple event named suspend
at the element. If and
when downloading of the resource resumes, the user agent must set
the networkState
to
NETWORK_LOADING
.
The preload
attribute provides a
hint regarding how much buffering the author thinks is advisable,
even in the absence of the autoplay
attribute.
When a user agent decides to completely stall a download, e.g. if it is waiting until the user starts playback before downloading any further content, the element's delaying-the-load-event flag must be set to false. This stops delaying the load event.
The user agent may use whatever means necessary to fetch the resource (within the constraints put forward by this and other specifications); for example, reconnecting to the server in the face of network errors, using HTTP range retrieval requests, or switching to a streaming protocol. The user agent must consider a resource erroneous only if it has given up trying to fetch it.
The networking task source tasks to process the data as it is being fetched must, when appropriate, include the relevant substeps from the following list:
codecs
parameter, if the
parameter is defined for that type), represents a type that
the user agent knows it cannot render (even if the actual
media data is in a supported format)DNS errors, HTTP 4xx and 5xx errors (and equivalents in other protocols), and other fatal network errors that occur before the user agent has established whether the current media resource is usable, as well as the file using an unsupported container format, or using unsupported codecs for all the data, must cause the user agent to execute the following steps:
The user agent should cancel the fetching process.
Abort this subalgorithm, returning to the resource selection algorithm.
This indicates that the resource is usable. The user agent must follow these substeps:
Establish the media timeline for the purposes of the current playback position, the earliest possible position, and the initial playback position, based on the media data.
Update the timeline offset to the date and time that corresponds to the zero time in the media timeline established in the previous step, if any. If no explicit time and date is given by the media resource, the timeline offset must be set to Not-a-Number (NaN).
Set the current playback position to the earliest possible position.
Update the duration
attribute with the time of the last frame of the resource, if
known, on the media timeline established above.
If it is not known (e.g. a stream that is in principle
infinite), update the duration
attribute to the
value positive Infinity.
The user agent will queue a task to
fire a simple event named durationchange
at the
element at this point.
For video
elements, set the videoWidth
and videoHeight
attributes.
Set the readyState
attribute to
HAVE_METADATA
.
A loadedmetadata
DOM
event will be fired as part
of setting the readyState
attribute to a
new value.
Let jumped be false.
If either the media resource or the address of the current media resource indicate a particular start time, then set the initial playback position to that time, seek to that time, and let jumped be true. Ignore any resulting exceptions (if the position is out of range, it is effectively ignored).
For example, with media formats that support the Media Fragments URI fragment identifier syntax, the fragment identifier can be used to indicate a start position. [MEDIAFRAG]
If either the media resource or the address
of the current media resource indicate a
particular set of audio or video tracks to enable, then the
selected audio tracks must be enabled in the element's audioTracks
object, and
the first selected video track must be selected in the
element's videoTracks
object.
If the media element has a current media controller, then: if jumped is true and the initial playback position, relative to the current media controller's timeline, is greater than the current media controller's media controller position, then seek the media controller to the media element's initial playback position, relative to the current media controller's timeline; otherwise, seek the media element to the media controller position, relative to the media element's timeline, discarding any resulting exceptions.
Once the readyState
attribute
reaches HAVE_CURRENT_DATA
,
after the loadeddata
event has been
fired, set the element's delaying-the-load-event
flag to false. This stops delaying the load event.
A user agent that is attempting to reduce
network usage while still fetching the metadata for each
media resource would also stop buffering at this
point, causing the networkState
attribute
to switch to the NETWORK_IDLE
value.
The user agent is required to determine the duration of the media resource and go through this step before playing.
Queue a task to fire a simple event
named progress
at the
media element.
Fatal network errors that occur after the user agent has established whether the current media resource is usable must cause the user agent to execute the following steps:
The user agent should cancel the fetching process.
Set the error
attribute to a new MediaError
object whose code
attribute is set to
MEDIA_ERR_NETWORK
.
Queue a task to fire a simple
event named error
at the media element.
If the media element's readyState
attribute has a
value equal to HAVE_NOTHING
, set the
element's networkState
attribute to
the NETWORK_EMPTY
value and queue a task to fire a simple
event named emptied
at the element. Otherwise, set the element's networkState
attribute to
the NETWORK_IDLE
value.
Set the element's delaying-the-load-event flag to false. This stops delaying the load event.
Abort the overall resource selection algorithm.
Fatal errors in decoding the media data that occur after the user agent has established whether the current media resource is usable must cause the user agent to execute the following steps:
The user agent should cancel the fetching process.
Set the error
attribute to a new MediaError
object whose code
attribute is set to
MEDIA_ERR_DECODE
.
Queue a task to fire a simple
event named error
at the media element.
If the media element's readyState
attribute has a
value equal to HAVE_NOTHING
, set the
element's networkState
attribute to
the NETWORK_EMPTY
value and queue a task to fire a simple
event named emptied
at the element. Otherwise, set the element's networkState
attribute to
the NETWORK_IDLE
value.
Set the element's delaying-the-load-event flag to false. This stops delaying the load event.
Abort the overall resource selection algorithm.
The fetching process is aborted by the user, e.g. because the
user navigated the browsing context to another page, the user
agent must execute the following steps. These steps are not
followed if the load()
method itself is invoked while these steps are running, as the
steps above handle that particular kind of abort.
The user agent should cancel the fetching process.
Set the error
attribute to a new MediaError
object whose code
attribute is set to
MEDIA_ERR_ABORTED
.
Queue a task to fire a simple
event named abort
at the media element.
If the media element's readyState
attribute has a
value equal to HAVE_NOTHING
, set the
element's networkState
attribute to
the NETWORK_EMPTY
value and queue a task to fire a simple
event named emptied
at the element. Otherwise, set the element's networkState
attribute to
the NETWORK_IDLE
value.
Set the element's delaying-the-load-event flag to false. This stops delaying the load event.
Abort the overall resource selection algorithm.
The server returning data that is partially usable but cannot be optimally rendered must cause the user agent to render just the bits it can handle, and ignore the rest.
If the media resource's origin is
the same origin as the media element's
Document
's origin, queue a
task to run the steps to expose a
media-resource-specific text track with the relevant
data.
Cross-origin files do not expose their subtitles in the DOM, for security reasons. However, user agents may still provide the user with access to such data in their user interface.
When the networking task source has queued the last task as part of fetching the media resource (i.e. once the download has completed), if the fetching process completes without errors, including decoding the media data, and if all of the data is available to the user agent without network access, then, the user agent must move on to the next step. This might never happen, e.g. when streaming an infinite resource such as Web radio, or if the resource is longer than the user agent's ability to cache data.
While the user agent might still need network access to obtain parts of the media resource, the user agent must remain on this step.
For example, if the user agent has discarded
the first half of a video, the user agent will remain at this step
even once the playback has
ended, because there is always the chance the user will
seek back to the start. In fact, in this situation, once playback has ended, the user agent
will end up dispatching a stalled
event, as described
earlier.
If the user agent ever reaches this step (which can only happen if the entire resource gets loaded and kept available): abort the overall resource selection algorithm.
The preload
attribute is an enumerated attribute. The following table
lists the keywords and states for the attribute — the keywords
in the left column map to the states in the cell in the second
column on the same row as the keyword.
Keyword | State | Brief description |
---|---|---|
none
| None | Hints to the user agent that either the author does not expect the user to need the media resource, or that the server wants to minimise unnecessary traffic. |
metadata
| Metadata | Hints to the user agent that the author does not expect the user to need the media resource, but that fetching the resource metadata (dimensions, first frame, track list, duration, etc) is reasonable. |
auto
| Automatic | Hints to the user agent that the user agent can put the user's needs first without risk to the server, up to and including optimistically downloading the entire resource. |
The empty string is also a valid keyword, and maps to the Automatic state. The attribute's missing value default is user-agent defined, though the Metadata state is suggested as a compromise between reducing server load and providing an optimal user experience.
The preload
attribute is
intended to provide a hint to the user agent about what the author
thinks will lead to the best user experience. The attribute may be
ignored altogether, for example based on explicit user preferences
or based on the available connectivity.
The preload
IDL
attribute must reflect the content attribute of the
same name, limited to only known values.
The autoplay
attribute can override
the preload
attribute (since
if the media plays, it naturally has to buffer first, regardless of
the hint given by the preload
attribute). Including
both is not an error, however.
buffered
Returns a TimeRanges
object that represents the
ranges of the media resource that the user agent has
buffered.
The buffered
attribute must return a new static normalized
TimeRanges
object that represents the ranges of
the media resource, if any, that the user agent has
buffered, at the time the attribute is evaluated. Users agents must
accurately determine the ranges available, even for media streams
where this can only be determined by tedious inspection.
Typically this will be a single range anchored at the zero point, but if, e.g. the user agent uses HTTP range requests in response to seeking, then there could be multiple ranges.
User agents may discard previously buffered data.
Thus, a time position included within a range of the
objects return by the buffered
attribute at one time can
end up being not included in the range(s) of objects returned by the
same attribute at later times.
duration
Returns the length of the media resource, in seconds, assuming that the start of the media resource is at time zero.
Returns NaN if the duration isn't available.
Returns Infinity for unbounded streams.
currentTime
[ = value ]Returns the current playback position, in seconds.
Can be set, to seek to the given time.
Will throw an INVALID_STATE_ERR
exception if there
is no selected media resource
or if there is a current media controller.
Will throw an
INDEX_SIZE_ERR
exception if the given time is not
within the ranges to which the user agent can seek.
initialTime
Returns the initial playback position, that is, time to which the media resource was automatically seeked when it was loaded. Returns zero if the initial playback position is still unknown.
A media resource has a media timeline that maps times (in seconds) to positions in the media resource. The origin of a timeline is its earliest defined position. The duration of a timeline is its last defined position.
Establishing the media timeline: If the media
resource somehow specifies an explicit timeline whose origin
is not negative, then the media timeline should be that
timeline. (Whether the media resource can specify a
timeline or not depends on the media
resource's format.) If the media resource
specifies an explicit start time and date, then that time
and date should be considered the zero point in the media
timeline; the timeline offset will be the time
and date, exposed using the startOffsetTime
attribute.
If the media resource has a discontinuous timeline, the user agent must extend the timeline used at the start of the resource across the entire resource, so that the media timeline of the media resource increases linearly starting from the earliest possible position (as defined below), even if the underlying media data has out-of-order or even overlapping time codes.
For example, if two clips have been concatenated into one video file, but the video format exposes the original times for the two clips, the video data might expose a timeline that goes, say, 00:15..00:29 and then 00:05..00:38. However, the user agent would not expose those times; it would instead expose the times as 00:15..00:29 and 00:29..01:02, as a single video.
In the absence of an explicit timeline, the zero time on the media timeline should correspond to the first frame of the media resource. For static audio and video files this is generally trivial. For streaming resources, if the user agent will be able to seek to an earlier point than the first frame originally provided by the server, then the zero time should correspond to the earliest seekable time of the media resource; otherwise, it should correspond to the first frame received from the server (the point in the media resource at which the user agent began receiving the stream).
Another example would be a stream that carries a
video with several concatenated fragments, broadcast by a server
that does not allow user agents to request specific times but
instead just streams the video data in a predetermined order. If a
user agent connects to this stream and receives fragments defined as
covering timestamps 2010-03-20 23:15:00 UTC to 2010-03-21 00:05:00
UTC and 2010-02-12 14:25:00 UTC to 2010-02-12 14:35:00 UTC, it would
expose this with a media timeline starting at 0s and
extending to 3,600s (one hour). Assuming the streaming server
disconnected at the end of the second clip, the duration
attribute would then
return 3,600. The startOffsetTime
attribute
would return a Date
object with a time corresponding to
2010-03-20 23:15:00 UTC. However, if a different user agent
connected five minutes later, it would (presumably) receive
fragments covering timestamps 2010-03-20 23:20:00 UTC to 2010-03-21
00:05:00 UTC and 2010-02-12 14:25:00 UTC to 2010-02-12 14:35:00 UTC,
and would expose this with a media timeline starting at
0s and extending to 3,300s (fifty five minutes). In this case, the
startOffsetTime
attribute would return a Date
object with a time
corresponding to 2010-03-20 23:20:00 UTC.
In any case, the user agent must ensure that the earliest possible position (as defined below) using the established media timeline, is greater than or equal to zero.
The media timeline also has an associated clock. Which clock is used is user-agent defined, and may be media resource-dependent, but it should approximate the user's wall clock.
All the media elements that share current media controller use the same clock for their media timeline.
Media elements have a current playback position, which must initially (i.e. in the absence of media data) be zero seconds. The current playback position is a time on the media timeline.
The currentTime
attribute must, on getting, return the current playback
position, expressed in seconds. On setting,
if the media element has a current media
controller, then it must throw an
INVALID_STATE_ERR
exception; otherwise,
the user agent
must seek to the new value
(which might raise an exception).
Media elements have an initial playback position, which must initially (i.e. in the absence of media data) be zero seconds. The initial playback position is updated when a media resource is loaded. The initial playback position is a time on the media timeline.
The initialTime
attribute must, on getting, return the initial playback
position, expressed in seconds.
If the media resource is a streaming resource, then the user agent might be unable to obtain certain parts of the resource after it has expired from its buffer. Similarly, some media resources might have a media timeline that doesn't start at zero. The earliest possible position is the earliest position in the stream or resource that the user agent can ever obtain again. It is also a time on the media timeline.
The earliest possible position is not
explicitly exposed in the API; it corresponds to the start time of
the first range in the seekable
attribute's
TimeRanges
object, if any, or the current
playback position otherwise.
When the earliest possible position changes, then:
if the current playback position is before the
earliest possible position, the user agent must seek to the earliest possible
position; otherwise, if the user agent has not fired a timeupdate
event at the
element in the past 15 to 250ms and is not still running event
handlers for such an event, then the user agent must queue a
task to fire a simple event named timeupdate
at the element.
Because of the above requirement and the requirement in the resource fetch algorithm that kicks in when the metadata of the clip becomes known, the current playback position can never be less than the earliest possible position.
The duration
attribute must return the time of the end of the media
resource, in seconds, on the media timeline. If
no media data is available, then the attributes must
return the Not-a-Number (NaN) value. If the media
resource is known to be unbounded (e.g. a streaming radio),
then the attribute must return the positive Infinity value.
The user agent must determine the duration of the media
resource before playing any part of the media
data and before setting readyState
to a value equal to
or greater than HAVE_METADATA
, even if doing
so requires fetching multiple parts of the resource.
When the length of the media
resource changes to a known value (e.g. from being unknown to
known, or from a previously established length to a new length) the
user agent must queue a task to fire a simple
event named durationchange
at the
media element. (The event is not fired when the
duration is reset as part of loading a new media resource.)
If an "infinite" stream ends for some reason,
then the duration would change from positive Infinity to the time of
the last frame or sample in the stream, and the durationchange
event would
be fired. Similarly, if the user agent initially estimated the
media resource's duration instead of determining it
precisely, and later revises the estimate based on new information,
then the duration would change and the durationchange
event would
be fired.
Some video files also have an explicit date and time corresponding to the zero time in the media timeline, known as the timeline offset. Initially, the timeline offset must be set to Not-a-Number (NaN).
The startOffsetTime
attribute must return a new Date
object representing
the current timeline offset.
The loop
attribute is a boolean attribute that, if specified,
indicates that the media element is to seek back to the
start of the media resource upon reaching the end.
The loop
attribute has no
effect while the element has a current media
controller.
The loop
IDL
attribute must reflect the content attribute of the
same name.
readyState
Returns a value that expresses the current state of the element with respect to rendering the current playback position, from the codes in the list below.
Media elements have a ready state, which describes to what degree they are ready to be rendered at the current playback position. The possible values are as follows; the ready state of a media element at any particular time is the greatest value describing the state of the element:
HAVE_NOTHING
(numeric value 0)networkState
attribute are set to NETWORK_EMPTY
are always in
the HAVE_NOTHING
state.HAVE_METADATA
(numeric value 1)video
element, the dimensions of the video are also available. The API
will no longer raise an exception when seeking. No media
data is available for the immediate current playback
position.
The text tracks
are ready.
HAVE_CURRENT_DATA
(numeric value 2)HAVE_METADATA
state, or
there is no more data to obtain in the direction of
playback. For example, in video this corresponds to the user
agent having data from the current frame, but not the next frame;
and to when playback has
ended.HAVE_FUTURE_DATA
(numeric value 3)HAVE_METADATA
state. For example, in video this corresponds to the user agent
having data for at least the current frame and the next frame. The
user agent cannot be in this state if playback has ended, as the current playback
position can never advance in this case.HAVE_ENOUGH_DATA
(numeric value 4)HAVE_FUTURE_DATA
state
are met, and, in addition, the user agent estimates that data is
being fetched at a rate where the current playback
position, if it were to advance at the effective
playback rate, would not overtake the available data before
playback reaches the end of the media resource.When the ready state of a media element whose networkState
is not NETWORK_EMPTY
changes, the
user agent must follow the steps given below:
Apply the first applicable set of substeps from the following list:
HAVE_NOTHING
, and the new
ready state is HAVE_METADATA
Queue a task to fire a simple event
named loadedmetadata
at the
element.
Before this task is run, as part of the event
loop mechanism, the rendering will have been updated to resize
the video
element if appropriate.
HAVE_METADATA
and
the new ready state is HAVE_CURRENT_DATA
or
greaterIf this is the first time this occurs for
this media element since the load()
algorithm was last invoked,
the user agent must queue a task to fire a
simple event named loadeddata
at the element.
If the new ready state is HAVE_FUTURE_DATA
or
HAVE_ENOUGH_DATA
,
then the relevant steps below must then be run also.
HAVE_FUTURE_DATA
or more,
and the new ready state is HAVE_CURRENT_DATA
or
lessIf the media
element was potentially playing before its
readyState
attribute
changed to a value lower than HAVE_FUTURE_DATA
, and
the element has not ended playback, and playback
has not stopped due to errors, and playback has not
paused for user interaction, the user agent must
queue a task to fire a simple event
named timeupdate
at
the element, and queue a task to fire a
simple event named waiting
at the element.
HAVE_CURRENT_DATA
or
less, and the new ready state is HAVE_FUTURE_DATA
The user agent must queue a task to fire a
simple event named canplay
.
If the element's paused
attribute is false, the user agent must queue a task
to fire a simple event named playing
.
HAVE_ENOUGH_DATA
If the previous ready state was HAVE_CURRENT_DATA
or
less, the user agent must queue a task to fire
a simple event named canplay
, and, if the element's
paused
attribute is false,
queue a task to fire a simple event
named playing
.
If the autoplaying flag is true, and the paused
attribute is true, and the
media element has an autoplay
attribute specified,
and the media element's Document
's
browsing context did not have the sandboxed
automatic features browsing context flag set when the
Document
was created, then the user agent may also
set the paused
attribute to
false, queue a task to fire a simple
event named play
, and
queue a task to fire a simple event
named playing
.
User agents do not need to support autoplay,
and it is suggested that user agents honor user preferences on the
matter. Authors are urged to use the autoplay
attribute rather than
using script to force the video to play, so as to allow the user
to override the behavior if so desired.
In any case, the user agent must finally queue a
task to fire a simple event named canplaythrough
.
If the media element has a current media controller, then report the controller state for the media element's current media controller.
It is possible for the ready state of a media
element to jump between these states discontinuously. For example,
the state of a media element can jump straight from HAVE_METADATA
to HAVE_ENOUGH_DATA
without
passing through the HAVE_CURRENT_DATA
and
HAVE_FUTURE_DATA
states.
The readyState
IDL
attribute must, on getting, return the value described above that
describes the current ready state of the media
element.
The autoplay
attribute is a boolean attribute. When present, the
user agent (as described in the algorithm
described herein) will automatically begin playback of the
media resource as soon as it can do so without
stopping.
Authors are urged to use the autoplay
attribute rather than
using script to trigger automatic playback, as this allows the user
to override the automatic playback when it is not desired, e.g. when
using a screen reader. Authors are also encouraged to consider not
using the automatic playback behavior at all, and instead to let the
user agent wait for the user to start playback explicitly.
The autoplay
IDL attribute must reflect the content attribute of the
same name.
paused
Returns true if playback is paused; false otherwise.
ended
Returns true if playback has reached the end of the media resource.
defaultPlaybackRate
[ = value ]Returns the default rate of playback, for when the user is not fast-forwarding or reversing through the media resource.
Can be set, to change the default rate of playback.
The default rate has no direct effect on playback, but if the user switches to a fast-forward mode, when they return to the normal playback mode, it is expected that the rate of playback will be returned to the default rate of playback.
When the element has a current media controller,
the defaultPlaybackRate
attribute is ignored and the current media
controller's defaultPlaybackRate
is used instead.
playbackRate
[ = value ]Returns the current rate playback, where 1.0 is normal speed.
Can be set, to change the rate of playback.
When the element has a current media controller,
the playbackRate
attribute is ignored and the current media
controller's playbackRate
is
used instead.
played
Returns a TimeRanges
object that represents the
ranges of the media resource that the user agent has
played.
play
()Sets the paused
attribute
to false, loading the media resource and beginning
playback if necessary. If the playback had ended, will restart it
from the start.
pause
()Sets the paused
attribute
to true, loading the media resource if necessary.
The paused
attribute represents whether the media element is
paused or not. The attribute must initially be true.
A media element is a blocked media
element if its readyState
attribute is in the
HAVE_NOTHING
state or
the HAVE_METADATA
state, or if the element has paused for user
interaction.
A media element is said to be potentially
playing when its paused
attribute is false, the element has not ended playback,
playback has not stopped due to errors,
the element either has no current media controller or
has a current media controller but is not blocked
on its media controller,
and the element is not a blocked media element.
A media element is said to have ended playback when:
readyState
attribute is HAVE_METADATA
or greater,
and
Either:
loop
attribute specified,
or the media element has a current media
controller.
Or:
The ended
attribute must return true if the media element has
ended playback and the direction of
playback is forwards, and false otherwise.
A media element is said to have stopped due to
errors when the element's readyState
attribute is HAVE_METADATA
or greater, and
the user agent encounters a
non-fatal error during the processing of the media
data, and due to that error, is not able to play the content
at the current playback position.
A media element is said to have paused for user
interaction when its paused
attribute is false, the readyState
attribute is either
HAVE_FUTURE_DATA
or
HAVE_ENOUGH_DATA
and
the user agent has reached a point in the media
resource where the user has to make a selection for the
resource to continue.
If the media element has a current media
controller when this happens, then the user agent must
report the controller state for the media
element's current media controller. If If the
media element has a current media
controller when the user makes a selection, allowing playback
to resume, the user agent must similarly report the controller
state for the media element's current
media controller.
It is possible for a media element to have both ended playback and paused for user interaction at the same time.
When a media element that is potentially
playing stops playing because it has paused for user
interaction, the user agent must queue a task to
fire a simple event named timeupdate
at the element.
A waiting
DOM event can be fired as a
result of an element that is potentially playing
stopping playback due to its readyState
attribute changing to
a value lower than HAVE_FUTURE_DATA
.
When the current playback position reaches the end of the media resource when the direction of playback is forwards, then the user agent must follow these steps:
If the media element has a loop
attribute specified
and does not have a current media controller,
then seek to the earliest
possible position of the media resource and
abort these steps.
Stop playback.
The ended
attribute becomes
true.
The user agent must queue a task to fire
a simple event named timeupdate
at the element.
The user agent must queue a task to fire
a simple event named ended
at the element.
When the current playback position reaches the earliest possible position of the media resource when the direction of playback is backwards, then the user agent must follow these steps:
Stop playback.
The user agent must queue a task to fire
a simple event named timeupdate
at the element.
The defaultPlaybackRate
attribute gives the desired speed at which the media
resource is to play, as a multiple of its intrinsic
speed. The attribute is mutable: on getting it must return the last
value it was set to, or 1.0 if it hasn't yet been set; on setting
the attribute must be set to the new value.
The defaultPlaybackRate
is
used by the user agent when it exposes a user interface to the user.
The playbackRate
attribute gives the effective playback rate
(assuming there is no current media controller overriding it),
which is the speed at which the media resource plays,
as a multiple of its intrinsic speed. If it is not equal to the
defaultPlaybackRate
,
then the implication is that the user is using a feature such as
fast forward or slow motion playback. The attribute is mutable: on
getting it must return the last value it was set to, or 1.0 if it
hasn't yet been set; on setting the attribute must be set to the new
value, and the playback will change speed
(if the element is potentially playing and there is no
current media controller).
When the defaultPlaybackRate
or
playbackRate
attributes
change value (either by being set by script or by being changed
directly by the user agent, e.g. in response to user control) the
user agent must queue a task to fire a simple
event named ratechange
at the media
element.
The defaultPlaybackRate
and
playbackRate
attributes
have no effect when the media element has a
current media controller; the namesake attributes on
the MediaController
object are used instead in that
situation.
The played
attribute must return a new static normalized
TimeRanges
object that represents the ranges of
the media resource, if any, that the user agent has so
far rendered, at the time the attribute is evaluated.
When the play()
method on a media element is invoked, the user agent
must run the following steps.
If the media element's networkState
attribute has
the value NETWORK_EMPTY
, invoke the
media element's resource selection
algorithm.
If the playback has ended and the direction of playback is forwards, and the media element does not have a current media controller, seek to the earliest possible position of the media resource.
This will cause the user
agent to queue a task to fire a simple
event named timeupdate
at the media
element.
If the media element has a current media controller, then bring the media element up to speed with its new media controller.
If the media element's paused
attribute is true, run
the following substeps:
Change the value of paused
to false.
Queue a task to fire a simple event
named play
at the element.
If the media element's readyState
attribute has the
value HAVE_NOTHING
,
HAVE_METADATA
, or
HAVE_CURRENT_DATA
,
queue a task to fire a simple event
named waiting
at the
element.
Otherwise, the media element's readyState
attribute has the
value HAVE_FUTURE_DATA
or
HAVE_ENOUGH_DATA
:
queue a task to fire a simple event
named playing
at the
element.
Set the media element's autoplaying flag to false.
If the media element has a current media controller, then report the controller state for the media element's current media controller.
When the pause()
method is invoked, and when the user agent is required to pause the
media element, the user agent must run the following
steps:
If the media element's networkState
attribute has
the value NETWORK_EMPTY
, invoke the
media element's resource selection
algorithm.
Set the media element's autoplaying flag to false.
If the media element's paused
attribute is false, run the
following steps:
Change the value of paused
to true.
Queue a task to fire a simple
event named timeupdate
at the
element.
Queue a task to fire a simple
event named pause
at the element.
If the media element has a current media controller, then report the controller state for the media element's current media controller.
The
effective playback rate is not necessarily the element's
playbackRate
. When a
media element has a current media
controller, its effective playback rate is the
MediaController
's media controller playback
rate. Otherwise, the
effective playback rate is just the element's playbackRate
.
Thus, the current media controller overrides the
media element.
If the effective playback rate is positive or zero, then the direction of playback is forwards. Otherwise, it is backwards.
When a media element is
potentially playing and its Document
is a
fully active Document
, its current
playback position must increase monotonically at
effective playback rate units of media time per unit time
of the media timeline's clock.
The effective playback rate can be 0.0,
in which case the current playback position doesn't
move, despite playback not being paused (paused
doesn't become true, and the
pause
event doesn't
fire).
This specification doesn't define how the user agent achieves the appropriate playback rate — depending on the protocol and media available, it is plausible that the user agent could negotiate with the server to have the server provide the media data at the appropriate rate, so that (except for the period between when the rate is changed and when the server updates the stream's playback rate) the client doesn't actually have to drop or interpolate any frames.
When the direction of playback is backwards, any corresponding audio must be muted. When the effective playback rate is so low or so high that the user agent cannot play audio usefully, the corresponding audio must also be muted. If the effective playback rate is not 1.0, the user agent may apply pitch adjustments to the audio as necessary to render it faithfully.
Media elements that are
potentially playing while not in a
Document
must not play any video, but should
play any audio component. Media elements must not stop playing just
because all references to them have been removed; only once a media
element is in a state where no further audio could ever be played by
that element may the element be garbage collected.
It is possible for an element to which no explicit references exist to play audio, even if such an element is not still actively playing: for instance, it could have a current media controller that still has references and can still be unpaused, or it could be unpaused but stalled waiting for content to buffer.
When the current playback position of a media element changes (e.g. due to playback or seeking), the user agent must run the following steps. If the current playback position changes while the steps are running, then the user agent must wait for the steps to complete, and then must immediately rerun the steps. (These steps are thus run as often as possible or needed — if one iteration takes a long time, this can cause certain cues to be skipped over as the user agent rushes ahead to "catch up".)
Let current cues be an ordered list of cues, initialized to contain all the cues of all the hidden, showing, or showing by default text tracks of the media element (not the disabled ones) whose start times are less than or equal to the current playback position and whose end times are greater than the current playback position, in text track cue order.
Let other cues be an ordered list of cues, initialized to contain all the cues of hidden, showing, and showing by default text tracks of the media element that are not present in current cues, also in text track cue order.
If the time was reached through the usual monotonic increase
of the current playback position during normal
playback, and if the user agent has not fired a timeupdate
event at the
element in the past 15 to 250ms and is not still running event
handlers for such an event, then the user agent must queue a
task to fire a simple event named timeupdate
at the element.
(In the other cases, such as explicit seeks, relevant events get
fired as part of the overall process of changing the current
playback position.)
The event thus is not to be fired faster than about 66Hz or slower than 4Hz (assuming the event handlers don't take longer than 250ms to run). User agents are encouraged to vary the frequency of the event based on the system load and the average cost of processing the event each time, so that the UI updates are not any more frequent than the user agent can comfortably handle while decoding the video.
If all of the cues in current cues have their text track cue active flag set, and none of the cues in other cues have their text track cue active flag set, then abort these steps.
If the time was reached through the usual monotonic increase of the current playback position during normal playback, and there are cues in other cues that have both their text track cue active flag set and their text track cue pause-on-exit flag set, then immediately pause the media element. (In the other cases, such as explicit seeks, playback is not paused by going past the end time of a cue, even if that cue has its text track cue pause-on-exit flag set.)
Let affected tracks be a list of text tracks, initially empty.
For each text track
cue in other cues that has its
text track cue active flag set, in list order,
queue a task to fire a simple event named
exit
at the
TextTrackCue
object, and add the cue's text track to affected tracks, if it's not already in the
list.
For each text track
cue in current cues that does not have
its text track cue active flag set, in list order,
queue a task to fire a simple event named
enter
at the
TextTrackCue
object, and add the cue's text track to affected tracks, if it's not already in the
list.
For each text track in affected
tracks, in the order they were added to the list (which will
match the relative order of the text
tracks in the media element's list of
text tracks), queue a task to fire a
simple event named cuechange
at the
TextTrack
object, and, if the text
track has a corresponding track
element, to
then fire a simple event named cuechange
at the track
element as well.
Set the text track cue active flag of all the cues in the current cues, and unset the text track cue active flag of all the cues in the other cues.
Run the rules for updating the text track rendering of each of the text tracks in affected tracks that are showing or showing by default.
For the purposes of the algorithm above, a text track cue is considered to be part of a text track only if it is listed in the text track list of cues, not merely if it is associated with the text track.
If the media element's
Document
stops being a fully active
document, then the playback will stop
until the document is active again.
When a media element is removed from a
Document
, the user agent must run
the following steps:
Asynchronously await a stable state, allowing
the task that removed the
media element from the Document
to
continue. The synchronous section consists of all the
remaining steps of this algorithm. (Steps in the synchronous
section are marked with ⌛.)
⌛ If the media element is in a
Document
, abort these steps.
⌛ If the media element's networkState
attribute has
the value NETWORK_EMPTY
, abort these
steps.
⌛ Pause the media element.
seeking
Returns true if the user agent is currently seeking.
seekable
Returns a TimeRanges
object that represents the
ranges of the media resource to which it is possible
for the user agent to seek.
The seeking
attribute must initially have the value false.
When the user agent is required to seek to a particular new playback position in the media resource, it means that the user agent must run the following steps. This algorithm interacts closely with the event loop mechanism; in particular, it has a synchronous section (which is triggered as part of the event loop algorithm). Steps in that section are marked with ⌛.
If the media element's readyState
is HAVE_NOTHING
, then raise an
INVALID_STATE_ERR
exception (if the seek was in
response to a DOM method call or setting of an IDL attribute), and
abort these steps.
If the element's seeking
IDL attribute is true,
then another instance of this algorithm is already running. Abort
that other instance of the algorithm without waiting for the step
that it is running to complete.
Set the seeking
IDL
attribute to true.
If the seek was in response to a DOM method call or setting of an IDL attribute, then continue the script. The remainder of these steps must be run asynchronously. With the exception of the steps marked with ⌛, they could be aborted at any time by another instance of this algorithm being invoked.
If the new playback position is later than the end of the media resource, then let it be the end of the media resource instead.
If the new playback position is less than the earliest possible position, let it be that position instead.
If the (possibly now changed) new playback
position is not in one of the ranges given in the seekable
attribute, then let it
be the position in one of the ranges given in the seekable
attribute that is the
nearest to the new playback position. If two
positions both satisfy that constraint (i.e. the new
playback position is exactly in the middle between two ranges
in the seekable
attribute)
then use the position that is closest to the current playback
position. If there are no ranges given in the seekable
attribute then set the
seeking
IDL attribute to
false and abort these steps.
Queue a task to fire a simple
event named seeking
at the element.
Set the current playback position to the given new playback position.
If the media element was
potentially playing immediately before it started
seeking, but seeking caused its readyState
attribute to change
to a value lower than HAVE_FUTURE_DATA
, then a
waiting
will be fired at the
element.
Wait until the user agent has established whether or not the media data for the new playback position is available, and, if it is, until it has decoded enough data to play back that position.
Await a stable state. The synchronous section consists of all the remaining steps of this algorithm. (Steps in the synchronous section are marked with ⌛.)
⌛ Set the seeking
IDL attribute to
false.
Queue a task to fire a
simple event named timeupdate
at the
element.
⌛ Queue a task to fire a simple
event named seeked
at the element.
The seekable
attribute must return a new static normalized
TimeRanges
object that represents the ranges of
the media resource, if any, that the user agent is able
to seek to, at the time the attribute is evaluated.
If the user agent can seek to anywhere in the
media resource, e.g. because it is a simple movie file
and the user agent and the server support HTTP Range requests, then
the attribute would return an object with one range, whose start is
the time of the first frame (the earliest possible
position, typically zero), and whose end is the same as the
time of the first frame plus the duration
attribute's value (which
would equal the time of the last frame, and might be positive
Infinity).
The range might be continuously changing, e.g. if the user agent is buffering a sliding window on an infinite stream. This is the behavior seen with DVRs viewing live TV, for instance.
Media resources might be internally scripted or interactive. Thus, a media element could play in a non-linear fashion. If this happens, the user agent must act as if the algorithm for seeking was used whenever the current playback position changes in a discontinuous fashion (so that the relevant events fire). If the media element has a current media controller, then the user agent must seek the media controller appropriately instead.
A media resource can have multiple embedded audio and video tracks. For example, in addition to the primary video and audio tracks, a media resource could have foreign-language dubbed dialogues, director's commentaries, audio descriptions, alternative angles, or sign-language overlays.
audioTracks
Returns a MultipleTrackList
object representing
the audio tracks available in the media resource.
videoTracks
Returns an ExclusiveTrackList
object representing
the video tracks available in the media resource.
The audioTracks
attribute of a media element must return a
live MultipleTrackList
object representing
the audio tracks available in the media element's
media resource. The same object must be returned each
time.
The videoTracks
attribute of a media element must return a
live ExclusiveTrackList
object
representing the video tracks available in the media
element's media resource. The same object must
be returned each time.
There are only ever two TrackList
objects (one MultipleTrackList
object and one
ExclusiveTrackList
object) per media
element, even if another media resource is
loaded into the element: the objects are reused.
TrackList
objectsThe MultipleTrackList
and
ExclusiveTrackList
interfaces, used by the attributes
defined in the previous section, are substantially similar. Their
common features are defined in the TrackList
interface,
from which they both inherit.
interface TrackList { readonly attribute unsigned long length; DOMString getID(in unsigned long index); DOMString getKind(in unsigned long index); DOMString getLabel(in unsigned long index); DOMString getLanguage(in unsigned long index); attribute Function onchange; }; interface MultipleTrackList : TrackList { boolean isEnabled(in unsigned long index); void enable(in unsigned long index); void disable(in unsigned long index); }; interface ExclusiveTrackList : TrackList { readonly attribute unsigned long selectedIndex; void select(in unsigned long index); };
length
Returns the number of tracks in the list.
getID
( index )Returns the ID of the given track. This is the ID that can be used with a fragment identifier if the format supports the Media Fragments URI syntax. [MEDIAFRAG]
getKind
( index )Returns the category the given track falls into. The possible track categories are given below.
getLabel
( index )Returns the label of the given track, if known, or the empty string otherwise.
getLanguage
( index )Returns the language of the given track, if known, or the empty string otherwise.
isEnabled
( index )Returns true if the given track is active, and false otherwise.
enable
( index )Enables the given track.
disable
( index )Disables the given track.
isEnabled
Returns the index of the currently selected track, if any, or −1 otherwise.
select
( index )Selects the given track.
The length
attribute must return the number of tracks represented by the
TrackList
object at the time of getting.
Tracks in a TrackList
object must be consistently
ordered. If the media resource is in a format that
defines an order, then that order must be used; otherwise, the order
must be the relative order in which the tracks are declared in the
media resource. Each track in a TrackList
thus has an index; the first has the index 0, and each subsequent
track is numbered one higher than the previous one.
The getID(index)
method must return the identifier
of the track with index index, if there is one.
If there is no such track, then the method must instead throw an
INDEX_SIZE_ERR
exception. If the media
resource is in a format that supports the Media
Fragments URI fragment identifier syntax, the returned
identifier must be the same identifier that would enable the track
if used as the name of a track in the track dimension of such a
fragment identifier. [MEDIAFRAG]
The getKind(index)
method must return the category
of the track with index index, if there is one.
If there is no such track, then the method must instead throw an
INDEX_SIZE_ERR
exception.
The category of a track is the string given in the first column of the table below that is the most appropriate for the track based on the definitions in the table's second and third columns, as determined by the metadata included in the track in the media resource. For Ogg files, the Role header of the track gives the relevant metadata. The cell in the third column of a row says what the category given in the cell in the first column of that row applies to; a category is only appropriate for an audio track if it applies to audio tracks, and a category is only appropriate for video tracks if it applies to video tracks.
Category | Definition | Applies to... | Examples |
---|---|---|---|
"alternative "
| A possible alternative to the main track, e.g. a different take of a song (audio), or a different angle (video). | Audio and video. | Ogg: "audio/alterate" or "video/alternate". |
"description "
| An audio description of a video track. | Audio only. | Ogg: "audio/audiodesc". |
"main "
| The primary audio or video track. | Audio and video. | Ogg: "audio/main" or "video/main"; WebM: the "FlagDefault" element is set. |
"sign "
| A sign-language interpretation of an audio track. | Video only. | Ogg: "video/sign". |
"translation "
| A translated version of the main track. | Audio only. | Ogg: "audio/dub". |
" " (empty string)
| No explicit kind, or the kind given by the track's metadata is not recognised by the user agent. | Audio and video. | Any other track type or track role. |
The getLabel(index)
method must return the label of
the track with index index, if there is one and
it has a label. If there is no such track, then the method must
instead throw an INDEX_SIZE_ERR
exception. If there is
a track with index index, but it has no label,
then the method must return the empty string.
The getLanguage(index)
method must return the BCP 47
language tag of the language of the track with index index, if there is one and it has a language. If
there is no such track, then the method must instead throw an
INDEX_SIZE_ERR
exception. If there is a track with
index index, but it has no language, or the user
agent is not able to express that language as a BCP 47 language tag
(for example because the language information in the media
resource's format is a free-form string without a defined
interpretation), then the method must return the empty string.
A MultipleTrackList
object represents a track list
where multiple tracks can be enabled simultaneously. Each track is
either enabled or disabled.
The isEnabled(index)
method must return true if there
is a track with index index, and it is currently
enabled, false if there is a track with index index, but it is currently disabled, and must throw
an INDEX_SIZE_ERR
exception if there is no track with
index index.
The enable(index)
method must enable the track with
index index, if there is one. If there is not,
it must instead throw an INDEX_SIZE_ERR
exception.
The disable(index)
method must disable the track with
index index, if there is one. If there is not,
it must instead throw an INDEX_SIZE_ERR
exception.
Whenever a track is enabled or disabled, the user agent must
queue a task to fire a simple event named
change
at the
MultipleTrackList
object.
An ExclusiveTrackList
object represents a track list
where exactly one track is selected at a time.
The selectedIndex
attribute must return the index of the currently selected track. If
the ExclusiveTrackList
object does not represent any
tracks, it must instead return −1.
The select(index)
must select the track with index
index, if there is one, unselecting whichever
track was previously selected. If there is no track with index index, it must instead throw an
INDEX_SIZE_ERR
exception.
Whenever the selected track is changed, the user agent must
queue a task to fire a simple event named
change
at the
MultipleTrackList
object.
The following are the event handlers (and their
corresponding event handler
event types) that must be supported, as IDL attributes, by
all objects implementing the TrackList
interface:
Event handler | Event handler event type |
---|---|
onchange | change
|
The task source for the tasks listed in this section is the DOM manipulation task source.
The audioTracks
and
videoTracks
attributes
allow scripts to select which track should play, but it is also
possible to select specific tracks declaratively, by specifying
particular tracks in the fragment identifier of the URL
of the media resource. The format of the fragment
identifier depends on the MIME type of the media
resource. [RFC2046] [RFC3986]
In this example, a video that uses a format that supports the Media Fragments URI fragment identifier syntax is embedded in such a way that the alternative angles labeled "Alternative" are enabled instead of the default video track. [MEDIAFRAG]
<video src="myvideo#track=Alternative"></video>
Each media element can have a
MediaController
. A MediaController
is an
object that coordinates the playback of multiple media elements, for instance so that a sign-language
interpreter track can be overlaid on a video track, with the two
being kept in sync.
By default, a media element has no
MediaController
. An implicit
MediaController
can be assigned using the mediagroup
content attribute.
An explicit MediaController
can be assigned directly
using the controller
IDL
attribute.
Media elements with a
MediaController
are said to be slaved to their
controller. The MediaController
modifies the playback
rate and the playback volume of each of the media elements slaved to it, and ensures that when
any of its slaved media elements
unexpectedly stall, the others are stopped at the same time.
When a media element is slaved to a
MediaController
, its playback rate is fixed to that of
the other tracks in the same MediaController
, and any
looping is disabled.
[Constructor] interface MediaController { readonly attribute TimeRanges buffered; readonly attribute TimeRanges seekable; readonly attribute double duration; attribute double currentTime; readonly attribute boolean paused; readonly attribute TimeRanges played; void play(); void pause(); attribute double defaultPlaybackRate; attribute double playbackRate; attribute double volume; attribute boolean muted; attribute Function onemptied; attribute Function onloadedmetadata; attribute Function onloadeddata; attribute Function oncanplay; attribute Function oncanplaythrough; attribute Function onplaying; attribute Function onwaiting; attribute Function ondurationchange; attribute Function ontimeupdate; attribute Function onplay; attribute Function onpause; attribute Function onratechange; attribute Function onvolumechange; };
MediaController
()Returns a new MediaController
object.
controller
[ = controller ]Returns the current MediaController
for the media element, if any; returns null otherwise.
Can be set, to set an explicit MediaController
.
Doing so removes the mediagroup
attribute, if
any.
buffered
Returns a TimeRanges
object that represents the
intersection of the time ranges for which the user agent has all
relevant media data for all the slaved media elements.
seekable
Returns a TimeRanges
object that represents the
intersection of the time ranges into which the user agent can seek
for all the slaved media
elements.
duration
Returns the difference between the earliest playable moment and the latest playable moment (not considering whether the data in question is actually buffered or directly seekable, but not including time in the future for infinite streams). Will return zero if there is no media.
currentTime
[ = value ]Returns the current playback position, in seconds,
as a position between zero time and the current duration
.
Can be set, to seek to the given time.
paused
Returns true if playback is paused; false otherwise. When this attribute is true, any media element slaved to this controller will be stopped.
played
Returns a TimeRanges
object that represents the
union of the time ranges in all the slaved media elements that have been played.
play
()Sets the paused
attribute to false.
pause
()Sets the paused
attribute to true.
defaultPlaybackRate
[ = value ]Returns the default rate of playback.
Can be set, to change the default rate of playback.
This default rate has no direct effect on playback, but if the
user switches to a fast-forward mode, when they return to the
normal playback mode, it is expected that rate of playback (playbackRate
) will
be returned to this default rate.
playbackRate
[ = value ]Returns the current rate of playback.
Can be set, to change the rate of playback.
volume
[ = value ]Returns the current playback volume multiplier, as a number in the range 0.0 to 1.0, where 0.0 is the quietest and 1.0 the loudest.
Can be set, to change the volume multiplier.
Throws an INDEX_SIZE_ERR
if the new value is not
in the range 0.0 .. 1.0.
muted
[ = value ]Returns true if all audio is muted (regardless of other attributes either on the controller or on any media elements slaved to this controller), and false otherwise.
Can be set, to change whether the audio is muted or not.
A media element can have a current media
controller, which is a MediaController
object.
When a media element is created without a mediagroup
attribute, it does
not have a current media controller. (If it is created
with such an attribute, then that attribute initializes the
current media controller, as defined below.)
The slaved media elements of a
MediaController
are the media elements whose current media
controller is that MediaController
. All the
slaved media elements of a MediaController
must use the same clock for their definition of their media
timeline's unit time.
The controller
attribute
on a media element, on getting, must return the
element's current media controller, if any, or null
otherwise. On setting, it must first remove the element's mediagroup
attribute, if any,
and then set the current media controller to the given
value. If the given value is null, the element no longer has a
current media controller; if it is not null, then the
user agent must bring the media element up to speed with its
new media controller.
The MediaController()
constructor, when invoked, must return a newly created
MediaController
object.
The seekable
attribute must return a new static normalized
TimeRanges
object that represents the
intersection of the ranges of the media
resources of the slaved media elements that the
user agent is able to seek to, at the time the attribute is
evaluated.
The buffered
attribute must return a new static normalized
TimeRanges
object that represents the
intersection of the ranges of the media
resources of the slaved media elements that the
user agent has buffered, at the time the attribute is evaluated.
Users agents must accurately determine the ranges available, even
for media streams where this can only be determined by tedious
inspection.
The duration
attribute must return the media controller
duration.
Every 15 to 250ms, or whenever the MediaController
's
media controller duration changes, whichever happens
least often, the user agent must queue a task to
fire a simple event named durationchange
at the MediaController
. If the
MediaController
's media controller
duration decreases such that the media controller
position is greater than the media controller
duration, the user agent must immediately seek the
media controller to media controller
duration.
The currentTime
attribute must return the media controller position on
getting, and on setting must seek the media controller
to the new value.
Every 15 to 250ms, or whenever the MediaController
's
media controller position changes, whichever happens
least often, the user agent must queue a task to
fire a simple event named timeupdate
at the
MediaController
.
When a MediaController
is created it is a
playing media controller. It can be changed into a
paused media controller and back either via the user
agent's user interface (when the element is exposing a user interface to the
user) or by script using the APIs defined in this section
(see below).
The paused
attribute must return true if the MediaController
object is a paused media controller, and false
otherwise.
The played
attribute must return a new static normalized
TimeRanges
object that represents the union of
the ranges of the media
resources of the slaved media elements that the
user agent has so far rendered, at the time the attribute is
evaluated.
When the pause()
method
is invoked, if the MediaController
is a playing
media controller then the user agent must change the
MediaController
into a paused media
controller, queue a task to fire a simple
event named pause
at the
MediaController
, and then report the controller
state of the MediaController
.
When the play()
method is
invoked, if the MediaController
is a paused media
controller, the user agent must change the
MediaController
into a playing media
controller, queue a task to fire a simple
event named play
at the
MediaController
, and then report the controller
state of the MediaController
.
A MediaController
has a media controller
default playback rate and a media controller playback
rate, which must both be set to 1.0 when the
MediaController
object is created.
The defaultPlaybackRate
attribute, on getting, must return the
MediaController
's media controller default
playback rate, and on setting, must set the
MediaController
's media controller default
playback rate to the new value, then queue a
task to fire a simple event named ratechange
at the
MediaController
.
The playbackRate
attribute, on getting, must return the
MediaController
's media controller playback
rate, and on setting, must set the
MediaController
's media controller playback
rate to the new value, then queue a task to
fire a simple event named ratechange
at the
MediaController
.
A MediaController
has a media controller volume
multiplier, which must be set to 1.0 when the
MediaController
object is created, and a media
controller mute override, much must initially be false.
The volume
attribute, on getting, must return the
MediaController
's media controller volume
multiplier, and on setting, if the new value is in the range
0.0 to 1.0 inclusive, must set the MediaController
's
media controller volume multiplier to the new value and
queue a task to fire a simple event named
volumechange
at the MediaController
. If the new value is outside the
range 0.0 to 1.0 inclusive, then, on setting, an
INDEX_SIZE_ERR
exception must be raised instead.
The muted
attribute, on getting, must return the
MediaController
's media controller mute
override, and on setting, must set the
MediaController
's media controller mute
override to the new value and queue a task to
fire a simple event named volumechange
at
the MediaController
.
The media resources of all
the slaved media elements of a
MediaController
have a defined temporal relationship
which provides relative offsets between the zero time of each such
media resource: for media
resources with a timeline offset, their relative
offsets are the difference between their timeline
offset; the zero times of all the media resources without a timeline
offset are not offset from each other (i.e. the origins of
their timelines are cotemporal); and finally, the zero time of the
media resource with the earliest timeline
offset (if any) is not offset from the zero times of the
media resources without a
timeline offset (i.e. the origins of media resources without a timeline
offset are further cotemporal with the earliest defined point
on the timeline of the media resource with the earliest
timeline offset).
The media resource end position of a media resource in a media element is defined as follows: if the media resource has a finite and known duration, the media resource end position is the duration of the media resource's timeline (the last defined position on that timeline); otherwise, the media resource's duration is infinite or unknown, and the media resource end position is the time of the last frame of media data currently available for that media resource.
Each MediaController
also has its own defined
timeline. On this timeline, all the media resources of all the slaved media
elements of the MediaController
are temporally
aligned according to their defined offsets. The media
controller duration of that MediaController
is
the time from the earliest earliest possible position,
relative to this MediaController
timeline, of any of
the media resources of the
slaved media elements of the
MediaController
, to the time of the latest media
resource end position of the media resources of the slaved media
elements of the MediaController
, again relative
to this MediaController
timeline.
Each MediaController
has a media controller
position. This is the time on the
MediaController
's timeline at which the user agent is
trying to play the slaved media elements. When a
MediaController
is created, its media controller
position is initially zero.
When the user agent is to bring a media element up to
speed with its new media controller, it must seek that media element
to the MediaController
's media controller
position relative to the media element's
timeline, discarding any resulting exceptions.
When the user agent is to seek the media controller to a particular new playback position, it must follow these steps:
If the new playback position is less than zero, then set it to zero.
If the new playback position is greater than the media controller duration, then set it to the media controller duration.
Set the media controller position to the new playback position.
Seek each slaved media element to the new playback position relative to the media element timeline, discarding any resulting exceptions.
A MediaController
is a blocked media
controller if the MediaController
is a
paused media controller, or if any of its slaved
media elements are blocked media elements, or if any of its
slaved media elements whose autoplaying
flag is true still have a paused
attribute that is true, or if
all of its slaved media elements have their paused
attribute set to true.
A media element is blocked on its media
controller if the MediaController
is a
blocked media controller, or if its media
controller position is either before the media
resource's earliest possible position relative
to the MediaController
's timeline or after the end of
the media resource relative to the
MediaController
's timeline.
When a MediaController
is
not a blocked media controller and it has at least one
slaved media element
whose Document
is a fully active
Document
, the MediaController
's
media controller position must increase monotonically
at media controller playback rate units of time on the
MediaController
's timeline per unit time of the clock
used by its slaved media elements.
When the zero point on the timeline of a
MediaController
moves relative to the timelines of the
slaved media elements by a time difference ΔT, the MediaController
's
media controller position must be decremented by ΔT.
In some situations, e.g. when playing back a live stream without buffering anything, the media controller position would increase motonically as described above at the same rate as the ΔT described in the previous paragraph decreases it, with the end result that for all intents and purposes, the media controller position would appear to remain constant (probably with the value 0).
A MediaController
has a most recently reported
readiness state, which is a number from 0 to 4 derived from
the numbers used for the media element readyState
attribute, and a
most recently reported playback state, which is either
playing, waiting, or ended.
When a MediaController
is created, its most
recently reported readiness state must be set to 0, and its
most recently reported playback state must be set to
waiting.
When a user agent is required to report the controller
state for a MediaController
, the user agent must
run the following steps:
If the MediaController
has no slaved media
elements, let new readiness state be
0.
Otherwise, let it have the lowest value of the readyState
IDL attributes of
all of its slaved media elements.
If the MediaController
's most recently
reported readiness state is not equal to new
readiness state then queue a task to fire
a simple event at the MediaController
object,
whose name is the event name corresponding to the value of new readiness state given in the table below:
Value of new readiness state | Event name |
---|---|
0 | emptied
|
1 | loadedmetadata
|
2 | loadeddata
|
3 | canplay
|
4 | canplaythrough
|
Let the MediaController
's most recently
reported readiness state be new readiness
state.
Initialize new playback state by setting it to the state given for the first matching condition from the following list:
MediaController
has no slaved
media elementsMediaController
's slaved
media elements have ended playback and the
media controller playback rate is positive or
zeroMediaController
is a blocked media
controllerIf the MediaController
's most recently
reported playback state is not equal to new
playback state then queue a task to fire a
simple event at the MediaController
object,
whose name is playing
if new playback state is playing, ended
if new playback state is ended, and waiting
otherwise.
Let the MediaController
's most recently
reported playback state be new playback
state.
The following are the event handlers that must be
supported, as IDL attributes, by all objects implementing the
MediaController
interface:
Event handler | Event handler event type |
---|---|
onemptied | emptied
|
onloadedmetadata | loadedmetadata
|
onloadeddata | loadeddata
|
oncanplay | canplay
|
oncanplaythrough | canplaythrough
|
onplaying | playing
|
onwaiting | waiting
|
ondurationchange | durationchange
|
ontimeupdate | durationchange
|
onplay | play
|
onpause | pause
|
onratechange | ratechange
|
onvolumechange | volumechange
|
The task source for the tasks listed in this section is the DOM manipulation task source.
The mediagroup
content
attribute on media elements can
be used to link multiple media
elements together by implicitly creating a
MediaController
.
When a media element is created with a mediagroup
attribute, and when
a media element's mediagroup
attribute is set,
changed, or removed, the user agent must run the following
steps:
Let m be the media element in question.
Let m have no current media controller, if it currently has one.
If m's mediagroup
attribute is being
removed, then abort these steps.
If there is another media element whose
Document
is the same as m's
Document
(even if one or both of these elements are
not actually in the
Document
), and which also has a mediagroup
attribute, and
whose mediagroup
attribute has the same value as the new value of m's mediagroup
attribute, then
let controller be that media
element's current media controller.
Otherwise, let controller be a newly created
MediaController
.
Let m's current media controller be controller.
Bring the media element up to speed with its new media controller.
The mediaGroup
IDL
attribute on media elements must
reflect the mediagroup
content
attribute.
Multiple media elements
referencing the same media resource will share a
single network request. This can be used to efficiently play two
(video) tracks from the same media resource in two
different places on the screen. Used with the mediagroup
attribute, these
elements can also be kept synchronised.
In this example, a sign-languge interpreter track from a movie
file is overlaid on the primary video track of that same video file
using two video
elements, some CSS, and an implicit
MediaController
:
<article> <style scoped> div { margin: 1em auto; position: relative; width: 400px; height: 300px; } video { position; absolute; bottom: 0; right: 0; } video:first-child { width: 100%; height: 100%; } video:last-child { width: 30%; } </style> <div> <video src="movie.vid#track=Video&track=English" autoplay controls mediagroup=movie></video> <video src="movie.vid#track=sign" autoplay mediagroup=movie></video> </div> </article>
A media element can have a group of associated text tracks, known as the media element's list of text tracks. The text tracks are sorted as follows:
track
element children of the media
element, in tree order.addTextTrack()
method, in
the order they were added, oldest first.A text track consists of:
This decides how the track is handled by the user agent. The kind is represented by a string. The possible strings are:
subtitles
captions
descriptions
chapters
metadata
The kind of track can
change dynamically, in the case of a text track
corresponding to a track
element.
This is a human-readable string intended to identify the track for the user. In certain cases, the label might be generated automatically.
The label of a track can
change dynamically, in the case of a text track
corresponding to a track
element or in the case of an
automatically-generated label whose value depends on variable
factors such as the user's preferred user interface language.
This is a string (a BCP 47 language tag) representing the language of the text track's cues. [BCP47]
The language of a text
track can change dynamically, in the case of a text
track corresponding to a track
element.
One of the following:
Indicates that the text track is known to exist (e.g. it has
been declared with a track
element), but its cues
have not been obtained.
Indicates that the text track is loading and there have been no fatal errors encountered so far. Further cues might still be added to the track.
Indicates that the text track has been loaded with no fatal
errors. No new cues will be added to the track except if the
text track corresponds to a
MutableTextTrack
object.
Indicates that the text track was enabled, but when the user agent attempted to obtain it, this failed in some way (e.g. URL could not be resolved, network error, unknown text track format). Some or all of the cues are likely missing and will not be obtained.
The readiness state of a text track changes dynamically as the track is obtained.
One of the following:
Indicates that the text track is not active. Other than for the purposes of exposing the track in the DOM, the user agent is ignoring the text track. No cues are active, no events are fired, and the user agent will not attempt to obtain the track's cues.
Indicates that the text track is active, but that the user agent is not actively displaying the cues. If no attempt has yet been made to obtain the track's cues, the user agent will perform such an attempt momentarily. The user agent is maintaining a list of which cues are active, and events are being fired accordingly.
Indicates that the text track is active. If no attempt has
yet been made to obtain the track's cues, the user agent will
perform such an attempt momentarily. The user agent is
maintaining a list of which cues are active, and events are
being fired accordingly. In addition, for text tracks whose
kind is subtitles
or captions
, the cues
are being displayed over the video as appropriate; for text
tracks whose kind is descriptions
,
the user agent is making the cues available to the user in a
non-visual fashion; and for text tracks whose kind is chapters
, the user
agent is making available to the user a mechanism by which the
user can navigate to any point in the media
resource by selecting a cue.
The showing by
default state is used in conjunction with the default
attribute on
track
elements to indicate that the text track was
enabled due to that attribute. This allows the user agent to
override the state if a later track is discovered that is more
appropriate per the user's preferences.
A list of text track cues, along with rules for updating the text track rendering.
The list of cues of a
text track can change dynamically, either because the
text track has not yet been loaded or is still loading, or because the text
track corresponds to a MutableTextTrack
object, whose API allows individual cues can be added or removed
dynamically.
Each text track has a corresponding
TextTrack
object.
The text tracks of a media element are ready if all the text tracks whose mode was not in the disabled state when the element's resource selection algorithm last started now have a text track readiness state of loaded or failed to load.
A text track cue is the unit of time-sensitive data in a text track, corresponding for instance for subtitles and captions to the text that appears at a particular time and disappears at another time.
Each text track cue consists of:
An arbitrary string.
A time, in seconds and fractions of a second, at which the cue becomes relevant.
A time, in seconds and fractions of a second, at which the cue stops being relevant.
A boolean indicating whether playback of the media resource is to pause when the cue stops being relevant.
A writing direction, either horizontal (a line extends horizontally and is positioned vertically, with consecutive lines displayed below each other), vertical growing left (a line extends vertically and is positioned horizontally, with consecutive lines displayed to the left of each other), or vertical growing right (a line extends vertically and is positioned horizontally, with consecutive lines displayed to the right of each other).
A number giving the size of the box within which the text of each line of the cue is to be aligned, to be interpreted as a percentage of the video, as defined by the writing direction.
The raw text of the cue, and rules for its interpretation, allowing the text to be rendered and converted to a DOM fragment.
A text track cue is immutable.
Each text track cue has a corresponding
TextTrackCue
object, and can be associated with a
particular text track. Once a text track
cue is associated with a particular text track,
the association is permanent.
In addition, each text track cue has two pieces of dynamic information:
This flag must be initially unset. The flag is used to ensure events are fired appropriately when the cue becomes active or inactive, and to make sure the right cues are rendered.
The user agent must synchronously unset this flag whenever the
text track cue is removed from its text
track's text track list of cues; whenever the
text track itself is removed from its media
element's list of text tracks or has its
text track mode changed to disabled; and whenever the media
element's readyState
is changed back to
HAVE_NOTHING
. When the
flag is unset in this way for one or more cues in text tracks that were showing or showing by default prior to the
relevant incident, the user agent must, after having unset the
flag for all the affected cues, apply the rules for updating
the text track rendering of those text tracks.
This is used as part of the rendering model, to keep cues in a consistent position. It must initially be empty. Whenever the text track cue active flag is unset, the user agent must empty the text track cue display state.
The text track cues of a media element's text tracks are ordered relative to each other in the text track cue order, which is determined as follows: first group the cues by their text track, with the groups being sorted in the same order as their text tracks appear in the media element's list of text tracks; then, within each group, cues must be sorted by their start time, earliest first; then, any cues with the same start time must be sorted by their end time, earliest first; and finally, any cues with identical end times must be sorted in the order they were created (so e.g. for cues from a WebVTT file, that would be the order in which the cues were listed in the file).
A media-resource-specific text track is a text track that corresponds to data found in the media resource.
Rules for processing and rendering such data are defined by the relevant specifications, e.g. the specification of the video format if the media resource is a video.
When a media resource contains data that the user agent recognises and supports as being equivalent to a text track, the user agent runs the steps to expose a media-resource-specific text track with the relevant data, as follows:
Associate the relevant data with a new text
track and its corresponding new TextTrack
object. The text track is a
media-resource-specific text track.
Set the new text track's kind, label, and language based on the semantics of the relevant data, as defined by the relevant specification.
Populate the new text track's list of cues with the cues parsed so far, folllowing the guidelines for exposing cues, and begin updating it dynamically as necessary.
Set the new text track's readiness state to the value that most correctly describes the current state, and begin updating it dynamically as necessary.
For example, if the relevant data in the media resource has been fully parsed and completely describes the cues, then the text track would be loaded. On the other hand, if the data for the cues is interleaved with the media data, and the media resource as a whole is still being downloaded, then the loading state might be more accurate.
Set the new text track's mode to the mode consistent with the user's preferences and the requirements of the relevant specification for the data.
Leave the text track list of cues empty, and associate with it the rules for updating the text track rendering appropriate for the format in question.
Add the new text track to the media element's list of text tracks.
When a media element is to forget the media element's media-resource-specific text tracks, the user agent must remove from the media element's list of text tracks all the media-resource-specific text tracks.
When a track
element is created, it must be
associated with a new text track (with its value set
as defined below) and its corresponding new TextTrack
object.
The text track kind is determined from the state of
the element's kind
attribute
according to the following table; for a state given in a cell of the
first column, the kind is the
string given in the second column:
State | String |
---|---|
Subtitles | subtitles
|
Captions | captions
|
Descriptions | descriptions
|
Chapters | chapters
|
Metadata | metadata
|
The text track label is the element's track label.
The text track language is the element's track language, if any, or the empty string otherwise.
As the kind
, label
, and srclang
attributes are set,
changed, or removed, the text track must update
accordingly, as per the definitions above.
Changes to the track URL are handled in the algorithm below.
The text track list of cues is initially empty. It is dynamically modified when the referenced file is parsed. Associated with the list are the rules for updating the text track rendering appropriate for the format in question; for WebVTT, this is the rules for updating the display of WebVTT text tracks.
When a track
element's parent element changes and
the new parent is a media element, then the user agent
must add the track
element's corresponding text
track to the media element's list of text
tracks.
When a track
element's parent element changes and
the old parent was a media element, then the user agent
must remove the track
element's corresponding
text track from the media element's
list of text tracks.
When a text track corresponding to a
track
element is added to a media
element's list of text tracks, the user agent
must set the text track mode appropriately, as
determined by the following conditions:
subtitles
or captions
and the user
has indicated an interest in having a track with this text
track kind, text track language, and
text track label enabled, and there is no other
text track in the media element's
list of text tracks with a text track
kind of either subtitles
or captions
whose
text track mode is showingdescriptions
and
the user has indicated an interest in having text descriptions with
this text track language and text track
label enabled, and there is no other text
track in the media element's list of
text tracks with a text track kind of descriptions
whose
text track mode is showingchapters
and the
text track language is one that the user agent has
reason to believe is appropriate for the user, and there is no
other text track in the media element's
list of text tracks with a text track
kind of chapters
whose
text track mode is showingLet the text track mode be showing.
If there is a text track in the media element's list of text tracks whose text track mode is showing by default, the user agent must furthermore change that text track's text track mode to hidden.
track
element has a default
attribute specified, and
there is no other text track in the media
element's list of text tracks whose
text track mode is showing or showing by defaultLet the text track mode be showing by default.
Let the text track mode be disabled.
When a text track corresponding to a
track
element is created with text track
mode set to hidden,
showing, or showing by default,
and when a text track corresponding to a
track
element is created with text track
mode set to disabled and subsequently changes its text
track mode to hidden,
showing, or showing by default for
the first time, the user agent must immediately and synchronously
run the following algorithm. This algorithm interacts closely with
the event loop mechanism; in particular, it has a
synchronous section (which is triggered as part of the
event loop algorithm). The step in that section is
marked with ⌛.
Set the text track readiness state to loading.
Asynchronously run the remaining steps, while continuing with whatever task was responsible for creating the text track or changing the text track mode.
Download: If URL is not the empty
string, and its origin is the same as the media
element's Document
's origin, then
fetch URL, from the media
element's Document
's origin, with
the force same-origin flag set.
The tasks queued by the fetching algorithm on the networking task source to process the data as it is being fetched must examine the resource's Content Type metadata, once it is available, if it ever is. If no Content Type metadata is ever available, or if the type is not recognised as a text track format, then the resource's format must be assumed to be unsupported (this causes the load to fail, as described below). If a type is obtained, and represents a supported text track format, then the resource's data must be passed to the appropriate parser as it is received, with the text track list of cues being used for that parser's output.
If the fetching algorithm fails for
any reason (network error, the server returns an error code, a
cross-origin check fails, etc), or if URL is
the empty string or has the wrong origin as
determined by the condition at the start of this step, or if the
fetched resource is not in a supported format, then queue a
task to first change the text track readiness
state to failed to
load and then fire a simple event named error
at the track
element; and then, once that task is queued, move on to the step below labeled
monitoring.
If the fetching algorithm does not
fail, then, when it completes, queue a task to first
change the text track readiness state to loaded and then fire a
simple event named load
at
the track
element; and then, once that task is queued, move on to the step below labeled
monitoring.
If, while the fetching algorithm is active, either:
...then the user agent must run the following steps:
Abort the fetching algorithm.
Queue a task to fire a simple
event named abort
at
the track
element.
Let URL be the new track URL.
Jump back to the top of the step labeled download.
Until one of the above circumstances occurs, the user agent must remain on this step.
Monitoring: Wait until the track URL is no longer equal to URL, at the same time as the text track mode is set to hidden, showing, or showing by default.
Wait until the text track readiness state is no longer set to loading.
Await a stable state. The synchronous section consists of the following step. (The step in the synchronous section is marked with ⌛.)
⌛ Set the text track readiness state to loading.
End the synchronous section, continuing the remaining steps asynchronously.
Jump to the step labeled download.
textTracks
. length
Returns the number of text tracks associated with the media element (e.g. from track
elements). This is the number of text tracks in the media element's list of text tracks.
textTracks[
n ]
Returns the TextTrack
object representing the nth text track in the media element's list of text tracks.
track
Returns the TextTrack
object representing the track
element's text track.
The textTracks
attribute of media elements must
return an array host object
for objects of type TextTrack
that is fixed
length and read only. The same object must be returned
each time the attribute is accessed. [WEBIDL]
The array must contain the TextTrack
objects of the
text tracks in the media
element's list of text tracks, in the same
order as in the list of text tracks.
interface TextTrack { readonly attribute DOMString kind; readonly attribute DOMString label; readonly attribute DOMString language; const unsigned short NONE = 0; const unsigned short LOADING = 1; const unsigned short LOADED = 2; const unsigned short ERROR = 3; readonly attribute unsigned short readyState; attribute Function onload; attribute Function onerror; const unsigned short OFF = 0; const unsigned short HIDDEN = 1; const unsigned short SHOWING = 2; attribute unsigned short mode; readonly attribute TextTrackCueList cues; readonly attribute TextTrackCueList activeCues; attribute Function oncuechange; }; TextTrack implements EventTarget;
kind
Returns the text track kind string.
label
Returns the text track label.
language
Returns the text track language string.
readyState
Returns the text track readiness state, represented by a number from the following list:
TextTrack
. NONE
(0)The text track not loaded state.
TextTrack
. LOADING
(1)The text track loading state.
TextTrack
. LOADED
(2)The text track loaded state.
TextTrack
. ERROR
(3)The text track failed to load state.
mode
Returns the text track mode, represented by a number from the following list:
TextTrack
. OFF
(0)The text track disabled mode.
TextTrack
. HIDDEN
(1)The text track hidden mode.
TextTrack
. SHOWING
(2)The text track showing and showing by default modes.
Can be set, to change the mode.
cues
Returns the text track list of cues, as a TextTrackCueList
object.
activeCues
Returns the text track cues from the text track list of cues that are currently active (i.e. that start before the current playback position and end after it), as a TextTrackCueList
object.
The kind
attribute must return the text track kind of the
text track that the TextTrack
object
represents.
The label
attribute must return the text track label of the
text track that the TextTrack
object
represents.
The language
attribute must return the text track language of the
text track that the TextTrack
object
represents.
The readyState
attribute must return the numeric value corresponding to the
text track readiness state of the text
track that the TextTrack
object represents, as
defined by the following list:
NONE
(numeric value 0)LOADING
(numeric value 1)LOADED
(numeric value 2)ERROR
(numeric value 3)The mode
attribute, on getting, must return the numeric value corresponding
to the text track mode of the text track
that the TextTrack
object represents, as defined by
the following list:
OFF
(numeric value 0)HIDDEN
(numeric value 1)SHOWING
(numeric value 2)On setting, if the new value is not either 0, 1, or 2, the user
agent must throw an INVALID_ACCESS_ERR
exception. Otherwise, if the new value isn't equal to what the
attribute would currently return, the new value must be processed as
follows:
Set the text track mode of the text
track that the TextTrack
object represents to
the text track disabled mode.
Set the text track mode of the text
track that the TextTrack
object represents to
the text track hidden mode.
Set the text track mode of the text
track that the TextTrack
object represents to
the text track showing mode.
If the mode had been showing by default, this will change it
to showing, even though
the value of mode
would
appear not to change.
If the text track mode of the text
track that the TextTrack
object represents is
not the text track disabled mode, then the cues
attribute must
return a live TextTrackCueList
object
that represents the subset of the text track list of
cues of the text track that the
TextTrack
object represents whose start times occur before the
earliest possible position when the script started, in
text track cue order. Otherwise, it must return
null. When an object is returned, the same object must be returned
each time.
The earliest possible position when the script started is whatever the earliest possible position was the last time the event loop reached step 1.
If the text track mode of the text
track that the TextTrack
object represents is
not the text track disabled mode, then the activeCues
attribute must return a live
TextTrackCueList
object that represents the subset of
the text track list of cues of the text
track that the TextTrack
object represents
whose active flag was set when the script started, in
text track cue order. Otherwise, it must return
null. When an object is returned, the same object must be returned
each time.
A text track cue's active flag was set when the script started if its text track cue active flag was set the last time the event loop reached step 1.
interface MutableTextTrack : TextTrack { void addCue(in TextTrackCue cue); void removeCue(in TextTrackCue cue); };
addTextTrack
( kind [, label [, language ] ] )Creates and returns a new MutableTextTrack
object, which is also added to the media element's list of text tracks.
addCue
( cue )Adds the given cue to mutableTextTrack's text track list of cues.
Raises an exception if the argument is null, associated with another text track, or already in the list of cues.
removeCue
( cue )Removes the given cue from mutableTextTrack's text track list of cues.
Raises an exception if the argument is null, associated with another text track, or not in the list of cues.
The addTextTrack(kind, label, language)
method of media elements, when invoked, must run the following
steps:
If kind is not one of the following
strings, then throw a SYNTAX_ERR
exception and abort
these steps:
If the label argument was omitted, let label be the empty string.
If the language argument was omitted, let language be the empty string.
Create a new text track, and set its text track kind to kind, its text track label to label, its text track language to language, its text track readiness state to the text track loaded state, its text track mode to the text track hidden mode, and its text track list of cues to an empty list.
Add the new text track to the media element's list of text tracks.
The addCue(cue)
method of
MutableTextTrack
objects, when invoked, must run the
following steps:
If cue is null, then throw an
INVALID_ACCESS_ERR
exception and abort these
steps.
If the given cue is already associated
with a text track other than the method's
MutableTextTrack
object's text track,
then throw an INVALID_STATE_ERR
exception and abort
these steps.
Associate cue with the method's
MutableTextTrack
object's text track,
if it is not currently associated with a text
track.
If the given cue is already listed in
the method's MutableTextTrack
object's text
track's text track list of cues, then throw an
INVALID_STATE_ERR
exception.
Add cue to the method's
MutableTextTrack
object's text track's
text track list of cues.
The removeCue(cue)
method of
MutableTextTrack
objects, when invoked, must run the
following steps:
If cue is null, then throw an
INVALID_ACCESS_ERR
exception and abort these
steps.
If the given cue is not associated with
the method's MutableTextTrack
object's text
track, then throw an INVALID_STATE_ERR
exception.
If the given cue is not currently listed
in the method's MutableTextTrack
object's text
track's text track list of cues, then throw a
NOT_FOUND_ERR
exception.
Remove cue from the method's
MutableTextTrack
object's text track's
text track list of cues.
In this example, an audio
element is used to play a
specific sound-effect from a sound file containing many sound
effects. A cue is used to pause the audio, so that it ends exactly
at the end of the clip, even if the browser is busy running some
script. If the page had relied on script to pause the audio, then
the start of the next clip might be heard if the browser was not
able to run the script at the exact time specified.
var sfx = new Audio('sfx.wav'); var sounds = a.addTextTrack('metadata'); // add sounds we care about sounds.addCue(new TextTrackCue('dog bark', 12.783, 13.612, '', '', '', true)); sounds.addCue(new TextTrackCue('kitten mew', 13.612, 15.091, '', '', '', true)); function playSound(id) { sfx.currentTime = sounds.getCueById(id).startTime; sfx.play(); } sfx.oncanplaythrough = function () { playSound('dog bark'); } window.onbeforeunload = function () { playSound('kitten mew'); return 'Are you sure you want to leave this awesome page?'; }
interface TextTrackCueList { readonly attribute unsigned long length; getter TextTrackCue (in unsigned long index); TextTrackCue getCueById(in DOMString id); };
length
Returns the number of cues in the list.
Returns the text track cue with index index in the list. The cues are sorted in text track cue order.
getCueById
( id )Returns the first text track cue (in text track cue order) with text track cue identifier id.
Returns null if none of the cues have the given identifier or if the argument is the empty string.
A TextTrackCueList
object represents a dynamically
updating list of text track
cues in a given order.
The length
attribute must return the number of cues in the list represented by the
TextTrackCueList
object.
The supported property indicies of a
TextTrackCueList
object at any instant are the numbers
from zero to the number of cues
in the list represented by the TextTrackCueList
object
minus one, if any. If there are no cues in the list, there are no supported property
indicies.
To determine the value of an indexed property for a
given index index, the user agent must return
the indexth text track cue in the
list represented by the TextTrackCueList
object.
The getCueById(id)
method, when called with an argument
other than the empty string, must return the first text track
cue in the list represented by the
TextTrackCueList
object whose text track cue
identifier is id, if any, or null
otherwise. If the argument is the empty string, then the method must
return null.
interface TextTrackCue { readonly attribute TextTrack track; readonly attribute DOMString id; readonly attribute double startTime; readonly attribute double endTime; readonly attribute boolean pauseOnExit; DOMString getCueAsSource(); DocumentFragment getCueAsHTML(); attribute Function onenter; attribute Function onexit; }; TextTrackCue implements EventTarget;
Returns the TextTrack
object to which this
text track cue belongs, if any, or null
otherwise.
Returns the text track cue identifier.
Returns the text track cue start time, in seconds.
Returns the text track cue end time, in seconds.
Returns true if the text track cue pause-on-exit flag is set, false otherwise.
Returns the text track cue text in raw unparsed form.
Returns the text track cue text as a DocumentFragment
of HTML elements and other DOM nodes.
The track
attribute must return the TextTrack
object of the
text track with which the text track cue
that the TextTrackCue
object represents is associated,
if any; or null otherwise.
The id
attribute must return the text track cue identifier of
the text track cue that the TextTrackCue
object represents.
The startTime
attribute must return the text track cue start time of
the text track cue that the TextTrackCue
object represents, in seconds.
The endTime
attribute must return the text track cue end time of
the text track cue that the TextTrackCue
object represents, in seconds.
The pauseOnExit
attribute must return true if the text track cue
pause-on-exit flag of the text track cue that
the TextTrackCue
object represents is set; or false
otherwise.
The direction
attribute must return the text track cue writing
direction of the text track cue that the
TextTrackCue
object represents.
The getCueAsSource()
method must return the raw text track cue text.
The getCueAsHTML()
method must convert the text track cue text to a
DocumentFragment
for the media element's
Document
, using the appropriate rules for doing
so.
The following are the event handlers that must be
supported, as IDL attributes, by all objects implementing the
TextTrack
interface:
Event handler | Event handler event type |
---|---|
onload | load
|
onerror | error
|
oncuechange | cuechange
|
The following are the event handlers that must be
supported, as IDL attributes, by all objects implementing the
TextTrackCue
interface:
Event handler | Event handler event type |
---|---|
onenter | enter
|
onexit | exit
|
The controls
attribute is a boolean attribute. If present, it
indicates that the author has not provided a scripted controller and
would like the user agent to provide its own set of controls.
If the attribute is present, or if scripting is disabled for the media element, then the user agent should expose a user interface to the user. This user interface should include features to begin playback, pause playback, seek to an arbitrary position in the content (if the content supports arbitrary seeking), change the volume, change the display of closed captions or embedded sign-language tracks, select different audio tracks or turn on audio descriptions, and show the media content in manners more suitable to the user (e.g. full-screen video or in an independent resizable window). Other controls may also be made available.
If the media element has a current media
controller, then the user agent should expose audio tracks
from all the slaved media elements (although avoiding
duplicates if the same media resource is being used
several times). If a media resource's audio track
exposed in this way has no known name, and it is the only audio
track for a particular media element, the user agent
should use the element's title
attribute, if any, as the name (or as part of the name) of that
track.
Even when the attribute is absent, however, user agents may provide controls to affect playback of the media resource (e.g. play, pause, seeking, and volume controls), but such features should not interfere with the page's normal rendering. For example, such features could be exposed in the media element's context menu.
Where possible (specifically, for starting, stopping, pausing, and unpausing playback, for seeking, for changing the rate of playback, for fast-forwarding or rewinding, for listing, enabling, and disabling text tracks, and for muting or changing the volume of the audio), user interface features exposed by the user agent must be implemented in terms of the DOM API described above, so that, e.g., all the same events fire.
When a media element has a current media
controller, the user agent's user interface for pausing and
unpausing playback, for seeking, for changing the rate of playback,
for fast-forwarding or rewinding, and for muting or changing the
volume of audio of the entire group must be implemented in terms of
the MediaController
API exposed on that current
media controller.
The "play" function in the user agent's interface must set the
playbackRate
attribute to the value of the
defaultPlaybackRate
attribute before invoking
the play()
method.
When a media element has a current media
controller, the attributes and method with those names on
that MediaController
object must be used. Otherwise,
the attributes and method with those names on the media
element itself must be used.
Features such as fast-forward or rewind must be implemented by
only changing the playbackRate
attribute (and
not the defaultPlaybackRate
attribute).
Again, when a media element has a current media
controller, the attributes with those names on that
MediaController
object must be used; otherwise, the
attributes with those names on the media element itself
must be used.
When a media element has a current media
controller, and all the slaved media elements of
that MediaController
are paused, the user agent should
unpause all the slaved media elements when the user
invokes a user agent interface control for beginning playback.
When a media element has a current media
controller, seeking must be implemented in terms of the seek()
method on that
MediaController
object. Otherwise, the user agent must
directly seek to the requested
position in the media element's media
timeline.
When a media element has a current media
controller, user agents may additionally provide the user
with controls that directly manipulate an individual media
element without affecting the MediaController
,
but such features are considered relatively advanced and unlikely to
be useful to most users.
For the purposes of listing chapters in the media
resource, only text tracks
in the media element's list of text
tracks showing or
showing by
default and whose text track kind is chapters
should be used.
Each cue in such a text
track represents a chapter starting at the cue's start time. The name of
the chapter is the text track cue text, interpreted
literally.
The controls
IDL attribute must reflect the content attribute of the
same name.
volume
[ = value ]Returns the current playback volume, as a number in the range 0.0 to 1.0, where 0.0 is the quietest and 1.0 the loudest.
Can be set, to change the volume.
Throws an INDEX_SIZE_ERR
if the new value is not
in the range 0.0 .. 1.0.
muted
[ = value ]Returns true if audio is muted, overriding the volume
attribute, and false if the
volume
attribute is being
honored.
Can be set, to change whether the audio is muted or not.
The volume
attribute must return the playback volume of any audio portions of
the media element, in the range 0.0 (silent) to 1.0
(loudest). Initially, the volume must be 1.0, but user agents may
remember the last set value across sessions, on a per-site basis or
otherwise, so the volume may start at other values. On setting, if
the new value is in the range 0.0 to 1.0 inclusive, the attribute
must be set to the new value. If the new value is outside the range
0.0 to 1.0 inclusive, then, on setting, an
INDEX_SIZE_ERR
exception must be raised instead.
The muted
attribute must return true if the audio channels are muted and false
otherwise. Initially, the audio channels should not be muted
(false), but user agents may remember the last set value across
sessions, on a per-site basis or otherwise, so the muted state may
start as muted (true). On setting, the attribute must be set to the
new value.
Whenever either the muted
or
volume
attributes are changed,
the user agent must queue a task to fire a simple
event named volumechange
at the media
element.
An element's effective media volume is determined as follows:
If the element's muted
attribute is true, the element's effective media
volume is zero. Abort these steps.
If the element has a current media controller
and that MediaController
object's media
controller mute override is true, the element's
effective media volume is zero. Abort these
steps.
Let volume be the value of the element's
volume
attribute.
If the element has a current media controller,
multiply volume by that
MediaController
object's media controller volume
multiplier.
The element's effective media volume is volume, interpreted relative to the range 0.0 to 1.0, with 0.0 being silent, and 1.0 being the loudest setting, values in between increasing in loudness. The range need not be linear. The loudest setting may be lower than the system's loudest possible setting; for example the user could have set a maximum volume.
The muted
attribute on the video
element controls the default
state of the audio channel of the media resource,
potentially overriding user preferences.
When a media element is created, if it has a muted
attribute specified, the user
agent must set the muted
IDL
attribute to true, overriding any user preference.
The defaultMuted
IDL
attribute must reflect the muted
content attribute.
This attribute has no dynamic effect (it only controls the default state of the element).
This video (an advertisment) autoplays, but to avoid annoying users, it does so without sound, and allows the user to turn the sound on.
<video src="adverts.cgi?kind=video" controls autoplay loop muted></video>
Objects implementing the TimeRanges
interface
represent a list of ranges (periods) of time.
interface TimeRanges { readonly attribute unsigned long length; double start(in unsigned long index); double end(in unsigned long index); };
length
Returns the number of ranges in the object.
start
(index)Returns the time for the start of the range with the given index.
Throws an INDEX_SIZE_ERR
if the index is out of range.
end
(index)Returns the time for the end of the range with the given index.
Throws an INDEX_SIZE_ERR
if the index is out of range.
The length
IDL attribute must return the number of ranges represented by the object.
The start(index)
method must return the position
of the start of the indexth range represented by
the object, in seconds measured from the start of the timeline that
the object covers.
The end(index)
method must return the position
of the end of the indexth range represented by
the object, in seconds measured from the start of the timeline that
the object covers.
These methods must raise INDEX_SIZE_ERR
exceptions
if called with an index argument greater than or
equal to the number of ranges represented by the object.
When a TimeRanges
object is said to be a
normalized TimeRanges
object, the ranges it
represents must obey the following criteria:
In other words, the ranges in such an object are ordered, don't overlap, aren't empty, and don't touch (adjacent ranges are folded into one bigger range).
The timelines used by the objects returned by the buffered
, seekable
and played
IDL attributes of media elements must be that element's
media timeline.
This section is non-normative.
The following events fire on media elements as part of the processing model described above:
Event name | Interface | Dispatched when... | Preconditions |
---|---|---|---|
loadstart
| Event
| The user agent begins looking for media data, as part of the resource selection algorithm. | networkState equals NETWORK_LOADING
|
progress
| Event
| The user agent is fetching media data. | networkState equals NETWORK_LOADING
|
suspend
| Event
| The user agent is intentionally not currently fetching media data, but does not have the entire media resource downloaded. | networkState equals NETWORK_IDLE
|
abort
| Event
| The user agent stops fetching the media data before it is completely downloaded, but not due to an error. | error is an object with the code MEDIA_ERR_ABORTED .
networkState equals either NETWORK_EMPTY or NETWORK_IDLE , depending on when the download was aborted.
|
error
| Event
| An error occurs while fetching the media data. | error is an object with the code MEDIA_ERR_NETWORK or higher.
networkState equals either NETWORK_EMPTY or NETWORK_IDLE , depending on when the download was aborted.
|
emptied
| Event
| A media element whose networkState was previously not in the NETWORK_EMPTY state has just switched to that state (either because of a fatal error during load that's about to be reported, or because the load() method was invoked while the resource selection algorithm was already running).
| networkState is NETWORK_EMPTY ; all the IDL attributes are in their initial states.
|
stalled
| Event
| The user agent is trying to fetch media data, but data is unexpectedly not forthcoming. | networkState is NETWORK_LOADING .
|
loadedmetadata
| Event
| The user agent has just determined the duration and dimensions of the media resource and the text tracks are ready. | readyState is newly equal to HAVE_METADATA or greater for the first time.
|
loadeddata
| Event
| The user agent can render the media data at the current playback position for the first time. | readyState newly increased to HAVE_CURRENT_DATA or greater for the first time.
|
canplay
| Event
| The user agent can resume playback of the media data, but estimates that if playback were to be started now, the media resource could not be rendered at the current playback rate up to its end without having to stop for further buffering of content. | readyState newly increased to HAVE_FUTURE_DATA or greater.
|
canplaythrough
| Event
| The user agent estimates that if playback were to be started now, the media resource could be rendered at the current playback rate all the way to its end without having to stop for further buffering. | readyState is newly equal to HAVE_ENOUGH_DATA .
|
playing
| Event
| Playback is ready to start after having been paused or delayed due to lack of media data. | readyState is newly equal to or greater than HAVE_FUTURE_DATA and paused is false, or paused is newly false and readyState is equal to or greater than HAVE_FUTURE_DATA . Even if this event fires, the element might still not be potentially playing, e.g. if
the element is blocked on its media controller (e.g. because the current media controller is paused, or another slaved media element is stalled somehow, or because the media resource has no data corresponding to the media controller position), or
the element is paused for user interaction.
|
waiting
| Event
| Playback has stopped because the next frame is not available, but the user agent expects that frame to become available in due course. | readyState is equal to or less than HAVE_CURRENT_DATA , and paused is false. Either seeking is true, or the current playback position is not contained in any of the ranges in buffered . It is possible for playback to stop for other reasons without paused being false, but those reasons do not fire this event (and when those situations resolve, a separate playing event is not fired either): e.g.
the element is newly blocked on its media controller, or
playback ended, or playback stopped due to errors, or the element has paused for user interaction.
|
seeking
| Event
| The seeking IDL attribute changed to true and the seek operation is taking long enough that the user agent has time to fire the event.
| |
seeked
| Event
| The seeking IDL attribute changed to false.
| |
ended
| Event
| Playback has stopped because the end of the media resource was reached. | currentTime equals the end of the media resource; ended is true.
|
durationchange
| Event
| The duration attribute has just been updated.
| |
timeupdate
| Event
| The current playback position changed as part of normal playback or in an especially interesting way, for example discontinuously. | |
play
| Event
| The element is no longer paused. Fired after the play() method has returned, or when the autoplay attribute has caused playback to begin.
| paused is newly false.
|
pause
| Event
| The element has been paused. Fired after the pause() method has returned.
| paused is newly true.
|
ratechange
| Event
| Either the defaultPlaybackRate or the playbackRate attribute has just been updated.
| |
volumechange
| Event
| Either the volume attribute or the muted attribute has changed. Fired after the relevant attribute's setter has returned.
|
The following events fire on MediaController
objects:
Event name | Interface | Dispatched when... |
---|---|---|
emptied
| Event
| All the slaved media elements newly have readyState set to HAVE_NOTHING or greater, or there are no longer any slaved media elements.
|
loadedmetadata
| Event
| All the slaved media elements newly have readyState set to HAVE_METADATA or greater.
|
loadeddata
| Event
| All the slaved media elements newly have readyState set to HAVE_CURRENT_DATA or greater.
|
canplay
| Event
| All the slaved media elements newly have readyState set to HAVE_FUTURE_DATA or greater.
|
canplaythrough
| Event
| All the slaved media elements newly have readyState set to HAVE_ENOUGH_DATA or greater.
|
playing
| Event
| The MediaController is no longer a blocked media controller.
|
waiting
| Event
| The MediaController is now a blocked media controller.
|
ended
| Event
| All the slaved media elements have newly ended playback. |
durationchange
| Event
| The duration attribute has just been updated.
|
timeupdate
| Event
| The media controller position changed. |
play
| Event
| The paused attribute is newly false.
|
pause
| Event
| The paused attribute is newly true.
|
ratechange
| Event
| Either the defaultPlaybackRate attribute or the playbackRate attribute has just been updated.
|
volumechange
| Event
| Either the volume attribute or the muted attribute has just been updated.
|
The main security and privacy implications of the
video
and audio
elements come from the
ability to embed media cross-origin. There are two directions that
threats can flow: from hostile content to a victim page, and from a
hostile page to victim content.
If a victim page embeds hostile content, the threat is that the
content might contain scripted code that attempts to interact with
the Document
that embeds the content. To avoid this,
user agents must ensure that there is no access from the content to
the embedding page. In the case of media content that uses DOM
concepts, the embedded content must be treated as if it was in its
own unrelated top-level browsing context.
For instance, if an SVG animation was embedded in
a video
element, the user agent would not give it
access to the DOM of the outer page. From the perspective of scripts
in the SVG resource, the SVG file would appear to be in a lone
top-level browsing context with no parent.
If a hostile page embeds victim content, the threat is that the
embedding page could obtain information from the content that it
would not otherwise have access to. The API does expose some
information: the existence of the media, its type, its duration, its
size, and the performance characteristics of its host. Such
information is already potentially problematic, but in practice the
same information can more or less be obtained using the
img
element, and so it has been deemed acceptable.
However, significantly more sensitive information could be obtained if the user agent further exposes metadata within the content such as subtitles or chapter titles. This version of the API does not expose such information. Future extensions to this API will likely reuse a mechanism such as CORS to check that the embedded content's site has opted in to exposing such information. [CORS]
An attacker could trick a user running within a corporate network into visiting a site that attempts to load a video from a previously leaked location on the corporation's intranet. If such a video included confidential plans for a new product, then being able to read the subtitles would present a confidentiality breach.
This section is non-normative.
Playing audio and video resources on small devices such as
set-top boxes or mobile phones is often constrained by limited
hardware resources in the device. For example, a device might only
support three simultaneous videos. For this reason, it is a good
practice to release resources held by media elements when they are done playing, either by
being very careful about removing all references to the element and
allowing it to be garbage collected, or, even better, by removing
the element's src
attribute and
any source
element descendants, and invoking the
element's load()
method.
Similarly, when the playback rate is not exactly 1.0, hardware, software, or format limitations can cause video frames to be dropped and audio to be choppy or muted.
This section is non-normative.
How accurately various aspects of the media element API are implemented is considered a quality-of-implementation issue.
For example, when implementing the buffered
attribute, how precise
an implementation reports the ranges that have been buffered depends
on how carefully the user agent inspects the data. Since the API
reports ranges as times, but the data is obtained in byte streams, a
user agent receiving a variable-bit-rate stream might only be able
to determine precise times by actually decoding all of the data.
User agents aren't required to do this, however; they can instead
return estimates (e.g. based on the average bit rate seen so far)
which get revised as more information becomes available.
As a general rule, user agents are urged to be conservative rather than optimistic. For example, it would be bad to report that everything had been buffered when it had not.
Another quality-of-implementation issue would be playing a video backwards when the codec is designed only for forward playback (e.g. there aren't many key frames, and they are far apart, and the intervening frames only have deltas from the previous frame). User agents could do a poor job, e.g. only showing key frames; however, better implementations would do more work and thus do a better job, e.g. actually decoding parts of the video forwards, storing the complete frames, and then playing the frames backwards.
Similarly, while implementations are allowed to drop buffered data at any time (there is no requirement that a user agent keep all the media data obtained for the lifetime of the media element), it is again a quality of implementation issue: user agents with sufficient resources to keep all the data around are encouraged to do so, as this allows for a better user experience. For example, if the user is watching a live stream, a user agent could allow the user only to view the live video; however, a better user agent would buffer everything and allow the user to seek through the earlier material, pause it, play it forwards and backwards, etc.
When multiple tracks are synchronised with a
MediaController
, it is possible for scripts to add and
remove media elements from the MediaController
's list
of slaved media elements, even while these tracks are
playing. How smoothly the media plays back in such situations is
another quality-of-implementation issue.
When a media element that is paused is removed from a document and not reinserted before the next time the event loop spins, implementations that are resource constrained are encouraged to take that opportunity to release all hardware resources (like video planes, networking resources, and data buffers) used by the media element. (User agents still have to keep track of the playback position and so forth, though, in case playback is later restarted.)
canvas
elementwidth
height
interface HTMLCanvasElement : HTMLElement {
attribute unsigned long width;
attribute unsigned long height;
DOMString toDataURL(in optional DOMString type, in any... args);
void toBlob(in FileCallback, in optional DOMString type, in any... args);
object getContext(in DOMString contextId, in any... args);
};
The canvas
element provides scripts with a
resolution-dependent bitmap canvas, which can be used for rendering
graphs, game graphics, or other visual images on the fly.
Authors should not use the canvas
element in a
document when a more suitable element is available. For example, it
is inappropriate to use a canvas
element to render a
page heading: if the desired presentation of the heading is
graphically intense, it should be marked up using appropriate
elements (typically h1
) and then styled using CSS and
supporting technologies such as XBL.
When authors use the canvas
element, they must also
provide content that, when presented to the user, conveys
essentially the same function or purpose as the bitmap canvas. This
content may be placed as content of the canvas
element. The contents of the canvas
element, if any,
are the element's fallback content.
In interactive visual media, if scripting is enabled for the
canvas
element, and if support for canvas
elements has been enabled, the canvas
element
represents embedded content consisting of
a dynamically created image.
In non-interactive, static, visual media, if the
canvas
element has been previously painted on (e.g. if
the page was viewed in an interactive visual medium and is now being
printed, or if some script that ran during the page layout process
painted on the element), then the canvas
element
represents embedded content with the
current image and size. Otherwise, the element represents its
fallback content instead.
In non-visual media, and in visual media if scripting is disabled for the
canvas
element or if support for canvas
elements has been disabled, the canvas
element
represents its fallback content
instead.
When a canvas
element represents
embedded content, the user can still focus descendants
of the canvas
element (in the fallback
content). When an element is focused, it is the target of
keyboard interaction events (even though the element itself is not
visible). This allows authors to make an interactive canvas
keyboard-accessible: authors should have a one-to-one mapping of
interactive regions to focusable elements in the fallback
content. (Focus has no effect on mouse interaction
events.) [DOMEVENTS]
The canvas
element has two attributes to control the
size of the coordinate space: width
and height
. These
attributes, when specified, must have values that are valid non-negative
integers. The rules for parsing
non-negative integers must be used to obtain their numeric
values. If an attribute is missing, or if parsing its value returns
an error, then the default value must be used instead. The
width
attribute defaults to
300, and the height
attribute defaults to 150.
The intrinsic dimensions of the canvas
element equal
the size of the coordinate space, with the numbers interpreted in
CSS pixels. However, the element can be sized arbitrarily by a
style sheet. During rendering, the image is scaled to fit this layout
size.
The size of the coordinate space does not necessarily represent the size of the actual bitmap that the user agent will use internally or during rendering. On high-definition displays, for instance, the user agent may internally use a bitmap with two device pixels per unit in the coordinate space, so that the rendering remains at high quality throughout.
When the canvas
element is created, and subsequently
whenever the width
and height
attributes are set (whether
to a new value or to the previous value), the bitmap and any
associated contexts must be cleared back to their initial state and
reinitialized with the newly specified coordinate space
dimensions.
When the canvas is initialized, its bitmap must be cleared to transparent black.
The width
and
height
IDL
attributes must reflect the respective content
attributes of the same name, with the same defaults.
Only one square appears to be drawn in the following example:
// canvas is a reference to a <canvas> element var context = canvas.getContext('2d'); context.fillRect(0,0,50,50); canvas.setAttribute('width', '300'); // clears the canvas context.fillRect(0,100,50,50); canvas.width = canvas.width; // clears the canvas context.fillRect(100,0,50,50); // only this square remains
getContext
(contextId [, ... ])Returns an object that exposes an API for drawing on the canvas. The first argument specifies the desired API. Subsequent arguments are handled by that API.
The list of defined contexts is given on the WHATWG Wiki CanvasContexts page. [WHATWGWIKI]
Returns null if the given context ID is not supported or if the
canvas has already been initialised with some other (incompatible)
context type (e.g. trying to get a "2d
" context after getting a
"webgl
" context).
A canvas
element can have a primary
context, which is the first context to have been obtained for
that element. When created, a canvas
element must not
have a primary context.
The most commonly used primary context is the HTML Canvas 2D Context.
The getContext(contextId, args...)
method of the canvas
element, when invoked, must run
the following steps:
Let contextId be the first argument to the method.
If contextId is not the name of a context supported by the user agent, return null and abort these steps.
An example of this would be a user agent that
theoretically supports the "webgl
" 3D context, in the case
where the platform does not have hardware support for OpenGL and
the user agent does not have a software OpenGL implementation.
Despite the user agent recognising the "webgl
" name, it would return
null at this step because that context is not, in practice,
supported at the time of the call.
If the element has a primary context and that context's entry in the WHATWG Wiki CanvasContexts page does not list contextId as a context with which it is compatible, return null and abort these steps. [WHATWGWIKI]
If the element does not have a primary context, let the element's primary context be contextId.
If the getContext()
method has
already been invoked on this element for the same contextId, return the same object as was returned
that time, and abort these steps. The additional arguments are
ignored.
Return a new object for contextId, as defined by the specification given for contextId's entry in the WHATWG Wiki CanvasContexts page. [WHATWGWIKI]
New context types may be registered in the WHATWG Wiki CanvasContexts page. [WHATWGWIKI]
Anyone is free to edit the WHATWG Wiki CanvasContexts page at any time to add a new context type. These new context types must be specified with the following information:
The value of contextID that will return the object for the new API.
A link to a formal specification of the context type's API. It could be another page on the Wiki, or a link to an external page. If the type does not have a formal specification, an informal description can be substituted until such time as a formal specification is available.
The list of context types that are compatible with this one (i.e. that operate on the same underlying bitmap). This list must be transitive and symmetric; if one context type is defined as compatible with another, then all types it is compatible with must be compatible with all types the other is compatible with.
Vendors may also define experimental contexts using the syntax
vendorname-context
, for example,
moz-3d
. Such contexts should be registered in the
WHATWG Wiki CanvasContexts page.
toDataURL
( [ type, ... ])Returns a data:
URL for the image in the canvas.
The first argument, if provided, controls the type of the image
to be returned (e.g. PNG or JPEG). The default is image/png
; that type is also used if the given
type isn't supported. The other arguments are specific to the
type, and control the way that the image is generated, as given in
the table below.
When trying to use types other than "image/png
",
authors can check if the image was really returned in the
requested format by checking to see if the returned string starts
with one of the exact strings "data:image/png,
" or "data:image/png;
". If it does, the image is PNG,
and thus the requested type was not supported. (The one exception
to this is if the canvas has either no height or no width, in
which case the result might simply be "data:,
".)
toBlob
(callback [, type, ... ])Creates a Blob
object representing a file
containing the image in the canvas, and invokes a callback with a
handle to that object.
The second argument, if provided, controls the type of the
image to be returned (e.g. PNG or JPEG). The default is image/png
; that type is also used if the given
type isn't supported. The other arguments are specific to the
type, and control the way that the image is generated, as given in
the table below.
The toDataURL()
method
must run the following steps:
If the canvas has no pixels (i.e. either its horizontal
dimension or its vertical dimension is zero) then return the string
"data:,
" and abort these steps. (This is the
shortest data:
URL; it represents the empty string in a text/plain
resource.)
Let file be a serialization of the image as a file, using the method's arguments (if any) as the arguments.
The toBlob()
method
must run the following steps:
Let callback be the first argument.
Let arguments be the second and subsequent arguments to the method, if any.
Let file be a serialization of the image as a file, using arguments.
Return, but continue running these steps asynchronously.
If callback is null, abort these steps.
Queue a task to invoke the
FileCallback
callback with a
Blob
object representing file as
its argument. The task source for this task is the
canvas blob serialization task source. [FILESYSTEMAPI] [FILEAPI]
When a user agent is to create a serialization of the image as a file, optionally with some given arguments, it must create an image file in the format given by the first value of arguments, or, if there are no arguments, in the PNG format. [PNG]
If arguments is not empty, the first value must be interpreted as a MIME type giving the format to use. If the type has any parameters, it must be treated as not supported.
For example, the value "image/png
" would
mean to generate a PNG image, the value "image/jpeg
"
would mean to generate a JPEG image, and the value
"image/svg+xml
" would mean to generate an SVG image
(which would probably require that the implementation actually keep
enough information to reliably render an SVG image from the canvas).
User agents must support PNG ("image/png
"). User
agents may support other types. If the user agent does not support
the requested type, it must create the file using the PNG format. [PNG]
User agents must convert the provided type to ASCII lowercase before establishing if they support that type.
For image types that do not support an alpha channel, the serialized image must be the canvas image composited onto a solid black background using the source-over operator.
If the first argument in arguments gives a type corresponding to one of the types given in the first column of the following table, and the user agent supports that type, then the subsequent arguments, if any, must be treated as described in the second cell of that row.
Type | Other arguments | Reference |
---|---|---|
image/jpeg
| The second argument, if it is a number in the range 0.0 to 1.0 inclusive, must be treated as the desired quality level. If it is not a number or is outside that range, the user agent must use its default value, as if the argument had been omitted. | [JPEG] |
For the purposes of these rules, an argument is considered to be
a number if it is converted to an IDL double value by the rules for
handling arguments of type any
in the Web IDL
specification. [WEBIDL]
Other arguments must be ignored and must not cause the user agent to raise an exception. A future version of this specification will probably define other parameters to be passed to these methods to allow authors to more carefully control compression settings, image metadata, etc.
The canvas
APIs must perform color correction at
only two points: when rendering images with their own gamma
correction and color space information onto the canvas, to convert
the image to the color space used by the canvas (e.g. using the 2D
Context's drawImage()
method with an HTMLImageElement
object), and when
rendering the actual canvas bitmap to the output device.
Thus, in the 2D context, colors used to draw shapes
onto the canvas will exactly match colors obtained through the getImageData()
method.
The toDataURL()
method
must not include color space information in the resource
returned. Where the output format allows it, the color of pixels in
resources created by toDataURL()
must match those
returned by the getImageData()
method.
In user agents that support CSS, the color space used by a
canvas
element must match the color space used for
processing any colors for that element in CSS.
The gamma correction and color space information of images must
be handled in such a way that an image rendered directly using an
img
element would use the same colors as one painted on
a canvas
element that is then itself
rendered. Furthermore, the rendering of images that have no color
correction information (such as those returned by the toDataURL()
method) must be
rendered with no color correction.
Thus, in the 2D context, calling the drawImage()
method to render
the output of the toDataURL()
method to the
canvas, given the appropriate dimensions, has no visible effect.
canvas
elementsInformation leakage can occur if scripts from one origin can access information (e.g. read pixels) from images from another origin (one that isn't the same).
To mitigate this, canvas
elements are defined to
have a flag indicating whether they are origin-clean. All
canvas
elements must start with their
origin-clean set to true. The flag must be set to false if
any of the following actions occur:
The element's 2D context's drawImage()
method is
called with an HTMLImageElement
or an
HTMLVideoElement
whose origin is not the
same as that of the
Document
object that owns the canvas
element.
The element's 2D context's drawImage()
method is
called with an HTMLCanvasElement
whose
origin-clean flag is false.
The element's 2D context's fillStyle
attribute is set
to a CanvasPattern
object that was created from an
HTMLImageElement
or an HTMLVideoElement
whose origin was not the same as that of the Document
object
that owns the canvas
element when the pattern was
created.
The element's 2D context's fillStyle
attribute is set
to a CanvasPattern
object that was created from an
HTMLCanvasElement
whose origin-clean flag was
false when the pattern was created.
The element's 2D context's strokeStyle
attribute is
set to a CanvasPattern
object that was created from an
HTMLImageElement
or an HTMLVideoElement
whose origin was not the same as that of the Document
object
that owns the canvas
element when the pattern was
created.
The element's 2D context's strokeStyle
attribute is
set to a CanvasPattern
object that was created from an
HTMLCanvasElement
whose origin-clean flag was
false when the pattern was created.
The element's 2D context's fillText()
or strokeText()
methods are
invoked and consider using a font that has an origin
that is not the same as that of
the Document
object that owns the canvas
element. (The font doesn't even have to be used; all that matters
is whether the font was considered for any of the glyphs
drawn.)
Whenever the toDataURL()
method of a
canvas
element whose origin-clean flag is set to
false is called, the method must raise a SECURITY_ERR
exception.
Whenever the getImageData()
method of
the 2D context of a canvas
element whose
origin-clean flag is set to false is called with otherwise
correct arguments, the method must raise a SECURITY_ERR
exception.
Whenever the measureText()
method of
the 2D context of a canvas
element ends up using a font
that has an origin that is not the same as that of the Document
object that
owns the canvas
element, the method must raise a
SECURITY_ERR
exception.
Even resetting the canvas state by changing its
width
or height
attributes doesn't reset
the origin-clean flag.
map
elementname
interface HTMLMapElement : HTMLElement { attribute DOMString name; readonly attribute HTMLCollection areas; readonly attribute HTMLCollection images; };
The map
element, in conjunction with any
area
element descendants, defines an image
map. The element represents its children.
The name
attribute
gives the map a name so that it can be referenced. The attribute
must be present and must have a non-empty value with no space characters. The value of the
name
attribute must not be a
compatibility-caseless
match for the value of the name
attribute of another map
element in the same
document. If the id
attribute is also
specified, both attributes must have the same value.
areas
Returns an HTMLCollection
of the area
elements in the map
.
images
Returns an HTMLCollection
of the img
and object
elements that use the map
.
The areas
attribute
must return an HTMLCollection
rooted at the
map
element, whose filter matches only
area
elements.
The images
attribute must return an HTMLCollection
rooted at the
Document
node, whose filter matches only
img
and object
elements that are
associated with this map
element according to the
image map processing model.
The IDL attribute name
must
reflect the content attribute of the same name.
Image maps can be defined in conjunction with other content on the page, to ease maintenance. This example is of a page with an image map at the top of the page and a corresponding set of text links at the bottom.
<!DOCTYPE HTML> <TITLE>Babies™: Toys</TITLE> <HEADER> <H1>Toys</H1> <IMG SRC="/images/menu.gif" ALT="Babies™ navigation menu. Select a department to go to its page." USEMAP="#NAV"> </HEADER> ... <FOOTER> <MAP NAME="NAV"> <P> <A HREF="/clothes/">Clothes</A> <AREA ALT="Clothes" COORDS="0,0,100,50" HREF="/clothes/"> | <A HREF="/toys/">Toys</A> <AREA ALT="Toys" COORDS="0,0,100,50" HREF="/toys/"> | <A HREF="/food/">Food</A> <AREA ALT="Food" COORDS="0,0,100,50" HREF="/food/"> | <A HREF="/books/">Books</A> <AREA ALT="Books" COORDS="0,0,100,50" HREF="/books/"> </MAP> </FOOTER>
area
elementmap
element ancestor.alt
coords
shape
href
target
rel
media
hreflang
type
interface HTMLAreaElement : HTMLElement { attribute DOMString alt; attribute DOMString coords; attribute DOMString shape; stringifier attribute DOMString href; attribute DOMString target; attribute DOMString rel; readonly attribute DOMTokenList relList; attribute DOMString media; attribute DOMString hreflang; attribute DOMString type; // URL decomposition IDL attributes attribute DOMString protocol; attribute DOMString host; attribute DOMString hostname; attribute DOMString port; attribute DOMString pathname; attribute DOMString search; attribute DOMString hash; };
The area
element represents either a
hyperlink with some text and a corresponding area on an image
map, or a dead area on an image map.
If the area
element has an href
attribute, then the
area
element represents a hyperlink. In
this case, the alt
attribute must be present. It specifies the text of the
hyperlink. Its value must be text that, when presented with the
texts specified for the other hyperlinks of the image
map, and with the alternative text of the image, but without
the image itself, provides the user with the same kind of choice as
the hyperlink would when used without its text but with its shape
applied to the image. The alt
attribute may be left blank if there is another area
element in the same image map that points to the same
resource and has a non-blank alt
attribute.
If the area
element has no href
attribute, then the area
represented by the element cannot be selected, and the alt
attribute must be omitted.
In both cases, the shape
and
coords
attributes specify the
area.
The shape
attribute is an enumerated attribute. The following
table lists the keywords defined for this attribute. The states
given in the first cell of the rows with keywords give the states to
which those keywords map. Some of the keywords
are non-conforming, as noted in the last column.
State | Keywords | Notes |
---|---|---|
Circle state | circle
| |
circ
| Non-conforming | |
Default state | default
| |
Polygon state | poly
| |
polygon
| Non-conforming | |
Rectangle state | rect
| |
rectangle
| Non-conforming |
The attribute may be omitted. The missing value default is the rectangle state.
The coords
attribute must, if specified, contain a valid list of
integers. This attribute gives the coordinates for the shape
described by the shape
attribute. The processing for this attribute is
described as part of the image map processing
model.
In the circle state,
area
elements must have a coords
attribute present, with three
integers, the last of which must be non-negative. The first integer
must be the distance in CSS pixels from the left edge of the image
to the center of the circle, the second integer must be the distance
in CSS pixels from the top edge of the image to the center of the
circle, and the third integer must be the radius of the circle,
again in CSS pixels.
In the default state
state, area
elements must not have a coords
attribute. (The area is the
whole image.)
In the polygon state,
area
elements must have a coords
attribute with at least six
integers, and the number of integers must be even. Each pair of
integers must represent a coordinate given as the distances from the
left and the top of the image in CSS pixels respectively, and all
the coordinates together must represent the points of the polygon,
in order.
In the rectangle state,
area
elements must have a coords
attribute with exactly four
integers, the first of which must be less than the third, and the
second of which must be less than the fourth. The four points must
represent, respectively, the distance from the left edge of the
image to the left side of the rectangle, the distance from the
top edge to the top side, the distance from the left edge to the
right side, and the distance from the top edge to the bottom side,
all in CSS pixels.
When user agents allow users to follow hyperlinks created using the
area
element, as described in the next section, the
href
,
target
attributes decide how the
link is followed. The rel
,
media
, hreflang
, and type
attributes may be used to
indicate to the user the likely nature of the target resource before
the user follows the link.
The target
,
rel
, media
, hreflang
, and type
attributes must be omitted
if the href
attribute is
not present.
The activation behavior of area
elements is to run the following steps:
If the click
event in
question is not trusted
(i.e. a click()
method call was the
reason for the event being dispatched), and the area
element's target
attribute is such that applying the rules for choosing a
browsing context given a browsing context name, using the
value of the target
attribute as the browsing context name, would result in there not
being a chosen browsing context, then raise an
INVALID_ACCESS_ERR
exception and abort these
steps.
area
element, if any.The IDL attributes alt
, coords
, href
, target
,
rel
, media
, hreflang
, and type
, each must
reflect the respective content attributes of the same
name.
The IDL attribute shape
must
reflect the shape
content attribute.
The IDL attribute relList
must
reflect the rel
content attribute.
The area
element also supports the complement of
URL decomposition IDL attributes, protocol
, host
, port
, hostname
, pathname
, search
, and hash
. These must follow the
rules given for URL decomposition IDL attributes, with
the input being the result of
resolving the element's href
attribute relative to the
element, if there is such an attribute and resolving it is
successful, or the empty string otherwise; and the common setter action being the
same as setting the element's href
attribute to the new output
value.
An image map allows geometric areas on an image to be associated with hyperlinks.
An image, in the form of an img
element or an
object
element representing an image, may be associated
with an image map (in the form of a map
element) by
specifying a usemap
attribute on
the img
or object
element. The usemap
attribute, if specified,
must be a valid hash-name reference to a
map
element.
Consider an image that looks as follows:
If we wanted just the colored areas to be clickable, we could do it as follows:
<p> Please select a shape: <img src="shapes.png" usemap="#shapes" alt="Four shapes are available: a red hollow box, a green circle, a blue triangle, and a yellow four-pointed star."> <map name="shapes"> <area shape=rect coords="50,50,100,100"> <!-- the hole in the red box --> <area shape=rect coords="25,25,125,125" href="red.html" alt="Red box."> <area shape=circle coords="200,75,50" href="green.html" alt="Green circle."> <area shape=poly coords="325,25,262,125,388,125" href="blue.html" alt="Blue triangle."> <area shape=poly coords="450,25,435,60,400,75,435,90,450,125,465,90,500,75,465,60" href="yellow.html" alt="Yellow star."> </map> </p>
If an img
element or an object
element
representing an image has a usemap
attribute specified,
user agents must process it as follows:
First, rules for parsing a hash-name reference
to a map
element must be followed. This will return
either an element (the map) or null.
If that returned null, then abort these steps. The image is not associated with an image map after all.
Otherwise, the user agent must collect all the
area
elements that are descendants of the map. Let those be the areas.
Having obtained the list of area
elements that form
the image map (the areas), interactive user
agents must process the list in one of two ways.
If the user agent intends to show the text that the
img
element represents, then it must use the following
steps.
In user agents that do not support images, or that
have images disabled, object
elements cannot represent
images, and thus this section never applies (the fallback
content is shown instead). The following steps therefore only
apply to img
elements.
Remove all the area
elements in areas that have no href
attribute.
Remove all the area
elements in areas that have no alt
attribute, or whose alt
attribute's value is the empty
string, if there is another area
element in
areas with the same value in the href
attribute and with a
non-empty alt
attribute.
Each remaining area
element in areas represents a hyperlink. Those
hyperlinks should all be made available to the user in a manner
associated with the text of the img
.
In this context, user agents may represent area
and
img
elements with no specified alt
attributes, or whose alt
attributes are the empty string or some other non-visible text, in
a user-agent-defined fashion intended to indicate the lack of
suitable author-provided text.
If the user agent intends to show the image and allow interaction
with the image to select hyperlinks, then the image must be
associated with a set of layered shapes, taken from the
area
elements in areas, in reverse
tree order (so the last specified area
element in the
map is the bottom-most shape, and the first
element in the map, in tree order, is the
top-most shape).
Each area
element in areas must
be processed as follows to obtain a shape to layer onto the
image:
Find the state that the element's shape
attribute represents.
Use the rules for parsing a list of integers to
parse the element's coords
attribute, if it is present, and let the result be the coords list. If the attribute is absent, let the
coords list be the empty list.
If the number of items in the coords
list is less than the minimum number given for the
area
element's current state, as per the following
table, then the shape is empty; abort these steps.
State | Minimum number of items |
---|---|
Circle state | 3 |
Default state | 0 |
Polygon state | 6 |
Rectangle state | 4 |
Check for excess items in the coords
list as per the entry in the following list corresponding to the
shape
attribute's state:
If the shape
attribute
represents the rectangle
state, and the first number in the list is numerically less
than the third number in the list, then swap those two numbers
around.
If the shape
attribute
represents the rectangle
state, and the second number in the list is numerically less
than the fourth number in the list, then swap those two numbers
around.
If the shape
attribute
represents the circle
state, and the third number in the list is less than or
equal to zero, then the shape is empty; abort these steps.
Now, the shape represented by the element is the one
described for the entry in the list below corresponding to the
state of the shape
attribute:
Let x be the first number in coords, y be the second number, and r be the third number.
The shape is a circle whose center is x CSS pixels from the left edge of the image and y CSS pixels from the top edge of the image, and whose radius is r pixels.
The shape is a rectangle that exactly covers the entire image.
Let xi be the (2i)th entry in coords, and yi be the (2i+1)th entry in coords (the first entry in coords being the one with index 0).
Let the coordinates be (xi, yi), interpreted in CSS pixels measured from the top left of the image, for all integer values of i from 0 to (N/2)-1, where N is the number of items in coords.
The shape is a polygon whose vertices are given by the coordinates, and whose interior is established using the even-odd rule. [GRAPHICS]
Let x1 be the first number in coords, y1 be the second number, x2 be the third number, and y2 be the fourth number.
The shape is a rectangle whose top-left corner is given by the coordinate (x1, y1) and whose bottom right corner is given by the coordinate (x2, y2), those coordinates being interpreted as CSS pixels from the top left corner of the image.
For historical reasons, the coordinates must be interpreted
relative to the displayed image, even if it stretched
using CSS or the image element's width
and
height
attributes.
Mouse clicks on an image associated with a set of layered shapes
per the above algorithm must be dispatched to the top-most shape
covering the point that the pointing device indicated (if any), and
then, must be dispatched again (with a new Event
object) to the image element itself. User agents may also allow
individual area
elements representing hyperlinks to be selected and activated
(e.g. using a keyboard); events from this are not also propagated to
the image.
Because a map
element (and its
area
elements) can be associated with multiple
img
and object
elements, it is possible
for an area
element to correspond to multiple focusable
areas of the document.
Image maps are live; if the DOM is mutated, then the user agent must act as if it had rerun the algorithms for image maps.
The math
element from the MathML
namespace falls into the embedded content,
phrasing content, and flow content
categories for the purposes of the content models in this
specification.
User agents must handle text other than inter-element
whitespace found in MathML elements whose content models do
not allow straight text by pretending for the purposes of MathML
content models, layout, and rendering that that text is actually
wrapped in an mtext
element in the
MathML namespace. (Such text is not, however,
conforming.)
User agents must act as if any MathML element whose contents does
not match the element's content model was replaced, for the purposes
of MathML layout and rendering, by an merror
element in the MathML namespace containing some
appropriate error message.
To enable authors to use MathML tools that only accept MathML in its XML form, interactive HTML user agents are encouraged to provide a way to export any MathML fragment as an XML namespace-well-formed XML fragment.
The semantics of MathML elements are defined by the MathML specification and other applicable specifications. [MATHML]
Here is an example of the use of MathML in an HTML document:
<!DOCTYPE html> <html> <head> <title>The quadratic formula</title> </head> <body> <h1>The quadratic formula</h1> <p> <math> <mi>x</mi> <mo>=</mo> <mfrac> <mrow> <mo form="prefix">−</mo> <mi>b</mi> <mo>±</mo> <msqrt> <msup> <mi>b</mi> <mn>2</mn> </msup> <mo>−</mo> <mn>4</mn> <mo></mo> <mi>a</mi> <mo></mo> <mi>c</mi> </msqrt> </mrow> <mrow> <mn>2</mn> <mo></mo> <mi>a</mi> </mrow> </mfrac> </math> </p> </body> </html>
The svg
element from the SVG
namespace falls into the embedded content,
phrasing content, and flow content
categories for the purposes of the content models in this
specification.
To enable authors to use SVG tools that only accept SVG in its XML form, interactive HTML user agents are encouraged to provide a way to export any SVG fragment as an XML namespace-well-formed XML fragment.
When the SVG foreignObject
element contains
elements from the HTML namespace, such elements must
all be flow content. [SVG]
The content model for title
elements in the
SVG namespace inside HTML documents is
phrasing content. (This further constrains the
requirements given in the SVG specification.)
The semantics of SVG elements are defined by the SVG specification and other applicable specifications. [SVG]
The SVG specification includes requirements regarding the
handling of elements in the DOM that are not in the SVG namespace,
that are in SVG fragments, and that are not included in a
foreignObject
element. This
specification does not define any processing for elements in SVG
fragments that are not in the HTML namespace; they are considered
neither conforming nor non-conforming from the perspective of this
specification.
Author requirements:
The width
and height
attributes on
img
, iframe
, embed
,
object
, video
, and, when their type
attribute is in the Image Button state,
input
elements may be specified to give the dimensions
of the visual content of the element (the width and height
respectively, relative to the nominal direction of the output
medium), in CSS pixels. The attributes, if specified, must have
values that are valid
non-negative integers.
The specified dimensions given may differ from the dimensions specified in the resource itself, since the resource may have a resolution that differs from the CSS pixel resolution. (On screens, CSS pixels have a resolution of 96ppi, but in general the CSS pixel resolution depends on the reading distance.) If both attributes are specified, then one of the following statements must be true:
The target ratio is the ratio of the
intrinsic width to the intrinsic height in the resource. The specified width and specified
height are the values of the width
and height
attributes respectively.
The two attributes must be omitted if the resource in question does not have both an intrinsic width and an intrinsic height.
If the two attributes are both zero, it indicates that the element is not intended for the user (e.g. it might be a part of a service to count page views).
The dimension attributes are not intended to be used to stretch the image.
User agent requirements: User agents are expected to use these attributes as hints for the rendering.
The width
and height
IDL attributes on
the iframe
, embed
, object
,
and video
elements must reflect the
respective content attributes of the same name.
For iframe
, embed
, and
object
the IDL attributes are DOMString
;
for video
the IDL attributes are unsigned
long
.
table
elementcaption
element,
followed by zero or more colgroup
elements, followed
optionally by a thead
element, followed optionally by
a tfoot
element, followed by either zero or more
tbody
elements or one or more tr
elements, followed optionally by a tfoot
element (but
there can only be one tfoot
element child in
total).border
interface HTMLTableElement : HTMLElement { attribute HTMLTableCaptionElement caption; HTMLElement createCaption(); void deleteCaption(); attribute HTMLTableSectionElement tHead; HTMLElement createTHead(); void deleteTHead(); attribute HTMLTableSectionElement tFoot; HTMLElement createTFoot(); void deleteTFoot(); readonly attribute HTMLCollection tBodies; HTMLElement createTBody(); readonly attribute HTMLCollection rows; HTMLElement insertRow(in optional long index); void deleteRow(in long index); attribute DOMString border; };
The table
element represents data with
more than one dimension, in the form of a table.
The table
element takes part in the table
model.
Tables have rows, columns, and cells given by their descendants. The rows and columns form a grid; a table's cells must completely cover that grid without overlap.
Precise rules for determining whether this conformance requirement is met are described in the description of the table model.
Authors are encouraged to provide information describing how to interpret complex tables. Guidance on how provide such information is given below.
If a table
element has a summary
attribute, and the user
agent has not classified the table as a layout table, the user agent
may report the contents of that attribute to the user.
Tables should not be used as layout aids. Historically, many Web authors have tables in HTML as a way to control their page layout making it difficult to extract tabular data from such documents. In particular, users of accessibility tools, like screen readers, are likely to find it very difficult to navigate pages with tables used for layout. If a table is to be used for layout it must be marked with the attribute role="presentation" for a user agent to properly represent the table to an assistive technology and to properly convey the intent of the author to tools that wish to extract tabular data from the document.
There are a variety of alternatives to using HTML tables for layout, primarily using CSS positioning and the CSS table model.
The border
attribute may be specified on a table
element to
explicitly indicate that the table
element is not being
used for layout purposes. If specified, the attribute's value must
either be the empty string or the value "1
".
The attribute is used by certain user agents as an indication that
borders should be drawn around cells of the table.
Tables can be complicated to understand and navigate. To help users with this, user agents should clearly dilineate cells in a table from each other, unless the user agent has classified the table as a layout table.
Authors and implementors are encouraged to consider using some of the table layout techniques described below to make tables easier to navigate for users.
User agents, especially those that do table analysis on arbitrary content, are encouraged to find heuristics to determine which tables actually contain data and which are merely being used for layout. This specification does not define a precise heuristic, but the following are suggested as possible indicators:
Feature | Indication |
---|---|
The use of the role attribute with the value presentation
| Probably a layout table |
The use of the border attribute with the non-conforming value 0
| Probably a layout table |
The use of the non-conforming cellspacing and cellpadding attributes with the value 0
| Probably a layout table |
The use of caption , thead , or th elements
| Probably a non-layout table |
The use of the headers and scope attributes
| Probably a non-layout table |
The use of the border attribute with a value other than 0
| Probably a non-layout table |
Explicit visible borders set using CSS | Probably a non-layout table |
The use of the summary attribute
| Not a good indicator (both layout and non-layout tables have historically been given this attribute) |
caption
[ = value ]Returns the table's caption
element.
Can be set, to replace the caption
element. If the
new value is not a caption
element, throws a
HIERARCHY_REQUEST_ERR
exception.
createCaption
()Ensures the table has a caption
element, and returns it.
deleteCaption
()Ensures the table does not have a caption
element.
tHead
[ = value ]Returns the table's thead
element.
Can be set, to replace the thead
element. If the
new value is not a thead
element, throws a
HIERARCHY_REQUEST_ERR
exception.
createTHead
()Ensures the table has a thead
element, and returns it.
deleteTHead
()Ensures the table does not have a thead
element.
tFoot
[ = value ]Returns the table's tfoot
element.
Can be set, to replace the tfoot
element. If the
new value is not a tfoot
element, throws a
HIERARCHY_REQUEST_ERR
exception.
createTFoot
()Ensures the table has a tfoot
element, and returns it.
deleteTFoot
()Ensures the table does not have a tfoot
element.
tBodies
Returns an HTMLCollection
of the tbody
elements of the table.
createTBody
()Creates a tbody
element, inserts it into the table, and returns it.
rows
Returns an HTMLCollection
of the tr
elements of the table.
insertRow
(index)Creates a tr
element, along with a tbody
if required, inserts them into the table at the position given by the argument, and returns the tr
.
The position is relative to the rows in the table. The index −1 is equivalent to inserting at the end of the table.
If the given position is less than −1 or greater than the number of rows, throws an INDEX_SIZE_ERR
exception.
deleteRow
(index)Removes the tr
element with the given position in the table.
The position is relative to the rows in the table. The index −1 is equivalent to deleting the last row of the table.
If the given position is less than −1 or greater than the index of the last row, or if there are no rows, throws an INDEX_SIZE_ERR
exception.
The caption
IDL
attribute must return, on getting, the first caption
element child of the table
element, if any, or null
otherwise. On setting, if the new value is a caption
element, the first caption
element child of the
table
element, if any, must be removed, and the new
value must be inserted as the first node of the table
element. If the new value is not a caption
element,
then a HIERARCHY_REQUEST_ERR
DOM exception must be
raised instead.
The createCaption()
method must return the first caption
element child of
the table
element, if any; otherwise a new
caption
element must be created, inserted as the first
node of the table
element, and then returned.
The deleteCaption()
method must remove the first caption
element child of
the table
element, if any.
The tHead
IDL
attribute must return, on getting, the first thead
element child of the table
element, if any, or null
otherwise. On setting, if the new value is a thead
element, the first thead
element child of the
table
element, if any, must be removed, and the new
value must be inserted immediately before the first element in the
table
element that is neither a caption
element nor a colgroup
element, if any, or at the end
of the table if there are no such elements. If the new value is not
a thead
element, then a
HIERARCHY_REQUEST_ERR
DOM exception must be raised
instead.
The createTHead()
method must return the first thead
element child of the
table
element, if any; otherwise a new
thead
element must be created and inserted immediately
before the first element in the table
element that is
neither a caption
element nor a colgroup
element, if any, or at the end of the table if there are no such
elements, and then that new element must be returned.
The deleteTHead()
method must remove the first thead
element child of the
table
element, if any.
The tFoot
IDL
attribute must return, on getting, the first tfoot
element child of the table
element, if any, or null
otherwise. On setting, if the new value is a tfoot
element, the first tfoot
element child of the
table
element, if any, must be removed, and the new
value must be inserted immediately before the first element in the
table
element that is neither a caption
element, a colgroup
element, nor a thead
element, if any, or at the end of the table if there are no such
elements. If the new value is not a tfoot
element, then
a HIERARCHY_REQUEST_ERR
DOM exception must be raised
instead.
The createTFoot()
method must return the first tfoot
element child of the
table
element, if any; otherwise a new
tfoot
element must be created and inserted immediately
before the first element in the table
element that is
neither a caption
element, a colgroup
element, nor a thead
element, if any, or at the end of
the table if there are no such elements, and then that new element
must be returned.
The deleteTFoot()
method must remove the first tfoot
element child of the
table
element, if any.
The tBodies
attribute must return an HTMLCollection
rooted at the
table
node, whose filter matches only
tbody
elements that are children of the
table
element.
The createTBody()
method must create a new tbody
element, insert it
immediately after the last tbody
element in the
table
element, if any, or at the end of the
table
element if the table
element has no
tbody
element children, and then must return the new
tbody
element.
The rows
attribute
must return an HTMLCollection
rooted at the
table
node, whose filter matches only tr
elements that are either children of the table
element,
or children of thead
, tbody
, or
tfoot
elements that are themselves children of the
table
element. The elements in the collection must be
ordered such that those elements whose parent is a
thead
are included first, in tree order, followed by
those elements whose parent is either a table
or
tbody
element, again in tree order, followed finally by
those elements whose parent is a tfoot
element, still
in tree order.
The behavior of the insertRow(index)
method depends on the state of
the table. When it is called, the method must act as required by the
first item in the following list of conditions that describes the
state of the table and the index argument:
rows
collection:INDEX_SIZE_ERR
exception.rows
collection has
zero elements in it, and the table
has no
tbody
elements in it:tbody
element, then
create a tr
element, then append the tr
element to the tbody
element, then append the
tbody
element to the table
element, and
finally return the tr
element.rows
collection has
zero elements in it:tr
element, append it to
the last tbody
element in the table, and return the
tr
element.rows
collection:tr
element, and append it
to the parent of the last tr
element in the rows
collection. Then, the newly
created tr
element must be returned.tr
element, insert it
immediately before the indexth tr
element in the rows
collection,
in the same parent, and finally must return the newly created
tr
element.When the deleteRow(index)
method is called, the user agent
must run the following steps:
If index is equal to −1, then
index must be set to the number if items in the
rows
collection, minus
one.
Now, if index is less than zero, or
greater than or equal to the number of elements in the rows
collection, the method must
instead raise an INDEX_SIZE_ERR
exception, and these
steps must be aborted.
Otherwise, the method must remove the indexth element in the rows
collection from its parent.
The border
IDL
attribute must reflect the content attribute of the
same name.
Here is an example of a table being used to mark up a Sudoku puzzle. Observe the lack of headers, which are not necessary in such a table.
<section> <style scoped> table { border-collapse: collapse; border: solid thick; } colgroup, tbody { border: solid medium; } td { border: solid thin; height: 1.4em; width: 1.4em; text-align: center; padding: 0; } </style> <h1>Today's Sudoku</h1> <table> <colgroup><col><col><col> <colgroup><col><col><col> <colgroup><col><col><col> <tbody> <tr> <td> 1 <td> <td> 3 <td> 6 <td> <td> 4 <td> 7 <td> <td> 9 <tr> <td> <td> 2 <td> <td> <td> 9 <td> <td> <td> 1 <td> <tr> <td> 7 <td> <td> <td> <td> <td> <td> <td> <td> 6 <tbody> <tr> <td> 2 <td> <td> 4 <td> <td> 3 <td> <td> 9 <td> <td> 8 <tr> <td> <td> <td> <td> <td> <td> <td> <td> <td> <tr> <td> 5 <td> <td> <td> 9 <td> <td> 7 <td> <td> <td> 1 <tbody> <tr> <td> 6 <td> <td> <td> <td> 5 <td> <td> <td> <td> 2 <tr> <td> <td> <td> <td> <td> 7 <td> <td> <td> <td> <tr> <td> 9 <td> <td> <td> 8 <td> <td> 2 <td> <td> <td> 5 </table> </section>
For tables that consist of more than just a grid of cells with headers in the first row and headers in the first column, and for any table in general where the reader might have difficulty understanding the content, authors should include explanatory information introducing the table. This information is useful for all users, but is especially useful for users who cannot see the table, e.g. users of screen readers.
Such explanatory information should introduce the purpose of the table, outline its basic cell structure, highlight any trends or patterns, and generally teach the user how to use the table.
For instance, the following table:
Negative | Characteristic | Positive |
---|---|---|
Sad | Mood | Happy |
Failing | Grade | Passing |
...might benefit from a description explaining the way the table is laid out, something like "Characteristics are given in the second column, with the negative side in the left column and the positive side in the right column".
There are a variety of ways to include this information, such as:
<p>In the following table, characteristics are given in the second column, with the negative side in the left column and the positive side in the right column.</p> <table> <caption>Characteristics with positive and negative sides</caption> <thead> <tr> <th id="n"> Negative <th> Characteristic <th> Positive <tbody> <tr> <td headers="n r1"> Sad <th id="r1"> Mood <td> Happy <tr> <td headers="n r2"> Failing <th id="r2"> Grade <td> Passing </table>
caption
<table> <caption> <strong>Characteristics with positive and negative sides.</strong> <p>Characteristics are given in the second column, with the negative side in the left column and the positive side in the right column.</p> </caption> <thead> <tr> <th id="n"> Negative <th> Characteristic <th> Positive <tbody> <tr> <td headers="n r1"> Sad <th id="r1"> Mood <td> Happy <tr> <td headers="n r2"> Failing <th id="r2"> Grade <td> Passing </table>
caption
, in a details
element<table> <caption> <strong>Characteristics with positive and negative sides.</strong> <details> <summary>Help</summary> <p>Characteristics are given in the second column, with the negative side in the left column and the positive side in the right column.</p> </details> </caption> <thead> <tr> <th id="n"> Negative <th> Characteristic <th> Positive <tbody> <tr> <td headers="n r1"> Sad <th id="r1"> Mood <td> Happy <tr> <td headers="n r2"> Failing <th id="r2"> Grade <td> Passing </table>
figure
<figure> <figcaption>Characteristics with positive and negative sides</figcaption> <p>Characteristics are given in the second column, with the negative side in the left column and the positive side in the right column.</p> <table> <thead> <tr> <th id="n"> Negative <th> Characteristic <th> Positive <tbody> <tr> <td headers="n r1"> Sad <th id="r1"> Mood <td> Happy <tr> <td headers="n r2"> Failing <th id="r2"> Grade <td> Passing </table> </figure>
figure
's figcaption
<figure> <figcaption> <strong>Characteristics with positive and negative sides</strong> <p>Characteristics are given in the second column, with the negative side in the left column and the positive side in the right column.</p> </figcaption> <table> <thead> <tr> <th id="n"> Negative <th> Characteristic <th> Positive <tbody> <tr> <td headers="n r1"> Sad <th id="r1"> Mood <td> Happy <tr> <td headers="n r2"> Failing <th id="r2"> Grade <td> Passing </table> </figure>
Authors may also use other techniques, or combinations of the above techniques, as appropriate.
The best option, of course, rather than writing a description explaining the way the table is laid out, is to adjust the table such that no explanation is needed.
In the case of the table used in the examples above, a simple
rearrangement of the table so that the headers are on the top and
left sides removes the need for an explanation as well as removing
the need for the use of headers
attributes:
<table> <caption>Characteristics with positive and negative sides</caption> <thead> <tr> <th> Characteristic <th> Negative <th> Positive <tbody> <tr> <th> Mood <td> Sad <td> Happy <tr> <th> Grade <td> Failing <td> Passing </table>
Good table layout is key to making tables more readable and usable.
In visual media, providing column and row borders and alternating row backgrounds can be very effective to make complicated tables more readable.
For tables with large volumes of numeric content, using monospaced fonts can help users see patterns, especially in situations where a user agent does not render the borders. (Unfortunately, for historical reasons, not rendering borders on tables is a common default.)
In speech media, table cells can be distinguished by reporting the corresponding headers before reading the cell's contents, and by allowing users to navigate the table in a grid fashion, rather than serializing the entire contents of the table in source order.
Authors are encouraged to use CSS to achieve these effects.
User agents are encouraged to render tables using these techniques whenever the page does not use CSS and the table is not classified as a layout table.
caption
elementtable
element.table
elements.interface HTMLTableCaptionElement : HTMLElement {};
The caption
element represents the title of the
table
that is its parent, if it has a parent and that
is a table
element.
The caption
element takes part in the table
model.
When a table
element is the only content in a
figure
element other than the figcaption
,
the caption
element should be omitted in favor of the
figcaption
.
A caption can introduce context for a table, making it significantly easier to understand.
Consider, for instance, the following table:
1 | 2 | 3 | 4 | 5 | 6 | |
---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 | 7 |
2 | 3 | 4 | 5 | 6 | 7 | 8 |
3 | 4 | 5 | 6 | 7 | 8 | 9 |
4 | 5 | 6 | 7 | 8 | 9 | 10 |
5 | 6 | 7 | 8 | 9 | 10 | 11 |
6 | 7 | 8 | 9 | 10 | 11 | 12 |
In the abstract, this table is not clear. However, with a caption giving the table's number (for reference in the main prose) and explaining its use, it makes more sense:
<caption> <p>Table 1. <p>This table shows the total score obtained from rolling two six-sided dice. The first row represents the value of the first die, the first column the value of the second die. The total is given in the cell that corresponds to the values of the two dice. </caption>
colgroup
elementtable
element, after any
caption
elements and before any thead
,
tbody
, tfoot
, and tr
elements.span
attribute is present: Empty.span
attribute is absent: Zero or more col
elements.span
interface HTMLTableColElement : HTMLElement { attribute unsigned long span; };
The colgroup
element represents a group of one or more columns in the table
that
is its parent, if it has a parent and that is a table
element.
If the colgroup
element contains no col
elements, then the element may have a span
content attribute
specified, whose value must be a valid non-negative
integer greater than zero.
The colgroup
element and its span
attribute take part in the
table model.
The span
IDL
attribute must reflect the content attribute of the
same name. The value must be limited to only non-negative
numbers greater than zero.
col
elementcolgroup
element that doesn't have
a span
attribute.span
HTMLTableColElement
, same as for
colgroup
elements. This interface defines one member,
span
.
If a col
element has a parent and that is a
colgroup
element that itself has a parent that is a
table
element, then the col
element
represents one or more columns in the column group represented by that
colgroup
.
The element may have a span
content attribute
specified, whose value must be a valid non-negative
integer greater than zero.
The col
element and its span
attribute take part in the
table model.
The span
IDL
attribute must reflect the content attribute of the
same name. The value must be limited to only non-negative
numbers greater than zero.
tbody
elementtable
element, after any
caption
, colgroup
, and
thead
elements, but only if there are no
tr
elements that are children of the
table
element.tr
elementsinterface HTMLTableSectionElement : HTMLElement { readonly attribute HTMLCollection rows; HTMLElement insertRow(in optional long index); void deleteRow(in long index); };
The HTMLTableSectionElement
interface is also
used for thead
and tfoot
elements.
The tbody
element represents a block of rows that consist of a body of data for
the parent table
element, if the tbody
element has a parent and it is a table
.
The tbody
element takes part in the table
model.
rows
Returns an HTMLCollection
of the tr
elements of the table section.
insertRow
( [ index ] )Creates a tr
element, inserts it into the table section at the position given by the argument, and returns the tr
.
The position is relative to the rows in the table section. The index −1, which is the default if the argument is omitted, is equivalent to inserting at the end of the table section.
If the given position is less than −1 or greater than the number of rows, throws an INDEX_SIZE_ERR
exception.
deleteRow
(index)Removes the tr
element with the given position in the table section.
The position is relative to the rows in the table section. The index −1 is equivalent to deleting the last row of the table section.
If the given position is less than −1 or greater than the index of the last row, or if there are no rows, throws an INDEX_SIZE_ERR
exception.
The rows
attribute
must return an HTMLCollection
rooted at the element,
whose filter matches only tr
elements that are children
of the element.
The insertRow(index)
method must, when invoked on an
element table section, act as follows:
If index is less than −1 or greater than the
number of elements in the rows
collection, the method must raise an INDEX_SIZE_ERR
exception.
If index is missing, equal to −1, or
equal to the number of items in the rows
collection, the method must
create a tr
element, append it to the element table section, and return the newly created
tr
element.
Otherwise, the method must create a tr
element,
insert it as a child of the table section
element, immediately before the indexth
tr
element in the rows
collection, and finally must
return the newly created tr
element.
The deleteRow(index)
method must remove the indexth element in the rows
collection from its parent. If
index is less than zero or greater than or equal
to the number of elements in the rows
collection, the method must
instead raise an INDEX_SIZE_ERR
exception.
thead
elementtable
element, after any
caption
, and colgroup
elements and before any tbody
, tfoot
, and
tr
elements, but only if there are no other
thead
elements that are children of the
table
element.tr
elementsHTMLTableSectionElement
, as defined for
tbody
elements.The thead
element represents the block of rows that consist of the column labels
(headers) for the parent table
element, if the
thead
element has a parent and it is a
table
.
The thead
element takes part in the table
model.
This example shows a thead
element being used.
Notice the use of both th
and td
elements
in the thead
element: the first row is the headers,
and the second row is an explanation of how to fill in the
table.
<table> <caption> School auction sign-up sheet </caption> <thead> <tr> <th><label for=e1>Name</label> <th><label for=e2>Product</label> <th><label for=e3>Picture</label> <th><label for=e4>Price</label> <tr> <td>Your name here <td>What are you selling? <td>Link to a picture <td>Your reserve price <tbody> <tr> <td>Ms Danus <td>Doughnuts <td><img src="http://example.com/mydoughnuts.png" title="Doughnuts from Ms Danus"> <td>$45 <tr> <td><input id=e1 type=text name=who required form=f> <td><input id=e2 type=text name=what required form=f> <td><input id=e3 type=url name=pic form=f> <td><input id=e4 type=number step=0.01 min=0 value=0 required form=f> </table> <form id=f action="/auction.cgi"> <input type=button name=add value="Submit"> </form>
tfoot
elementtable
element, after any
caption
, colgroup
, and thead
elements and before any tbody
and tr
elements, but only if there are no other tfoot
elements that are children of the table
element.table
element, after any
caption
, colgroup
, thead
,
tbody
, and tr
elements, but only if there
are no other tfoot
elements that are children of the
table
element.tr
elementsHTMLTableSectionElement
, as defined for
tbody
elements.The tfoot
element represents the block of rows that consist of the column summaries
(footers) for the parent table
element, if the
tfoot
element has a parent and it is a
table
.
The tfoot
element takes part in the table
model.
tr
elementthead
element.tbody
element.tfoot
element.table
element, after any
caption
, colgroup
, and thead
elements, but only if there are no tbody
elements that
are children of the table
element.td
or th
elementsinterface HTMLTableRowElement : HTMLElement { readonly attribute long rowIndex; readonly attribute long sectionRowIndex; readonly attribute HTMLCollection cells; HTMLElement insertCell(in optional long index); void deleteCell(in long index); };
The tr
element represents a row of cells in a table.
The tr
element takes part in the table
model.
rowIndex
Returns the position of the row in the table's rows
list.
Returns −1 if the element isn't in a table.
sectionRowIndex
Returns the position of the row in the table section's rows
list.
Returns −1 if the element isn't in a table section.
cells
Returns an HTMLCollection
of the td
and th
elements of the row.
insertCell
( [ index ] )Creates a td
element, inserts it into the table
row at the position given by the argument, and returns the
td
.
The position is relative to the cells in the row. The index −1, which is the default if the argument is omitted, is equivalent to inserting at the end of the row.
If the given position is less than −1 or greater than
the number of cells, throws an INDEX_SIZE_ERR
exception.
deleteCell
(index)Removes the td
or th
element with the
given position in the row.
The position is relative to the cells in the row. The index −1 is equivalent to deleting the last cell of the row.
If the given position is less than −1 or greater than
the index of the last cell, or if there are no cells, throws an
INDEX_SIZE_ERR
exception.
The rowIndex
attribute must, if the element has a parent table
element, or a parent tbody
, thead
, or
tfoot
element and a grandparent
table
element, return the index of the tr
element in that table
element's rows
collection. If there is no such
table
element, then the attribute must return
−1.
The sectionRowIndex
attribute must, if the element has a parent table
,
tbody
, thead
, or tfoot
element, return the index of the tr
element in the
parent element's rows
collection (for tables,
that's the HTMLTableElement.rows
collection; for table sections, that's the HTMLTableRowElement.rows
collection). If there is no such parent element, then the attribute
must return −1.
The cells
attribute
must return an HTMLCollection
rooted at the
tr
element, whose filter matches only td
and th
elements that are children of the
tr
element.
The insertCell(index)
method must act as follows:
If index is less than −1 or greater than the
number of elements in the cells
collection, the method must raise an INDEX_SIZE_ERR
exception.
If index is missing, equal to −1, or
equal to the number of items in cells
collection, the method must create
a td
element, append it to the tr
element,
and return the newly created td
element.
Otherwise, the method must create a td
element,
insert it as a child of the tr
element, immediately
before the indexth td
or
th
element in the cells
collection, and finally must
return the newly created td
element.
The deleteCell(index)
method must remove the indexth element in the cells
collection from its parent. If
index is less than zero or greater than or equal
to the number of elements in the cells
collection, the method must
instead raise an INDEX_SIZE_ERR
exception.
td
elementtr
element.colspan
rowspan
headers
interface HTMLTableDataCellElement : HTMLTableCellElement {};
The td
element represents a data cell in a table.
The td
element and its colspan
, rowspan
, and headers
attributes take part in the
table model.
th
elementtr
element.colspan
rowspan
headers
scope
interface HTMLTableHeaderCellElement : HTMLTableCellElement { attribute DOMString scope; };
The th
element represents a header cell in a table.
The th
element may have a scope
content attribute
specified. The scope
attribute is
an enumerated attribute with five states, four of which
have explicit keywords:
row
keyword, which maps to the row statecol
keyword, which maps to the column staterowgroup
keyword,
which maps to the row group stateth
element's
scope
attribute must not be in
the row group state if
the element is not anchored in a row group.colgroup
keyword,
which maps to the column group stateth
element's scope
attribute must
not be in the column
group state if the element is not anchored in a column group.The scope
attribute's
missing value default is the auto state.
The th
element and its colspan
, rowspan
, headers
, and scope
attributes take part in the
table model.
The scope
IDL
attribute must reflect the content attribute of the
same name, limited to only known values.
The following example shows how the scope
attribute's rowgroup
value affects which
data cells a header cell applies to.
Here is a markup fragment showing a table:
<table> <thead> <tr> <th> ID <th> Measurement <th> Average <th> Maximum <tbody> <tr> <td> <th scope=rowgroup> Cats <td> <td> <tr> <td> 93 <th scope=row> Legs <td> 3.5 <td> 4 <tr> <td> 10 <th scope=row> Tails <td> 1 <td> 1 <tbody> <tr> <td> <th scope=rowgroup> English speakers <td> <td> <tr> <td> 32 <th scope=row> Legs <td> 2.67 <td> 4 <tr> <td> 35 <th scope=row> Tails <td> 0.33 <td> 1 </table>
This would result in the following table:
ID | Measurement | Average | Maximum |
---|---|---|---|
Cats | |||
93 | Legs | 3.5 | 4 |
10 | Tails | 1 | 1 |
English speakers | |||
32 | Legs | 2.67 | 4 |
35 | Tails | 0.33 | 1 |
The headers in the first row all apply directly down to the rows in their column.
The headers with the explicit scope
attributes apply to all the
cells in their row group other than the cells in the first column.
The remaining headers apply just to the cells to the right of them.
td
and th
elementsThe td
and th
elements may have a colspan
content
attribute specified, whose value must be a valid non-negative
integer greater than zero.
The td
and th
elements may also have a
rowspan
content
attribute specified, whose value must be a valid non-negative
integer.
These attributes give the number of columns and rows respectively that the cell is to span. These attributes must not be used to overlap cells, as described in the description of the table model.
The td
and th
element may have a headers
content
attribute specified. The headers
attribute, if specified,
must contain a string consisting of an unordered set of unique
space-separated tokens that are case-sensitive,
each of which must have the value of an ID of a th
element taking
part in the same table as the
td
or th
element (as
defined by the table model).
A th
element with ID id is said
to be directly targeted by all td
and
th
elements in the same table that have headers
attributes whose values
include as one of their tokens the ID id. A
th
element A is said to be
targeted by a th
or td
element
B if either A is directly
targeted by B or if there exists an element
C that is itself targeted by the element
B and A is directly
targeted by C.
A th
element must not be targeted by
itself.
The colspan
, rowspan
, and headers
attributes take part in the
table model.
The td
and th
elements implement
interfaces that inherit from the HTMLTableCellElement
interface:
interface HTMLTableCellElement : HTMLElement { attribute unsigned long colSpan; attribute unsigned long rowSpan; [PutForwards=value] readonly attribute DOMSettableTokenList headers; readonly attribute long cellIndex; };
cellIndex
Returns the position of the cell in the row's cells
list. This does not necessarily
correspond to the x-position of the cell in
the table, since earlier cells might cover multiple rows or
columns.
Returns 0 if the element isn't in a row.
The colSpan
IDL
attribute must reflect the content attribute of the
same name. The value must be limited to only non-negative
numbers greater than zero.
The rowSpan
IDL
attribute must reflect the content attribute of the
same name. Its default value, which must be used if parsing the
attribute as a non-negative integer returns an error, is 1.
The headers
IDL
attribute must reflect the content attribute of the
same name.
The cellIndex
IDL attribute must, if the element has a parent tr
element, return the index of the cell's element in the parent
element's cells
collection. If
there is no such parent element, then the attribute must return
0.
The various table elements and their content attributes together define the table model.
A table consists of cells
aligned on a two-dimensional grid of slots with coordinates (x, y). The grid is finite, and is
either empty or has one or more slots. If the grid has one or more
slots, then the x coordinates are always in the
range 0 ≤ x < xwidth, and the y
coordinates are always in the range 0 ≤ y < yheight. If one or both of xwidth and yheight are zero, then the table is empty (has
no slots). Tables correspond to table
elements.
A cell is a set of slots anchored
at a slot (cellx, celly), and with a particular
width and height such that
the cell covers all the slots with coordinates (x, y) where cellx ≤ x < cellx+width and
celly ≤ y < celly+height. Cells can
either be data cells or header cells. Data cells
correspond to td
elements, and header cells correspond
to th
elements. Cells of both types can have zero or
more associated header cells.
It is possible, in certain error cases, for two cells to occupy the same slot.
A row is a complete set of slots
from x=0 to x=xwidth-1, for a particular value of y. Rows correspond to tr
elements.
A column is a complete set of
slots from y=0 to y=yheight-1, for a particular value of x. Columns can correspond to col
elements. In the absence of col
elements, columns are
implied.
A row group is a set of
rows anchored at a slot (0, groupy) with a particular height such that the row group covers all the slots
with coordinates (x, y)
where 0 ≤ x < xwidth and groupy ≤ y < groupy+height. Row groups
correspond to tbody
, thead
, and
tfoot
elements. Not every row is necessarily in a row
group.
A column group is a set
of columns anchored at a slot
(groupx, 0) with a
particular width such that the column group
covers all the slots with coordinates (x, y) where groupx ≤ x < groupx+width and
0 ≤ y < yheight. Column groups
correspond to colgroup
elements. Not every column is
necessarily in a column group.
Row groups cannot overlap each other. Similarly, column groups cannot overlap each other.
A cell cannot cover slots that are from two or more row groups. It is, however, possible for a cell to be in multiple column groups. All the slots that form part of one cell are part of zero or one row groups and zero or more column groups.
In addition to cells, columns, rows, row
groups, and column
groups, tables can have a
caption
element associated with them. This gives the
table a heading, or legend.
A table model error is an error with the data
represented by table
elements and their
descendants. Documents must not have table model errors.
To determine which elements correspond to which slots in a table associated with a
table
element, to determine the dimensions of the table
(xwidth and yheight), and to determine if
there are any table model
errors, user agents must use the following algorithm:
Let xwidth be zero.
Let yheight be zero.
Let pending tfoot
elements be
a list of tfoot
elements, initially empty.
Let the table be the table represented by the
table
element. The xwidth and yheight variables give the
table's dimensions. The table is
initially empty.
If the table
element has no children elements,
then return the table (which will be empty),
and abort these steps.
Associate the first caption
element child of the
table
element with the table. If
there are no such children, then it has no associated
caption
element.
Let the current element be the first
element child of the table
element.
If a step in this algorithm ever requires the current element to be advanced to the next child of the
table
when there is no such next child, then
the user agent must jump to the step labeled end, near the
end of this algorithm.
While the current element is not one of the
following elements, advance the current element to the next child of the
table
:
If the current element is a
colgroup
, follow these substeps:
Column groups: Process the current element according to the appropriate case below:
col
element childrenFollow these steps:
Let xstart have the value of xwidth.
Let the current column be the first
col
element child of the colgroup
element.
Columns: If the current column
col
element has a span
attribute, then parse its
value using the rules for parsing non-negative
integers.
If the result of parsing the value is not an error or zero, then let span be that value.
Otherwise, if the col
element has no span
attribute, or if trying to
parse the attribute's value resulted in an error or zero,
then let span be 1.
Increase xwidth by span.
Let the last span columns in the
table correspond to the current
column col
element.
If current column is not the last
col
element child of the colgroup
element, then let the current column be
the next col
element child of the
colgroup
element, and return to the step
labeled columns.
Let all the last columns in the
table from x=xstart to x=xwidth-1 form a
new column group,
anchored at the slot (xstart, 0), with width xwidth-xstart,
corresponding to the colgroup
element.
col
element childrenIf the colgroup
element has a span
attribute, then parse
its value using the rules for parsing non-negative
integers.
If the result of parsing the value is not an error or zero, then let span be that value.
Otherwise, if the colgroup
element has no
span
attribute, or
if trying to parse the attribute's value resulted in an
error or zero, then let span be 1.
Increase xwidth by span.
Let the last span columns in the
table form a new column group, anchored
at the slot (xwidth-span,
0), with width span, corresponding to
the colgroup
element.
While the current element is not one of
the following elements, advance the current element to the next child of the
table
:
If the current element is a
colgroup
element, jump to the step labeled
column groups above.
Let ycurrent be zero.
Let the list of downward-growing cells be an empty list.
Rows: While the current element is
not one of the following elements, advance the current element to the next child of the
table
:
If the current element is a
tr
, then run the algorithm for processing
rows, advance
the current element to the next child of the
table
, and return to the step labeled
rows.
Run the algorithm for ending a row group.
If the current element is a
tfoot
, then add that element to the list of pending tfoot
elements, advance the current element to the next child of the
table
, and return to the step labeled
rows.
The current element is either a
thead
or a tbody
.
Run the algorithm for processing row groups.
Return to the step labeled rows.
End: For each tfoot
element in the list of
pending tfoot
elements, in tree
order, run the algorithm for processing row
groups.
If there exists a row or column in the table containing only slots that do not have a cell anchored to them, then this is a table model error.
Return the table.
The algorithm for processing row groups, which is
invoked by the set of steps above for processing
thead
, tbody
, and tfoot
elements, is:
Let ystart have the value of yheight.
For each tr
element that is a child of the element
being processed, in tree order, run the algorithm for
processing rows.
If yheight > ystart, then let all the last rows in the table from y=ystart to y=yheight-1 form a new row group, anchored at the slot with coordinate (0, ystart), with height yheight-ystart, corresponding to the element being processed.
Run the algorithm for ending a row group.
The algorithm for ending a row group, which is invoked by the set of steps above when starting and ending a block of rows, is:
While ycurrent is less than yheight, follow these steps:
Increase ycurrent by 1.
Empty the list of downward-growing cells.
The algorithm for processing rows, which is invoked by
the set of steps above for processing tr
elements,
is:
If yheight is equal to ycurrent, then increase yheight by 1. (ycurrent is never greater than yheight.)
Let xcurrent be 0.
If the tr
element being processed has no
td
or th
element children, then increase
ycurrent by 1, abort this
set of steps, and return to the algorithm above.
Let current cell be the first
td
or th
element in the tr
element being processed.
Cells: While xcurrent is less than xwidth and the slot with coordinate (xcurrent, ycurrent) already has a cell assigned to it, increase xcurrent by 1.
If xcurrent is equal to xwidth, increase xwidth by 1. (xcurrent is never greater than xwidth.)
If the current cell has a colspan
attribute, then parse that
attribute's value, and let colspan be
the result.
If parsing that value failed, or returned zero, or if the attribute is absent, then let colspan be 1, instead.
If the current cell has a rowspan
attribute, then parse that attribute's
value, and let rowspan be the
result.
If parsing that value failed or if the attribute is absent, then let rowspan be 1, instead.
If rowspan is zero, then let cell grows downward be true, and set rowspan to 1. Otherwise, let cell grows downward be false.
If xwidth < xcurrent+colspan, then let xwidth be xcurrent+colspan.
If yheight < ycurrent+rowspan, then let yheight be ycurrent+rowspan.
Let the slots with coordinates (x, y) such that xcurrent ≤ x < xcurrent+colspan and ycurrent ≤ y < ycurrent+rowspan be covered by a new cell c, anchored at (xcurrent, ycurrent), which has width colspan and height rowspan, corresponding to the current cell element.
If the current cell element is a
th
element, let this new cell c
be a header cell; otherwise, let it be a data cell.
To establish which header cells apply to the current cell element, use the algorithm for assigning header cells described in the next section.
If any of the slots involved already had a cell covering them, then this is a table model error. Those slots now have two cells overlapping.
If cell grows downward is true, then add the tuple {c, xcurrent, colspan} to the list of downward-growing cells.
Increase xcurrent by colspan.
If current cell is the last td
or th
element in the tr
element being
processed, then increase ycurrent by 1, abort this set of steps, and
return to the algorithm above.
Let current cell be the next
td
or th
element in the tr
element being processed.
Return to the step labelled cells.
When the algorithms above require the user agent to run the algorithm for growing downward-growing cells, the user agent must, for each {cell, cellx, width} tuple in the list of downward-growing cells, if any, extend the cell cell so that it also covers the slots with coordinates (x, ycurrent), where cellx ≤ x < cellx+width.
Each cell can be assigned zero or more header cells. The algorithm for assigning header cells to a cell principal cell is as follows.
Let header list be an empty list of cells.
Let (principalx, principaly) be the coordinate of the slot to which the principal cell is anchored.
headers
attribute specifiedTake the value of the principal cell's
headers
attribute and
split it on
spaces, letting id list be the list
of tokens obtained.
For each token in the id list, if the
first element in the Document
with an ID equal to
the token is a cell in the same table, and that cell is not the
principal cell, then add that cell to header list.
headers
attribute specifiedLet principalwidth be the width of the principal cell.
Let principalheight be the height of the principal cell.
For each value of y from principaly to principaly+principalheight-1, run the internal algorithm for scanning and assigning header cells, with the principal cell, the header list, the initial coordinate (principalx,y), and the increments Δx=−1 and Δy=0.
For each value of x from principalx to principalx+principalwidth-1, run the internal algorithm for scanning and assigning header cells, with the principal cell, the header list, the initial coordinate (x,principaly), and the increments Δx=0 and Δy=−1.
If the principal cell is anchored in a row group, then add all header cells that are row group headers and are anchored in the same row group with an x-coordinate less than or equal to principalx+principalwidth-1 and a y-coordinate less than or equal to principaly+principalheight-1 to header list.
If the principal cell is anchored in a column group, then add all header cells that are column group headers and are anchored in the same column group with an x-coordinate less than or equal to principalx+principalwidth-1 and a y-coordinate less than or equal to principaly+principalheight-1 to header list.
Remove all the empty cells from the header list.
Remove any duplicates from the header list.
Remove principal cell from the header list if it is there.
Assign the headers in the header list to the principal cell.
The internal algorithm for scanning and assigning header cells, given a principal cell, a header list, an initial coordinate (initialx, initialy), and Δx and Δy increments, is as follows:
Let x equal initialx.
Let y equal initialy.
Let opaque headers be an empty list of cells.
Let in header block be true, and let headers from current header block be a list of cells containing just the principal cell.
Let in header block be false and let headers from current header block be an empty list of cells.
Loop: Increment x by Δx; increment y by Δy.
For each invocation of this algorithm, one of Δx and Δy will be −1, and the other will be 0.
If either x or y is less than 0, then abort this internal algorithm.
If there is no cell covering slot (x, y), or if there is more than one cell covering slot (x, y), return to the substep labeled loop.
Let current cell be the cell covering slot (x, y).
Set in header block to true.
Add current cell to headers from current header block.
Let blocked be false.
If there are any cells in the opaque headers list anchored with the same x-coordinate as the current cell, and with the same width as current cell, then let blocked be true.
If the current cell is not a column header, then let blocked be true.
If there are any cells in the opaque headers list anchored with the same y-coordinate as the current cell, and with the same height as current cell, then let blocked be true.
If the current cell is not a row header, then let blocked be true.
If blocked is false, then add the current cell to the headers list.
Set in header block to false. Add all the cells in headers from current header block to the opaque headers list, and empty the headers from current header block list.
Return to the step labeled loop.
A header cell anchored at the slot with coordinate (x, y) with width width and height height is said to be a column header if any of the following conditions are true:
scope
attribute
is in the column state, orscope
attribute
is in the auto state, and
there are no data cells in any of the cells covering slots with
y-coordinates y
.. y+height-1.A header cell anchored at the slot with coordinate (x, y) with width width and height height is said to be a row header if any of the following conditions are true:
scope
attribute
is in the row state, orscope
attribute
is in the auto state, the
cell is not a column header, and there are no data
cells in any of the cells covering slots with x-coordinates x .. x+width-1.A header cell is said to be a column group header if
its scope
attribute is in the
column group state.
A header cell is said to be a row group header if
its scope
attribute is in the
row group state.
A cell is said to be an empty cell if it contains no elements and its text content, if any, consists only of White_Space characters.
This section is non-normative.
The following shows how might one mark up the bottom part of table 45 of the Smithsonian physical tables, Volume 71:
<table> <caption>Specification values: <b>Steel</b>, <b>Castings</b>, Ann. A.S.T.M. A27-16, Class B;* P max. 0.06; S max. 0.05.</caption> <thead> <tr> <th rowspan=2>Grade.</th> <th rowspan=2>Yield Point.</th> <th colspan=2>Ultimate tensile strength</th> <th rowspan=2>Per cent elong. 50.8mm or 2 in.</th> <th rowspan=2>Per cent reduct. area.</th> </tr> <tr> <th>kg/mm<sup>2</sup></th> <th>lb/in<sup>2</sup></th> </tr> </thead> <tbody> <tr> <td>Hard</td> <td>0.45 ultimate</td> <td>56.2</td> <td>80,000</td> <td>15</td> <td>20</td> </tr> <tr> <td>Medium</td> <td>0.45 ultimate</td> <td>49.2</td> <td>70,000</td> <td>18</td> <td>25</td> </tr> <tr> <td>Soft</td> <td>0.45 ultimate</td> <td>42.2</td> <td>60,000</td> <td>22</td> <td>30</td> </tr> </tbody> </table>
This table could look like this:
Grade. | Yield Point. | Ultimate tensile strength | Per cent elong. 50.8 mm or 2 in. | Per cent reduct. area. | |
---|---|---|---|---|---|
kg/mm2 | lb/in2 | ||||
Hard | 0.45 ultimate | 56.2 | 80,000 | 15 | 20 |
Medium | 0.45 ultimate | 49.2 | 70,000 | 18 | 25 |
Soft | 0.45 ultimate | 42.2 | 60,000 | 22 | 30 |
The following shows how one might mark up the gross margin table on page 46 of Apple, Inc's 10-K filing for fiscal year 2008:
<table> <thead> <tr> <th> <th>2008 <th>2007 <th>2006 <tbody> <tr> <th>Net sales <td>$ 32,479 <td>$ 24,006 <td>$ 19,315 <tr> <th>Cost of sales <td> 21,334 <td> 15,852 <td> 13,717 <tbody> <tr> <th>Gross margin <td>$ 11,145 <td>$ 8,154 <td>$ 5,598 <tfoot> <tr> <th>Gross margin percentage <td>34.3% <td>34.0% <td>29.0% </table>
The following shows how one might mark up the operating expenses table from lower on the same page of that document:
<table> <colgroup> <col> <colgroup> <col> <col> <col> <thead> <tr> <th> <th>2008 <th>2007 <th>2006 <tbody> <tr> <th scope=rowgroup> Research and development <td> $ 1,109 <td> $ 782 <td> $ 712 <tr> <th scope=row> Percentage of net sales <td> 3.4% <td> 3.3% <td> 3.7% <tbody> <tr> <th scope=rowgroup> Selling, general, and administrative <td> $ 3,761 <td> $ 2,963 <td> $ 2,433 <tr> <th scope=row> Percentage of net sales <td> 11.6% <td> 12.3% <td> 12.6% </table>
This table could look like this:
2008 | 2007 | 2006 | |
---|---|---|---|
Research and development | $ 1,109 | $ 782 | $ 712 |
Percentage of net sales | 3.4% | 3.3% | 3.7% |
Selling, general, and administrative | $ 3,761 | $ 2,963 | $ 2,433 |
Percentage of net sales | 11.6% | 12.3% | 12.6% |
This section is non-normative.
A form is a component of a Web page that has form controls, such as text fields, buttons, checkboxes, range controls, or color pickers. A user can interact with such a form, providing data that can then be sent to the server for further processing (e.g. returning the results of a search or calculation). No client-side scripting is needed in many cases, though an API is available so that scripts can augment the user experience or use forms for purposes other than submitting data to a server.
Writing a form consists of several steps, which can be performed in any order: writing the user interface, implementing the server-side processing, and configuring the user interface to communicate with the server.
This section is non-normative.
For the purposes of this brief introduction, we will create a pizza ordering form.
Any form starts with a form
element, inside which
are placed the controls. Most controls are represented by the
input
element, which by default provides a one-line
text field. To label a control, the label
element is
used; the label text and the control itself go inside the
label
element. Each part of a form is considered a
paragraph, and is typically separated from other parts
using p
elements. Putting this together, here is how
one might ask for the customer's name:
<form> <p><label>Customer name: <input></label></p> </form>
To let the user select the size of the pizza, we can use a set of
radio buttons. Radio buttons also use the input
element, this time with a type
attribute with the value radio
. To make the radio
buttons work as a group, they are given a common name using the
name
attribute. To group a batch
of controls together, such as, in this case, the radio buttons, one
can use the fieldset
element. The title of such a group
of controls is given by the first element in the
fieldset
, which has to be a legend
element.
<form> <p><label>Customer name: <input></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size> Small </label></p> <p><label> <input type=radio name=size> Medium </label></p> <p><label> <input type=radio name=size> Large </label></p> </fieldset> </form>
Changes from the previous step are highlighted.
To pick toppings, we can use checkboxes. These use the
input
element with a type
attribute with the value checkbox
:
<form> <p><label>Customer name: <input></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size> Small </label></p> <p><label> <input type=radio name=size> Medium </label></p> <p><label> <input type=radio name=size> Large </label></p> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <p><label> <input type=checkbox> Bacon </label></p> <p><label> <input type=checkbox> Extra Cheese </label></p> <p><label> <input type=checkbox> Onion </label></p> <p><label> <input type=checkbox> Mushroom </label></p> </fieldset> </form>
The pizzeria for which this form is being written is always
making mistakes, so it needs a way to contact the customer. For this
purpose, we can use form controls specifically for telephone numbers
(input
elements with their type
attribute set to tel
) and e-mail addresses
(input
elements with their type
attribute set to email
):
<form> <p><label>Customer name: <input></label></p> <p><label>Telephone: <input type=tel></label></p> <p><label>E-mail address: <input type=email></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size> Small </label></p> <p><label> <input type=radio name=size> Medium </label></p> <p><label> <input type=radio name=size> Large </label></p> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <p><label> <input type=checkbox> Bacon </label></p> <p><label> <input type=checkbox> Extra Cheese </label></p> <p><label> <input type=checkbox> Onion </label></p> <p><label> <input type=checkbox> Mushroom </label></p> </fieldset> </form>
We can use an input
element with its type
attribute set to time
to ask for a delivery
time. Many of these form controls have attributes to control exactly
what values can be specified; in this case, three attributes of
particular interest are min
,
max
, and step
. These set the minimum time, the
maximum time, and the interval between allowed values (in
seconds). This pizzeria only delivers between 11am and 9pm, and
doesn't promise anything better than 15 minute increments, which we
can mark up as follows:
<form> <p><label>Customer name: <input></label></p> <p><label>Telephone: <input type=tel></label></p> <p><label>E-mail address: <input type=email></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size> Small </label></p> <p><label> <input type=radio name=size> Medium </label></p> <p><label> <input type=radio name=size> Large </label></p> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <p><label> <input type=checkbox> Bacon </label></p> <p><label> <input type=checkbox> Extra Cheese </label></p> <p><label> <input type=checkbox> Onion </label></p> <p><label> <input type=checkbox> Mushroom </label></p> </fieldset> <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900"></label></p> </form>
The textarea
element can be used to provide a
free-form text field. In this instance, we are going to use it to
provide a space for the customer to give delivery instructions:
<form> <p><label>Customer name: <input></label></p> <p><label>Telephone: <input type=tel></label></p> <p><label>E-mail address: <input type=email></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size> Small </label></p> <p><label> <input type=radio name=size> Medium </label></p> <p><label> <input type=radio name=size> Large </label></p> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <p><label> <input type=checkbox> Bacon </label></p> <p><label> <input type=checkbox> Extra Cheese </label></p> <p><label> <input type=checkbox> Onion </label></p> <p><label> <input type=checkbox> Mushroom </label></p> </fieldset> <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900"></label></p> <p><label>Delivery instructions: <textarea></textarea></label></p> </form>
Finally, to make the form submittable we use the
button
element:
<form> <p><label>Customer name: <input></label></p> <p><label>Telephone: <input type=tel></label></p> <p><label>E-mail address: <input type=email></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size> Small </label></p> <p><label> <input type=radio name=size> Medium </label></p> <p><label> <input type=radio name=size> Large </label></p> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <p><label> <input type=checkbox> Bacon </label></p> <p><label> <input type=checkbox> Extra Cheese </label></p> <p><label> <input type=checkbox> Onion </label></p> <p><label> <input type=checkbox> Mushroom </label></p> </fieldset> <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900"></label></p> <p><label>Delivery instructions: <textarea></textarea></label></p> <p><button>Submit order</button></p> </form>
This section is non-normative.
The exact details for writing a server-side processor are out of
scope for this specification. For the purposes of this introduction,
we will assume that the script at https://pizza.example.com/order.cgi
is configured to
accept submissions using the application/x-www-form-urlencoded
format, expecting the following parameters sent in an HTTP POST
body:
custname
custtel
custemail
size
small
, medium
, or large
toppings
bacon
, cheese
, onion
, and mushroom
delivery
comments
This section is non-normative.
Form submissions are exposed to servers in a variety of ways,
most commonly as HTTP GET or POST requests. To specify the exact
method used, the method
attribute is specified on the form
element. This
doesn't specify how the form data is encoded, though; to specify
that, you use the enctype
attribute. You also have to specify the URL of the
service that will handle the submitted data, using the action
attribute.
For each form control you want submitted, you then have to give a
name that will be used to refer to the data in the submission. We
already specified the name for the group of radio buttons; the same
attribute (name
) also specifies
the submission name. Radio buttons can be distinguished from each
other in the submission by giving them different values, using the
value
attribute.
Multiple controls can have the same name; for example, here we
give all the checkboxes the same name, and the server distinguishes
which checkbox was checked by seeing which values are submitted with
that name — like the radio buttons, they are also given unique
values with the value
attribute.
Given the settings in the previous section, this all becomes:
<form method="post" enctype="application/x-www-form-urlencoded" action="https://pizza.example.com/order.cgi"> <p><label>Customer name: <input name="custname"></label></p> <p><label>Telephone: <input type=tel name="custtel"></label></p> <p><label>E-mail address: <input type=email name="custemail"></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size value="small"> Small </label></p> <p><label> <input type=radio name=size value="medium"> Medium </label></p> <p><label> <input type=radio name=size value="large"> Large </label></p> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p> <p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p> <p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p> <p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p> </fieldset> <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery"></label></p> <p><label>Delivery instructions: <textarea name="comments"></textarea></label></p> <p><button>Submit order</button><p> </form>
For example, if the customer entered "Denise Lawrence" as their name, "555-321-8642" as their telephone number, did not specify an e-mail address, asked for a medium-sized pizza, selected the Extra Cheese and Mushroom toppings, entered a delivery time of 7pm, and left the delivery instructions text field blank, the user agent would submit the following to the online Web service:
custname=Denise+Lawrence&custtel=555-321-8624&custemail=&size=medium&topping=cheese&topping=mushroom&delivery=19%3A00&comments=
This section is non-normative.
Forms can be annotated in such a way that the user agent will check the user's input before the form is submitted. The server still has to verify the input is valid (since hostile users can easily bypass the form validation), but it allows the user to avoid the wait incurred by having the server be the sole checker of the user's input.
The simplest annotation is the required
attribute, which can be
specified on input
elements to indicate that the form
is not to be submitted until a value is given. By adding this
attribute to the customer name and delivery time fields, we allow
the user agent to notify the user when the user submits the form
without filling in those fields:
<form method="post" enctype="application/x-www-form-urlencoded" action="https://pizza.example.com/order.cgi"> <p><label>Customer name: <input name="custname" required></label></p> <p><label>Telephone: <input type=tel name="custtel"></label></p> <p><label>E-mail address: <input type=email name="custemail"></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size value="small"> Small </label></p> <p><label> <input type=radio name=size value="medium"> Medium </label></p> <p><label> <input type=radio name=size value="large"> Large </label></p> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p> <p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p> <p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p> <p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p> </fieldset> <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery" required></label></p> <p><label>Delivery instructions: <textarea name="comments"></textarea></label></p> <p><button>Submit order</button><p> </form>
It is also possible to limit the length of the input, using the
maxlength
attribute. By
adding this to the textarea
element, we can limit users
to 1000 characters, preventing them from writing huge essays to the
busy delivery drivers instead of staying focused and to the
point:
<form method="post" enctype="application/x-www-form-urlencoded" action="https://pizza.example.com/order.cgi"> <p><label>Customer name: <input name="custname" required></label></p> <p><label>Telephone: <input type=tel name="custtel"></label></p> <p><label>E-mail address: <input type=email name="custemail"></label></p> <fieldset> <legend> Pizza Size </legend> <p><label> <input type=radio name=size value="small"> Small </label></p> <p><label> <input type=radio name=size value="medium"> Medium </label></p> <p><label> <input type=radio name=size value="large"> Large </label></p> </fieldset> <fieldset> <legend> Pizza Toppings </legend> <p><label> <input type=checkbox name="topping" value="bacon"> Bacon </label></p> <p><label> <input type=checkbox name="topping" value="cheese"> Extra Cheese </label></p> <p><label> <input type=checkbox name="topping" value="onion"> Onion </label></p> <p><label> <input type=checkbox name="topping" value="mushroom"> Mushroom </label></p> </fieldset> <p><label>Preferred delivery time: <input type=time min="11:00" max="21:00" step="900" name="delivery" required></label></p> <p><label>Delivery instructions: <textarea name="comments" maxlength=1000></textarea></label></p> <p><button>Submit order</button><p> </form>
Mostly for historical reasons, elements in this section fall into several overlapping (but subtly different) categories in addition to the usual ones like flow content, phrasing content, and interactive content.
A number of the elements are form-associated elements, which means they can have a
form owner and, to expose this, have a form
content attribute with a matching
form
IDL attribute.
The form-associated elements fall into several subcategories:
Denotes elements that are listed in the form.elements
and fieldset.elements
APIs.
Denotes elements that can be associated with label
elements.
Denotes elements that can be used for constructing the form data
set when a form
element is submitted.
Denotes elements that can be affected when a form
element is reset.
In addition, some submittable elements can be, depending on their attributes, buttons. The prose below defines when an element is a button. Some buttons are specifically submit buttons.
The object
element is also a
form-associated element and can, with the use of a
suitable plugin, partake in form
submission.
form
elementform
element descendants.accept-charset
action
autocomplete
enctype
method
name
novalidate
target
[OverrideBuiltins] interface HTMLFormElement : HTMLElement { attribute DOMString acceptCharset; attribute DOMString action; attribute DOMString autocomplete; attribute DOMString enctype; attribute DOMString encoding; attribute DOMString method; attribute DOMString name; attribute boolean noValidate; attribute DOMString target; readonly attribute HTMLFormControlsCollection elements; readonly attribute long length; caller getter any (in unsigned long index); caller getter any (in DOMString name); void submit(); void reset(); boolean checkValidity(); };
The form
element represents a
collection of form-associated
elements, some of which can represent editable values that
can be submitted to a server for processing.
The accept-charset
attribute gives the character encodings that are to be used for the
submission. If specified, the value must be an ordered set of
unique space-separated tokens that are ASCII
case-insensitive, and each token must be an ASCII
case-insensitive match for the preferred MIME
name of an ASCII-compatible character encoding.
[IANACHARSET]
The name
attribute
represents the form
's name within the forms
collection. The value must
not be the empty string, and the value must be unique amongst the
form
elements in the forms
collection that it is in, if
any.
The autocomplete
attribute is an enumerated attribute. The attribute has
two states. The on
keyword maps to the on state, and the
off
keyword maps to
the off
state. The attribute may also be omitted. The missing value
default is the on state. The off state indicates
that by default, input
elements in the form will have
their resulting autocompletion state set to off; the on state indicates
that by default, input
elements in the form will have
their resulting autocompletion state set to on.
The action
, enctype
, method
, novalidate
, and target
attributes are attributes
for form submission.
elements
Returns an HTMLCollection
of the form controls in
the form (excluding image buttons for historical reasons).
length
Returns the number of form controls in the form (excluding image buttons for historical reasons).
Returns the indexth element in the form (excluding image buttons for historical reasons).
Returns the form control in the form with the given ID or name
(excluding image buttons for
historical reasons).
Once an element has been referenced using a particular name,
that name will continue being available as a way to reference that
element in this method, even if the element's actual ID or name
changes, for as long as the
element remains in the Document
.
If there are multiple matching items, then a
NodeList
object containing all those elements is
returned.
Returns null if no element with that ID or name
could be found.
submit
()Submits the form.
reset
()Resets the form.
checkValidity
()Returns true if the form's controls are all valid; otherwise, returns false.
The autocomplete
IDL
attribute must reflect the content attribute of the
same name, limited to only known values.
The name
IDL
attribute must reflect the content attribute of the
same name.
The acceptCharset
IDL
attribute must reflect the accept-charset
content
attribute.
The elements
IDL attribute must return an HTMLFormControlsCollection
rooted at the Document
node, whose filter matches listed elements whose form
owner is the form
element, with the exception of
input
elements whose type
attribute is in the Image Button state, which must,
for historical reasons, be excluded from this particular
collection.
The length
IDL
attribute must return the number of nodes represented by the elements
collection.
The supported property indices at any instant are
the indices supported by the object returned by the elements
attribute at that
instant.
When a form
element is indexed for indexed property retrieval,
the user agent must return the value returned by the item
method on
the elements
collection, when
invoked with the given index as its argument.
Each form
element has a mapping of names to elements
called the past names map. It is used to persist names of
controls even when they change names.
The supported property names are the union of the
names currently supported by the object returned by the elements
attribute, and the names
currently in the past names map.
When a form
element is indexed for named property
retrieval, the user agent must run the following steps:
If name is one of the supported
property names of the object returned by the elements
attribute, then run
these substeps:
Let candidate be the object returned
by the namedItem()
method on the object returned by the elements
attribute when passed
the name argument.
If candidate is an element, then add a
mapping from name to candidate in the form
element's
past names map, replacing the previous entry with
the same name, if any.
Return candidate and abort these steps.
Otherwise, name is the name of one of
the entries in the form
element's past names
map: return the object associated with name in that map.
If an element listed in the form
element's past
names map is removed from the Document
, then its
entries must be removed from the map.
The submit()
method, when invoked, must submit the form
element from the form
element itself, with the scripted-submit flag set.
The reset()
method, when invoked, must run the following steps:
If the form
element is marked as locked for
reset, then abort these steps.
Mark the form
element as locked for
reset.
Unmark the form
element as locked for
reset.
If the checkValidity()
method is invoked, the user agent must statically validate the
constraints of the form
element, and return true
if the constraint validation return a positive result, and
false if it returned a negative result.
This example shows two search forms:
<form action="http://www.google.com/search" method="get"> <label>Google: <input type="search" name="q"></label> <input type="submit" value="Search..."> </form> <form action="http://www.bing.com/search" method="get"> <label>Bing: <input type="search" name="q"></label> <input type="submit" value="Search..."> </form>
fieldset
elementlegend
element, followed by flow content.disabled
form
name
interface HTMLFieldSetElement : HTMLElement { attribute boolean disabled; readonly attribute HTMLFormElement form; attribute DOMString name; readonly attribute DOMString type; readonly attribute HTMLFormControlsCollection elements; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); void setCustomValidity(in DOMString error); };
The fieldset
element represents a set
of form controls optionally grouped under a common name.
The name of the group is given by the first legend
element that is a child of the fieldset
element, if
any. The remainder of the descendants form the group.
The disabled
attribute, when specified, causes all the form control descendants
of the fieldset
element, excluding those that are
descendants of the fieldset
element's first
legend
element child, if any, to be disabled.
The form
attribute is used to
explicitly associate the fieldset
element with its
form owner. The name
attribute represents the element's name.
type
Returns the string "fieldset".
elements
Returns an HTMLFormControlsCollection
of the form
controls in the element.
The disabled
IDL
attribute must reflect the content attribute of the
same name.
The type
IDL
attribute must return the string "fieldset
".
The elements
IDL
attribute must return an HTMLFormControlsCollection
rooted at the fieldset
element, whose filter matches
listed elements.
The willValidate
, validity
, and validationMessage
attributes, and the checkValidity()
and setCustomValidity()
methods, are part of the constraint validation API. The
form
and name
IDL attributes are part of the
element's forms API.
Constraint validation: fieldset
elements are always barred from constraint
validation.
The following snippet shows a fieldset with a checkbox in the legend that controls whether or not the fieldset is enabled. The contents of the fieldset consist of two required text fields and an optional year/month control.
<fieldset name="clubfields" disabled> <legend> <label> <input type=checkbox name=club onchange="form.clubfields.disabled = !checked"> Use Club Card </label> </legend> <p><label>Name on card: <input name=clubname required></label></p> <p><label>Card number: <input name=clubnum required pattern="[-0-9]+"></label></p> <p><label>Expiry date: <input name=clubexp type=month></label></p> </fieldset>
You can also nest fieldset
elements. Here is an
example expanding on the previous one that does so:
<fieldset name="clubfields" disabled> <legend> <label> <input type=checkbox name=club onchange="form.clubfields.disabled = !checked"> Use Club Card </label> </legend> <p><label>Name on card: <input name=clubname required></label></p> <fieldset name="numfields"> <legend> <label> <input type=radio checked name=clubtype onchange="form.numfields.disabled = !checked"> My card has numbers on it </label> </legend> <p><label>Card number: <input name=clubnum required pattern="[-0-9]+"></label></p> </fieldset> <fieldset name="letfields" disabled> <legend> <label> <input type=radio name=clubtype onchange="form.letfields.disabled = !checked"> My card has letters on it </label> </legend> <p><label>Card code: <input name=clublet required pattern="[A-Za-z]+"></label></p> </fieldset> </fieldset>
In this example, if the outer "Use Club Card" checkbox is not
checked, everything inside the outer fieldset
,
including the two radio buttons in the legends of the two nested
fieldset
s, will be disabled. However, if the checkbox
is checked, then the radio buttons will both be enabled and will
let you select which of the two inner fieldset
s is to
be enabled.
legend
elementfieldset
element.interface HTMLLegendElement : HTMLElement { readonly attribute HTMLFormElement form; };
The legend
element represents a caption
for the rest of the contents of the legend
element's
parent fieldset
element, if
any.
form
Returns the element's form
element, if any, or
null otherwise.
The form
IDL
attribute's behavior depends on whether the legend
element is in a fieldset
element or not. If the
legend
has a fieldset
element as its
parent, then the form
IDL
attribute must return the same value as the form
IDL attribute on that
fieldset
element. Otherwise, it must return null.
label
elementlabel
elements.form
for
interface HTMLLabelElement : HTMLElement { readonly attribute HTMLFormElement form; attribute DOMString htmlFor; readonly attribute HTMLElement control; };
The label
represents a caption in a
user interface. The caption can be associated with a specific form
control, known as the label
element's labeled control, either using for
attribute, or by putting the form
control inside the label
element itself.
Except where otherwise specified by the following rules, a
label
element has no labeled control.
The for
attribute
may be specified to indicate a form control with which the caption
is to be associated. If the attribute is specified, the attribute's
value must be the ID of a labelable
form-associated element in the same Document
as
the label
element. If the attribute
is specified and there is an element in the Document
whose ID is equal to the value of the for
attribute, and the first such
element is a labelable form-associated
element, then that element is the label
element's labeled control.
If the for
attribute is not
specified, but the label
element has a labelable form-associated element
descendant, then the first such descendant in tree
order is the label
element's labeled
control.
The label
element's exact default presentation and
behavior, in particular what its activation behavior
might be, if anything, should match the platform's label
behavior.
For example, on platforms where clicking a checkbox label checks
the checkbox, clicking the label
in the following
snippet could trigger the user agent to run synthetic click
activation steps on the input
element, as if
the element itself had been triggered by the user:
<label><input type=checkbox name=lost> Lost</label>
On other platforms, the behavior might be just to focus the control, or do nothing.
control
Returns the form control that is associated with this element.
The form
attribute is used to
explicitly associate the label
element with its
form owner.
The htmlFor
IDL
attribute must reflect the for
content attribute.
The control
IDL
attribute must return the label
element's labeled
control, if any, or null if there isn't one.
labels
Returns a NodeList
of all the label
elements that the form control is associated with.
Labelable form-associated
elements have a NodeList
object associated with
them that represents the list of label
elements, in
tree order, whose labeled control is the
element in question. The labels
IDL attribute of
labelable form-associated
elements, on getting, must return that NodeList
object.
The form
IDL attribute is part
of the element's forms API.
The following example shows three form controls each with a label, two of which have small text showing the right format for users to use.
<p><label>Full name: <input name=fn> <small>Format: First Last</small></label></p> <p><label>Age: <input name=age type=number min=0></label></p> <p><label>Post code: <input name=pc> <small>Format: AB12 3CD</small></label></p>
input
elementtype
attribute is not in the Hidden state: Interactive content.type
attribute is not in the Hidden state: Listed, labelable, submittable, and resettable form-associated element.type
attribute is in the Hidden state: Listed, submittable, and resettable form-associated element.accept
alt
autocomplete
autofocus
checked
dirname
disabled
form
formaction
formenctype
formmethod
formnovalidate
formtarget
height
list
max
maxlength
min
multiple
name
pattern
placeholder
readonly
required
size
src
step
type
value
width
interface HTMLInputElement : HTMLElement {
attribute DOMString accept;
attribute DOMString alt;
attribute DOMString autocomplete;
attribute boolean autofocus;
attribute boolean defaultChecked;
attribute boolean checked;
attribute DOMString dirName;
attribute boolean disabled;
readonly attribute HTMLFormElement form;
readonly attribute FileList files;
attribute DOMString formAction;
attribute DOMString formEnctype;
attribute DOMString formMethod;
attribute boolean formNoValidate;
attribute DOMString formTarget;
attribute DOMString height;
attribute boolean indeterminate;
readonly attribute HTMLElement list;
attribute DOMString max;
attribute long maxLength;
attribute DOMString min;
attribute boolean multiple;
attribute DOMString name;
attribute DOMString pattern;
attribute DOMString placeholder;
attribute boolean readOnly;
attribute boolean required;
attribute unsigned long size;
attribute DOMString src;
attribute DOMString step;
attribute DOMString type;
attribute DOMString defaultValue;
attribute DOMString value;
attribute Date valueAsDate;
attribute double valueAsNumber;
readonly attribute HTMLOptionElement selectedOption;
attribute DOMString width;
void stepUp(in optional long n);
void stepDown(in optional long n);
readonly attribute boolean willValidate;
readonly attribute ValidityState validity;
readonly attribute DOMString validationMessage;
boolean checkValidity();
void setCustomValidity(in DOMString error);
readonly attribute NodeList labels;
void select();
attribute unsigned long selectionStart;
attribute unsigned long selectionEnd;
attribute DOMString selectionDirection;
void setSelectionRange(in unsigned long start, in unsigned long end, in optional DOMString direction);
};
The input
element represents a typed data field,
usually with a form control to allow the user to edit the data.
The type
attribute controls the data type (and associated control) of the
element. It is an enumerated attribute. The following
table lists the keywords and states for the attribute — the
keywords in the left column map to the states in the cell in the
second column on the same row as the keyword.
Keyword | State | Data type | Control type |
---|---|---|---|
hidden
| Hidden | An arbitrary string | n/a |
text
| Text | Text with no line breaks | Text field |
search
| Search | Text with no line breaks | Search field |
tel
| Telephone | Text with no line breaks | A text field |
url
| URL | An absolute IRI | A text field |
email
| An e-mail address or list of e-mail addresses | A text field | |
password
| Password | Text with no line breaks (sensitive information) | Text field that obscures data entry |
datetime
| Date and Time | A date and time (year, month, day, hour, minute, second, fraction of a second) with the time zone set to UTC | A date and time control |
date
| Date | A date (year, month, day) with no time zone | A date control |
month
| Month | A date consisting of a year and a month with no time zone | A month control |
week
| Week | A date consisting of a week-year number and a week number with no time zone | A week control |
time
| Time | A time (hour, minute, seconds, fractional seconds) with no time zone | A time control |
datetime-local
| Local Date and Time | A date and time (year, month, day, hour, minute, second, fraction of a second) with no time zone | A date and time control |
number
| Number | A numerical value | A text field or spinner control |
range
| Range | A numerical value, with the extra semantic that the exact value is not important | A slider control or similar |
color
| Color | An sRGB color with 8-bit red, green, and blue components | A color well |
checkbox
| Checkbox | A set of zero or more values from a predefined list | A checkbox |
radio
| Radio Button | An enumerated value | A radio button |
file
| File Upload | Zero or more files each with a MIME type and optionally a file name | A label and a button |
submit
| Submit Button | An enumerated value, with the extra semantic that it must be the last value selected and initiates form submission | A button |
image
| Image Button | A coordinate, relative to a particular image's size, with the extra semantic that it must be the last value selected and initiates form submission | Either a clickable image, or a button |
reset
| Reset Button | n/a | A button |
button
| Button | n/a | A button |
The missing value default is the Text state.
Which of the accept
, alt
, autocomplete
, checked
, dirname
, formaction
, formenctype
, formmethod
, formnovalidate
, formtarget
, height
, list
, max
, maxlength
, min
, multiple
, pattern
, placeholder
, readonly
, required
, size
, src
, step
, and width
content attributes, the checked
, files
, valueAsDate
, valueAsNumber
, list
, and selectedOption
IDL
attributes, the select()
method, the selectionStart
,
selectionEnd
, and
selectionDirection
,
IDL attributes, the setSelectionRange()
method, the stepUp()
and
stepDown()
methods, and the
input
and change
events apply to an
input
element depends on the state of its type
attribute. The following table
is non-normative and summarizes which of
those content attributes, IDL attributes, methods, and events apply
to each state:
Hidden | Text, Search | URL, Telephone | Password | Date and Time, Date, Month, Week, Time | Local Date and Time, Number | Range | Color | Checkbox, Radio Button | File Upload | Submit Button | Image Button | Reset Button, Button | ||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Content attributes | ||||||||||||||
accept
| · | · | · | · | · | · | · | · | · | · | Yes | · | · | · |
alt
| · | · | · | · | · | · | · | · | · | · | · | · | Yes | · |
autocomplete
| · | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | · | · | · | · | · |
checked
| · | · | · | · | · | · | · | · | · | Yes | · | · | · | · |
dirname
| · | Yes | · | · | · | · | · | · | · | · | · | · | · | · |
formaction
| · | · | · | · | · | · | · | · | · | · | · | Yes | Yes | · |
formenctype
| · | · | · | · | · | · | · | · | · | · | · | Yes | Yes | · |
formmethod
| · | · | · | · | · | · | · | · | · | · | · | Yes | Yes | · |
formnovalidate
| · | · | · | · | · | · | · | · | · | · | · | Yes | Yes | · |
formtarget
| · | · | · | · | · | · | · | · | · | · | · | Yes | Yes | · |
height
| · | · | · | · | · | · | · | · | · | · | · | · | Yes | · |
list
| · | Yes | Yes | Yes | · | Yes | Yes | Yes | Yes | · | · | · | · | · |
max
| · | · | · | · | · | Yes | Yes | Yes | · | · | · | · | · | · |
maxlength
| · | Yes | Yes | Yes | Yes | · | · | · | · | · | · | · | · | · |
min
| · | · | · | · | · | Yes | Yes | Yes | · | · | · | · | · | · |
multiple
| · | · | · | Yes | · | · | · | · | · | · | Yes | · | · | · |
pattern
| · | Yes | Yes | Yes | Yes | · | · | · | · | · | · | · | · | · |
placeholder
| · | Yes | Yes | Yes | Yes | · | · | · | · | · | · | · | · | · |
readonly
| · | Yes | Yes | Yes | Yes | Yes | Yes | · | · | · | · | · | · | · |
required
| · | Yes | Yes | Yes | Yes | Yes | Yes | · | · | Yes | Yes | · | · | · |
size
| · | Yes | Yes | Yes | Yes | · | · | · | · | · | · | · | · | · |
src
| · | · | · | · | · | · | · | · | · | · | · | · | Yes | · |
step
| · | · | · | · | · | Yes | Yes | Yes | · | · | · | · | · | · |
width
| · | · | · | · | · | · | · | · | · | · | · | · | Yes | · |
IDL attributes and methods | ||||||||||||||
checked
| · | · | · | · | · | · | · | · | · | Yes | · | · | · | · |
files
| · | · | · | · | · | · | · | · | · | · | Yes | · | · | · |
value
| default | value | value | value | value | value | value | value | value | default/on | filename | default | default | default |
valueAsDate
| · | · | · | · | · | Yes | · | · | · | · | · | · | · | · |
valueAsNumber
| · | · | · | · | · | Yes | Yes | Yes | · | · | · | · | · | · |
list
| · | Yes | Yes | Yes | · | Yes | Yes | Yes | Yes | · | · | · | · | · |
selectedOption
| · | Yes | Yes | Yes† | · | Yes | Yes | Yes | Yes | · | · | · | · | · |
select()
| · | Yes | Yes | · | Yes | · | · | · | · | · | · | · | · | · |
selectionStart
| · | Yes | Yes | · | Yes | · | · | · | · | · | · | · | · | · |
selectionEnd
| · | Yes | Yes | · | Yes | · | · | · | · | · | · | · | · | · |
selectionDirection
| · | Yes | Yes | · | Yes | · | · | · | · | · | · | · | · | · |
setSelectionRange()
| · | Yes | Yes | · | Yes | · | · | · | · | · | · | · | · | · |
stepDown()
| · | · | · | · | · | Yes | Yes | Yes | · | · | · | · | · | · |
stepUp()
| · | · | · | · | · | Yes | Yes | Yes | · | · | · | · | · | · |
Events | ||||||||||||||
input event
| · | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | · | · | · | · | · |
change event
| · | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | · | · | · |
† The dagger symbol (†) indicates that
the feature only applies when the multiple
attribute is not
specified.
Some states of the type
attribute define a value sanitization algorithm.
Each input
element has a value, which is exposed by the value
IDL attribute. Some states
define an algorithm
to convert a string to a number, an algorithm to convert a
number to a string, an algorithm to convert a
string to a Date
object, and an algorithm to convert a
Date
object to a string, which are used by
max
,
min
,
step
,
valueAsDate
,
valueAsNumber
,
stepDown()
, and
stepUp()
.
Each input
element has a boolean dirty value flag. The
dirty value flag
must be initially set to false when the element is created, and must
be set to true whenever the user interacts with the control in a way
that changes the value.
The value
content attribute gives the default value of the input
element. When the value
content attribute is added,
set, or removed, if the control's dirty value flag is
false, the user agent must set the value of the element to the value of
the value
content attribute,
if there is one, or the empty string otherwise, and then run the
current value sanitization algorithm, if one is
defined.
Each input
element has a checkedness, which is exposed by
the checked
IDL
attribute.
Each input
element has a boolean dirty checkedness
flag. When it is true, the element is said to have a dirty
checkedness. The dirty checkedness
flag must be initially set to false when the element is
created, and must be set to true whenever the user interacts with
the control in a way that changes the checkedness.
The checked
content attribute is a boolean attribute that gives the
default checkedness of the
input
element. When the checked
content attribute is
added, if the control does not have dirty checkedness, the user
agent must set the checkedness of the element to
true; when the checked
content attribute is removed, if the control does not have dirty checkedness, the user
agent must set the checkedness of the element to
false.
The reset
algorithm for input
elements is to set the dirty value flag and
dirty checkedness
flag back to false, set the value of the element to the value of
the value
content attribute,
if there is one, or the empty string otherwise, set the checkedness of the element to true
if the element has a checked
content attribute and false if it does not, empty the list of selected files, and
then invoke the value sanitization algorithm, if the
type
attribute's current state
defines one.
Each input
element is either mutable or immutable. Except where
otherwise specified, an input
element is always mutable. Similarly, except where
otherwise specified, the user agent should not allow the user to
modify the element's value or
checkedness.
When an input
element is disabled, it is immutable.
When an input
element does not have a
Document
node as one of its ancestors (i.e. when it is
not in the document), it is immutable.
The readonly
attribute can also in
some cases (e.g. for the Date state, but not the Checkbox state) make an
input
element immutable.
When an input
element is cloned, the element's value, dirty value flag,
checkedness, and dirty checkedness
flag must be propagated to the clone when it is created.
When an input
element is first created, the
element's rendering and behavior must be set to the rendering and
behavior defined for the type
attribute's state, and the value sanitization
algorithm, if one is defined for the type
attribute's state, must be
invoked.
When an input
element's type
attribute changes state, the
user agent must run the following steps:
If the previous state of the element's type
attribute put the value
IDL attribute in the value mode, and the element's
value is not the empty
string, and the new state of the element's type
attribute puts the value
IDL attribute in either the default mode or the default/on mode, then set
the element's value
content
attribute to the element's value.
Otherwise, if the previous state of the element's type
attribute put the value
IDL attribute in any mode
other than the value mode, and
the new state of the element's type
attribute puts the value
IDL attribute in the value mode, then set the value of the element to the value
of the value
content
attribute, if there is one, or the empty string otherwise, and
then set the control's dirty value flag to
false.
Update the element's rendering and behavior to the new state's.
Invoke the value sanitization algorithm, if one
is defined for the type
attribute's new state.
The form
attribute is used to
explicitly associate the input
element with its
form owner. The name
attribute represents the element's name. The disabled
attribute is used to make
the control non-interactive and to prevent its value from being
submitted. The autofocus
attribute controls focus.
The indeterminate
IDL
attribute must initially be set to false. On getting, it must return
the last value it was set to. On setting, it must be set to the new
value. It has no effect except for changing the appearance of checkbox controls.
The accept
, alt
, max
, min
, multiple
, pattern
, placeholder
, required
, size
, src
, and step
IDL attributes must
reflect the respective content attributes of the same
name. The dirName
IDL attribute
must reflect the dirname
content attribute. The readOnly
IDL attribute
must reflect the readonly
content attribute. The
defaultChecked
IDL attribute must reflect the checked
content attribute. The
defaultValue
IDL attribute must reflect the value
content attribute.
The autocomplete
and
type
IDL attributes
must reflect the respective content attributes of the
same name, limited to only known values. The maxLength
IDL
attribute must reflect the maxlength
content attribute,
limited to only non-negative numbers.
The willValidate
, validity
, and validationMessage
attributes, and the checkValidity()
and setCustomValidity()
methods, are part of the constraint validation API. The
labels
attribute provides a list
of the element's label
s. The select()
, selectionStart
,
selectionEnd
,
selectionDirection
,
and setSelectionRange()
methods and attributes expose the element's text selection. The
autofocus
, disabled
, form
, and name
IDL attributes are part of the
element's forms API.
type
attributeThe input
element represents a value
that is not intended to be examined or manipulated by the user.
Constraint validation: If an input
element's type
attribute is in
the Hidden state, it is
barred from constraint validation.
If the name
attribute is
present and has a value that is a case-sensitive match
for the string "_charset_
", then the element's
value
attribute must be
omitted.
The
value
IDL attribute applies to this element and is
in mode default.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
autocomplete
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
list
,
max
,
maxlength
,
min
,
multiple
,
pattern
,
placeholder
,
readonly
,
required
,
size
,
src
,
step
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
list
,
selectedOption
,
selectionStart
,
selectionEnd
,
selectionDirection
,
valueAsDate
, and
valueAsNumber
IDL attributes;
select()
,
setSelectionRange()
,
stepDown()
, and
stepUp()
methods.
When an input
element's type
attribute is in the Text state or the Search state, the rules in
this section apply.
The input
element represents a one line
plain text edit control for the element's value.
The difference between the Text state and the Search state is primarily stylistic: on platforms where search fields are distinguished from regular text fields, the Search state might result in an appearance consistent with the platform's search fields rather than appearing like a regular text field.
If the element is mutable, its value should be editable by the user. User agents must not allow users to insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the element's value.
If the element is mutable, the user agent should allow the user to change the writing direction of the element, setting it either to a left-to-right writing direction or a right-to-left writing direction. If the user does so, the user agent must then run the following steps:
Set the element's dir
attribute to "ltr
" if the user
selected a left-to-right writing direction, and "rtl
" if the user selected a
right-to-left writing direction.
Queue a task to fire a simple
event that bubbles named input
at the input
element.
The value
attribute, if
specified, must have a value that contains no U+000A LINE FEED (LF)
or U+000D CARRIAGE RETURN (CR) characters.
The value sanitization algorithm is as follows: Strip line breaks from the value.
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
,
dirname
,
list
,
maxlength
,
pattern
,
placeholder
,
readonly
,
required
, and
size
content attributes;
list
,
selectedOption
,
selectionStart
,
selectionEnd
,
selectionDirection
, and
value
IDL attributes;
select()
and
setSelectionRange()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
max
,
min
,
multiple
,
src
,
step
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
valueAsDate
, and
valueAsNumber
IDL attributes;
stepDown()
and
stepUp()
methods.
The input
element represents a control
for editing a telephone number given in the element's value.
If the element is mutable, its value should be editable by the user. User agents may change the spacing and, with care, the punctuation of values that the user enters. User agents must not allow users to insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the element's value.
The value
attribute, if
specified, must have a value that contains no U+000A LINE FEED (LF)
or U+000D CARRIAGE RETURN (CR) characters.
The value sanitization algorithm is as follows: Strip line breaks from the value.
Unlike the URL and E-mail types, the Telephone type does not enforce a
particular syntax. This is intentional; in practice, telephone
number fields tend to be free-form fields, because there are a wide
variety of valid phone numbers. Systems that need to enforce a
particular format are encouraged to use the pattern
attribute or the setCustomValidity()
method
to hook into the client-side validation mechanism.
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
,
list
,
maxlength
,
pattern
,
placeholder
,
readonly
,
required
, and
size
content attributes;
list
,
selectedOption
,
selectionStart
,
selectionEnd
,
selectionDirection
, and
value
IDL attributes;
select()
and
setSelectionRange()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
max
,
min
,
multiple
,
src
,
step
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
valueAsDate
, and
valueAsNumber
IDL attributes;
stepDown()
and
stepUp()
methods.
The input
element represents a control
for editing a single absolute URL given in the
element's value.
If the element is mutable, the user agent should allow the user to change the URL represented by its value. User agents may allow the user to set the value to a string that is not a valid absolute URL, but may also or instead automatically escape characters entered by the user so that the value is always a valid absolute URL (even if that isn't the actual value seen and edited by the user in the interface). User agents should allow the user to set the value to the empty string. User agents must not allow users to insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the value.
The value
attribute, if
specified and not empty, must have a value that is a valid URL
potentially surrounded by spaces that is also an
absolute URL.
The value sanitization algorithm is as follows: Strip line breaks from the value, then strip leading and trailing whitespace from the value.
Constraint validation: While the value of the element is neither the empty string nor a valid absolute URL, the element is suffering from a type mismatch.
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
,
list
,
maxlength
,
pattern
,
placeholder
,
readonly
,
required
, and
size
content attributes;
list
,
selectedOption
,
selectionStart
,
selectionEnd
,
selectionDirection
, and
value
IDL attributes;
select()
and
setSelectionRange()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
max
,
min
,
multiple
,
src
,
step
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
valueAsDate
, and
valueAsNumber
IDL attributes;
stepDown()
and
stepUp()
methods.
If a document contained the following markup:
<input type="url" name="location" list="urls"> <datalist id="urls"> <option label="MIME: Format of Internet Message Bodies" value="http://tools.ietf.org/html/rfc2045"> <option label="HTML 4.01 Specification" value="http://www.w3.org/TR/html4/"> <option label="Form Controls" value="http://www.w3.org/TR/xforms/slice8.html#ui-commonelems-hint"> <option label="Scalable Vector Graphics (SVG) 1.1 Specification" value="http://www.w3.org/TR/SVG/"> <option label="Feature Sets - SVG 1.1 - 20030114" value="http://www.w3.org/TR/SVG/feature.html"> <option label="The Single UNIX Specification, Version 3" value="http://www.unix-systems.org/version3/"> </datalist>
...and the user had typed "www.w3", and the user
agent had also found that the user had visited
http://www.w3.org/Consortium/#membership
and
http://www.w3.org/TR/XForms/
in the recent past, then
the rendering might look like this:
The first four URLs in this sample consist of the four URLs in the author-specified list that match the text the user has entered, sorted in some UA-defined manner (maybe by how frequently the user refers to those URLs). Note how the UA is using the knowledge that the values are URLs to allow the user to omit the scheme part and perform intelligent matching on the domain name.
The last two URLs (and probably many more, given the scrollbar's indications of more values being available) are the matches from the user agent's session history data. This data is not made available to the page DOM. In this particular case, the UA has no titles to provide for those values.
How the E-mail state
operates depends on whether the multiple
attribute is specified
or not.
multiple
attribute is not specified on the elementThe input
element represents a
control for editing an e-mail address given in the element's value.
If the element is mutable, the user agent should allow the user to change the e-mail address represented by its value. User agents may allow the user to set the value to a string that is not a valid e-mail address. The user agent should act in a manner consistent with expecting the user to provide a single e-mail address. User agents should allow the user to set the value to the empty string. User agents must not allow users to insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the value. User agents may transform the value for display and editing; in particular, user agents should convert punycode in the value to IDN in the display and vice versa.
The value
attribute, if
specified and not empty, must have a value that is a single
valid e-mail address.
The value sanitization algorithm is as follows: Strip line breaks from the value.
When the multiple
attribute is removed, the user agent must run the value
sanitization algorithm.
Constraint validation: While the value of the element is neither the empty string nor a single valid e-mail address, the element is suffering from a type mismatch.
multiple
attribute is specified on the elementThe element's values are the result of splitting on commas the element's value.
The input
element represents a
control for adding, removing, and editing the e-mail addresses
given in the element's values.
If the element is mutable, the user agent should allow the user to add, remove, and edit the e-mail addresses represented by its values. User agents may allow the user to set any individual value in the list of values to a string that is not a valid e-mail address, but must not allow users to set any individual value to a string containing U+002C COMMA (,), U+000A LINE FEED (LF), or U+000D CARRIAGE RETURN (CR) characters. User agents should allow the user to remove all the addresses in the element's values. User agents may transform the values for display and editing; in particular, user agents should convert punycode in the value to IDN in the display and vice versa.
Whenever the user changes the element's values, the user agent must run the following steps:
Let latest values be a copy of the element's values.
Strip leading and trailing whitespace from each value in latest values.
Let the element's value be the result of concatenating all the values in latest values, separating each value from the next by a single U+002C COMMA character (,), maintaining the list's order.
The value
attribute, if
specified, must have a value that is a valid e-mail address
list.
The value sanitization algorithm is as follows:
Split on commas the element's value, strip leading and trailing whitespace from each resulting token, if any, and let the element's values be the (possibly empty) resulting list of (possibly empty) tokens, maintaining the original order.
Let the element's value be the result of concatenating the element's values, separating each value from the next by a single U+002C COMMA character (,), maintaining the list's order.
When the multiple
attribute is set, the user agent must run the value
sanitization algorithm.
Constraint validation: While the value of the element is not a valid e-mail address list, the element is suffering from a type mismatch.
A valid e-mail address is a string that matches the
ABNF production 1*( atext / "." ) "@" ldh-str *( "." ldh-str )
where atext
is defined in RFC 5322 section
3.2.3, and ldh-str
is defined in RFC 1034
section 3.5. [ABNF] [RFC5322] [RFC1034]
This requirement is a willful violation of RFC 5322, which defines a syntax for e-mail addresses that is simultaneously too strict (before the "@" character), too vague (after the "@" character), and too lax (allowing comments, white space characters, and quoted strings in manners unfamiliar to most users) to be of practical use here.
A valid e-mail address list is a set of comma-separated tokens, where each token is itself a valid e-mail address. To obtain the list of tokens from a valid e-mail address list, and implementation must split the string on commas.
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
,
list
,
maxlength
,
multiple
,
pattern
,
placeholder
,
readonly
,
required
, and
size
content attributes;
list
and
value
IDL attributes.
The following common input
element content
attributes, IDL attributes, and methods apply to the element when
the multiple
attribute is
not specified:
selectedOption
IDL attribute.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
max
,
min
,
src
,
step
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
selectionStart
,
selectionEnd
,
selectionDirection
,
valueAsDate
, and
valueAsNumber
IDL attributes;
select()
,
setSelectionRange()
,
stepDown()
and
stepUp()
methods.
The input
element represents a one line
plain text edit control for the element's value. The user agent should obscure
the value so that people other than the user cannot see it.
If the element is mutable, its value should be editable by the user. User agents must not allow users to insert U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters into the value.
The value
attribute, if
specified, must have a value that contains no U+000A LINE FEED (LF)
or U+000D CARRIAGE RETURN (CR) characters.
The value sanitization algorithm is as follows: Strip line breaks from the value.
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
,
maxlength
,
pattern
,
placeholder
,
readonly
,
required
, and
size
content attributes;
selectionStart
,
selectionEnd
,
selectionDirection
, and
value
IDL attributes;
select()
, and
setSelectionRange()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
list
,
max
,
min
,
multiple
,
src
,
step
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
list
,
selectedOption
,
valueAsDate
, and
valueAsNumber
IDL attributes;
stepDown()
and
stepUp()
methods.
When an input
element's type
attribute is in the Date and Time state, the
rules in this section apply.
The input
element represents a control
for setting the element's value to a string representing a
specific global date and
time. User agents may display the date and
time in whatever time zone is appropriate for the user.
If the element is mutable, the user agent should allow the user to change the global date and time represented by its value, as obtained by parsing a global date and time from it. User agents must not allow the user to set the value to a non-empty string that is not a valid global date and time string expressed in UTC, though user agents may allow the user to set and view the time in another time zone and silently translate the time to and from the UTC time zone in the value. If the user agent provides a user interface for selecting a global date and time, then the value must be set to a valid global date and time string expressed in UTC representing the user's selection. User agents should allow the user to set the value to the empty string.
The format shown to the user is independent of the format used for form submission. Browsers are encouraged to use user interfaces that present dates and times according to the conventions of the user's preferred locale.
The value
attribute, if
specified and not empty, must have a value that is a valid
global date and time string.
The value sanitization algorithm is as follows: If the value of the element is a valid global date and time string, then adjust the time so that the value represents the same point in time but expressed in the UTC time zone, otherwise, set it to the empty string instead.
The min
attribute, if
specified, must have a value that is a valid global date and
time string. The max
attribute, if specified, must have a value that is a valid
global date and time string.
The step
attribute is
expressed in seconds. The step scale factor is 1000
(which converts the seconds to milliseconds, as used in the other
algorithms). The default step is 60
seconds.
When the element is suffering from a step mismatch, the user agent may round the element's value to the nearest global date and time for which the element would not suffer from a step mismatch.
The algorithm to convert a
string to a number, given a string input,
is as follows: If parsing a global date and time from input results in an error, then return an error;
otherwise, return the number of milliseconds elapsed from midnight
UTC on the morning of 1970-01-01 (the time represented by the value
"1970-01-01T00:00:00.0Z
") to the parsed global date and time, ignoring leap
seconds.
The algorithm to convert a
number to a string, given a number input,
is as follows: Return a valid global date and time
string expressed in UTC that represents the global date and time that is input milliseconds after midnight UTC on the morning
of 1970-01-01 (the time represented by the value "1970-01-01T00:00:00.0Z
").
The algorithm to convert a
string to a Date
object, given a string input, is as follows: If parsing a global date and time
from input results in an error, then return an
error; otherwise, return a Date
object representing the
parsed global date and time,
expressed in UTC.
The algorithm to convert a
Date
object to a string, given a
Date
object input, is as
follows: Return a valid global date and time
string expressed in UTC that represents the global date and time that is
represented by input.
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
,
list
,
max
,
min
,
readonly
,
required
, and
step
content attributes;
list
,
value
,
valueAsDate
,
valueAsNumber
, and
selectedOption
IDL attributes;
stepDown()
and
stepUp()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
maxlength
,
multiple
,
pattern
,
placeholder
,
size
,
src
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
selectionStart
,
selectionEnd
, and
selectionDirection
IDL attributes;
select()
and
setSelectionRange()
methods.
The following fragment shows part of a calendar application. A user can specify a date and time for a meeting (in his local time zone, probably, though the user agent can allow the user to change that), and since the submitted data includes the time-zone offset, the application can ensure that the meeting is shown at the correct time regardless of the time zones used by all the participants.
<fieldset> <legend>Add Meeting</legend> <p><label>Meeting name: <input type=text name="meeting.label"></label> <p><label>Meeting time: <input type=datetime name="meeting.start"></label> </fieldset>
Had the application used the datetime-local
type
instead, the calendar application would have also had to explicitly
determine which time zone the user intended.
The input
element represents a control
for setting the element's value to a string representing a
specific date.
If the element is mutable, the user agent should allow the user to change the date represented by its value, as obtained by parsing a date from it. User agents must not allow the user to set the value to a non-empty string that is not a valid date string. If the user agent provides a user interface for selecting a date, then the value must be set to a valid date string representing the user's selection. User agents should allow the user to set the value to the empty string.
The format shown to the user is independent of the format used for form submission. Browsers are encouraged to use user interfaces that present dates according to the conventions of the user's preferred locale.
The value
attribute, if
specified and not empty, must have a value that is a valid
date string.
The value sanitization algorithm is as follows: If the value of the element is not a valid date string, then set it to the empty string instead.
The min
attribute, if
specified, must have a value that is a valid date
string. The max
attribute, if specified, must have a value that is a valid
date string.
The step
attribute is
expressed in days. The step scale factor is
86,400,000 (which converts the days to milliseconds, as used in the
other algorithms). The default step is 1 day.
When the element is suffering from a step mismatch, the user agent may round the element's value to the nearest date for which the element would not suffer from a step mismatch.
The algorithm to convert a
string to a number, given a string input,
is as follows: If parsing
a date from input results in an error,
then return an error; otherwise, return the number of milliseconds
elapsed from midnight UTC on the morning of 1970-01-01 (the time
represented by the value "1970-01-01T00:00:00.0Z
") to midnight UTC on the
morning of the parsed date,
ignoring leap seconds.
The algorithm to convert a
number to a string, given a number input,
is as follows: Return a valid date string that
represents the date that, in UTC,
is current input milliseconds after midnight UTC
on the morning of 1970-01-01 (the time represented by the value
"1970-01-01T00:00:00.0Z
").
The algorithm to convert a
string to a Date
object, given a string input, is as follows: If parsing a date from input
results in an error, then return an error; otherwise, return a
Date
object representing midnight UTC on the morning of
the parsed date.
The algorithm to convert a
Date
object to a string, given a
Date
object input, is as
follows: Return a valid date string that
represents the date current at the
time represented by input in the UTC
time zone.
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
,
list
,
max
,
min
,
readonly
,
required
, and
step
content attributes;
list
,
value
,
valueAsDate
,
valueAsNumber
, and
selectedOption
IDL attributes;
stepDown()
and
stepUp()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
maxlength
,
multiple
,
pattern
,
placeholder
,
size
,
src
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
selectionStart
,
selectionEnd
, and
selectionDirection
IDL attributes;
select()
and
setSelectionRange()
methods.
The input
element represents a control
for setting the element's value to a string representing a
specific month.
If the element is mutable, the user agent should allow the user to change the month represented by its value, as obtained by parsing a month from it. User agents must not allow the user to set the value to a non-empty string that is not a valid month string. If the user agent provides a user interface for selecting a month, then the value must be set to a valid month string representing the user's selection. User agents should allow the user to set the value to the empty string.
The format shown to the user is independent of the format used for form submission. Browsers are encouraged to use user interfaces that present months according to the conventions of the user's preferred locale.
The value
attribute, if
specified and not empty, must have a value that is a valid
month string.
The value sanitization algorithm is as follows: If the value of the element is not a valid month string, then set it to the empty string instead.
The min
attribute, if
specified, must have a value that is a valid month
string. The max
attribute, if specified, must have a value that is a valid
month string.
The step
attribute is
expressed in months. The step scale factor is 1
(there is no conversion needed as the algorithms use months).
The default step is
1 month.
When the element is suffering from a step mismatch, the user agent may round the element's value to the nearest month for which the element would not suffer from a step mismatch.
The algorithm to convert a string to a number, given a string input, is as follows: If parsing a month from input results in an error, then return an error; otherwise, return the number of months between January 1970 and the parsed month.
The algorithm to convert a number to a string, given a number input, is as follows: Return a valid month string that represents the month that has input months between it and January 1970.
The algorithm to convert a
string to a Date
object, given a string input, is as follows: If parsing a month from input results in an error, then return an error;
otherwise, return a Date
object representing midnight
UTC on the morning of the first day of the parsed month.
The algorithm to convert a
Date
object to a string, given a
Date
object input, is as
follows: Return a valid month string that
represents the month current at
the time represented by input in the UTC
time zone.
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
,
list
,
max
,
min
,
readonly
,
required
, and
step
content attributes;
list
,
value
,
valueAsDate
,
valueAsNumber
, and
selectedOption
IDL attributes;
stepDown()
and
stepUp()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
maxlength
,
multiple
,
pattern
,
placeholder
,
size
,
src
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
selectionStart
,
selectionEnd
, and
selectionDirection
IDL attributes;
select()
and
setSelectionRange()
methods.
The input
element represents a control
for setting the element's value to a string representing a
specific week.
If the element is mutable, the user agent should allow the user to change the week represented by its value, as obtained by parsing a week from it. User agents must not allow the user to set the value to a non-empty string that is not a valid week string. If the user agent provides a user interface for selecting a week, then the value must be set to a valid week string representing the user's selection. User agents should allow the user to set the value to the empty string.
The format shown to the user is independent of the format used for form submission. Browsers are encouraged to use user interfaces that present weeks according to the conventions of the user's preferred locale.
The value
attribute, if
specified and not empty, must have a value that is a valid
week string.
The value sanitization algorithm is as follows: If the value of the element is not a valid week string, then set it to the empty string instead.
The min
attribute, if
specified, must have a value that is a valid week
string. The max
attribute, if specified, must have a value that is a valid
week string.
The step
attribute is
expressed in weeks. The step scale factor is
604,800,000 (which converts the weeks to milliseconds, as used in
the other algorithms). The default step is 1
week. The default step base is
−259,200,000 (the start of week 1970-W01).
When the element is suffering from a step mismatch, the user agent may round the element's value to the nearest week for which the element would not suffer from a step mismatch.
The algorithm to convert a
string to a number, given a string input,
is as follows: If parsing
a week string from input results in an
error, then return an error; otherwise, return the number of
milliseconds elapsed from midnight UTC on the morning of 1970-01-01
(the time represented by the value "1970-01-01T00:00:00.0Z
") to midnight UTC on the
morning of the Monday of the parsed week, ignoring leap seconds.
The algorithm to convert a
number to a string, given a number input,
is as follows: Return a valid week string that
represents the week that, in UTC,
is current input milliseconds after midnight UTC
on the morning of 1970-01-01 (the time represented by the value
"1970-01-01T00:00:00.0Z
").
The algorithm to convert a
string to a Date
object, given a string input, is as follows: If parsing a week from input
results in an error, then return an error; otherwise, return a
Date
object representing midnight UTC on the morning of
the Monday of the parsed week.
The algorithm to convert a
Date
object to a string, given a
Date
object input, is as
follows: Return a valid week string that
represents the week current at the
time represented by input in the UTC
time zone.
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
,
list
,
max
,
min
,
readonly
,
required
, and
step
content attributes;
list
,
value
,
valueAsDate
,
valueAsNumber
, and
selectedOption
IDL attributes;
stepDown()
and
stepUp()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
maxlength
,
multiple
,
pattern
,
placeholder
,
size
,
src
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
selectionStart
,
selectionEnd
, and
selectionDirection
IDL attributes;
select()
and
setSelectionRange()
methods.
The input
element represents a control
for setting the element's value to a string representing a
specific time.
If the element is mutable, the user agent should allow the user to change the time represented by its value, as obtained by parsing a time from it. User agents must not allow the user to set the value to a non-empty string that is not a valid time string. If the user agent provides a user interface for selecting a time, then the value must be set to a valid time string representing the user's selection. User agents should allow the user to set the value to the empty string.
The format shown to the user is independent of the format used for form submission. Browsers are encouraged to use user interfaces that present times according to the conventions of the user's preferred locale.
The value
attribute, if
specified and not empty, must have a value that is a valid
time string.
The value sanitization algorithm is as follows: If the value of the element is not a valid time string, then set it to the empty string instead.
The min
attribute, if
specified, must have a value that is a valid time
string. The max
attribute, if specified, must have a value that is a valid
time string.
The step
attribute is
expressed in seconds. The step scale factor is 1000
(which converts the seconds to milliseconds, as used in the other
algorithms). The default step is 60
seconds.
When the element is suffering from a step mismatch, the user agent may round the element's value to the nearest time for which the element would not suffer from a step mismatch.
The algorithm to convert a string to a number, given a string input, is as follows: If parsing a time from input results in an error, then return an error; otherwise, return the number of milliseconds elapsed from midnight to the parsed time on a day with no time changes.
The algorithm to convert a number to a string, given a number input, is as follows: Return a valid time string that represents the time that is input milliseconds after midnight on a day with no time changes.
The algorithm to convert a
string to a Date
object, given a string input, is as follows: If parsing a time from input
results in an error, then return an error; otherwise, return a
Date
object representing the parsed time in UTC on 1970-01-01.
The algorithm to convert a
Date
object to a string, given a
Date
object input, is as
follows: Return a valid time string that
represents the UTC time component
that is represented by input.
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
,
list
,
max
,
min
,
readonly
,
required
, and
step
content attributes;
list
,
value
,
valueAsDate
,
valueAsNumber
, and
selectedOption
IDL attributes;
stepDown()
and
stepUp()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
maxlength
,
multiple
,
pattern
,
placeholder
,
size
,
src
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
selectionStart
,
selectionEnd
, and
selectionDirection
IDL attributes;
select()
and
setSelectionRange()
methods.
When an input
element's type
attribute is in the Local Date and Time
state, the rules in this section apply.
The input
element represents a control
for setting the element's value to a string representing a
local date and time,
with no time-zone offset information.
If the element is mutable, the user agent should allow the user to change the date and time represented by its value, as obtained by parsing a date and time from it. User agents must not allow the user to set the value to a non-empty string that is not a valid local date and time string. If the user agent provides a user interface for selecting a local date and time, then the value must be set to a valid local date and time string representing the user's selection. User agents should allow the user to set the value to the empty string.
The format shown to the user is independent of the format used for form submission. Browsers are encouraged to use user interfaces that present dates and times according to the conventions of the user's preferred locale.
The value
attribute, if
specified and not empty, must have a value that is a valid
local date and time string.
The value sanitization algorithm is as follows: If the value of the element is not a valid local date and time string, then set it to the empty string instead.
The min
attribute, if
specified, must have a value that is a valid local date and
time string. The max
attribute, if specified, must have a value that is a valid
local date and time string.
The step
attribute is
expressed in seconds. The step scale factor is 1000
(which converts the seconds to milliseconds, as used in the other
algorithms). The default step is 60
seconds.
When the element is suffering from a step mismatch, the user agent may round the element's value to the nearest local date and time for which the element would not suffer from a step mismatch.
The algorithm to convert a
string to a number, given a string input,
is as follows: If parsing a date and time from input results in an error, then return an error;
otherwise, return the number of milliseconds elapsed from midnight
on the morning of 1970-01-01 (the time represented by the value
"1970-01-01T00:00:00.0
") to the parsed local date and time, ignoring
leap seconds.
The algorithm to convert a
number to a string, given a number input,
is as follows: Return a valid local date and time
string that represents the date and time that is input milliseconds after midnight on the morning of
1970-01-01 (the time represented by the value "1970-01-01T00:00:00.0
").
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
,
list
,
max
,
min
,
readonly
,
required
, and
step
content attributes;
list
,
value
,
valueAsNumber
, and
selectedOption
IDL attributes;
stepDown()
and
stepUp()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
maxlength
,
multiple
,
pattern
,
placeholder
,
size
,
src
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
selectionStart
,
selectionEnd
,
selectionDirection
, and
valueAsDate
IDL attributes;
select()
and
setSelectionRange()
methods.
The following example shows part of a flight booking
application. The application uses an input
element
with its type
attribute set to
datetime-local
,
and it then interprets the given date and time in the time zone of
the selected airport.
<fieldset> <legend>Destination</legend> <p><label>Airport: <input type=text name=to list=airports></label></p> <p><label>Departure time: <input type=datetime-local name=totime step=3600></label></p> </fieldset> <datalist id=airports> <option value=ATL label="Atlanta"> <option value=MEM label="Memphis"> <option value=LHR label="London Heathrow"> <option value=LAX label="Los Angeles"> <option value=FRA label="Frankfurt"> </datalist>
If the application instead used the datetime
type, then the
user would have to work out the time-zone conversions himself,
which is clearly not a good user experience!
The input
element represents a control
for setting the element's value to a string representing a
number.
If the element is mutable, the user agent should allow the user to change the number represented by its value, as obtained from applying the rules for parsing floating point number values to it. User agents must not allow the user to set the value to a non-empty string that is not a valid floating point number. If the user agent provides a user interface for selecting a number, then the value must be set to the best representation of the number representing the user's selection as a floating point number. User agents should allow the user to set the value to the empty string.
The value
attribute, if
specified and not empty, must have a value that is a valid
floating point number.
The value sanitization algorithm is as follows: If the value of the element is not a valid floating point number, then set it to the empty string instead.
The min
attribute, if
specified, must have a value that is a valid floating point
number. The max
attribute, if specified, must have a value that is a valid
floating point number.
The step scale factor is
1. The default
step is 1 (allowing only integers, unless the min
attribute has a non-integer
value).
When the element is suffering from a step mismatch, the user agent may round the element's value to the nearest number for which the element would not suffer from a step mismatch. If there are two such numbers, user agents are encouraged to pick the one nearest positive infinity.
The algorithm to convert a string to a number, given a string input, is as follows: If applying the rules for parsing floating point number values to input results in an error, then return an error; otherwise, return the resulting number.
The algorithm to convert a number to a string, given a number input, is as follows: Return a valid floating point number that represents input.
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
,
list
,
max
,
min
,
readonly
,
required
, and
step
content attributes;
list
,
value
,
valueAsNumber
, and
selectedOption
IDL attributes;
stepDown()
and
stepUp()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
maxlength
,
multiple
,
pattern
,
placeholder
,
size
,
src
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
selectionStart
,
selectionEnd
,
selectionDirection
, and
valueAsDate
IDL attributes;
select()
and
setSelectionRange()
methods.
The input
element represents a control
for setting the element's value to a string representing a
number, but with the caveat that the exact value is not important,
letting UAs provide a simpler interface than they do for the Number state.
In this state, the range and step constraints are enforced even during user input, and there is no way to set the value to the empty string.
If the element is mutable, the user agent should allow the user to change the number represented by its value, as obtained from applying the rules for parsing floating point number values to it. User agents must not allow the user to set the value to a string that is not a valid floating point number. If the user agent provides a user interface for selecting a number, then the value must be set to a best representation of the number representing the user's selection as a floating point number. User agents must not allow the user to set the value to the empty string.
The value
attribute, if
specified, must have a value that is a valid floating point
number.
The value sanitization algorithm is as follows: If the value of the element is not a valid floating point number, then set it to a valid floating point number that represents the default value.
The min
attribute, if
specified, must have a value that is a valid floating point
number. The default
minimum is 0. The max
attribute, if specified, must have a value that is a valid
floating point number. The default maximum is 100.
The default value is the minimum plus half the difference between the minimum and the maximum, unless the maximum is less than the minimum, in which case the default value is the minimum.
When the element is suffering from an underflow, the user agent must set the element's value to a valid floating point number that represents the minimum.
When the element is suffering from an overflow, if the maximum is not less than the minimum, the user agent must set the element's value to a valid floating point number that represents the maximum.
The step scale factor is
1. The default
step is 1 (allowing only integers, unless the min
attribute has a non-integer
value).
When the element is suffering from a step mismatch, the user agent must round the element's value to the nearest number for which the element would not suffer from a step mismatch, and which is greater than or equal to the minimum, and, if the maximum is not less than the minimum, which is less than or equal to the maximum. If two numbers match these constraints, then user agents must use the one nearest to positive infinity.
For example, the markup
<input type="range" min=0 max=100 step=20 value=50>
results in a range control whose initial value is 60.
The algorithm to convert a string to a number, given a string input, is as follows: If applying the rules for parsing floating point number values to input results in an error, then return an error; otherwise, return the resulting number.
The algorithm to convert a number to a string, given a number input, is as follows: Return a valid floating point number that represents input.
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
,
list
,
max
,
min
, and
step
content attributes;
list
,
value
,
valueAsNumber
, and
selectedOption
IDL attributes;
stepDown()
and
stepUp()
methods.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
maxlength
,
multiple
,
pattern
,
placeholder
,
readonly
,
required
,
size
,
src
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
selectionStart
,
selectionEnd
,
selectionDirection
, and
valueAsDate
IDL attributes;
select()
and
setSelectionRange()
methods.
Here is an example of a range control using an autocomplete list
with the list
attribute. This
could be useful if there are values along the full range of the
control that are especially important, such as preconfigured light
levels or typical speed limits in a range control used as a speed
control. The following markup fragment:
<input type="range" min="-100" max="100" value="0" step="10" name="power" list="powers"> <datalist id="powers"> <option value="0"> <option value="-30"> <option value="30"> <option value="+50"> </datalist>
...with the following style sheet applied:
input { height: 75px; width: 49px; background: #D5CCBB; color: black; }
...might render as:
Note how the UA determined the orientation of the control from
the ratio of the style-sheet-specified height and width properties.
The colors were similiarly derived from the style sheet. The tick
marks, however, were derived from the markup. In particular, the
step
attribute has not
affected the placement of tick marks, the UA deciding to only use
the author-specified completion values and then adding longer tick
marks at the extremes.
Note also how the invalid value +50
was
completely ignored.
For another example, consider the following markup fragment:
<input name=x type=range min=100 max=700 step=9.09090909 value=509.090909>
A user agent could display in a variety of ways, for instance:
Or, alternatively, for instance:
The user agent could pick which one to display based on the dimensions given in the style sheet. This would allow it to maintain the same resolution for the tick marks, despite the differences in width.
The input
element represents a color
well control, for setting the element's value to a string representing a
simple color.
In this state, there is always a color picked, and there is no way to set the value to the empty string.
If the element is mutable, the user agent should allow the user to change the color represented by its value, as obtained from applying the rules for parsing simple color values to it. User agents must not allow the user to set the value to a string that is not a valid lowercase simple color. If the user agent provides a user interface for selecting a color, then the value must be set to the result of using the rules for serializing simple color values to the user's selection. User agents must not allow the user to set the value to the empty string.
The value
attribute, if
specified and not empty, must have a value that is a valid
simple color.
The value sanitization algorithm is as
follows: If the value
of the element is a valid simple color, then set it to
the value of the element
converted to ASCII lowercase; otherwise, set it to the string
"#000000
".
The following common input
element content
attributes, IDL attributes, and methods apply to the element:
autocomplete
and
list
content attributes;
list
,
value
, and
selectedOption
IDL attributes.
The value
IDL attribute is
in mode value.
The input
and change
events apply.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
maxlength
,
max
,
min
,
multiple
,
pattern
,
placeholder
,
readonly
,
required
,
size
,
src
,
step
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
selectionStart
,
selectionEnd
,
selectionDirection
,
valueAsDate
, and
valueAsNumber
IDL attributes;
select()
,
setSelectionRange()
,
stepDown()
, and
stepUp()
methods.
The input
element represents a
two-state control that represents the element's checkedness state. If the
element's checkedness state
is true, the control represents a positive selection, and if it is
false, a negative selection. If the element's indeterminate
IDL attribute
is set to true, then the control's selection should be obscured as
if the control was in a third, indeterminate, state.
The control is never a true tri-state control, even
if the element's indeterminate
IDL attribute
is set to true. The indeterminate
IDL attribute
only gives the appearance of a third state.
If the element is mutable,
then: The pre-click activation steps consist of setting
the element's checkedness to
its opposite value (i.e. true if it is false, false if it is true),
and of setting the element's indeterminate
IDL attribute
to false. The canceled activation steps consist of
setting the checkedness and
the element's indeterminate
IDL attribute
back to the values they had before the pre-click activation
steps were run. The activation behavior is to
fire a simple event that bubbles named change
at the element.
Constraint validation: If the element is required and its checkedness is false, then the element is suffering from being missing.
indeterminate
[ = value ]When set, overrides the rendering of checkbox controls so that the current value is not visible.
The following common input
element content
attributes and IDL attributes apply to the element:
checked
, and
required
content attributes;
checked
and
value
IDL attributes.
The value
IDL attribute is
in mode default/on.
The change
event applies.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
autocomplete
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
list
,
max
,
maxlength
,
min
,
multiple
,
pattern
,
placeholder
,
readonly
,
size
,
src
,
step
, and
width
.
The following IDL attributes and methods do not apply to the
element:
files
,
list
,
selectedOption
,
selectionStart
,
selectionEnd
,
selectionDirection
,
valueAsDate
, and
valueAsNumber
IDL attributes;
select()
,
setSelectionRange()
,
stepDown()
, and
stepUp()
methods.
The input
event does not apply.
When an input
element's type
attribute is in the Radio Button state, the rules
in this section apply.
The input
element represents a control
that, when used in conjunction with other input
elements, forms a radio button group in which only one
control can have its checkedness state set to true. If
the element's checkedness
state is true, the control represents the selected control in the
group, and if it is false, it indicates a control in the group that
is not selected.
The radio button group that contains an
input
element a also contains all
the other input
elements b that
fulfill all of the following conditions:
input
element b's type
attribute is in the Radio Button state.name
attribute, their name
attributes
are not empty, and the value of a's name
attribute is a compatibility
caseless match for the value of b's
name
attribute.A document must not contain an input
element whose
radio button group contains only that element.
When any of the following phenomena occur, if the element's checkedness state is true after the occurrence, the checkedness state of all the other elements in the same radio button group must be set to false:
name
attribute
is set, changed, or removed.If the element is mutable,
then: The pre-click activation steps consist of setting
the element's checkedness to
true. The canceled activation steps consist of setting
the element's checkedness to
false. The activation behavior is to fire a
simple event that bubbles named change
at the element. .
Constraint validation: If an element in the
radio button group is required, and all of the
input
elements in the radio button group have a
checkedness that is false,
then the element is suffering from being missing.
If none of the radio buttons in a radio button group are checked when they are inserted into the document, then they will all be initially unchecked in the interface, until such time as one of them is checked (either by the user or by script).
The following common input
element content
attributes and IDL attributes apply to the element:
checked
and
required
content attributes;
checked
and
value
IDL attributes.
The value
IDL attribute is
in mode default/on.
The change
event applies.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
autocomplete
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
list
,
max
,
maxlength
,
min
,
multiple
,
pattern
,
placeholder
,
readonly
,
size
,
src
,
step
, and
width
.
The following IDL attributes and methods do not apply to the
element:
files
,
list
,
selectedOption
,
selectionStart
,
selectionEnd
,
selectionDirection
,
valueAsDate
, and
valueAsNumber
IDL attributes;
select()
,
setSelectionRange()
,
stepDown()
, and
stepUp()
methods.
The input
event does not apply.
When an input
element's type
attribute is in the File Upload state, the rules in this
section apply.
The input
element represents a list of
selected files,
each file consisting of a file name, a file type, and a file body
(the contents of the file).
File names may contain partial paths, e.g. in the case that a user has selected an entire directory hierarchy. Path components should be separated from each other using U+005C REVERSE SOLIDUS character (\).
If the element is mutable, the user agent should allow the user to change the files on the list, e.g. adding or removing files. Files can be from the filesystem or created on the fly, e.g. a picture taken from a camera connected to the user's device.
Constraint validation: If the element is required and the list of selected files is empty, then the element is suffering from being missing.
Unless the multiple
attribute is set, there must be no more than one file in the list of
selected
files.
The accept
attribute may be specified to provide user agents with a hint of
what file types will be accepted.
If specified, the attribute must consist of a set of comma-separated tokens, each of which must be an ASCII case-insensitive match for one of the following:
audio/*
video/*
image/*
The tokens must not be ASCII case-insensitive matches for any of the other tokens (i.e. duplicates are not allowed). To obtain the list of tokens from the attribute, the user agent must split the attribute value on commas.
User agents may use the value of this attribute to display a more
appropriate user interface than a generic file picker. For instance,
given the value image/*
, a user agent could
offer the user the option of using a local camera or selecting a
photograph from their photo collection; given the value audio/*
, a user agent could offer the user the
option of recording a clip using a headset microphone.
User agents should prevent the user from selecting files that are not accepted by one (or more) of these tokens.
For historical reasons, the value
IDL attribute prefixes the
filename with the string "C:\fakepath\
". Some
legacy user agents actually included the full path (which was a
security vulnerability). As a result of this, obtaining the
filename from the value
IDL
attribute in a backwards-compatible way is non-trivial. The
following function extracts the filename in a suitably compatible
manner:
function extractFilename(path) { var x; x = path.lastIndexOf('\\'); if (x >= 0) // Windows-based path return path.substr(x+1); x = path.lastIndexOf('/'); if (x >= 0) // Unix-based path return path.substr(x+1); return path; // just the filename }
This can be used as follows:
<p><input type=file name=image onchange="updateFilename(this.value)"></p> <p>The name of the file you picked is: <span id="filename">(none)</span></p> <script> function updateFilename(path) { var name = extractFilename(path); document.getElementById('filename').textContent = name; } </script>
The following common input
element content
attributes apply to the element:
The following common input
element content
attributes and IDL attributes apply to the element:
accept
,
multiple
, and
required
;
files
and
value
IDL attributes.
The value
IDL attribute is
in mode filename.
The change
event applies.
The following content attributes must not be specified and do not
apply to the element:
alt
,
autocomplete
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
list
,
max
,
maxlength
,
min
,
pattern
,
placeholder
,
readonly
,
size
,
src
,
step
, and
width
.
The element's value
attribute must be omitted.
The following IDL attributes and methods do not apply to the
element:
checked
,
list
,
selectedOption
,
selectionStart
,
selectionEnd
,
selectionDirection
,
valueAsDate
, and
valueAsNumber
IDL attributes;
select()
,
setSelectionRange()
,
stepDown()
, and
stepUp()
methods.
The input
event does not apply.
When an input
element's type
attribute is in the Submit Button state, the rules
in this section apply.
The input
element represents a button
that, when activated, submits the form. If the
element has a value
attribute,
the button's label must be the value of that attribute; otherwise,
it must be an implementation-defined string that means "Submit" or
some such. The element is a button, specifically a submit button.
If the element is mutable, the user agent should allow the user to activate the element.
The element's activation behavior, if the element
has a form owner, is to submit the form
owner from the input
element; otherwise, it is
to do nothing.
The formaction
, formenctype
, formmethod
, formnovalidate
, and formtarget
attributes are attributes
for form submission.
The formnovalidate
attribute can
be used to make submit buttons that do not trigger the constraint
validation.
The following common input
element content
attributes and IDL attributes apply to the element:
formaction
,
formenctype
,
formmethod
,
formnovalidate
, and
formtarget
content attributes;
value
IDL attribute.
The value
IDL attribute is
in mode default.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
autocomplete
,
checked
,
dirname
,
height
,
list
,
max
,
maxlength
,
min
,
multiple
,
pattern
,
placeholder
,
readonly
,
required
,
size
,
src
,
step
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
list
,
selectedOption
,
selectionStart
,
selectionEnd
,
selectionDirection
,
valueAsDate
, and
valueAsNumber
IDL attributes;
select()
,
setSelectionRange()
,
stepDown()
, and
stepUp()
methods.
When an input
element's type
attribute is in the Image Button state, the rules
in this section apply.
The input
element represents either an
image from which a user can select a coordinate and submit the form,
or alternatively a button from which the user can submit the
form. The element is a button,
specifically a submit
button.
The image is given by the src
attribute. The src
attribute must be present, and
must contain a valid non-empty URL potentially surrounded by
spaces referencing a non-interactive, optionally animated,
image resource that is neither paged nor scripted.
When any of the following events occur, unless the user agent
cannot support images, or its support for images has been disabled,
or the user agent only fetches elements on demand, or the src
attribute's value is the empty
string, the user agent must resolve the value of the src
attribute, relative to the
element, and if that is successful, must fetch the
resulting absolute URL:
input
element's type
attribute is first set to the
Image Button state
(possibly when the element is first created), and the src
attribute is present.input
element's type
attribute is changed back to
the Image Button state,
and the src
attribute is
present, and its value has changed since the last time the type
attribute was in the Image Button state.input
element's type
attribute is in the Image Button state, and the
src
attribute is set or
changed.Fetching the image must delay the load event of the element's document until the task that is queued by the networking task source once the resource has been fetched (defined below) has been run.
If the image was successfully obtained, with no network errors, and the image's type is a supported image type, and the image is a valid image of that type, then the image is said to be available. If this is true before the image is completely downloaded, each task that is queued by the networking task source while the image is being fetched must update the presentation of the image appropriately.
The user agents should apply the image sniffing rules to determine the type of the image, with the image's associated Content-Type headers giving the official type. If these rules are not applied, then the type of the image must be the type given by the image's associated Content-Type headers.
User agents must not support non-image resources with the
input
element. User agents must not run executable code
embedded in the image resource. User agents must only display the
first page of a multipage resource. User agents must not allow the
resource to act in an interactive fashion, but should honor any
animation in the resource.
The task that is queued by the networking task
source once the resource has been fetched, must, if the download was successful
and the image is available,
queue a task to fire a simple event named
load
at the input
element; and otherwise, if the fetching process fails without a
response from the remote server, or completes but the image is not a
valid or supported image, queue a task to fire a
simple event named error
on
the input
element.
The alt
attribute
provides the textual label for the alternative button for users and
user agents who cannot use the image. The alt
attribute must also be present,
and must contain a non-empty string.
The input
element supports dimension
attributes.
If the src
attribute is set,
and the image is available and
the user agent is configured to display that image, then: The
element represents a control for selecting a coordinate from
the image specified by the src
attribute; if the element is mutable, the user agent should
allow the user to select this coordinate. The
activation behavior in this case consists of taking the
user's selected coordinate, and
then, if the element has a form owner, submitting the input
element's form owner from the input
element. If the user activates the control without explicitly
selecting a coordinate, then the coordinate (0,0) must be
assumed.
Otherwise, the element represents a submit button
whose label is given by the value of the alt
attribute; if the element is mutable, the user agent should
allow the user to activate the button. The activation
behavior in this case consists of setting the selected
coordinate to (0,0), and then, if the element has a
form owner, submitting the input
element's form owner from the input
element.
The selected coordinate must consist of an x-component and a y-component. The coordinates represent the position relative to the edge of the image, with the coordinate space having the positive x direction to the right, and the positive y direction downwards.
The x-component must be a valid integer representing a number x in the range −(borderleft+paddingleft) ≤ x ≤ width+borderright+paddingright, where width is the rendered width of the image, borderleft is the width of the border on the left of the image, paddingleft is the width of the padding on the left of the image, borderright is the width of the border on the right of the image, and paddingright is the width of the padding on the right of the image, with all dimensions given in CSS pixels.
The y-component must be a valid integer representing a number y in the range −(bordertop+paddingtop) ≤ y ≤ height+borderbottom+paddingbottom, where height is the rendered height of the image, bordertop is the width of the border above the image, paddingtop is the width of the padding above the image, borderbottom is the width of the border below the image, and paddingbottom is the width of the padding below the image, with all dimensions given in CSS pixels.
Where a border or padding is missing, its width is zero CSS pixels.
The formaction
, formenctype
, formmethod
, formnovalidate
, and formtarget
attributes are attributes
for form submission.
The following common input
element content
attributes and IDL attributes apply to the element:
alt
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
src
, and
width
content attributes;
value
IDL attribute.
The value
IDL attribute is
in mode default.
The following content attributes must not be specified and do not
apply to the element:
accept
,
autocomplete
,
checked
,
dirname
,
list
,
max
,
maxlength
,
min
,
multiple
,
pattern
,
placeholder
,
readonly
,
required
,
size
, and
step
.
The element's value
attribute must be omitted.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
list
,
selectedOption
,
selectionStart
,
selectionEnd
,
selectionDirection
,
valueAsDate
, and
valueAsNumber
IDL attributes;
select()
,
setSelectionRange()
,
stepDown()
, and
stepUp()
methods.
Many aspects of this state's behavior are similar to
the behavior of the img
element. Readers are encouraged
to read that section, where many of the same requirements are
described in more detail.
When an input
element's type
attribute is in the Reset Button state, the rules
in this section apply.
The input
element represents a button
that, when activated, resets the form. If the
element has a value
attribute,
the button's label must be the value of that attribute; otherwise,
it must be an implementation-defined string that means "Reset" or
some such. The element is a button.
If the element is mutable, the user agent should allow the user to activate the element.
The element's activation behavior, if the element has a form owner, is to reset the form owner; otherwise, it is to do nothing.
Constraint validation: The element is barred from constraint validation.
The value
IDL attribute
applies to this element and is in mode default.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
autocomplete
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
list
,
max
,
maxlength
,
min
,
multiple
,
pattern
,
placeholder
,
readonly
,
required
,
size
,
src
,
step
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
list
,
selectedOption
,
selectionStart
,
selectionEnd
,
selectionDirection
,
valueAsDate
, and
valueAsNumber
IDL attributes;
select()
,
setSelectionRange()
,
stepDown()
, and
stepUp()
methods.
The input
element represents a button
with no default behavior. A label for the button must be provided in
the value
attribute, though it
may be the empty string. If the element has a
value
attribute, the button's
label must be the value of that attribute; otherwise, it must be the
empty string. The element is a button.
If the element is mutable, the user agent should allow the user to activate the element. The element's activation behavior is to do nothing.
Constraint validation: The element is barred from constraint validation.
The value
IDL attribute
applies to this element and is in mode default.
The following content attributes must not be specified and do not
apply to the element:
accept
,
alt
,
autocomplete
,
checked
,
dirname
,
formaction
,
formenctype
,
formmethod
,
formnovalidate
,
formtarget
,
height
,
list
,
max
,
maxlength
,
min
,
multiple
,
pattern
,
placeholder
,
readonly
,
required
,
size
,
src
,
step
, and
width
.
The following IDL attributes and methods do not apply to the
element:
checked
,
files
,
list
,
selectedOption
,
selectionStart
,
selectionEnd
,
selectionDirection
,
valueAsDate
, and
valueAsNumber
IDL attributes;
select()
,
setSelectionRange()
,
stepDown()
, and
stepUp()
methods.
input
element attributesThese attributes only apply to an input
element if
its type
attribute is in a
state whose definition declares that the attribute applies. When an
attribute doesn't apply to an input
element, user
agents must ignore the attribute, regardless of the
requirements and definitions below.
autocomplete
attributeUser agents sometimes have features for helping users fill forms in, for example prefilling the user's address based on earlier user input.
The autocomplete
attribute is an enumerated attribute. The attribute has
three states. The on
keyword maps to the on state, and the
off
keyword maps to
the off
state. The attribute may also be omitted. The missing value
default is the default
state.
The off state indicates either that the control's input data is particularly sensitive (for example the activation code for a nuclear weapon); or that it is a value that will never be reused (for example a one-time-key for a bank login) and the user will therefore have to explicitly enter the data each time, instead of being able to rely on the UA to prefill the value for him; or that the document provides its own autocomplete mechanism and does not want the user agent to provide autocompletion values.
Conversely, the on state indicates that the value is not particularly sensitive and the user can expect to be able to rely on his user agent to remember values he has entered for that control.
The default state
indicates that the user agent is to use the autocomplete
attribute on the
element's form owner instead. (By default, the autocomplete
attribute of
form
elements is in the on state.)
Each input
element has a resulting
autocompletion state, which is either on or off.
When an input
element is in one of the following
conditions, the input
element's resulting
autocompletion state is on; otherwise, the
input
element's resulting autocompletion
state is off:
autocomplete
attribute is in the on state.autocomplete
attribute is in the default state,
and the element has no form owner.autocomplete
attribute is in the default state,
and the element's form owner's autocomplete
attribute is in
the on
state.When an input
element's resulting
autocompletion state is on, the user agent
may store the value entered by the user so that if the user returns
to the page, the UA can prefill the form. Otherwise, the user agent
should not remember the control's value, and should not offer past
values to the user.
In addition, if the resulting autocompletion state is off, values are reset when traversing the history.
The autocompletion mechanism must be implemented by the user agent acting as if the user had modified the element's value, and must be done at a time where the element is mutable (e.g. just after the element has been inserted into the document, or when the user agent stops parsing).
Banks frequently do not want UAs to prefill login information:
<p><label>Account: <input type="text" name="ac" autocomplete="off"></label></p> <p><label>PIN: <input type="password" name="pin" autocomplete="off"></label></p>
A user agent may allow the user to override the resulting autocompletion state and set it to always on, always allowing values to be remembered and prefilled), or always off, never remembering values. However, the ability to override the resulting autocompletion state to on should not be trivially accessible, as there are significant security implications for the user if all values are always remembered, regardless of the site's preferences.
dirname
attributeThe dirname
attribute, when it applies, is a form control dirname
attribute.
In this example, a form contains a text field and a submission button:
<form action="addcomment.cgi" method=post> <p><label>Comment: <input type=text name="comment" dirname="comment.dir" required></label></p> <p><button name="mode" type=submit value="add">Post Comment</button></p> </form>
When the user submits the form, the user agent includes three fields, one called "comment", one called "comment.dir", and one called "mode"; so if the user types "Hello", the submission body might be something like:
comment=Hello&comment.dir=ltr&mode=add
If the user manually switches to a right-to-left writing direction and enters "مرحبًا", the submission body might be something like:
comment=%D9%85%D8%B1%D8%AD%D8%A8%D9%8B%D8%A7&comment.dir=rtl&mode=add
list
attributeThe list
attribute is used to identify an element that lists predefined
options suggested to the user.
If present, its value must be the ID of a datalist
element in
the same document.
The suggestions source
element is the first element in the document in tree
order to have an ID equal to
the value of the list
attribute, if that element is a datalist
element. If
there is no list
attribute, or
if there is no element with that ID,
or if the first element with that ID
is not a datalist
element, then there is no suggestions source element.
If there is a suggestions source
element, then, when the user agent is allowing the user to
edit the input
element's value, the user agent should offer
the suggestions represented by the suggestions source element to the
user in a manner suitable for the type of control used. The user
agent may use the suggestion's label to identify the suggestion
if appropriate.
How user selections of suggestions are handled depends on whether the element is a control accepting a single value only, or whether it accepts multiple values:
multiple
attribute specified or
if the multiple
attribute
does not applyWhen the user selects a suggestion, the input
element's value must be set
to the selected suggestion's value, as if the user had
written that value himself.
multiple
attribute specified,
and the multiple
attribute
does applyWhen the user selects a suggestion, the user agent must either
add a new entry to the input
element's values, whose value is
the selected suggestion's value, or change an existing
entry in the input
element's values to have the value
given by the selected suggestion's value, as if the user had
himself added an entry with that value, or edited an existing
entry to be that value. Which behavior is to be applied depends on
the user interface in a user-agent-defined manner.
If the list
attribute does
not apply, there is no suggestions
source element.
This URL field offers some suggestions.
<label>Homepage: <input name=hp type=url list=hpurls></label> <datalist id=hpurls> <option value="http://www.google.com/" label="Google"> <option value="http://www.reddit.com/" label="Reddit"> </datalist>
Other URLs from the user's history might show also; this is up to the user agent.
This example demonstrates how to design a form that uses the autocompletion list feature while still degrading usefully in legacy user agents.
If the autocompletion list is merely an aid, and is not
important to the content, then simply using a datalist
element with children option
elements is enough. To
prevent the values from being rendered in legacy user agents, they
should be placed inside the value
attribute instead of
inline.
<p> <label> Enter a breed: <input type="text" name="breed" list="breeds"> <datalist id="breeds"> <option value="Abyssinian"> <option value="Alpaca"> <!-- ... --> </datalist> </label> </p>
However, if the values need to be shown in legacy UAs, then
fallback content can be placed inside the datalist
element, as follows:
<p> <label> Enter a breed: <input type="text" name="breed" list="breeds"> </label> <datalist id="breeds"> <label> or select one from the list: <select name="breed"> <option value=""> (none selected) <option>Abyssinian <option>Alpaca <!-- ... --> </select> </label> </datalist> </p>
The fallback content will only be shown in UAs that don't
support datalist
. The options, on the other hand, will
be detected by all UAs, even though they are not direct children of
the datalist
element.
Note that if an option
element used in a
datalist
is selected
, it will be selected
by default by legacy UAs (because it affects the
select
), but it will not have any effect on the
input
element in UAs that support
datalist
.
readonly
attributeThe readonly
attribute is a boolean attribute that controls whether
or not the user can edit the form control. When
specified, the element is immutable.
Constraint validation: If the readonly
attribute is specified
on an input
element, the element is barred from
constraint validation.
In the following example, the existing product identifiers cannot be modified, but they are still displayed as part of the form, for consistency with the row representing a new product (where the identifier is not yet filled in).
<form action="products.cgi" method=post enctype="multipart/form-data"> <table> <tr> <th> Product ID <th> Product name <th> Price <th> Action <tr> <td> <input readonly name="1.pid" value="H412"> <td> <input required name="1.pname" value="Floor lamp Ulke"> <td> $<input required type=number min=0 step=0.01 name="1.pprice" value="49.99"> <td> <button formnovalidate name="action" value="delete:1">Delete</button> <tr> <td> <input readonly name="2.pid" value="FG28"> <td> <input required name="2.pname" value="Table lamp Ulke"> <td> $<input required type=number min=0 step=0.01 name="2.pprice" value="24.99"> <td> <button formnovalidate name="action" value="delete:2">Delete</button> <tr> <td> <input required name="3.pid" value="" pattern="[A-Z0-9]+"> <td> <input required name="3.pname" value=""> <td> $<input required type=number min=0 step=0.01 name="3.pprice" value=""> <td> <button formnovalidate name="action" value="delete:3">Delete</button> </table> <p> <button formnovalidate name="action" value="add">Add</button> </p> <p> <button name="action" value="update">Save</button> </p> </form>
size
attributeThe size
attribute gives the number of characters that, in a visual
rendering, the user agent is to allow the user to see while editing
the element's value.
The size
attribute, if
specified, must have a value that is a valid non-negative
integer greater than zero.
If the attribute is present, then its value must be parsed using the rules for parsing non-negative integers, and if the result is a number greater than zero, then the user agent should ensure that at least that many characters are visible.
The size
IDL attribute is
limited to only non-negative numbers greater than
zero and has a default value of 20.
required
attributeThe required
attribute is a boolean attribute. When specified, the
element is required.
Constraint validation: If the element is required, and its value
IDL attribute applies and is in
the mode value, and the
element is mutable, and the
element's value is the empty
string, then the element is suffering from being
missing.
The following form has two required fields, one for an e-mail address and one for a password. It also has a third field that is only considerd valid if the user types the same password in the password field and this third field.
<h1>Create new account</h1> <form action="/newaccount" method=post oninput="up2.setCustomValidity(up2.value != up.value ? 'Passwords do not match.' : '')"> <p> <label for="username">E-mail address:</label> <input id="username" type=email required name=un> <p> <label for="password1">Password:</label> <input id="password1" type=password required name=up> <p> <label for="password2">Confirm password:</label> <input id="password2" type=password name=up2> <p> <input type=submit value="Create account"> </form>
multiple
attributeThe multiple
attribute is a boolean attribute that indicates whether
the user is to be allowed to specify more than one value.
The following extract shows how an e-mail client's "Cc" field could accept multiple e-mail addresses.
<label>Cc: <input type=email multiple name=cc></label>
If the user had, amongst many friends in his user contacts database, two friends "Arthur Dent" (with address "art@example.net") and "Adam Josh" (with address "adamjosh@example.net"), then, after the user has typed "a", the user agent might suggest these two e-mail addresses to the user.
The page could also link in the user's contacts database from the site:
<label>Cc: <input type=email multiple name=cc list=contacts></label> ... <datalist id="contacts"> <option value="hedral@damowmow.com"> <option value="pillar@example.com"> <option value="astrophy@cute.example"> <option value="astronomy@science.example.org"> </datalist>
Suppose the user had entered "bob@example.net" into this text
field, and then started typing a second e-mail address starting
with "a". The user agent might show both the two friends mentioned
earlier, as well as the "astrophy" and "astronomy" values given in
the datalist
element.
The following extract shows how an e-mail client's "Attachments" field could accept multiple files for upload.
<label>Attachments: <input type=file multiple name=att></label>
maxlength
attributeThe maxlength
attribute, when it applies, is a form control maxlength
attribute
controlled by the input
element's dirty value
flag.
If the input
element has a maximum allowed
value length, then the code-point length of the
value of the element's value
attribute must be equal to or less than the element's maximum
allowed value length.
The following extract shows how a messaging client's text entry could be arbitrarily restricted to a fixed number of characters, thus forcing any conversation through this medium to be terse and discouraging intelligent discourse.
What are you doing? <input name=status maxlength=140>
pattern
attributeThe pattern
attribute specifies a regular expression against which the control's
value, or, when the multiple
attribute applies and is
set, the control's values, are to be
checked.
If specified, the attribute's value must match the JavaScript Pattern production. [ECMA262]
If an input
element has a pattern
attribute specified, and
the attribute's value, when compiled as a JavaScript regular
expression with the global
, ignoreCase
, and multiline
flags disabled (see ECMA262 Edition 5, sections 15.10.7.2
through 15.10.7.4), compiles successfully, then the resulting
regular expression is the element's compiled pattern regular
expression. If the element has no such attribute, or if the
value doesn't compile successfully, then the element has no
compiled pattern regular expression. [ECMA262]
Constraint validation: If the element's value is not the empty string, and
either the element's multiple
attribute is not
specified or it does not apply to the input
element
given its type
attribute's
current state, and the element has a compiled pattern regular
expression but that regular expression does not match the
entirety of the element's value, then the element is
suffering from a pattern mismatch.
Constraint validation: If the element's value is not the empty string, and
the element's multiple
attribute is specified and applies to the input
element, and the element has a compiled pattern regular
expression but that regular expression does not match the
entirety of each of the element's values, then the element
is suffering from a pattern mismatch.
This implies that the regular expression language
used for this attribute is the same as that used in JavaScript,
except that the pattern
attribute must match the entire value, not just any subset (somewhat
as if it implied a ^(?:
at the start of the
pattern and a )$
at the end).
When an input
element has a pattern
attribute specified,
authors should include a title
attribute to give a description of the pattern. User agents may use
the contents of this attribute, if it is present, when informing the
user that the pattern is not matched, or at any other suitable time,
such as in a tooltip or read out by assistive technology when the
control gains focus.
For example, the following snippet:
<label> Part number: <input pattern="[0-9][A-Z]{3}" name="part" title="A part number is a digit followed by three uppercase letters."/> </label>
...could cause the UA to display an alert such as:
A part number is a digit followed by three uppercase letters. You cannot submit this form when the field is incorrect.
When a control has a pattern
attribute, the title
attribute, if used, must describe
the pattern. Additional information could also be included, so long
as it assists the user in filling in the control. Otherwise,
assistive technology would be impaired.
For instance, if the title attribute contained the caption of the control, assistive technology could end up saying something like The text you have entered does not match the required pattern. Birthday, which is not useful.
UAs may still show the title
in non-error situations
(for example, as a tooltip when hovering over the control), so
authors should be careful not to word title
s as if an
error has necessarily occurred.
min
and max
attributesThe min
and max
attributes indicate
the allowed range of values for the element.
Their syntax is defined by the section that defines the type
attribute's current state.
If the element has a min
attribute, and the result of applying the algorithm to convert a
string to a number to the value of the min
attribute is a number, then that
number is the element's minimum; otherwise, if the type
attribute's current state
defines a default
minimum, then that is the minimum; otherwise, the element has
no minimum.
Constraint validation: When the element has a minimum, and the result of applying the algorithm to convert a string to a number to the string given by the element's value is a number, and the number obtained from that algorithm is less than the minimum, the element is suffering from an underflow.
The min
attribute also
defines the step
base.
If the element has a max
attribute, and the result of applying the algorithm to convert a
string to a number to the value of the max
attribute is a number, then that
number is the element's maximum; otherwise, if the type
attribute's current state
defines a default
maximum, then that is the maximum; otherwise, the element has
no maximum.
Constraint validation: When the element has a maximum, and the result of applying the algorithm to convert a string to a number to the string given by the element's value is a number, and the number obtained from that algorithm is more than the maximum, the element is suffering from an overflow.
The max
attribute's value
(the maximum) must not be
less than the min
attribute's
value (its minimum).
If an element has a maximum that is less than its minimum, then so long as the element has a value, it will either be suffering from an underflow or suffering from an overflow.
An element has range limitations if it has a defined minimum or a defined maximum.
The following date control limits input to dates that are before the 1980s:
<input name=bday type=date max="1979-12-31">
The following number control limits input to whole numbers greater than zero:
<input name=quantity required type=number min=1 value=1>
step
attributeThe step
attribute indicates the granularity that is expected (and required)
of the value, by limiting the
allowed values. The section that defines the
type
attribute's current state
also defines the default
step, the step scale
factor, and in some cases the default step base,
which are used in processing the attribute as described
below.
The step
attribute, if
specified, must either have a value that is a valid floating
point number that parses to a number that is greater than
zero, or must have a value that is an ASCII
case-insensitive match for the string "any
".
The attribute provides the allowed value step for the element, as follows:
any
", then there is no allowed value step.The step base is the
result of applying the algorithm to convert a
string to a number to the value of the min
attribute, unless the element does
not have a min
attribute
specified or the result of applying that algorithm is an error, in
which case the step base
is the default step
base, if one is defined, or zero, if not.
Constraint validation: When the element has an allowed value step, and the result of applying the algorithm to convert a string to a number to the string given by the element's value is a number, and that number subtracted from the step base is not an integral multiple of the allowed value step, the element is suffering from a step mismatch.
The following range control only accepts values in the range 0..1, and allows 256 steps in that range:
<input name=opacity type=range min=0 max=1 step=0.00392156863>
The following control allows any time in the day to be selected, with any accuracy (e.g. thousandth-of-a-second accuracy or more):
<input name=favtime type=time step=any>
Normally, time controls are limited to an accuracy of one minute.
placeholder
attributeThe placeholder
attribute represents a short hint (a word or short phrase)
intended to aid the user with data entry. A hint could be a sample
value or a brief description of the expected format. The attribute,
if specified, must have a value that contains no U+000A LINE FEED
(LF) or U+000D CARRIAGE RETURN (CR) characters.
For a longer hint or other advisory text, the title
attribute is more appropriate.
The placeholder
attribute should not be used as an alternative to a
label
.
User agents should present this hint to the user, after having stripped line breaks from it, when the element's value is the empty string and the control is not focused (e.g. by displaying it inside a blank unfocused control).
Here is an example of a mail configuration user interface that
uses the placeholder
attribute:
<fieldset> <legend>Mail Account</legend> <p><label>Name: <input type="text" name="fullname" placeholder="John Ratzenberger"></label></p> <p><label>Address: <input type="email" name="address" placeholder="john@example.net"></label></p> <p><label>Password: <input type="password" name="password"></label></p> <p><label>Description: <input type="text" name="desc" placeholder="My Email Account"></label></p> </fieldset>
input
element APIsvalue
[ = value ]Returns the current value of the form control.
Can be set, to change the value.
Throws an INVALID_STATE_ERR
exception if it is
set to any value other than the empty string when the control is a
file upload control.
checked
[ = value ]Returns the current checkedness of the form control.
Can be set, to change the checkedness.
files
Returns a FileList
object listing the selected files of
the form control.
Returns null if the control isn't a file control.
valueAsDate
[ = value ]Returns a Date
object representing the form
control's value, if
applicable; otherwise, returns null.
Can be set, to change the value.
Throws an INVALID_STATE_ERR
exception if the
control isn't date- or time-based.
valueAsNumber
[ = value ]Returns a number representing the form control's value, if applicable; otherwise, returns null.
Can be set, to change the value.
Throws an INVALID_STATE_ERR
exception if the
control is neither date- or time-based nor numeric.
stepUp
( [ n ] )stepDown
( [ n ] )Changes the form control's value by the value given in the
step
attribute, multiplied by
n. The default value for n
is 1.
Throws INVALID_STATE_ERR
exception if the control
is neither date- or time-based nor numeric, if the step
attribute's value is "any
", if the current value could not be parsed, or if
stepping in the given direction by the given amount would take the
value out of range.
list
Returns the datalist
element indicated by the
list
attribute.
selectedOption
Returns the option
element from the
datalist
element indicated by the list
attribute that matches the
form control's value.
The value
IDL
attribute allows scripts to manipulate the value of an input
element. The attribute is in one of the following modes, which
define its behavior:
On getting, it must return the current value of the element. On setting,
it must set the element's value to the new value, set the
element's dirty value
flag to true, and then invoke the value sanitization
algorithm, if the element's type
attribute's current state
defines one.
On getting, if the element has a value
attribute, it must return
that attribute's value; otherwise, it must return the empty
string. On setting, it must set the element's value
attribute to the new
value.
On getting, if the element has a value
attribute, it must return
that attribute's value; otherwise, it must return the string
"on
". On setting, it must set the element's
value
attribute to the new
value.
On getting, it must return the string "C:\fakepath\
" followed by the filename of the
first file in the list of selected files, if
any, or the empty string if the list is empty. On setting, if the
new value is the empty string, it must empty the list of selected files;
otherwise, it must throw an INVALID_STATE_ERR
exception.
This "fakepath" requirement is a sad accident of history. See the example in the File Upload state section for more information.
The checked
IDL
attribute allows scripts to manipulate the checkedness of an
input
element. On getting, it must return the current
checkedness of the element;
and on setting, it must set the element's checkedness to the new value and
set the element's dirty checkedness
flag to true.
The files
IDL
attribute allows scripts to access the element's selected files. On
getting, if the IDL attribute applies, it must return a
FileList
object that represents the current selected files. The
same object must be returned until the list of selected files
changes. If the IDL attribute does not apply, then it must instead
return null. [FILEAPI]
The valueAsDate
IDL
attribute represents the value of the element, interpreted
as a date.
On getting, if the valueAsDate
attribute does not
apply, as defined for the input
element's type
attribute's current state, then
return null. Otherwise, run the algorithm to convert a
string to a Date
object defined for that state;
if the algorithm returned a Date
object, then return
it, otherwise, return null.
On setting, if the valueAsDate
attribute does not
apply, as defined for the input
element's type
attribute's current state, then
throw an INVALID_STATE_ERR
exception; otherwise, if
the new value is null, then set the value of the element to the empty
string; otherwise, run the algorithm to convert a
Date
object to a string, as defined for that
state, on the new value, and set the value of the element to resulting
string.
The valueAsNumber
IDL
attribute represents the value
of the element, interpreted as a number.
On getting, if the valueAsNumber
attribute does
not apply, as defined for the input
element's type
attribute's current state, then
return a Not-a-Number (NaN) value. Otherwise, if the valueAsDate
attribute applies, run the algorithm to convert a
string to a Date
object defined for that state;
if the algorithm returned a Date
object, then return
the time value of the object (the number of milliseconds from
midnight UTC the morning of 1970-01-01 to the time represented by
the Date
object), otherwise, return a Not-a-Number
(NaN) value. Otherwise, run the algorithm to convert a
string to a number defined for that state; if the algorithm
returned a number, then return it, otherwise, return a Not-a-Number
(NaN) value.
On setting, if the valueAsNumber
attribute does
not apply, as defined for the input
element's type
attribute's current state, then
throw an INVALID_STATE_ERR
exception. Otherwise, if
the valueAsDate
attribute applies, run the algorithm to convert a
Date
object to a string defined for that state,
passing it a Date
object whose time value is the
new value, and set the value
of the element to resulting string. Otherwise, run the algorithm to convert a
number to a string, as defined for that state, on the new
value, and set the value of
the element to resulting string.
The stepDown(n)
and stepUp(n)
methods, when invoked, must run the
following algorithm:
If the stepDown()
and
stepUp()
methods do not
apply, as defined for the input
element's type
attribute's current state, then
throw an INVALID_STATE_ERR
exception, and abort these
steps.
If the element has no allowed value step, then throw an
INVALID_STATE_ERR
exception, and abort these
steps.
If applying the algorithm to convert a
string to a number to the string given by the element's
value results in an error,
then throw an INVALID_STATE_ERR
exception, and abort
these steps; otherwise, let value be the result
of that algorithm.
Let n be the argument, or 1 if the argument was omitted.
Let delta be the allowed value step multiplied by n.
If the method invoked was the stepDown()
method, negate delta.
Let value be the result of adding delta to value.
If the element has a minimum, and the value is less than that minimum, then throw a
INVALID_STATE_ERR
exception.
If the element has a maximum, and the value is greater than that maximum, then throw a
INVALID_STATE_ERR
exception.
Let value as string be the result of
running the algorithm to convert a
number to a string, as defined for the input
element's type
attribute's
current state, on value.
Set the value of the element to value as string.
The list
IDL
attribute must return the current suggestions source element, if
any, or null otherwise.
The selectedOption
IDL attribute must return the value determined by the following
steps:
If there is no suggestions
source element (e.g. because the list
attribute doesn't apply or is
not specified), then return null and abort these steps.
If the multiple
attribute is specified and applies, then return null and abort
these steps. (The selectedOption
IDL
attribute doesn't apply.)
Return the first option
element, in tree
order, to be a child of the suggestions source element and
whose value matches the
input
element's value, if any. If the suggestions source element
contains no matching option
element, then return null
instead.
When the input
event applies, any time the user causes the element's value to change, the user agent must
queue a task to fire a simple event that
bubbles named input
at the
input
element. User agents may wait for a suitable
break in the user's interaction before queuing the task; for
example, a user agent could wait for the user to have not hit a key
for 100ms, so as to only fire the event when the user pauses,
instead of continuously for each keystroke.
Examples of a user changing the element's value would include the user typing into a text field, pasting a new value into the field, or undoing an edit in that field. Some user interactions do not cause changes to the value, e.g. hitting the "delete" key in an empty text field, or replacing some text in the field with text from the clipboard that happens to be exactly the same text.
When the change
event applies,
if the element does not have an activation behavior
defined but uses a user interface that involves an explicit commit
action, then any time the user commits a change to the element's
value or list of selected files, the
user agent must queue a task to fire a simple
event that bubbles named change
at the input
element.
An example of a user interface with a commit action would be a File Upload control that consists of a single button that brings up a file selection dialog: when the dialog is closed, if that the file selection changed as a result, then the user has committed a new file selection.
Another example of a user interface with a commit action would be a Date control that allows both text-based user input and user selection from a drop-down calendar: while text input might not have an explicit commit step, selecting a date from the drop down calendar and then dismissing the drop down would be a commit action.
When the user agent changes the element's value on behalf of the user (e.g. as part of a form prefilling feature), the user agent must follow these steps:
input
event
applies, queue a task to fire a simple
event that bubbles named input
at the input
element.change
event
applies, queue a task to fire a simple
event that bubbles named change
at the input
element.In addition, when the change
event applies, change
events can also be fired as part
of the element's activation behavior and as part of the
unfocusing steps.
The task source for these tasks is the user interaction task source.
button
elementautofocus
disabled
form
formaction
formenctype
formmethod
formnovalidate
formtarget
name
type
value
interface HTMLButtonElement : HTMLElement { attribute boolean autofocus; attribute boolean disabled; readonly attribute HTMLFormElement form; attribute DOMString formAction; attribute DOMString formEnctype; attribute DOMString formMethod; attribute DOMString formNoValidate; attribute DOMString formTarget; attribute DOMString name; attribute DOMString type; attribute DOMString value; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); void setCustomValidity(in DOMString error); readonly attribute NodeList labels; };
The button
element represents a
button. If the element is not disabled, then the user agent
should allow the user to activate the button.
The element is a button.
The type
attribute controls the behavior of the button when it is activated.
It is an enumerated attribute. The following table
lists the keywords and states for the attribute — the keywords
in the left column map to the states in the cell in the second
column on the same row as the keyword.
Keyword | State | Brief description |
---|---|---|
submit
| Submit Button | Submits the form. |
reset
| Reset Button | Resets the form. |
button
| Button | Does nothing. |
The missing value default is the Submit Button state.
If the type
attribute is in
the Submit Button
state, the element is specifically a submit button.
Constraint validation: If the type
attribute is in the Reset Button state or
the Button state,
the element is barred from constraint validation.
If the element is not disabled, the activation
behavior of the button
element is to run the
steps defined in the following list for the current state of the
element's type
attribute.
If the element has a form owner, the element
must submit the form
owner from the button
element.
If the element has a form owner, the element must reset the form owner.
Do nothing.
The form
attribute is used to
explicitly associate the button
element with its
form owner. The name
attribute represents the element's name. The disabled
attribute is used to make
the control non-interactive and to prevent its value from being
submitted. The autofocus
attribute controls focus. The formaction
, formenctype
, formmethod
, formnovalidate
, and formtarget
attributes are
attributes for form submission.
The formnovalidate
attribute can
be used to make submit buttons that do not trigger the constraint
validation.
The formaction
, formenctype
, formmethod
, formnovalidate
, and formtarget
must not be specified
if the element's type
attribute is not in the Submit Button
state.
The value
attribute gives the element's value for the purposes of form
submission. The element's value is the value of the element's
value
attribute, if there is
one, or the empty string otherwise.
A button (and its value) is only included in the form submission if the button itself was used to initiate the form submission.
The value
IDL
attribute must reflect the content attribute of the
same name.
The type
IDL
attribute must reflect the content attribute of the
same name, limited to only known values.
The willValidate
, validity
, and validationMessage
attributes, and the checkValidity()
and setCustomValidity()
methods, are part of the constraint validation API. The
labels
attribute provides a list
of the element's label
s. The autofocus
, disabled
, form
, and name
IDL attributes are part of the
element's forms API.
The following button is labeled "Show hint" and pops up a dialog box when activated:
<button type=button onclick="alert('This 15-20 minute piece was composed by George Gershwin.')"> Show hint </button>
select
elementoption
or optgroup
elements.autofocus
disabled
form
multiple
name
required
size
interface HTMLSelectElement : HTMLElement { attribute boolean autofocus; attribute boolean disabled; readonly attribute HTMLFormElement form; attribute boolean multiple; attribute DOMString name; attribute boolean required; attribute unsigned long size; readonly attribute DOMString type; readonly attribute HTMLOptionsCollection options; attribute unsigned long length; getter any item(in unsigned long index); any namedItem(in DOMString name); void add(in HTMLElement element, in optional HTMLElement before); void add(in HTMLElement element, in long before); void remove(in long index); readonly attribute HTMLCollection selectedOptions; attribute long selectedIndex; attribute DOMString value; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); void setCustomValidity(in DOMString error); readonly attribute NodeList labels; };
The select
element represents a control for
selecting amongst a set of options.
The multiple
attribute is a boolean attribute. If the attribute is
present, then the select
element
represents a control for selecting zero or more options
from the list of
options. If the attribute is absent, then the
select
element represents a control for
selecting a single option from the list of options.
The size
attribute gives the number of options to show to the user. The size
attribute, if specified, must
have a value that is a valid non-negative integer
greater than zero. If the multiple
attribute is present,
then the size
attribute's
default value is 4. If the multiple
attribute is absent,
then the size
attribute's
default value is 1.
The display size of a
select
element is the result of applying the
rules for parsing non-negative integers to the value of
element's size
attribute, if it
has one and parsing it is successful. If applying those rules to the
attribute's value is not successful, or if the size
attribute is absent, the
element's display size is
the default value of the attribute.
The list of options
for a select
element consists of all the
option
element children of the select
element, and all the option
element children of all the
optgroup
element children of the select
element, in tree order.
The required
attribute is a boolean attribute. When specified, the
user will be required to select a value before submitting the
form.
If a select
element has a required
attribute specified,
does not have a multiple
attribute specified, and has a display size of 1;
and if the value of the
first option
element in the select
element's list of
options (if any) is the empty string, and that
option
element's parent node is the select
element (and not an optgroup
element), then that
option
is the select
element's
placeholder label option.
If a select
element has a required
attribute specified,
does not have a multiple
attribute specified, and has a display size of 1,
then the select
element must have a placeholder
label option.
Constraint validation: If the element has its
required
attribute
specified, and either none of the option
elements in
the select
element's list of options have their
selectedness set to
true, or the only option
element in the
select
element's list of options with its
selectedness set to
true is the placeholder label option, then the element
is suffering from being missing.
If the multiple
attribute is absent, and the element is not disabled, then the user agent
should allow the user to pick an option
element in its
list of options that
is itself not disabled.
Upon this option
element being picked (either through a click, or
through unfocusing the element after changing its value, or through
a menu command, or through any
other mechanism), and before the relevant user interaction event
is queued (e.g. before the
click
event), the user agent must
set the selectedness of the
picked option
element to true and then queue a
task to fire a simple event that bubbles named
change
at the select
element, using the user interaction task source as the
task source.
If the multiple
attribute is absent, whenever an option
element in the
select
element's list of options has its
selectedness set to
true, and whenever an option
element with its selectedness set to true
is added to the select
element's list of options, the user
agent must set the selectedness of all the
other option
element in its list of options to
false.
If the multiple
attribute is absent and the element's display size is greater than 1,
then the user agent should also allow the user to request that the
option
whose selectedness is true, if
any, be unselected. Upon this request being conveyed to the user
agent, and before the relevant user interaction event is queued (e.g. before the click
event), the user agent must set the
selectedness of
that option
element to false and then queue a
task to fire a simple event that bubbles named
change
at the select
element, using the user interaction task source as the
task source.
If the multiple
attribute is absent and the element's display size is 1, then whenever
there are no option
elements in the select
element's list of
options that have their selectedness set to true,
the user agent must set the selectedness of the first
option
element in the list of options in
tree order that is not disabled, if any, to
true.
If the multiple
attribute is present, and the element is not disabled, then the user agent
should allow the user to toggle the selectedness of the
option
elements in its list of options that are
themselves not disabled
(either through a click, or through a menu command, or any other mechanism).
Upon the selectedness of one or
more option
elements being changed by the user, and
before the relevant user interaction event is queued (e.g. before a related click
event), the user agent must
queue a task to fire a simple event that
bubbles named change
at the
select
element, using the user interaction task
source as the task source.
The reset
algorithm for select
elements is to go through
all the option
elements in the element's list of options, and set
their selectedness
to true if the option
element has a selected
attribute, and false
otherwise.
The form
attribute is used to
explicitly associate the select
element with its
form owner. The name
attribute represents the element's name. The disabled
attribute is used to make
the control non-interactive and to prevent its value from being
submitted. The autofocus
attribute controls focus.
type
Returns "select-multiple
" if the element
has a multiple
attribute, and "select-one
"
otherwise.
options
Returns an HTMLOptionsCollection
of the list of options.
length
[ = value ]Returns the number of elements in the list of options.
When set to a smaller number, truncates the number of option
elements in the select
.
When set to a greater number, adds new blank option
elements to the select
.
item
(index)Returns the item with index index from the list of options. The items are sorted in tree order.
Returns null if index is out of range.
namedItem
(name)Returns the item with ID or name
name from the list of options.
If there are multiple matching items, then a NodeList
object containing all those elements is returned.
Returns null if no element with that ID could be found.
add
(element [, before ])Inserts element before the node given by before.
The before argument can be a number, in which case element is inserted before the item with that number, or an element from the list of options, in which case element is inserted before that element.
If before is omitted, null, or a number out of range, then element will be added at the end of the list.
This method will throw a HIERARCHY_REQUEST_ERR
exception if element is an ancestor of the
element into which it is to be inserted. If element is not an option
or
optgroup
element, then the method does nothing.
selectedOptions
Returns an HTMLCollection
of the list of options that are
selected.
selectedIndex
[ = value ]Returns the index of the first selected item, if any, or −1 if there is no selected item.
Can be set, to change the selection.
value
[ = value ]Returns the value of the first selected item, if any, or the empty string if there is no selected item.
Can be set, to change the selection.
The type
IDL
attribute, on getting, must return the string "select-one
" if the multiple
attribute is absent,
and the string "select-multiple
" if the multiple
attribute is
present.
The options
IDL attribute must return an HTMLOptionsCollection
rooted at the select
node, whose filter matches the
elements in the list of
options.
The options
collection is
also mirrored on the HTMLSelectElement
object. The
supported property indices at any instant are the
indices supported by the object returned by the options
attribute at that
instant.
The length
IDL
attribute must return the number of nodes represented by the options
collection. On setting, it
must act like the attribute of the same name on the options
collection.
The item(index)
method must return the value
returned by the method of the same name on the options
collection, when invoked
with the same argument.
The namedItem(name)
method must return the value
returned by the method of the same name on the options
collection, when invoked
with the same argument.
Similarly, the add()
and remove()
methods must
act like their namesake methods on that same options
collection.
The selectedOptions
IDL attribute must return an HTMLCollection
rooted at
the select
node, whose filter matches the elements in
the list of options
that have their selectedness set to
true.
The selectedIndex
IDL attribute, on getting, must return the index of the first
option
element in the list of options in
tree order that has its selectedness set to true,
if any. If there isn't one, then it must return −1.
On setting, the selectedIndex
attribute must
set the selectedness of all the
option
elements in the list of options to false,
and then the option
element in the list of options whose
index is the given new
value, if any, must have its selectedness set to
true.
The value
IDL
attribute, on getting, must return the value of the first
option
element in the list of options in
tree order that has its selectedness set to true,
if any. If there isn't one, then it must return the empty
string.
On setting, the value
attribute must set the selectedness of all the
option
elements in the list of options to false,
and then the first option
element in the list of options, in
tree order, whose value is equal to the given new
value, if any, must have its selectedness set to
true.
The multiple
,
required
, and
size
IDL attributes
must reflect the respective content attributes of the
same name. The size
IDL
attribute is limited to only non-negative numbers, with
the default value zero (which for historical reasons is different
from the default value of the size
content attribute that it
reflects).
The willValidate
, validity
, and validationMessage
attributes, and the checkValidity()
and setCustomValidity()
methods, are part of the constraint validation API. The
labels
attribute provides a list
of the element's label
s. The autofocus
, disabled
, form
, and name
IDL attributes are part of the
element's forms API.
The following example shows how a select
element
can be used to offer the user with a set of options from which the
user can select a single option. The default option is
preselected.
<p> <label for="unittype">Select unit type:</label> <select id="unittype" name="unittype"> <option value="1"> Miner </option> <option value="2"> Puffer </option> <option value="3" selected> Snipey </option> <option value="4"> Max </option> <option value="5"> Firebot </option> </select> </p>
Here, the user is offered a set of options from which he can select any number. By default, all five options are selected.
<p> <label for="allowedunits">Select unit types to enable on this map:</label> <select id="allowedunits" name="allowedunits" multiple> <option value="1" selected> Miner </option> <option value="2" selected> Puffer </option> <option value="3" selected> Snipey </option> <option value="4" selected> Max </option> <option value="5" selected> Firebot </option> </select> </p>
datalist
elementoption
elements.interface HTMLDataListElement : HTMLElement { readonly attribute HTMLCollection options; };
The datalist
element represents a set of
option
elements that represent predefined options for
other controls. The contents of the element represents fallback
content for legacy user agents, intermixed with option
elements that represent the predefined options. In the rendering,
the datalist
element represents
nothing and it, along with its children, should
be hidden.
The datalist
element is hooked up to an
input
element using the list
attribute on the
input
element.
Each option
element that is a descendant of the
datalist
element, that is not disabled, and whose value is a string that isn't the
empty string, represents a suggestion. Each suggestion has a value and a label.
options
Returns an HTMLCollection
of the options
elements of the table.
The options
IDL attribute must return an HTMLCollection
rooted at
the datalist
node, whose filter matches
option
elements.
Constraint validation: If an element has a
datalist
element ancestor, it is barred from
constraint validation.
optgroup
elementselect
element.option
elements.disabled
label
interface HTMLOptGroupElement : HTMLElement { attribute boolean disabled; attribute DOMString label; };
The optgroup
element represents a group of
option
elements with a common label.
The element's group of option
elements consists of
the option
elements that are children of the
optgroup
element.
When showing option
elements in select
elements, user agents should show the option
elements
of such groups as being related to each other and separate from
other option
elements.
The disabled
attribute
is a boolean attribute and can be used to disable a group of
option
elements together.
The label
attribute must be specified. Its value gives the name of the group,
for the purposes of the user interface. User
agents should use this attribute's value when labelling the group of
option
elements in a select
element.
The disabled
and label
attributes must
reflect the respective content attributes of the same
name.
The following snippet shows how a set of lessons from three
courses could be offered in a select
drop-down
widget:
<form action="courseselector.dll" method="get"> <p>Which course would you like to watch today? <p><label>Course: <select name="c"> <optgroup label="8.01 Physics I: Classical Mechanics"> <option value="8.01.1">Lecture 01: Powers of Ten <option value="8.01.2">Lecture 02: 1D Kinematics <option value="8.01.3">Lecture 03: Vectors <optgroup label="8.02 Electricity and Magnestism"> <option value="8.02.1">Lecture 01: What holds our world together? <option value="8.02.2">Lecture 02: Electric Field <option value="8.02.3">Lecture 03: Electric Flux <optgroup label="8.03 Physics III: Vibrations and Waves"> <option value="8.03.1">Lecture 01: Periodic Phenomenon <option value="8.03.2">Lecture 02: Beats <option value="8.03.3">Lecture 03: Forced Oscillations with Damping </select> </label> <p><input type=submit value="▶ Play"> </form>
option
elementselect
element.datalist
element.optgroup
element.disabled
label
selected
value
[NamedConstructor=Option(), NamedConstructor=Option(in DOMString text), NamedConstructor=Option(in DOMString text, in DOMString value), NamedConstructor=Option(in DOMString text, in DOMString value, in boolean defaultSelected), NamedConstructor=Option(in DOMString text, in DOMString value, in boolean defaultSelected, in boolean selected)] interface HTMLOptionElement : HTMLElement { attribute boolean disabled; readonly attribute HTMLFormElement form; attribute DOMString label; attribute boolean defaultSelected; attribute boolean selected; attribute DOMString value; attribute DOMString text; readonly attribute long index; };
The option
element represents an option
in a select
element or as part of a list of suggestions
in a datalist
element.
In certain circumstances described in the definition of the
select
element, an option
element can be a
select
element's placeholder label option.
A placeholder label option does not represent an actual
option, but instead represents a label for the select
control.
The disabled
attribute is a boolean attribute. An
option
element is disabled if its disabled
attribute is present or
if it is a child of an optgroup
element whose disabled
attribute is
present.
An option
element that is disabled must prevent any click
events that are queued on the user interaction task
source from being dispatched on the element.
The label
attribute provides a label for element. The label of an option
element is the value of the label
attribute, if there is one,
or the textContent
of the element, if there isn't.
The value
attribute provides a value for element. The value of an option
element is the value of the value
attribute, if there is one,
or the textContent
of the element, if there isn't.
The selected
attribute is a boolean attribute. It represents the
default selectedness of the
element.
The selectedness
of an option
element is a boolean state, initially
false. Except where otherwise
specified, when the element is created, its selectedness must be set
to true if the element has a selected
attribute. Whenever an
option
element's selected
attribute is added, its
selectedness must
be set to true.
The Option()
constructor with three or fewer arguments overrides the initial
state of the selectedness state to
always be false even if the third argument is true (implying that a
selected
attribute is to
be set). The fourth argument can be used to explicitly set the
initial selectedness state when
using the constructor.
A select
element whose multiple
attribute is not
specified must not have more than one descendant option
element with its selected
attribute set.
An option
element's index is the number of
option
element that are in the same list of options but that
come before it in tree order. If the
option
element is not in a list of options, then the
option
element's index is zero.
selected
Returns true if the element is selected, and false otherwise.
Can be set, to override the current state of the element.
index
Returns the index of the element in its select
element's options
list.
form
Returns the element's form
element, if any, or
null otherwise.
text
Same as textContent
, except that spaces are collapsed.
Option
( [ text [, value [, defaultSelected [, selected ] ] ] ] )Returns a new option
element.
The text argument sets the contents of the element.
The value argument sets the value
attribute.
The defaultSelected argument sets the selected
attribute.
The selected argument sets whether or not the element is selected. If it is omitted, even if the defaultSelected argument is true, the element is not selected.
The disabled
and label
IDL
attributes must reflect the respective content
attributes of the same name. The defaultSelected
IDL attribute must reflect the selected
content attribute.
The value
IDL
attribute, on getting, must return the value of the element's value
content attribute, if it has
one, or else the value of the element's textContent
IDL
attribute. On setting, the element's value
content attribute must be set
to the new value.
The selected
IDL attribute, on getting, must return true if the element's selectedness is true, and
false otherwise. On setting, it must set the element's selectedness to the new
value.
The index
IDL
attribute must return the element's index.
The text
IDL
attribute, on getting, must return the value of the
textContent
IDL attribute on the element with leading
and trailing space characters
removed, and with any sequences of two or more space characters replaced by a single U+0020 SPACE
character. On setting, it must act as if the
textContent
IDL attribute on the element had been set
to the new value.
The form
IDL
attribute's behavior depends on whether the option
element is in a select
element or not. If the
option
has a select
element as its parent,
or has a colgroup
element as its parent and that
colgroup
element has a select
element as
its parent, then the form
IDL
attribute must return the same value as the form
IDL attribute on that
select
element. Otherwise, it must return null.
Several constructors are provided for creating
HTMLOptionElement
objects (in addition to the factory
methods from DOM Core such as createElement()
): Option()
, Option(text)
, Option(text, value)
, Option(text, value, defaultSelected)
, and Option(text, value, defaultSelected, selected)
. When invoked as constructors,
these must return a new HTMLOptionElement
object (a new
option
element). If the text
argument is present, the new object must have as its only child a
Node
with node type TEXT_NODE
(3)
whose data is the value of that argument. If the value argument is present, the new object must have a
value
attribute set with the
value of the argument as its value. If the defaultSelected argument is present and true, the new
object must have a selected
attribute set with no
value. If the selected argument is present and
true, the new object must have its selectedness set to true;
otherwise the fourth argument is absent or false, and the selectedness must be set
to false, even if the defaultSelected argument
is present and true. The element's document must be the active
document of the browsing context of the
Window
object on which the interface object of the
invoked constructor is found.
textarea
elementautofocus
cols
dirname
disabled
form
maxlength
name
placeholder
readonly
required
rows
wrap
interface HTMLTextAreaElement : HTMLElement { attribute boolean autofocus; attribute unsigned long cols; attribute DOMString dirName; attribute boolean disabled; readonly attribute HTMLFormElement form; attribute long maxLength; attribute DOMString name; attribute DOMString placeholder; attribute boolean readOnly; attribute boolean required; attribute unsigned long rows; attribute DOMString wrap; readonly attribute DOMString type; attribute DOMString defaultValue; attribute DOMString value; readonly attribute unsigned long textLength; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); void setCustomValidity(in DOMString error); readonly attribute NodeList labels; void select(); attribute unsigned long selectionStart; attribute unsigned long selectionEnd; attribute DOMString selectionDirection; void setSelectionRange(in unsigned long start, in unsigned long end, in optional DOMString direction); };
The textarea
element represents a
multiline plain text edit control for the
element's raw
value. The contents of the control represent the
control's default value.
The raw value of
a textarea
control must be initially the empty
string.
A newline in a textarea
element, and in its raw value, should separate
paragraphs for the purposes of the Unicode bidirectional algorithm.
This requirement may be implemented indirectly through the style
layer. For example, an HTML+CSS user agent could implement these
requirements by implementing the CSS 'unicode-bidi' property. [BIDI] [CSS]
The readonly
attribute
is a boolean attribute used to control whether the text
can be edited by the user or not.
Constraint validation: If the readonly
attribute is
specified on a textarea
element, the element is
barred from constraint validation.
A textarea
element is mutable if it is neither
disabled nor has a readonly
attribute
specified.
When a textarea
is mutable, its raw value should be
editable by the user: the user agent should allow the user to edit,
insert, and remove text, and to insert and remove line breaks in the
form of U+000A LINE FEED (LF) characters. Any time the user causes
the element's raw
value to change, the user agent must queue a
task to fire a simple event that bubbles named
input
at the textarea
element. User agents may wait for a suitable break in the user's
interaction before queuing the task; for example, a user agent could
wait for the user to have not hit a key for 100ms, so as to only
fire the event when the user pauses, instead of continuously for
each keystroke.
A textarea
element has a dirty value flag, which must be
initially set to false, and must be set to true whenever the user
interacts with the control in a way that changes the raw value.
When the textarea
element's textContent
IDL attribute changes value, if the element's dirty value flag is false,
then the element's raw
value must be set to the value of the element's
textContent
IDL attribute.
The reset
algorithm for textarea
elements is to set the
element's value to
the value of the element's textContent
IDL
attribute.
If the element is mutable, the user agent should allow the user to change the writing direction of the element, setting it either to a left-to-right writing direction or a right-to-left writing direction. If the user does so, the user agent must then run the following steps:
Set the element's dir
attribute to "ltr
" if the user
selected a left-to-right writing direction, and "rtl
" if the user selected a
right-to-left writing direction.
Queue a task to fire a simple
event that bubbles named input
at the textarea
element.
The cols
attribute specifies the expected maximum number of characters per
line. If the cols
attribute
is specified, its value must be a valid non-negative
integer greater than zero. If applying the
rules for parsing non-negative integers to the
attribute's value results in a number greater than zero, then the
element's character
width is that value; otherwise, it is 20.
The user agent may use the textarea
element's character width as a hint to
the user as to how many characters the server prefers per line
(e.g. for visual user agents by making the width of the control be
that many characters). In visual renderings, the user agent should
wrap the user's input in the rendering so that each line is no wider
than this number of characters.
The rows
attribute specifies the number of lines to show. If the rows
attribute is specified, its
value must be a valid non-negative integer greater than
zero. If applying the rules for parsing
non-negative integers to the attribute's value results in a
number greater than zero, then the element's character height is that
value; otherwise, it is 2.
Visual user agents should set the height of the control to the number of lines given by character height.
The wrap
attribute is an enumerated attribute with two keywords
and states: the soft
keyword
which maps to the Soft state, and the
hard
keyword
which maps to the Hard state. The
missing value default is the Soft state.
The Soft state
indicates that the text in the textarea
is not to be
wrapped when it is submitted (though it can still be wrapped in the
rendering).
The Hard state
indicates that the text in the textarea
is to have
newlines added by the user agent so that the text is wrapped when it
is submitted.
If the element's wrap
attribute is in the Hard state, the cols
attribute must be
specified.
The element's value is defined to be the element's raw value with the following transformation applied:
Replace every occurrence of a U+000D CARRIAGE RETURN (CR) character not followed by a U+000A LINE FEED (LF) character, and every occurrence of a U+000A LINE FEED (LF) character not preceded by a U+000D CARRIAGE RETURN (CR) character, by a two-character string consisting of a U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pair.
If the element's wrap
attribute is in the Hard state, insert
U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF) character pairs
into the string using a UA-defined algorithm so that each line has
no more than character
width characters. For the purposes of this requirement,
lines are delimited by the start of the string, the end of the
string, and U+000D CARRIAGE RETURN U+000A LINE FEED (CRLF)
character pairs.
The maxlength
attribute is a form control maxlength
attribute controlled by the
textarea
element's dirty value flag.
If the textarea
element has a maximum allowed
value length, then the element's children must be such that
the code-point length of the value of the element's
textContent
IDL attribute is equal to or less than the
element's maximum allowed value length.
The required
attribute
is a boolean attribute. When specified, the user will
be required to enter a value before submitting the form.
Constraint validation: If the element has its
required
attribute
specified, and the element is mutable, and the element's
value is the empty string,
then the element is suffering from being missing.
The placeholder
attribute represents a hint (a word or short phrase) intended to aid
the user with data entry. A hint could be a sample value or a brief
description of the expected format. The attribute, if specified,
must have a value that contains no U+000A LINE FEED (LF) or U+000D
CARRIAGE RETURN (CR) characters.
For a longer hint or other advisory text, the title
attribute is more appropriate.
The placeholder
attribute should not be used as an alternative to a
label
.
User agents should present this hint to the user, after having stripped line breaks from it, when the element's value is the empty string and the control is not focused (e.g. by displaying it inside a blank unfocused control).
The dirname
attribute is a form control dirname
attribute.
The form
attribute is used to
explicitly associate the textarea
element with its
form owner. The name
attribute represents the element's name. The disabled
attribute is used to make
the control non-interactive and to prevent its value from being
submitted. The autofocus
attribute controls focus.
type
Returns the string "textarea
".
value
Returns the current value of the element.
Can be set, to change the value.
The cols
, placeholder
,
required
, rows
, and wrap
attributes must
reflect the respective content attributes of the same
name. The cols
and rows
attributes are limited
to only non-negative numbers greater than zero. The cols
attribute's default value is
20. The rows
attribute's
default value is 2. The dirName
IDL
attribute must reflect the dirname
content attribute. The
maxLength
IDL
attribute must reflect the maxlength
content attribute,
limited to only non-negative numbers. The readOnly
IDL
attribute must reflect the readonly
content
attribute.
The type
IDL
attribute must return the value "textarea
".
The defaultValue
IDL attribute must act like the element's textContent
IDL attribute.
The value
attribute must, on getting, return the element's raw value; on setting, it
must set the element's raw
value to the new value.
The textLength
IDL
attribute must return the code-point length of the
element's value.
The willValidate
, validity
, and validationMessage
attributes, and the checkValidity()
and setCustomValidity()
methods, are part of the constraint validation API. The
labels
attribute provides a list
of the element's label
s. The select()
, selectionStart
,
selectionEnd
,
selectionDirection
,
and setSelectionRange()
methods and attributes expose the element's text selection. The
autofocus
, disabled
, form
, and name
IDL attributes are part of the
element's forms API.
Here is an example of a textarea
being used for
unrestricted free-form text input in a form:
<p>If you have any comments, please let us know: <textarea cols=80 name=comments></textarea></p>
To specify a maximum length for the comments, one can use
the maxlength
attribute:
<p>If you have any short comments, please let us know: <textarea cols=80 name=comments maxlength=200></textarea></p>
To give a default value, text can be included inside the element:
<p>If you have any comments, please let us know: <textarea cols=80 name=comments>You rock!</textarea></p>
To have the browser submit the directionality of
the element along with the value, the dirname
attribute can be
specified:
<p>If you have any comments, please let us know (you may use either English or Hebrew for your comments): <textarea cols=80 name=comments dirname=comments.dir></textarea></p>
keygen
elementautofocus
challenge
disabled
form
keytype
name
interface HTMLKeygenElement : HTMLElement { attribute boolean autofocus; attribute DOMString challenge; attribute boolean disabled; readonly attribute HTMLFormElement form; attribute DOMString keytype; attribute DOMString name; readonly attribute DOMString type; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); void setCustomValidity(in DOMString error); readonly attribute NodeList labels; };
The keygen
element represents a key
pair generator control. When the control's form is submitted, the
private key is stored in the local keystore, and the public key is
packaged and sent to the server.
The challenge
attribute
may be specified. Its value will be packaged with the submitted
key.
The keytype
attribute is an enumerated attribute. The following
table lists the keywords and states for the attribute — the
keywords in the left column map to the states listed in the cell in
the second column on the same row as the keyword. User agents are
not required to support these values, and must only recognize values
whose corresponding algorithms they support.
Keyword | State |
---|---|
rsa
| RSA |
The invalid value default state is the unknown state. The missing value default state is the RSA state, if it is supported, or the unknown state otherwise.
This specification does not specify what key types user agents are to support — it is possible for a user agent to not support any key types at all.
The user agent may expose a user interface for each
keygen
element to allow the user to configure settings
of the element's key pair generator, e.g. the key length.
The reset
algorithm for keygen
elements is to set these
various configuration settings back to their defaults.
The element's value is the string returned from the following algorithm:
Use the appropriate step from the following list:
keytype
attribute is in the RSA stateGenerate an RSA key pair using the settings given by the
user, if appropriate, using the md5WithRSAEncryption
RSA signature algorithm
(the signature algorithm with MD5 and the RSA encryption
algorithm) referenced in section 2.2.1 ("RSA Signature
Algorithm") of RFC 3279, and defined in RFC 2313. [RFC3279] [RFC2313]
keytype
attribute is in the unknown stateThe given key type is not supported. Return the empty string and abort this algorithm.
Let private key be the generated private key.
Let public key be the generated public key.
Let signature algorithm be the selected signature algorithm.
If the element has a challenge
attribute, then let
challenge be that attribute's value.
Otherwise, let challenge be the empty
string.
Let algorithm be an ASN.1 AlgorithmIdentifier
structure as defined by
RFC 5280, with the algorithm
field giving the
ASN.1 OID used to identify signature
algorithm, using the OIDs defined in section 2.2 ("Signature
Algorithms") of RFC 3279, and the parameters
field set up as required by RFC 3279 for AlgorithmIdentifier
structures for that
algorithm. [X690] [RFC5280] [RFC3279]
Let spki be an ASN.1 SubjectPublicKeyInfo
structure as defined by
RFC 5280, with the algorithm
field set to the
algorithm structure from the previous step,
and the subjectPublicKey
field set to the
BIT STRING value resulting from ASN.1 DER encoding the public key. [X690] [RFC5280]
Let publicKeyAndChallenge be an ASN.1
PublicKeyAndChallenge
structure as defined below,
with the spki
field set to the spki structure from the previous step, and the
challenge
field set to the string challenge obtained earlier. [X690]
Let signature be the BIT STRING value resulting from ASN.1 DER encoding the signature generated by applying the signature algorithm to the byte string obtained by ASN.1 DER encoding the publicKeyAndChallenge structure, using private key as the signing key. [X690]
Let signedPublicKeyAndChallenge be an ASN.1
SignedPublicKeyAndChallenge
structure as defined
below, with the publicKeyAndChallenge
field
set to the publicKeyAndChallenge structure,
the signatureAlgorithm
field set to the algorithm structure, and the signature
field set to the BIT STRING signature from the previous step. [X690]
Return the result of base64 encoding the result of ASN.1 DER encoding the signedPublicKeyAndChallenge structure. [RFC4648] [X690]
The data objects used by the above algorithm are defined as follows. These definitions use the same "ASN.1-like" syntax defined by RFC 5280. [RFC5280]
PublicKeyAndChallenge ::= SEQUENCE { spki SubjectPublicKeyInfo, challenge IA5STRING } SignedPublicKeyAndChallenge ::= SEQUENCE { publicKeyAndChallenge PublicKeyAndChallenge, signatureAlgorithm AlgorithmIdentifier, signature BIT STRING }
Constraint validation: The keygen
element is barred from constraint validation.
The form
attribute is used to
explicitly associate the keygen
element with its
form owner. The name
attribute represents the element's name. The disabled
attribute is used to make
the control non-interactive and to prevent its value from being
submitted. The autofocus
attribute controls focus.
type
Returns the string "keygen
".
The challenge
IDL
attribute must reflect the content attribute of the
same name.
The keytype
IDL attribute must reflect the content attribute of the
same name, limited to only known values.
The type
IDL
attribute must return the value "keygen
".
The willValidate
, validity
, and validationMessage
attributes, and the checkValidity()
and setCustomValidity()
methods, are part of the constraint validation API. The
labels
attribute provides a list
of the element's label
s. The autofocus
, disabled
, form
, and name
IDL attributes are part of the
element's forms API.
This specification does not specify how the private
key generated is to be used. It is expected that after receiving the
SignedPublicKeyAndChallenge
(SPKAC) structure, the
server will generate a client certificate and offer it back to the
user for download; this certificate, once downloaded and stored in
the key store along with the private key, can then be used to
authenticate to services that use TLS and certificate
authentication.
To generate a key pair, add the private key to the user's key store, and submit the public key to the server, markup such as the following can be used:
<form action="processkey.cgi" method="post" enctype="multipart/form-data"> <p><keygen name="key"></p> <p><input type=submit value="Submit key..."></p> </form>
The server will then receive a form submission with a packaged
RSA public key as the value of "key
". This
can then be used for various purposes, such as generating a client
certificate, as mentioned above.
output
elementfor
form
name
interface HTMLOutputElement : HTMLElement { [PutForwards=value] readonly attribute DOMSettableTokenList htmlFor; readonly attribute HTMLFormElement form; attribute DOMString name; readonly attribute DOMString type; attribute DOMString defaultValue; attribute DOMString value; readonly attribute boolean willValidate; readonly attribute ValidityState validity; readonly attribute DOMString validationMessage; boolean checkValidity(); void setCustomValidity(in DOMString error); readonly attribute NodeList labels; };
The output
element represents the result of a
calculation.
The for
content
attribute allows an explicit relationship to be made between the
result of a calculation and the elements that represent the values
that went into the calculation or that otherwise influenced the
calculation. The for
attribute,
if specified, must contain a string consisting of an unordered
set of unique space-separated tokens that are
case-sensitive, each of which must have the value of an
ID of an element in the same
Document
.
The form
attribute is used to
explicitly associate the output
element with its
form owner. The name
attribute represents the element's name.
The element has a value mode flag which is either value or default. Initially, the value mode flag must be set to default.
The element also has a default value. Initially, the default value must be the empty string.
When the value mode flag
is in mode default, the
contents of the element represent both the value of the element and
its default
value. When the value mode
flag is in mode value, the contents of the
element represent the value of the element only, and the default value is only
accessible using the defaultValue
IDL
attribute.
Whenever the element's descendants are changed in any way, if the
value mode flag is in mode
default, the element's
default value must
be set to the value of the element's textContent
IDL
attribute.
The reset
algorithm for output
elements is to set the
element's value mode flag
to default and then to
set the element's textContent
IDL attribute to the
value of the element's default value (thus
replacing the element's child nodes).
value
[ = value ]Returns the element's current value.
Can be set, to change the value.
defaultValue
[ = value ]Returns the element's current default value.
Can be set, to change the default value.
type
Returns the string "output
".
The value
IDL
attribute must act like the element's textContent
IDL
attribute, except that on setting, in addition, before the child
nodes are changed, the element's value mode flag must be set to value.
The defaultValue
IDL
attribute, on getting, must return the element's default value. On
setting, the attribute must set the element's default value, and, if
the element's value mode
flag is in the mode default, set the element's
textContent
IDL attribute as well.
The type
attribute must return the string "output
".
The htmlFor
IDL attribute must reflect the for
content attribute.
The willValidate
, validity
, and validationMessage
attributes, and the checkValidity()
and setCustomValidity()
methods, are part of the constraint validation API. The
labels
attribute provides a list
of the element's label
s. The form
and name
IDL attributes are part of the
element's forms API.
Constraint validation: output
elements are always barred from constraint
validation.
A simple calculator could use output
for its
display of calculated results:
<form onsubmit="return false" oninput="o.value = a.valueAsNumber + b.valueAsNumber"> <input name=a type=number step=any> + <input name=b type=number step=any> = <output name=o></output> </form>
progress
elementprogress
element descendants.value
max
form
interface HTMLProgressElement : HTMLElement { attribute double value; attribute double max; readonly attribute double position; readonly attribute HTMLFormElement form; readonly attribute NodeList labels; };
The progress
element represents the
completion progress of a task. The progress is either indeterminate,
indicating that progress is being made but that it is not clear how
much more work remains to be done before the task is complete (e.g.
because the task is waiting for a remote host to respond), or the
progress is a number in the range zero to a maximum, giving the
fraction of work that has so far been completed.
There are two attributes that determine the current task
completion represented by the element. The value
attribute
specifies how much of the task has been completed, and the max
attribute specifies
how much work the task requires in total. The units are arbitrary
and not specified.
To make an determinate progress bar, add a value
attribute with the current
progress (either a number from 0.0 to 1.0, or, if the max
attribute is specified, a
number from 0 to the value of the max
attribute. To make an
indeterminate progress bar, remove the value
attribute.
Authors are encouraged to also include the current value and the maximum value inline as text inside the element, so that the progress is made available to users of legacy user agents.
Here is a snippet of a Web application that shows the progress of some automated task:
<section> <h2>Task Progress</h2> <p>Progress: <progress id="p" max=100><span>0</span>%</progress></p> <script> var progressBar = document.getElementById('p'); function updateProgress(newValue) { progressBar.value = newValue; progressBar.getElementsByTagName('span')[0].textContent = newValue; } </script> </section>
(The updateProgress()
method in this example would
be called by some other code on the page to update the actual
progress bar as the task progressed.)
The value
and max
attributes, when present, must
have values that are valid
floating point numbers. The value
attribute, if present, must
have a value equal to or greater than zero, and less than or equal
to the value of the max
attribute, if present, or 1.0, otherwise. The max
attribute, if present, must
have a value greater than zero.
The progress
element is the wrong
element to use for something that is just a gauge, as opposed to
task progress. For instance, indicating disk space usage using
progress
would be inappropriate. Instead, the
meter
element is available for such use cases.
User agent requirements: If the value
attribute is omitted, then
the progress bar is an indeterminate progress bar. Otherwise, it is
a determinate progress bar.
If the progress bar is a determinate progress bar and the element
has a max
attribute, the user
agent must parse the max
attribute's value according to the rules for parsing floating
point number values. If this does not result in an error, and
if the parsed value is greater than zero, then the maximum value of the progress
bar is that value. Otherwise, if the element has no max
attribute, or if it has one but
parsing it resulted in an error, or if the parsed value was less
than or equal to zero, then the maximum value of the
progress bar is 1.0.
If the progress bar is a determinate progress bar, user agents
must parse the value
attribute's value according to the rules for parsing floating
point number values. If this does not result in an error, and
if the parsed value is less than the maximum value and greater
than zero, then the current
value of the progress bar is that parsed value. Otherwise, if
the parsed value was greater than or equal to the maximum value, then the
current value of the
progress bar is the maximum
value of the progress bar. Otherwise, if parsing the value
attribute's value resulted
in an error, or a number less than or equal to zero, then the current value of the
progress bar is zero.
UA requirements for showing the progress bar:
When representing a progress
element to the user, the
UA should indicate whether it is a determinate or indeterminate
progress bar, and in the former case, should indicate the relative
position of the current
value relative to the maximum value.
The form
attribute is used to
explicitly associate the progress
element with its
form owner.
position
For a determinate progress bar (one with known current and maximum values), returns the result of dividing the current value by the maximum value.
For an indeterminate progress bar, returns −1.
If the progress bar is an indeterminate progress bar, then the
position
IDL
attribute must return −1. Otherwise, it must return the
result of dividing the current value by the maximum value.
If the progress bar is an indeterminate progress bar, then the
value
IDL
attribute, on getting, must return 0. Otherwise, it must return the
current value. On
setting, the given value must be converted to the best
representation of the number as a floating point number and
then the value
content
attribute must be set to that string.
Setting the value
IDL attribute to itself when
the corresponding content attribute is absent would change the
progress bar from an indeterminate progress bar to a determinate
progress bar with no progress.
The max
IDL
attribute must reflect the content attribute of the
same name. The default value for max
is 1.0.
The labels
attribute provides
a list of the element's label
s. The form
IDL attribute is part of the
element's forms API.
meter
elementmeter
element descendants.value
min
max
low
high
optimum
form
interface HTMLMeterElement : HTMLElement { attribute double value; attribute double min; attribute double max; attribute double low; attribute double high; attribute double optimum; readonly attribute HTMLFormElement form; readonly attribute NodeList labels; };
The meter
element represents a scalar
measurement within a known range, or a fractional value; for example
disk usage, the relevance of a query result, or the fraction of a
voting population to have selected a particular candidate.
This is also known as a gauge.
The meter
element should not be used to
indicate progress (as in a progress bar). For that role, HTML
provides a separate progress
element.
The meter
element also does not
represent a scalar value of arbitrary range — for example, it
would be wrong to use this to report a weight, or height, unless
there is a known maximum value.
There are six attributes that determine the semantics of the gauge represented by the element.
The min
attribute
specifies the lower bound of the range, and the max
attribute specifies
the upper bound. The value
attribute
specifies the value to have the gauge indicate as the "measured"
value.
The other three attributes can be used to segment the gauge's
range into "low", "medium", and "high" parts, and to indicate which
part of the gauge is the "optimum" part. The low
attribute specifies
the range that is considered to be the "low" part, and the high
attribute specifies
the range that is considered to be the "high" part. The optimum
attribute
gives the position that is "optimum"; if that is higher than the
"high" value then this indicates that the higher the value, the
better; if it's lower than the "low" mark then it indicates that
lower values are better, and naturally if it is in between then it
indicates that neither high nor low values are good.
Authoring
requirements: The value
attribute must be
specified. The value
, min
, low
, high
, max
, and optimum
attributes, when present,
must have values that are valid floating point numbers.
In addition, the attributes' values are further constrained:
Let value be the value
attribute's number.
If the min
attribute
attribute is specified, then let minimum be that
attribute's value; otherwise, let it be zero.
If the max
attribute
attribute is specified, then let maximum be that
attribute's value; otherwise, let it be 1.0.
The following inequalities must hold, as applicable:
low
≤ maximum (if low
is specified)high
≤ maximum (if high
is specified)optimum
≤ maximum (if optimum
is specified)low
≤ high
(if both low
and high
are specified)If no minimum or maximum is specified, then the range is assumed to be 0..1, and the value thus has to be within that range.
Authors are encouraged to include a textual representation of the
gauge's state in the element's contents, for users of user agents
that do not support the meter
element.
The following examples show three gauges that would all be three-quarters full:
Storage space usage: <meter value=6 max=8>6 blocks used (out of 8 total)</meter> Voter turnout: <meter value=0.75><img alt="75%" src="graph75.png"></meter> Tickets sold: <meter min="0" max="100" value="75"></meter>
The following example is incorrect use of the element, because it doesn't give a range (and since the default maximum is 1, both of the gauges would end up looking maxed out):
<p>The grapefruit pie had a radius of <meter value=12>12cm</meter> and a height of <meter value=2>2cm</meter>.</p> <!-- BAD! -->
Instead, one would either not include the meter element, or use the meter element with a defined range to give the dimensions in context compared to other pies:
<p>The grapefruit pie had a radius of 12cm and a height of 2cm.</p> <dl> <dt>Radius: <dd> <meter min=0 max=20 value=12>12cm</meter> <dt>Height: <dd> <meter min=0 max=10 value=2>2cm</meter> </dl>
There is no explicit way to specify units in the
meter
element, but the units may be specified in the
title
attribute in free-form text.
The example above could be extended to mention the units:
<dl> <dt>Radius: <dd> <meter min=0 max=20 value=12 title="centimeters">12cm</meter> <dt>Height: <dd> <meter min=0 max=10 value=2 title="centimeters">2cm</meter> </dl>
User agent requirements: User agents must parse
the min
, max
, value
, low
, high
, and optimum
attributes using the
rules for parsing floating point number values.
User agents must then use all these numbers to obtain values for six points on the gauge, as follows. (The order in which these are evaluated is important, as some of the values refer to earlier ones.)
If the min
attribute is
specified and a value could be parsed out of it, then the minimum
value is that value. Otherwise, the minimum value is zero.
If the max
attribute is
specified and a value could be parsed out of it, the maximum value
is that value. Otherwise, the maximum value is 1.0.
If the maximum value would be less than the minimum value, then the maximum value is actually the same as the minimum value.
If the value
attribute is
specified and a value could be parsed out of it, then that value
is the actual value. Otherwise, the actual value is zero.
If the actual value would be less than the minimum value, then the actual value is actually the same as the minimum value.
If, on the other hand, the actual value would be greater than the maximum value, then the actual value is the maximum value.
If the low
attribute is
specified and a value could be parsed out of it, then the low
boundary is that value. Otherwise, the low boundary is the same as
the minimum value.
If the low boundary is then less than the minimum value, then the low boundary is actually the same as the minimum value. Similarly, if the low boundary is greater than the maximum value, then it is actually the maximum value instead.
If the high
attribute is
specified and a value could be parsed out of it, then the high
boundary is that value. Otherwise, the high boundary is the same
as the maximum value.
If the high boundary is then less than the low boundary, then the high boundary is actually the same as the low boundary. Similarly, if the high boundary is greater than the maximum value, then it is actually the maximum value instead.
If the optimum
attribute is specified and a value could be parsed out of it, then
the optimum point is that value. Otherwise, the optimum point is
the midpoint between the minimum value and the maximum value.
If the optimum point is then less than the minimum value, then the optimum point is actually the same as the minimum value. Similarly, if the optimum point is greater than the maximum value, then it is actually the maximum value instead.
All of which will result in the following inequalities all being true:
UA requirements for regions of the gauge: If the optimum point is equal to the low boundary or the high boundary, or anywhere in between them, then the region between the low and high boundaries of the gauge must be treated as the optimum region, and the low and high parts, if any, must be treated as suboptimal. Otherwise, if the optimum point is less than the low boundary, then the region between the minimum value and the low boundary must be treated as the optimum region, the region between the low boundary and the high boundary must be treated as a suboptimal region, and the region between the high boundary and the maximum value must be treated as an even less good region. Finally, if the optimum point is higher than the high boundary, then the situation is reversed; the region between the high boundary and the maximum value must be treated as the optimum region, the region between the high boundary and the low boundary must be treated as a suboptimal region, and the remaining region between the low boundary and the minimum value must be treated as an even less good region.
UA requirements for showing the gauge: When
representing a meter
element to the user, the UA should
indicate the relative position of the actual value to the minimum
and maximum values, and the relationship between the actual value
and the three regions of the gauge.
The following markup:
<h3>Suggested groups</h3> <menu type="toolbar"> <a href="?cmd=hsg" onclick="hideSuggestedGroups()">Hide suggested groups</a> </menu> <ul> <li> <p><a href="/group/comp.infosystems.www.authoring.stylesheets/view">comp.infosystems.www.authoring.stylesheets</a> - <a href="/group/comp.infosystems.www.authoring.stylesheets/subscribe">join</a></p> <p>Group description: <strong>Layout/presentation on the WWW.</strong></p> <p><meter value="0.5">Moderate activity,</meter> Usenet, 618 subscribers</p> </li> <li> <p><a href="/group/netscape.public.mozilla.xpinstall/view">netscape.public.mozilla.xpinstall</a> - <a href="/group/netscape.public.mozilla.xpinstall/subscribe">join</a></p> <p>Group description: <strong>Mozilla XPInstall discussion.</strong></p> <p><meter value="0.25">Low activity,</meter> Usenet, 22 subscribers</p> </li> <li> <p><a href="/group/mozilla.dev.general/view">mozilla.dev.general</a> - <a href="/group/mozilla.dev.general/subscribe">join</a></p> <p><meter value="0.25">Low activity,</meter> Usenet, 66 subscribers</p> </li> </ul>
Might be rendered as follows:
User agents may combine the value of
the title
attribute and the other
attributes to provide context-sensitive help or inline text
detailing the actual values.
For example, the following snippet:
<meter min=0 max=60 value=23.2 title=seconds></meter>
...might cause the user agent to display a gauge with a tooltip saying "Value: 23.2 out of 60." on one line and "seconds" on a second line.
The form
attribute is used to
explicitly associate the meter
element with its
form owner.
The value
IDL
attribute, on getting, must return the actual value. On setting, the
given value must be converted to the best representation of
the number as a floating point number and then the value
content attribute must be set
to that string.
The min
, max
, low
, high
, and optimum
IDL attributes
must reflect the respective content attributes of the
same name.
The labels
attribute provides
a list of the element's label
s. The form
IDL attribute is part of the
element's forms API.
The following example shows how a gauge could fall back to localized or pretty-printed text.
<p>Disk usage: <meter min=0 value=170261928 max=233257824>170 261 928 bytes used out of 233 257 824 bytes available</meter></p>
A form-associated element can have a relationship
with a form
element, which is called the element's
form owner. If a form-associated element is
not associated with a form
element, its form
owner is said to be null.
A form-associated element is, by default, associated
with its nearest ancestor
form
element (as described
below), but may have a form
attribute specified to
override this.
This feature allows authors to work around the lack
of support for nested form
elements.
If a form-associated element has a form
attribute specified, then that
attribute's value must be the ID of a form
element in
the element's owner Document
.
The rules in this section are complicated by the
fact that although conforming documents will never contain nested
form
elements, it is quite possible (e.g. using a
script that performs DOM manipulation) to generate documents that
have such nested elements. They are also complicated by rules in the
HTML parser that, for historical reasons, can result in a
form-associated element being associated with a
form
element that is not its ancestor.
When a form-associated element is created, its form owner must be initialized to null (no owner).
When a form-associated element is to be associated with a form, its form owner must be set to that form.
When a form-associated element's ancestor chain
changes, e.g. because it or one of its ancestors was inserted or removed from a
Document
, then the user agent must reset the form
owner of that element. The HTML
parser overrides this requirement when inserting form
controls.
When a form-associated element's form
attribute is set, changed, or
removed, then the user agent must reset the form owner
of that element.
When a form-associated element has a form
attribute and the ID of any of the
elements in the Document
changes, then the user agent
must reset the form owner of that form-associated
element.
When a form-associated element has a form
attribute and an element with an
ID is inserted
into or removed from the Document
, then the
user agent must reset the form owner of that
form-associated element.
When the user agent is to reset the form owner of a form-associated element, it must run the following steps:
If the element's form owner is not null, and
the element's form
content
attribute is not present, and the element's form owner
is its nearest form
element ancestor after the change
to the ancestor chain, then do nothing, and abort these
steps.
Let the element's form owner be null.
If the element has a form
content attribute, then run these substeps:
If the first element in the
Document
to have an ID that is case-sensitively equal to the
element's form
content
attribute's value is a form
element, then associate the
form-associated element with that form
element.
Abort the "reset the form owner" steps.
Otherwise, if the form-associated element in
question has an ancestor form
element, then associate the
form-associated element with the nearest such ancestor
form
element.
Otherwise, the element is left unassociated.
In the following non-conforming snippet:
... <form id="a"> <div id="b"></div> </form> <script> document.getElementById('b').innerHTML = '<table><tr><td><form id="c"><input id="d"></table>' + '<input id="e">'; </script> ...
The form owner of "d" would be the inner nested form "c", while the form owner of "e" would be the outer form "a".
This happens as follows: First, the "e" node gets associated
with "c" in the HTML parser. Then, the innerHTML
algorithm moves the nodes
from the temporary document to the "b" element. At this point, the
nodes see their ancestor chain change, and thus all the "magic"
associations done by the parser are reset to normal ancestor
associations.
This example is a non-conforming document, though, as it is a
violation of the content models to nest form
elements.
form
Returns the element's form owner.
Returns null if there isn't one.
Form-associated
elements have a form
IDL attribute, which,
on getting, must return the element's form owner, or
null if there isn't one.
The name
content
attribute gives the name of the form control, as used in form
submission and in the form
element's elements
object. If the attribute
is specified, its value must not be the empty string.
Any non-empty value for name
is allowed, but the names "_charset_
" and "isindex
" are special:
isindex
This value, if used as the name of a Text control that is the first
control in a form that is submitted using the application/x-www-form-urlencoded
mechanism, causes the submission to only include the value of this
control, with no name.
_charset_
This value, if used as the name of a Hidden control with no value
attribute, is automatically
given a value during submission consisting of the submission
character encoding.
The disabled
content attribute is a boolean attribute.
A form control is disabled
if its disabled
attribute is
set, or if it is a descendant of a fieldset
element
whose disabled
attribute
is set and is not a descendant of that
fieldset
element's first legend
element
child, if any.
A form control that is disabled must prevent any click
events that are queued on the user interaction task
source from being dispatched on the element.
Constraint validation: If an element is disabled, it is barred from constraint validation.
The disabled
IDL
attribute must reflect the disabled
content attribute.
Form controls have a value
and a checkedness. (The latter
is only used by input
elements.) These are used to
describe how the user interacts with the control.
To define the behaviour of constraint validation in the face of
the input
element's multiple
attribute,
input
elements can also have separately defined values.
The autofocus
content attribute allows the author to indicate that a control is to
be focused as soon as the page is loaded, allowing the user to just
start typing without having to manually focus the main control.
The autofocus
attribute is
a boolean attribute.
There must not be more than one element in the document with the
autofocus
attribute
specified.
When an element with the autofocus
attribute specified is
inserted into a
document, user agents should run the following steps:
Let target be the element's
Document
.
If target has no browsing context, abort these steps.
If target's browsing context has no top-level browsing context (e.g. it is a nested browsing context with no parent browsing context), abort these steps.
If target's browsing context had the sandboxed automatic features browsing context flag set when target was created, abort these steps.
If target's origin is not
the same as the
origin of the Document
of the currently
focused element in target's top-level
browsing context, abort these steps.
If target's origin is not the same as the origin of the active document of target's top-level browsing context, abort these steps.
If the user agent has already reached the last step of this
list of steps in response to an element being inserted into a
Document
whose top-level browsing
context's active document is the same as target's top-level browsing context's
active document, abort these steps.
If the user has indicated (for example, by starting to type in a form control) that he does not wish focus to be changed, then optionally abort these steps.
Queue a task that checks to see if the element is focusable, and if so, runs the focusing steps for that element. User agents may also change the scrolling position of the document, or perform some other action that brings the element to the user's attention. The task source for this task is the DOM manipulation task source.
Focusing the control does not imply that the user agent must focus the browser window if it has lost focus.
The autofocus
IDL attribute must reflect the content attribute of the
same name.
In the following snippet, the text control would be focused when the document was loaded.
<input maxlength="256" name="q" value="" autofocus> <input type="submit" value="Search">
A form control maxlength
attribute, controlled by a dirty value flag, declares a limit on the number of
characters a user can input.
If an element has its form
control maxlength
attribute specified,
the attribute's value must be a valid non-negative
integer. If the attribute is specified and applying the
rules for parsing non-negative integers to its value
results in a number, then that number is the element's maximum
allowed value length. If the attribute is omitted or parsing
its value results in an error, then there is no maximum
allowed value length.
Constraint validation: If an element has a maximum allowed value length, its dirty value flag is true, its value was last changed by a user edit (as opposed to a change made by a script), and the code-point length of the element's value is greater than the element's maximum allowed value length, then the element is suffering from being too long.
User agents may prevent the user from causing the element's value to be set to a value whose code-point length is greater than the element's maximum allowed value length.
Attributes for form submission can be specified both
on form
elements and on submit buttons (elements that
represent buttons that submit forms, e.g. an input
element whose type
attribute is
in the Submit Button
state).
The attributes for form submission that may be
specified on form
elements are action
, enctype
, method
, novalidate
, and target
.
The corresponding attributes for form submission
that may be specified on submit
buttons are formaction
, formenctype
, formmethod
, formnovalidate
, and formtarget
. When omitted, they
default to the values given on the corresponding attributes on the
form
element.
The action
and
formaction
content attributes, if specified, must have a value that is a
valid non-empty URL potentially surrounded by
spaces.
The action of an element is
the value of the element's formaction
attribute, if the
element is a submit
button and has such an attribute, or the value of its
form owner's action
attribute, if it has one, or else the empty string.
The method
and
formmethod
content attributes are enumerated
attributes with the following keywords and states:
get
, mapping
to the state GET, indicating
the HTTP GET method.post
, mapping
to the state POST, indicating
the HTTP POST method.The missing value default for these attributes is the GET state.
The method of an element is
one of those states. If the element is a submit button and has a formmethod
attribute, then the
element's method is that
attribute's state; otherwise, it is the form owner's
method
attribute's state.
The enctype
and
formenctype
content attributes are enumerated
attributes with the following keywords and states:
application/x-www-form-urlencoded
" keyword and corresponding state.multipart/form-data
" keyword and corresponding state.text/plain
" keyword and corresponding state.The missing value default for these attributes is the
application/x-www-form-urlencoded
state.
The enctype of an element
is one of those three states. If the element is a submit button and has a formenctype
attribute, then the
element's enctype is that
attribute's state; otherwise, it is the form owner's
enctype
attribute's state.
The target
and
formtarget
content attributes, if specified, must have values that are valid browsing
context names or keywords.
The target of an element is
the value of the element's formtarget
attribute, if the
element is a submit
button and has such an attribute; or the value of its
form owner's target
attribute, if it has such an attribute; or, if the
Document
contains a base
element with a
target
attribute, then the
value of the target
attribute
of the first such base
element; or, if there is no such
element, the empty string.
The novalidate
and formnovalidate
content attributes are boolean
attributes. If present, they indicate that the form is not to
be validated during submission.
The no-validate state of
an element is true if the element is a submit button and the element's
formnovalidate
attribute
is present, or if the element's form owner's novalidate
attribute is present,
and false otherwise.
This attribute is useful to include "save" buttons on forms that have validation constraints, to allow users to save their progress even though they haven't fully entered the data in the form. The following example shows a simple form that has two required fields. There are three buttons: one to submit the form, which requires both fields to be filled in; one to save the form so that the user can come back and fill it in later; and one to cancel the form altogether.
<form action="editor.cgi" method="post"> <p><label>Name: <input required name=fn></label></p> <p><label>Essay: <textarea required name=essay></textarea></label></p> <p><input type=submit name=submit value="Submit essay"></p> <p><input type=submit formnovalidate name=save value="Save essay"></p> <p><input type=submit formnovalidate name=cancel value="Cancel"></p> </form>
The action
IDL
attribute must reflect the content attribute of the
same name, except that on getting, when the content attribute is
missing or its value is the empty string, the document's
address must be returned instead. The target
IDL attribute must
reflect the content attribute of the same name. The
method
and enctype
IDL attributes
must reflect the respective content attributes of the
same name, limited to only known values. The encoding
IDL attribute
must reflect the enctype
content attribute,
limited to only known values. The noValidate
IDL
attribute must reflect the novalidate
content attribute. The
formAction
IDL
attribute must reflect the formaction
content attribute,
except that on getting, when the content attribute is missing or its
value is the empty string, the document's address must
be returned instead. The formEnctype
IDL
attribute must reflect the formenctype
content attribute,
limited to only known values. The formMethod
IDL
attribute must reflect the formmethod
content attribute,
limited to only known values. The formNoValidate
IDL
attribute must reflect the formnovalidate
content
attribute. The formTarget
IDL
attribute must reflect the formtarget
content attribute.
A form control dirname
attribute
on a form control element enables the submission of the
directionality of the element, and gives the name of the
field that contains this value during form submission.
If such an attribute is specified, its value must not be the empty
string.
The input
and textarea
elements define
the following members in their DOM interfaces for handling their
selection:
void select(); attribute unsigned long selectionStart; attribute unsigned long selectionEnd; attribute DOMString selectionDirection; void setSelectionRange(in unsigned long start, in unsigned long end, in optional DOMString direction);
These methods and attributes expose and control the selection of
input
and textarea
text fields.
select
()Selects everything in the text field.
selectionStart
[ = value ]Returns the offset to the start of the selection.
Can be set, to change the start of the selection.
selectionEnd
[ = value ]Returns the offset to the end of the selection.
Can be set, to change the end of the selection.
selectionDirection
[ = value ]Returns the current direction of the selection.
Can be set, to change the direction of the selection.
The possible values are "forward
", "backward
", and "none
".
setSelectionRange
(start, end [, direction] )Changes the selection to cover the given substring in the given direction. If the direction is omitted, it will be reset to be the platform default (none or forward).
When these methods and attributes are used with
input
elements while they don't apply, they must raise
an INVALID_STATE_ERR
exception. Otherwise, they must
act as described below.
For input
elements, these methods and attributes
must operate on the element's value. For textarea
elements, these methods and attributes must operate on the element's
raw value.
Where possible, user interface features for changing the text
selection in input
and textarea
elements
must be implemented in terms of the DOM API described in this
section, so that, e.g., all the same events fire.
The selections of input
and textarea
elements have a direction, which is either forward,
backward, or none. This direction is set when the user
manipulates the selection. The exact meaning of the selection
direction depends on the platform.
On Windows, the direction indicates the position of the caret relative to the selection: a forward selection has the caret at the end of the selection and a backward selection has the caret at the start of the selection. Windows has no none direction. On Mac, the direction indicates which end of the selection is affected when the user adjusts the size of the selection using the arrow keys with the Shift modifier: the forward direction means the end of the selection is modified, and the backwards direction means the start of the selection is modified. The none direction is the default on Mac, it indicates that no particular direction has yet been selected. The user sets the direction implicitly when first adjusting the selection, based on which directional arrow key was used.
The select()
method
must cause the contents of the text field to be fully selected, with
the selection direction being none, if the platform support
selections with the direction none, or otherwise
forward. The user agent must then queue a task
to fire a simple event that bubbles named select
at the element, using the
user interaction task source as the task source.
The selectionStart
attribute must, on getting, return the offset (in logical order) to
the character that immediately follows the start of the
selection. If there is no selection, then it must return the offset
(in logical order) to the character that immediately follows the
text entry cursor.
On setting, it must act as if the setSelectionRange()
method had been called, with the new value as the first argument;
the current value of the selectionEnd
attribute as the second argument, unless the current value of the
selectionEnd
is
less than the new value, in which case the second argument must also
be the new value; and the current value of the selectionDirection
as the third argument.
The selectionEnd
attribute must, on getting, return the offset (in logical order) to
the character that immediately follows the end of the selection. If
there is no selection, then it must return the offset (in logical
order) to the character that immediately follows the text entry
cursor.
On setting, it must act as if the setSelectionRange()
method had been called, with the current value of the selectionStart
attribute as the first argument, the new value as the second
argument, and the current value of the selectionDirection
as the third argument.
The selectionDirection
attribute must, on getting, return the string corresponding to the
current selection direction: if the direction is forward,
"forward
"; if the direction is
backward, "backward
"; and otherwise,
"none
".
On setting, it must act as if the setSelectionRange()
method had been called, with the current value of the selectionStart
attribute as the first argument, the current value of the selectionEnd
attribute as the first argument, and the new value as the third
argument.
The setSelectionRange(start, end, direction)
method must set the selection
of the text field to the sequence of characters starting with the
character at the startth position (in logical
order) and ending with the character at the (end-1)th position. Arguments greater than the
length of the value in the text field must be treated as pointing at
the end of the text field. If end is less than
or equal to start then the start of the
selection and the end of the selection must both be placed
immediately before the character with offset end. In UAs where there is no concept of an empty
selection, this must set the cursor to be just before the character
with offset end. The direction of the selection
must be set to backward if direction is a
case-sensitive match for the string "backward
", forward if direction is a case-sensitive match for
the string "forward
" or if the platform does
not support selections with the direction none, and
none otherwise (including if the argument is omitted). The
user agent must then queue a task to fire a
simple event that bubbles named select
at the element, using the
user interaction task source as the task source.
All elements to which this API applies have either a selection or a text entry cursor position at all times (even for elements that are not being rendered). User agents should follow platform conventions to determine their initial state.
Characters with no visible rendering, such as U+200D ZERO WIDTH JOINER, still count as characters. Thus, for instance, the selection can include just an invisible character, and the text insertion cursor can be placed to one side or another of such a character.
To obtain the currently selected text, the following JavaScript suffices:
var selectionText = control.value.substring(control.selectionStart, control.selectionEnd);
To add some text at the start of a text control, while maintaining the text selection, the three attributes must be preserved:
var oldStart = control.selectionStart; var oldEnd = control.selectionEnd; var oldDirection = control.selectionDirection; var prefix = "http://"; control.value = prefix + control.value; control.setSelectionRange(oldStart + prefix.length, oldEnd + prefix.length, oldDirection);
A listed form-associated
element is a candidate for constraint validation
except when a condition has barred the element from constraint
validation. (For example, an element is barred from
constraint validation if it is an output
or
fieldset
element.)
An element can have a custom validity error message
defined. Initially, an element must have its custom validity
error message set to the empty string. When its value is not
the empty string, the element is suffering from a custom
error. It can be set using the setCustomValidity()
method. The user agent should use the custom validity error
message when alerting the user to the problem with the
control.
An element can be constrained in various ways. The following is the list of validity states that a form control can be in, making the control invalid for the purposes of constraint validation. (The definitions below are non-normative; other parts of this specification define more precisely when each state applies or does not.)
When a control has no value but has a required
attribute (input
required
, select
required
,
textarea
required
), or, in the case of
an element in a radio button group, any of the other
elements in the group has a required
attribute.
When a control that allows arbitrary user input has a value that is not in the correct syntax (E-mail, URL).
When a control has a value that doesn't satisfy the
pattern
attribute.
When a control has a value that is too long for the
form control maxlength
attribute (input
maxlength
,
textarea
maxlength
).
When a control has a value that is too low for the min
attribute.
When a control has a value that is too high for the
max
attribute.
When a control has a value that doesn't fit the rules
given by the step
attribute.
When a control's custom validity error
message (as set by the element's setCustomValidity()
method) is not the empty string.
An element can still suffer from these states even when the element is disabled; thus these states can be represented in the DOM even if validating the form during submission wouldn't indicate a problem to the user.
An element satisfies its constraints if it is not suffering from any of the above validity states.
When the user agent is required to statically validate the
constraints of form
element form, it must run the following steps, which return
either a positive result (all the controls in the form are
valid) or a negative result (there are invalid controls)
along with a (possibly empty) list of elements that are invalid and
for which no script has claimed responsibility:
Let controls be a list of all the submittable elements whose form owner is form, in tree order.
Let invalid controls be an initially empty list of elements.
For each element field in controls, in tree order, run the following substeps:
If field is not a candidate for constraint validation, then move on to the next element.
Otherwise, if field satisfies its constraints, then move on to the next element.
Otherwise, add field to invalid controls.
If invalid controls is empty, then return a positive result and abort these steps.
Let unhandled invalid controls be an initially empty list of elements.
For each element field in invalid controls, if any, in tree order, run the following substeps:
Fire a simple event named invalid
that is cancelable at field.
If the event was not canceled, then add field to unhandled invalid controls.
Return a negative result with the list of elements in the unhandled invalid controls list.
If a user agent is to interactively validate the
constraints of form
element form, then the user agent must run the following
steps:
Statically validate the constraints of form, and let unhandled invalid controls be the list of elements returned if the result was negative.
If the result was positive, then return that result and abort these steps.
Report the problems with the constraints of at least one of
the elements given in unhandled invalid
controls to the user. User agents may focus one of those
elements in the process, by running the focusing steps
for that element, and may change the scrolling position of the
document, or perform some other action that brings the element to
the user's attention. User agents may report more than one
constraint violation. User agents may coalesce related constraint
violation reports if appropriate (e.g. if multiple radio buttons in
a group are marked as
required, only one error need be reported). If one of the controls
is not being rendered (e.g. it has the hidden
attribute set) then user agents
may report a script error.
Return a negative result.
willValidate
Returns true if the element will be validated when the form is submitted; false otherwise.
setCustomValidity
(message)Sets a custom error, so that the element would fail to validate. The given message is the message to be shown to the user when reporting the problem to the user.
If the argument is the empty string, clears the custom error.
validity
. valueMissing
Returns true if the element has no value but is a required field; false otherwise.
validity
. typeMismatch
Returns true if the element's value is not in the correct syntax; false otherwise.
validity
. patternMismatch
Returns true if the element's value doesn't match the provided pattern; false otherwise.
validity
. tooLong
Returns true if the element's value is longer than the provided maximum length; false otherwise.
validity
. rangeUnderflow
Returns true if the element's value is lower than the provided minimum; false otherwise.
validity
. rangeOverflow
Returns true if the element's value is higher than the provided maximum; false otherwise.
validity
. stepMismatch
Returns true if the element's value doesn't fit the rules given by the step
attribute; false otherwise.
validity
. customError
Returns true if the element has a custom error; false otherwise.
validity
. valid
Returns true if the element's value has no validity problems; false otherwise.
checkValidity
()Returns true if the element's value has no validity problems;
false otherwise. Fires an invalid
event at the element in the
latter case.
validationMessage
Returns the error message that would be shown to the user if the element was to be checked for validity.
The willValidate
attribute must return true if an element is a candidate for
constraint validation, and false otherwise (i.e. false if any
conditions are barring it from constraint validation).
The setCustomValidity(message)
, when invoked, must set the
custom validity error message to the value of the given
message argument.
In the following example, a script checks the value of a form
control each time it is edited, and whenever it is not a valid
value, uses the setCustomValidity()
method
to set an appropriate message.
<label>Feeling: <input name=f type="text" oninput="check(this)"></label> <script> function check(input) { if (input.value == "good" || input.value == "fine" || input.value == "tired") { input.setCustomValidity('"' + input.value + '" is not a feeling.'); } else { // input is fine -- reset the error message input.setCustomValidity(''); } } </script>
The validity
attribute must return a ValidityState
object that
represents the validity states of the element. This
object is live, and the same object must be returned
each time the element's validity
attribute is retrieved.
interface ValidityState { readonly attribute boolean valueMissing; readonly attribute boolean typeMismatch; readonly attribute boolean patternMismatch; readonly attribute boolean tooLong; readonly attribute boolean rangeUnderflow; readonly attribute boolean rangeOverflow; readonly attribute boolean stepMismatch; readonly attribute boolean customError; readonly attribute boolean valid; };
A ValidityState
object has the following
attributes. On getting, they must return true if the corresponding
condition given in the following list is true, and false
otherwise.
valueMissing
The control is suffering from being missing.
typeMismatch
The control is suffering from a type mismatch.
patternMismatch
The control is suffering from a pattern mismatch.
tooLong
The control is suffering from being too long.
rangeUnderflow
The control is suffering from an underflow.
rangeOverflow
The control is suffering from an overflow.
stepMismatch
The control is suffering from a step mismatch.
customError
The control is suffering from a custom error.
valid
None of the other conditions are true.
When the checkValidity()
method is invoked, if the element is a candidate for
constraint validation and does not satisfy its constraints, the user
agent must fire a simple event named invalid
that is cancelable (but in this
case has no default action) at the element and return
false. Otherwise, it must only return true without doing anything
else.
The validationMessage
attribute must return the empty string if the element is not a
candidate for constraint validation or if it is one but
it satisfies its constraints;
otherwise, it must return a suitably localized message that the user
agent would show the user if this were the only form control with a
validity constraint problem. If the user agent would not actually
show a textual message in such a situation (e.g. it would show a
graphical cue instead), then the attribute must return a suitably
localized message that expresses (one or more of) the validity
constraint(s) that the control does not satisfy. If the element is a
candidate for constraint validation and is
suffering from a custom error, then the custom
validity error message should be present in the return
value.
Servers should not rely on client-side validation. Client-side validation can be intentionally bypassed by hostile users, and unintentionally bypassed by users of older user agents or automated tools that do not implement these features. The constraint validation features are only intended to improve the user experience, not to provide any kind of security mechanism.
This section is non-normative.
When a form is submitted, the data in the form is converted into the structure specified by the enctype, and then sent to the destination specified by the action using the given method.
For example, take the following form:
<form action="/find.cgi" method=get> <input type=text name=t> <input type=search name=q> <input type=submit> </form>
If the user types in "cats" in the first field and "fur" in the
second, and then hits the submit button, then the user agent will
load /find.cgi?t=cats&q=fur
.
On the other hand, consider this form:
<form action="/find.cgi" method=post enctype="multipart/form-data"> <input type=text name=t> <input type=search name=q> <input type=submit> </form>
Given the same user input, the result on submission is quite different: the user agent instead does an HTTP POST to the given URL, with as the entity body something like the following text:
------kYFrd4jNJEgCervE Content-Disposition: form-data; name="t" cats ------kYFrd4jNJEgCervE Content-Disposition: form-data; name="q" fur ------kYFrd4jNJEgCervE--
User agents may establish a button in each form as being the
form's default button. This should be the first submit button in tree
order whose form owner is that form
element, but user agents may pick another button if another would be
more appropriate for the platform. If the platform supports letting
the user submit a form implicitly (for example, on some platforms
hitting the "enter" key while a text field is focused implicitly
submits the form), then doing so must cause the form's default
button's activation behavior, if any, to be
run.
Consequently, if the default button is disabled, the form is not submitted when such an implicit submission mechanism is used. (A button has no activation behavior when disabled.)
If the form has no submit
button, then the implicit submission mechanism must just
submit the
form
element from the form
element
itself.
When a form
element form is submitted from an element submitter (typically a button), optionally with a
scripted-submit flag set, the user agent must
run the following steps:
Let form document be the form's Document
.
If form
document has no associated browsing context or
its browsing context had its sandboxed forms
browsing context flag set when the Document
was
created, then abort these steps without doing anything.
Let form browsing context be the browsing context of form document.
If form is already being submitted
(i.e. the form was submitted again while processing
the events fired from the next two steps, probably from a script
redundantly calling the submit()
method on form), then abort these steps. This doesn't affect
the earlier instance of this algorithm.
If the scripted-submit flag is not set, and the submitter element's no-validate state is false, then interactively validate the constraints of form and examine the result: if the result is negative (the constraint validation concluded that there were invalid fields and probably informed the user of this) then abort these steps.
If the scripted-submit flag is not set,
then fire a simple event that is cancelable named
submit
, at form. If the event's default action is prevented
(i.e. if the event is canceled) then abort these steps. Otherwise,
continue (effectively the default action is to perform the
submission).
Let form data set be the result of constructing the form data set for form.
Let action be the submitter element's action.
If action is the empty string, let action be the document's address of the form document.
This step is a willful violation of RFC 3986, which would require base URL processing here. This violation is motivated by a desire for compatibility with legacy content. [RFC3986]
Resolve the URL action, relative to the submitter element. If this fails, abort these steps. Otherwise, let action be the resulting absolute URL.
Let scheme be the <scheme> of the resulting absolute URL.
Let enctype be the submitter element's enctype.
Let method be the submitter element's method.
Let target be the submitter element's target.
If the user indicated a specific browsing context to use when submitting the form, then let target browsing context be that browsing context. Otherwise, apply the rules for choosing a browsing context given a browsing context name using target as the name and form browsing context as the context in which the algorithm is executed, and let target browsing context be the resulting browsing context.
If target browsing context was created in the previous step, or if the form document has not yet completely loaded, then let replace be true. Otherwise, let it be false.
Select the appropriate row in the table below based on the value of scheme as given by the first cell of each row. Then, select the appropriate cell on that row based on the value of method as given in the first cell of each column. Then, jump to the steps named in that cell and defined below the table.
GET | POST | |
---|---|---|
http
| Mutate action URL | Submit as entity body |
https
| Mutate action URL | Submit as entity body |
ftp
| Get action URL | Get action URL |
javascript
| Get action URL | Get action URL |
data
| Get action URL | Post to data: |
mailto
| Mail with headers | Mail as body |
If scheme is not one of those listed in this table, then the behavior is not defined by this specification. User agents should, in the absence of another specification defining this, act in a manner analogous to that defined in this specification for similar schemes.
The behaviors are as follows:
Let query be the result of encoding the
form data set using the application/x-www-form-urlencoded
encoding
algorithm, interpreted as a US-ASCII string.
Let destination be a new URL that is equal to the action except that its <query> component is replaced by query (adding a U+003F QUESTION MARK character (?) if appropriate).
Navigate target browsing context to destination. If replace is true, then target browsing context must be navigated with replacement enabled.
Let entity body be the result of encoding the form data set using the appropriate form encoding algorithm.
Let MIME type be determined as follows:
application/x-www-form-urlencoded
application/x-www-form-urlencoded
".multipart/form-data
multipart/form-data;
", a
U+0020 SPACE character, the string "boundary=
", and the multipart/form-data
boundary string
generated by the multipart/form-data
encoding
algorithm.text/plain
text/plain
".Otherwise, navigate target browsing context to action using the HTTP method given by method and with entity body as the entity body, of type MIME type. If replace is true, then target browsing context must be navigated with replacement enabled.
Navigate target browsing context to action. If replace is true, then target browsing context must be navigated with replacement enabled.
Let data be the result of encoding the form data set using the appropriate form encoding algorithm.
If action contains the string "%%%%
" (four U+0025 PERCENT SIGN characters),
then %-escape all bytes in data that, if
interpreted as US-ASCII, do not match the unreserved
production in the URI Generic Syntax,
and then, treating the result as a US-ASCII string, further
%-escape all the U+0025 PERCENT SIGN characters in the resulting
string and replace the first occurrence of "%%%%
" in action with the
resulting double-escaped string. [RFC3986]
Otherwise, if action contains the string
"%%
" (two U+0025 PERCENT SIGN characters
in a row, but not four), then %-escape all characters in data that, if interpreted as US-ASCII, do not
match the unreserved
production in the URI
Generic Syntax, and then, treating the result as a US-ASCII
string, replace the first occurrence of "%%
" in action with the
resulting escaped string. [RFC3986]
Navigate target
browsing context to the potentially modified action (which will be a data:
URL). If replace is true, then target
browsing context must be navigated with replacement
enabled.
Let headers be the resulting encoding the
form data set using the application/x-www-form-urlencoded
encoding
algorithm, interpreted as a US-ASCII string.
Replace occurrences of U+002B PLUS SIGN characters (+) in
headers with the string "%20
".
Let destination consist of all the characters from the first character in action to the character immediately before the first U+003F QUESTION MARK character (?), if any, or the end of the string if there are none.
Append a single U+003F QUESTION MARK character (?) to destination.
Append headers to destination.
Navigate target browsing context to destination. If replace is true, then target browsing context must be navigated with replacement enabled.
Let body be the resulting encoding the
form data set using the appropriate
form encoding algorithm and then %-escaping all the bytes
in the resulting byte string that, when interpreted as US-ASCII,
do not match the unreserved
production in
the URI Generic Syntax. [RFC3986]
Let destination have the same value as action.
If destination does not contain a U+003F QUESTION MARK character (?), append a single U+003F QUESTION MARK character (?) to destination. Otherwise, append a single U+0026 AMPERSAND character (&).
Append the string "body=
" to destination.
Append body, interpreted as a US-ASCII string, to destination.
Navigate target browsing context to destination. If replace is true, then target browsing context must be navigated with replacement enabled.
The appropriate form encoding algorithm is determined as follows:
application/x-www-form-urlencoded
application/x-www-form-urlencoded
encoding
algorithm.multipart/form-data
multipart/form-data
encoding
algorithm.text/plain
text/plain
encoding
algorithm.The algorithm to construct the form data set for a form form is as follows:
Let controls be a list of all the submittable elements whose form owner is form, in tree order.
Let the form data set be a list of name-value-type tuples, initially empty.
Loop: For each element field in controls, in tree order, run the following substeps:
If any of the following conditions are met, then skip these substeps for this element:
datalist
element ancestor.input
element whose type
attribute is in the Checkbox state and
whose checkedness is
false.input
element whose type
attribute is in the Radio Button state and
whose checkedness is
false.input
element whose type
attribute is in the Image Button state, and
either the field element does not have a
name
attribute specified, or
its name
attribute's value is
the empty string.object
element that is not using a
plugin.Otherwise, process field as follows:
Let type be the value of the type
IDL attribute of field.
If the field element is an
input
element whose type
attribute is in the Image Button state,
then run these further nested substeps:
If the field element has a name
attribute specified and its
value is not the empty string, let name be
that value followed by a single U+002E FULL STOP character (.).
Otherwise, let name be the empty
string.
Let namex be the string consisting of the concatenation of name and a single U+0078 LATIN SMALL LETTER X character (x).
Let namey be the string consisting of the concatenation of name and a single U+0079 LATIN SMALL LETTER Y character (y).
The field element is submitter, and before this algorithm was invoked the user indicated a coordinate. Let x be the x-component of the coordinate selected by the user, and let y be the y-component of the coordinate selected by the user.
Append an entry to the form data set with the name namex, the value x, and the type type.
Append an entry to the form data set with the name namey and the value y, and the type type.
Skip the remaining substeps for this element: if there are any more elements in controls, return to the top of the loop step, otherwise, jump to the end step below.
Let name be the value of the field element's name
attribute.
If the field element is a
select
element, then for each option
element in the select
element whose selectedness is true,
append an entry to the form data set with the
name as the name, the value of the
option
element as the value, and type as the type.
Otherwise, if the field element is an
input
element whose type
attribute is in the Checkbox state or the
Radio Button state,
then run these further nested substeps:
If the field element has a value
attribute specified, then
let value be the value of that attribute;
otherwise, let value be the string
"on
".
Append an entry to the form data set with name as the name, value as the value, and type as the type.
Otherwise, if the field element is an
input
element whose type
attribute is in the File Upload state, then for
each file selected in the
input
element, append an entry to the form data set with the name as
the name, the file (consisting of the name, the type, and the
body) as the value, and type as the type. If
there are no selected files,
then append an entry to the form data set
with the name as the name, the empty string
as the value, and application/octet-stream
as the
type.
Otherwise, if the field element is an
object
element: try to obtain a form submission
value from the plugin,
and if that is successful, append an entry to the form data set with name as the
name, the returned form submission value as the value, and the
string "object
" as the type.
Otherwise, append an entry to the form data set with name as the name, the value of the field element as the value, and type as the type.
If the element has a form control dirname
attribute, and that attribute's
value is not the empty string, then run these substeps:
Let dirname be the value of the
element's dirname
attribute.
Let dir be the string "ltr
" if the directionality of the
element is 'ltr', and "rtl
" otherwise (i.e. when the
directionality of the element is 'rtl').
Append an entry to the form data set
with dirname as the name, dir as the value, and the string "direction
" as the type.
An element can only have a form control
dirname
attribute if it is a
textarea
element or an input
element
whose type
attribute is in
either the Text state
or the Search
state.
End: Return the form data step.
The application/x-www-form-urlencoded
encoding
algorithm is as follows:
Let result be the empty string.
If the form
element has an accept-charset
attribute,
then, taking into account the characters found in the form data set's names and values, and the character
encodings supported by the user agent, select a character encoding
from the list given in the form
's accept-charset
attribute
that is an ASCII-compatible character encoding. If
none of the encodings are supported, or if none are listed, then
let the selected character encoding be UTF-8.
Otherwise, if the document's character encoding is an ASCII-compatible character encoding, then that is the selected character encoding.
Otherwise, let the selected character encoding be UTF-8.
Let charset be the preferred MIME name of the selected character encoding.
For each entry in the form data set, perform these substeps:
If the entry's name is "_charset_
"
and its type is "hidden
", replace its value
with charset.
If the entry's type is "file
",
replace its value with the file's filename only.
For each character in the entry's name and value that cannot be expressed using the selected character encoding, replace the character by a string consisting of a U+0026 AMPERSAND character (&), a U+0023 NUMBER SIGN character (#), one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) representing the Unicode code point of the character in base ten, and finally a U+003B SEMICOLON character (;).
For each character in the entry's name and value, apply the appropriate subsubsteps from the following list:
Replace the character with a string formed as follows:
Let s be an empty string.
For each byte b of the character when expressed in the selected character encoding in turn, run the appropriate subsubsubstep from the list below:
Append to s the Unicode character with the code point equal to the byte.
Append to the string a U+0025 PERCENT SIGN character (%) followed by two characters in the ranges U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) and U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F representing the hexadecimal value of the byte (zero-padded if necessary).
Leave the character as is.
If the entry's name is "isindex
",
its type is "text
", and this is the first
entry in the form data set, then append the
value to result and skip the rest of the
substeps for this entry, moving on to the next entry, if any, or
the next step in the overall algorithm otherwise.
If this is not the first entry, append a single U+0026 AMPERSAND character (&) to result.
Append the entry's name to result.
Append a single U+003D EQUALS SIGN character (=) to result.
Append the entry's value to result.
Encode result as US-ASCII and return the resulting byte stream.
The multipart/form-data
encoding
algorithm is as follows:
Let result be the empty string.
If the algorithm was invoked with an explicit character
encoding, let the selected character encoding be that encoding.
(This algorithm is used by other specifications, which provide an
explicit character encoding to avoid the dependency on the
form
element described in the next paragraph.)
Otherwise, if the form
element has an accept-charset
attribute,
then, taking into account the characters found in the form data set's names and values, and the character
encodings supported by the user agent, select a character encoding
from the list given in the form
's accept-charset
attribute
that is an ASCII-compatible character encoding. If
none of the encodings are supported, or if none are listed, then
let the selected character encoding be UTF-8.
Otherwise, if the document's character encoding is an ASCII-compatible character encoding, then that is the selected character encoding.
Otherwise, let the selected character encoding be UTF-8.
Let charset be the preferred MIME name of the selected character encoding.
For each entry in the form data set, perform these substeps:
If the entry's name is "_charset_
" and its type is
"hidden
", replace its value with charset.
For each character in the entry's name and value that cannot be expressed using the selected character encoding, replace the character by a string consisting of a U+0026 AMPERSAND character (&), a U+0023 NUMBER SIGN character (#), one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9) representing the Unicode code point of the character in base ten, and finally a U+003B SEMICOLON character (;).
Encode the (now mutated) form data set
using the rules described by RFC 2388, Returning Values from
Forms: multipart/form-data
, and
return the resulting byte stream. [RFC2388]
Each entry in the form data set is a field, the name of the entry is the field name and the value of the entry is the field value.
The order of parts must be the same as the order of fields in the form data set. Multiple entries with the same name must be treated as distinct fields.
In particular, this means that multiple files
submitted as part of a single <input type=file multiple>
element
will result in each file having its own field; the "sets of files"
feature ("multipart/mixed
") of RFC 2388 is
not used.
The parts of the generated multipart/form-data
resource that correspond to
non-file fields must not have a Content-Type
header
specified. Their names and values must be encoded using the
character encoding selected above (field names in particular do
not get converted to a 7-bit safe encoding as suggested in RFC
2388).
The boundary used by the user agent in generating the return
value of this algorithm is the multipart/form-data
boundary string. (This
value is used to generate the MIME type of the form submission
payload generated by this algorithm.)
The text/plain
encoding
algorithm is as follows:
Let result be the empty string.
If the form
element has an accept-charset
attribute,
then, taking into account the characters found in the form data set's names and values, and the character
encodings supported by the user agent, select a character encoding
from the list given in the form
's accept-charset
attribute.
If none of the encodings are supported, or if none are listed,
then let the selected character encoding be UTF-8.
Otherwise, the selected character encoding is the document's character encoding.
Let charset be the preferred MIME name of the selected character encoding.
If the entry's name is "_charset_
" and its type is
"hidden
", replace its value with charset.
If the entry's type is "file
", replace
its value with the file's filename only.
For each entry in the form data set, perform these substeps:
Append the entry's name to result.
Append a single U+003D EQUALS SIGN character (=) to result.
Append the entry's value to result.
Append a U+000D CARRIAGE RETURN (CR) U+000A LINE FEED (LF) character pair to result.
Encode result using the selected character encoding and return the resulting byte stream.
When a form
element form is reset, the user agent must
fire a simple event named reset
, that is cancelable, at form, and then, if that event is not canceled, must
invoke the reset
algorithm of each resettable
element whose form owner is form.
Each resettable element
defines its own reset
algorithm. Changes made to form controls as part of these
algorithms do not count as changes caused by the user (and thus,
e.g., do not cause input
events to
fire).
details
elementsummary
element followed by flow content.open
interface HTMLDetailsElement : HTMLElement { attribute boolean open; };
The details
element represents a
disclosure widget from which the user can obtain additional
information or controls.
The details
element is not appropriate
for footnotes. Please see the section on
footnotes for details on how to mark up footnotes.
The first summary
element
child of the element, if any, represents the summary or
legend of the details. If there is no child
summary
element, the user agent should provide its own
legend (e.g. "Details").
The open
content attribute is a boolean attribute. If present,
it indicates that the details are to be shown to the user. If the
attribute is absent, the details are not to be shown.
When the element is created, if the attribute is absent, the details should be hidden; if the attribute is absent, the details should be shown. Subsequently, if the attribute is removed, then the details should be hidden; if the attribute is added, the details should be shown.
The user agent should allow the user to request that the details
be shown or hidden. To honor a request for the details to be shown,
the user agent must set the open
attribute on the element to
the value open
. To honor a request for the
details to be hidden, the user agent must remove the open
attribute from the
element.
The open
IDL
attribute must reflect the open
content attribute.
The following example shows the details
element
being used to hide technical details in a progress report.
<section class="progress window"> <h1>Copying "Really Achieving Your Childhood Dreams"</h1> <details> <summary>Copying... <progress max="375505392" value="97543282"></progress> 25%</summary> <dl> <dt>Transfer rate:</dt> <dd>452KB/s</dd> <dt>Local filename:</dt> <dd>/home/rpausch/raycd.m4v</dd> <dt>Remote filename:</dt> <dd>/var/www/lectures/raycd.m4v</dd> <dt>Duration:</dt> <dd>01:16:27</dd> <dt>Color profile:</dt> <dd>SD (6-1-6)</dd> <dt>Dimensions:</dt> <dd>320×240</dd> </dl> </details> </section>
The following shows how a details
element can be
used to hide some controls by default:
<details> <summary><label for=fn>Name & Extension:</label></summary> <p><input type=text id=fn name=fn value="Pillar Magazine.pdf"> <p><label><input type=checkbox name=ext checked> Hide extension</label> </details>
One could use this in conjunction with other details
in a list to allow the user to collapse a set of fields down to a
small set of headings, with the ability to open each one.
In these examples, the summary really just summarises what the controls can change, and not the actual values, which is less than ideal.
summary
elementdetails
element.HTMLElement
.The summary
element represents a
summary, caption, or legend for the rest of the contents of the
summary
element's parent details
element, if any.
command
elementtype
label
icon
disabled
checked
radiogroup
title
attribute has special semantics on this element.interface HTMLCommandElement : HTMLElement { attribute DOMString type; attribute DOMString label; attribute DOMString icon; attribute boolean disabled; attribute boolean checked; attribute DOMString radiogroup;};
The command
element represents a command that the user
can invoke.
A command can be part of a context menu or toolbar, using the
menu
element, or can be put anywhere else in the page,
to define a keyboard shortcut.
The type
attribute indicates the kind of command: either a normal command
with an associated action, or a state or option that can be toggled,
or a selection of one item from a list of items.
The attribute is an enumerated attribute with three
keywords and states. The "command
"
keyword maps to the Command state, the
"checkbox
"
keyword maps to the Checkbox state, and
the "radio
"
keyword maps to the Radio state. The
missing value default is the Command state.
The element represents a normal command with an associated action.
The element represents a state or option that can be toggled.
The element represents a selection of one item from a list of items.
The label
attribute gives the name of the command, as shown to the user. The
label
attribute must be
specified and must have a value that is not the empty string.
The title
attribute gives a hint describing the command, which might be shown
to the user to help him.
The icon
attribute gives a picture that represents the command. If the
attribute is specified, the attribute's value must contain a
valid non-empty URL potentially surrounded by
spaces. To obtain the absolute
URL of the icon when the attribute's value is not the empty
string, the attribute's value must be resolved relative to the element. When the attribute is
absent, or its value is the empty string, or resolving its value fails, there is no icon.
The disabled
attribute
is a boolean attribute that, if present, indicates that
the command is not available in the current state.
The distinction between disabled
and hidden
is subtle. A command would be
disabled if, in the same context, it could be enabled if only
certain aspects of the situation were changed. A command would be
marked as hidden if, in that situation, the command will never be
enabled. For example, in the context menu for a water faucet, the
command "open" might be disabled if the faucet is already open, but
the command "eat" would be marked hidden since the faucet could
never be eaten.
The checked
attribute is a boolean attribute that, if present,
indicates that the command is selected. The attribute must be
omitted unless the type
attribute is in either the Checkbox state or
the Radio
state.
The radiogroup
attribute gives the name of the group of commands that will be
toggled when the command itself is toggled, for commands whose type
attribute has the value "radio
". The scope of the name is the child list of
the parent element. The attribute must be omitted unless the type
attribute is in the Radio state.
The type
IDL
attribute must reflect the content attribute of the
same name, limited to only known values.
The label
, icon
, disabled
, checked
, and radiogroup
IDL attributes must reflect the respective content
attributes of the same name.
The element's activation behavior depends on the
value of the type
attribute
of the element, as follows:
type
attribute is
in the Checkbox stateIf the element has a checked
attribute, the UA must
remove that attribute. Otherwise, the UA must add a checked
attribute, with the
literal value checked
. The UA must then
fire a click
event at the
element.
type
attribute is
in the Radio stateIf the element has a parent, then the UA must walk the list
of child nodes of that parent element, and for each node that is a
command
element, if that element has a radiogroup
attribute whose
value exactly matches the current element's (treating missing radiogroup
attributes as if
they were the empty string), and has a checked
attribute, must remove
that attribute.
Then, the element's checked
attribute attribute
must be set to the literal value checked
and
the user agent must fire a click
event at the element.
The element has no activation behavior.
Firing a synthetic click
event at the element does not cause
any of the actions described above to happen.
command
elements are not rendered
unless they form part of a menu.
Here is an example of a toolbar with three buttons that let the user toggle between left, center, and right alignment. One could imagine such a toolbar as part of a text editor. The toolbar also has a separator followed by another button labeled "Publish", though that button is disabled.
<menu type="toolbar"> <command type="radio" radiogroup="alignment" checked="checked" label="Left" icon="icons/alL.png" onclick="setAlign('left')"> <command type="radio" radiogroup="alignment" label="Center" icon="icons/alC.png" onclick="setAlign('center')"> <command type="radio" radiogroup="alignment" label="Right" icon="icons/alR.png" onclick="setAlign('right')"> <hr> <command type="command" disabled label="Publish" icon="icons/pub.png" onclick="publish()"> </menu>
menu
elementtype
attribute is in the toolbar state: Interactive content.li
elements.type
label
interface HTMLMenuElement : HTMLElement { attribute DOMString type; attribute DOMString label; };
The menu
element represents a list of commands.
The type
attribute
is an enumerated attribute indicating the kind of menu
being declared. The attribute has three states. The context
keyword maps to the
context menu state, in which
the element is declaring a context menu. The toolbar
keyword maps to the
toolbar state, in which the
element is declaring a toolbar. The attribute may also be
omitted. The missing value default is the list state, which indicates that the element is merely
a list of commands that is neither declaring a context menu nor
defining a toolbar.
If a menu
element's type
attribute is in the context menu state, then the
element represents the commands of a context menu, and
the user can only interact with the commands if that context menu is
activated.
If a menu
element's type
attribute is in the toolbar state, then the element
represents a list of active commands that the user can
immediately interact with.
If a menu
element's type
attribute is in the list state, then the element either
represents an unordered list of items (each represented
by an li
element), each of which represents a command
that the user can perform or activate, or, if the element has no
li
element children, flow content
describing available commands.
The label
attribute gives the label of the menu. It is used by user agents to
display nested menus in the UI. For example, a context menu
containing another menu would use the nested menu's label
attribute for the submenu's
menu label.
The type
and label
IDL attributes must
reflect the respective content attributes of the same
name.
This section is non-normative.
The menu
element is used to define context menus and
toolbars.
For example, the following represents a toolbar with three menu buttons on it, each of which has a dropdown menu with a series of options:
<menu type="toolbar"> <li> <menu label="File"> <button type="button" onclick="fnew()">New...</button> <button type="button" onclick="fopen()">Open...</button> <button type="button" onclick="fsave()">Save</button> <button type="button" onclick="fsaveas()">Save as...</button> </menu> </li> <li> <menu label="Edit"> <button type="button" onclick="ecopy()">Copy</button> <button type="button" onclick="ecut()">Cut</button> <button type="button" onclick="epaste()">Paste</button> </menu> </li> <li> <menu label="Help"> <li><a href="help.html">Help</a></li> <li><a href="about.html">About</a></li> </menu> </li> </menu>
In a supporting user agent, this might look like this:
In a legacy user agent, the above would look like a bulleted list with three items, the first of which has four buttons, the second of which has three, and the third of which has two nested bullet points with two items consisting of links.
The following implements a similar toolbar, with a single button whose values, when selected, redirect the user to Web sites.
<form action="redirect.cgi"> <menu type="toolbar"> <label for="goto">Go to...</label> <menu label="Go"> <select id="goto"> <option value="" selected="selected"> Select site: </option> <option value="http://www.apple.com/"> Apple </option> <option value="http://www.mozilla.org/"> Mozilla </option> <option value="http://www.opera.com/"> Opera </option> </select> <span><input type="submit" value="Go"></span> </menu> </menu> </form>
The behavior in supporting user agents is similar to the example
above, but here the legacy behavior consists of a single
select
element with a submit button. The submit button
doesn't appear in the toolbar, because it is not a direct child of
the menu
element or of its li
children.
A menu (or toolbar) consists of a list of zero or more of the following components:
The list corresponding to a particular menu
element
is built by iterating over its child nodes. For each child node in
tree order, the required behavior depends on what the
node is, as follows:
hr
elementoption
element that has a value
attribute set to the empty
string, and has a disabled
attribute, and whose
textContent
consists of a string of one or more
hyphens (U+002D HYPHEN-MINUS)li
elementlabel
elementmenu
element with no label
attributeselect
elementmenu
or select
element, then
append another separator.menu
element with a label
attributeoptgroup
element with a label
attributelabel
attribute as the label of the menu. The
submenu must be constructed by taking the element and creating a
new menu for it using the complete process described in this
section.Once all the nodes have been processed as described above, the user agent must the post-process the menu as follows:
The contextmenu
attribute gives the element's context
menu. The value must be the ID of a menu
element
in the DOM. If the node that would be obtained by
the invoking the getElementById()
method
using the attribute's value as the only argument is null or not a
menu
element, then the element has no assigned context
menu. Otherwise, the element's assigned context menu is the element
so identified.
When an element's context menu is requested (e.g. by the user right-clicking the element, or pressing a context menu key), the user agent must apply the appropriate rules from the following list:
The user agent must dispatch an event with the name contextmenu
, that bubbles and is
cancelable, and that uses the MouseEvent
interface, at
the element for which the menu was requested. The context
information of the event must be set to the same values as the last
MouseEvent
user interaction event that was dispatched
as part of the gesture that that was interpreted as a request for
the context menu.
The user agent must fire a synthetic mouse event named contextmenu
that bubbles
and is cancelable at the element for which the menu was
requested.
Typically, therefore, the firing of the contextmenu
event will be the
default action of a mouseup
or keyup
event. The exact sequence of events
is UA-dependent, as it will vary based on platform conventions.
The default action of the contextmenu
event depends on
whether the element or one of its ancestors has a context menu
assigned (using the contextmenu
attribute) or not. If
there is no context menu assigned, the default action must be for
the user agent to show its default context menu, if it has one.
If the element or one of its ancestors does have a
context menu assigned, then the user agent must fire a simple
event named show
at the
menu
element of the context menu of the nearest
ancestor (including the element itself) with one assigned.
The default action of this event is that the user agent
must show a context menu built from the menu
element.
The user agent may also provide access to its default context menu, if any, with the context menu shown. For example, it could merge the menu items from the two menus together, or provide the page's context menu as a submenu of the default menu.
If the user dismisses the menu without making a selection, nothing in particular happens.
If the user selects a menu item that represents a command, then the UA must invoke that command's Action.
Context menus must not, while being shown, reflect changes in the
DOM; they are constructed as the default action of the show
event and must remain as constructed
until dismissed.
User agents may provide means for bypassing the context menu
processing model, ensuring that the user can always access the UA's
default context menus. For example, the user agent could handle
right-clicks that have the Shift key depressed in such a way that it
does not fire the contextmenu
event and instead always shows the default context menu.
The contextMenu
IDL attribute must reflect the contextmenu
content attribute.
Here is an example of a context menu for an input control:
<form name="npc"> <label>Character name: <input name=char type=text contextmenu=namemenu required></label> <menu type=context id=namemenu> <command label="Pick random name" onclick="document.forms.npc.elements.char.value = getRandomName()"> <command label="Prefill other fields based on name" onclick="prefillFields(document.forms.npc.elements.char.value)"> </menu> </form>
This adds two items to the control's context menu, one called "Pick random name", and one called "Prefill other fields based on name". They invoke scripts that are not shown in the example above.
When a menu
element has a type
attribute in the toolbar state, then the user agent
must build the
menu for that menu
element, and use the result in the
rendering.
The user agent must reflect changes made to the
menu
's DOM, by immediately rebuilding the menu.
A command is the abstraction behind menu items, buttons, and links.
Commands are defined to have the following facets:
These facets are exposed on elements using the command API:
commandType
Exposes the Type facet of the command.
id
Exposes the ID facet of the command.
label
Exposes the Label facet of the command.
title
Exposes the Hint facet of the command.
icon
Exposes the Icon facet of the command.
accessKeyLabel
Exposes the Access Key facet of the command.
hidden
Exposes the state of the element's hidden
attribute, which is generally
equivalent to the Hidden
State facet of the command. For label
and
legend
elements (used in conjunction with the accesskey
attribute), the Hidden State facet is
derived from another element (the one that the assigned
access key will trigger), and cannot be directly accessed
from the element.
disabled
Exposes the Disabled State facet of the command.
checked
Exposes the Checked State facet of the command.
click
()Triggers the Action of the command.
The commandType
attribute must return a string whose value is either "command
", "radio
", or "checkbox
", depending on whether the Type of the command defined by the
element is "command", "radio", or "checkbox" respectively. If the
element does not define a command, it must return null.
The label
attribute must return the command's Label, or null if the element
does not define a command or does not specify a Label. This attribute will be
shadowed by the label
IDL attribute on
various elements.
The icon
attribute must return the absolute URL of the command's
Icon. If the element does
not specify an icon, or if the element does not define a command,
then the attribute must return null. This attribute will be shadowed
by the icon
IDL attribute on
command
elements.
The disabled
attribute must return true if the command's Disabled State is that
the command is disabled, and false if the command is not
disabled. This attribute is not affected by the command's Hidden State. If the
element does not define a command, the attribute must return
false. This attribute will be shadowed by the disabled
IDL attribute on various elements.
The checked
attribute
must return true if the command's Checked State is that the
command is checked, and false if it is that the command is not
checked. If the element does not define a command, the attribute
must return false. This attribute will be shadowed by the checked
IDL attribute on input
and
command
elements.
The ID facet
is exposed by the id
IDL attribute,
the Hint facet is exposed by
the title
IDL attribute, the AccessKey facet is exposed by
the accessKeyLabel
IDL
attribute, and the Hidden
State facet is exposed by the hidden
IDL attribute.
commands
Returns an HTMLCollection
of the elements in the
Document
that define commands and have IDs.
The commands
attribute
of the document's HTMLDocument
interface must return an
HTMLCollection
rooted at the Document
node, whose filter matches only elements that define commands and have IDs.
User agents may expose the commands whose Hidden State facet is false (visible), e.g. in the user agent's menu bar. User agents are encouraged to do this especially for commands that have Access Keys, as a way to advertise those keys to the user.
a
element to define a commandAn a
element with an href
attribute defines a command.
The Type of the command is "command".
The ID of the command is
the value of the id
attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an anonymous command.
The Label of the command
is the string given by the element's textContent
IDL
attribute.
The Hint of the command
is the value of the title
attribute
of the element. If the attribute is not present, the Hint is the empty string.
The Icon of the command
is the absolute URL obtained from resolving the value of the src
attribute of the first
img
element descendant of the element, relative to that
element, if there is such an element and resolving its attribute is
successful. Otherwise, there is no Icon for the command.
The AccessKey of the command is the element's assigned access key, if any.
The Hidden State
of the command is true (hidden) if the element has a hidden
attribute, and false
otherwise.
The Disabled State facet of the command is always false. (The command is always enabled.)
The Checked State of the command is always false. (The command is never checked.)
The Action of the
command is to fire a click
event at the element.
button
element to define a commandA button
element always defines a command.
The Type, ID, Label, Hint, Icon, Access Key, Hidden State, Checked State, and Action facets of the command are
determined as for a
elements (see the previous section).
The Disabled State of the command mirrors the disabled state of the button.
input
element to define a commandAn input
element whose type
attribute is in one of the Submit Button, Reset Button, Image Button, Button, Radio Button, or Checkbox states defines a command.
The Type of the command
is "radio" if the type
attribute is in the Radio
Button
state, "checkbox" if the type
attribute is in the Checkbox
state, and
"command" otherwise.
The ID of the command is
the value of the id
attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an anonymous command.
The Label of the command depends on the Type of the command:
If the Type is "command",
then it is the string given by the value
attribute, if any, and a
UA-dependent, locale-dependent value that the UA uses to label the
button itself if the attribute is absent.
Otherwise, the Type is
"radio" or "checkbox". If the element is a labeled
control, the textContent
of the first
label
element in tree order whose
labeled control is the element in question is the Label (in DOM terms, this is the
string given by element.labels[0].textContent
). Otherwise,
the value of the value
attribute, if present, is the Label. Otherwise, the Label is the empty string.
The Hint of the command
is the value of the title
attribute
of the input
element. If the attribute is not present, the
Hint is the empty
string.
If the element's type
attribute is in the Image
Button state, and the element has a src
attribute, and that attribute's
value can be successfully resolved relative to the element, then the Icon of the command is the
absolute URL obtained from resolving that attribute
that way. Otherwise, there is no Icon for the command.
The AccessKey of the command is the element's assigned access key, if any.
The Hidden State
of the command is true (hidden) if the element has a hidden
attribute, and false
otherwise.
The Disabled State of the command mirrors the disabled state of the control.
The Checked State of the command is true if the command is of Type "radio" or "checkbox" and the element is checked attribute, and false otherwise.
The Action of the
command, if the element has a defined activation
behavior, is to run synthetic click activation
steps on the element. Otherwise, it is just to fire a
click
event at the
element.
option
element to define a commandAn option
element with an ancestor
select
element and either no value
attribute or a value
attribute that is not the
empty string defines a
command.
The Type of the command
is "radio" if the option
's nearest ancestor
select
element has no multiple
attribute, and
"checkbox" if it does.
The ID of the command is
the value of the id
attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an anonymous command.
The Label of the command
is the value of the option
element's label
attribute, if there is one,
or the value of the option
element's
textContent
IDL attribute if there isn't.
The Hint of the command
is the string given by the element's title
attribute, if any, and the empty
string if the attribute is absent.
There is no Icon for the command.
The AccessKey of the command is the element's assigned access key, if any.
The Hidden State
of the command is true (hidden) if the element has a hidden
attribute, and false
otherwise.
The Disabled
State of the command is true (disabled) if the element is
disabled or if its
nearest ancestor select
element is disabled, and false
otherwise.
The Checked State of the command is true (checked) if the element's selectedness is true, and false otherwise.
The Action of the
command depends on its Type. If the command is of Type "radio" then it must pick the option
element. Otherwise, it must toggle the option
element.
command
element to define
a commandA command
element defines a command.
The Type of the command
is "radio" if the command
's type
attribute is
"radio
", "checkbox" if the attribute's value is
"checkbox
", and "command" otherwise.
The ID of the command is
the value of the id
attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an anonymous command.
The Label of the command
is the value of the element's label
attribute, if there is one,
or the empty string if it doesn't.
The Hint of the command
is the string given by the element's title
attribute, if any, and the
empty string if the attribute is absent.
The Icon for the command
is the absolute URL obtained from resolving the value of the element's icon
attribute, relative to the
element, if it has such an attribute and resolving it is
successful. Otherwise, there is no Icon for the command.
The AccessKey of the command is the element's assigned access key, if any.
The Hidden State
of the command is true (hidden) if the element has a hidden
attribute, and false
otherwise.
The Disabled
State of the command is true (disabled) if the element has a
disabled
attribute, and
false otherwise.
The Checked State
of the command is true (checked) if the element has a checked
attribute, and false
otherwise.
The Action of the
command, if the element has a defined activation
behavior, is to run synthetic click activation
steps on the element. Otherwise, it is just to fire a
click
event at the
element.
accesskey
attribute on a label
element to define a commandA label
element that has an assigned access
key and a labeled control and whose
labeled control defines a
command, itself defines a
command.
The Type of the command is "command".
The ID of the command is
the value of the id
attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an anonymous command.
The Label of the command
is the string given by the element's textContent
IDL
attribute.
The Hint of the command
is the value of the title
attribute
of the element.
There is no Icon for the command.
The AccessKey of the command is the element's assigned access key.
The Hidden State, Disabled State, and Action facets of the command are the same as the respective facets of the element's labeled control.
The Checked State of the command is always false. (The command is never checked.)
accesskey
attribute on a legend
element to define a commandA legend
element that has an assigned access
key and is a child of a fieldset
element that
has a descendant that is not a descendant of the legend
element and is neither a label
element nor a
legend
element but that defines a command, itself defines a command.
The Type of the command is "command".
The ID of the command is
the value of the id
attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an anonymous command.
The Label of the command
is the string given by the element's textContent
IDL
attribute.
The Hint of the command
is the value of the title
attribute
of the element.
There is no Icon for the command.
The AccessKey of the command is the element's assigned access key.
The Hidden State,
Disabled State, and
Action facets of the
command are the same as the respective facets of the first element
in tree order that is a descendant of the parent of the
legend
element that defines a command but is not a
descendant of the legend
element and is neither a
label
nor a legend
element.
The Checked State of the command is always false. (The command is never checked.)
accesskey
attribute to define a command on other elementsAn element that has an assigned access key defines a command.
If one of the other sections that define elements that define commands define that this element defines a command, then that section applies to this element, and this section does not. Otherwise, this section applies to that element.
The Type of the command is "command".
The ID of the command is
the value of the id
attribute of the
element, if the attribute is present and not empty. Otherwise the
command is an anonymous command.
The Label of the command
depends on the element. If the element is a labeled
control, the textContent
of the first
label
element in tree order whose
labeled control is the element in question is the Label (in DOM terms, this is the
string given by element.labels[0].textContent
). Otherwise, the
Label is the
textContent
of the element itself.
The Hint of the command
is the value of the title
attribute
of the element. If the attribute is not present, the Hint is the empty string.
There is no Icon for the command.
The AccessKey of the command is the element's assigned access key.
The Hidden State
of the command is true (hidden) if the element has a hidden
attribute, and false
otherwise.
The Disabled State facet of the command is always false. (The command is always enabled.)
The Checked State of the command is always false. (The command is never checked.)
The Action of the command is to run the following steps:
click
event at the element.Links are a conceptual construct, created by a
,
area
, and link
elements, that represent a connection between two
resources, one of which is the current Document
. There
are two kinds of links in HTML:
These are links to resources that are to be used to augment the current document, generally automatically processed by the user agent.
These are links to other resources that are generally exposed to the user by the user agent so that the user can cause the user agent to navigate to those resources, e.g. to visit them in a browser or download them.
For link
elements with an href
attribute and a rel
attribute, links must be created
for the keywords of the rel
attribute, as defined for those keywords in the link types section.
Similarly, for a
and area
elements with
an href
attribute and a
rel
attribute, links must be
created for the keywords of the rel
attribute as defined for those
keywords in the link types section. Unlike
link
elements, however, a
and
area
element with an href
attribute that either do not
have a rel
attribute, or
whose rel
attribute has no
keywords that are defined as specifying hyperlinks, must also create a
hyperlink. This implied hyperlink has no special
meaning (it has no link type) beyond
linking the element's document to the resource given by the
element's href
attribute.
A hyperlink can have one or more hyperlink annotations that modify the processing semantics of that hyperlink.
a
and area
elementsThe href
attribute on a
and area
elements must have
a value that is a valid URL potentially surrounded by
spaces.
The href
attribute on a
and area
elements is not
required; when those elements do not have href
attributes they do not
create hyperlinks.
The target
attribute, if present, must be a valid browsing context name
or keyword. It gives the name of the browsing
context that will be used. User agents use
this name when following hyperlinks.
The rel
attribute on a
and area
elements controls
what kinds of links the elements create. The attribue's value must
be a set of space-separated tokens. The allowed keywords and their meanings are
defined below.
The rel
attribute has
no default value. If the attribute is omitted or if none of the
values in the attribute are recognized by the user agent, then the
document has no particular relationship with the destination
resource other than there being a hyperlink between the two.
The media
attribute describes for which media the target document was
designed. It is purely advisory. The value must be a valid
media query. The default, if the media
attribute is omitted, is
"all
".
The hreflang
attribute on a
and area
elements that
create hyperlinks, if present, gives
the language of the linked resource. It is purely advisory. The
value must be a valid BCP 47 language tag. [BCP47] User agents must
not consider this attribute authoritative — upon fetching the
resource, user agents must use only language information associated
with the resource to determine its language, not metadata included
in the link to the resource.
The type
attribute, if present, gives the MIME type of the
linked resource. It is purely advisory. The value must be a
valid MIME type. User agents must
not consider the type
attribute authoritative — upon fetching the resource, user
agents must not use metadata included in the link to the resource to
determine its type.
When a user follows a hyperlink created by an element,
the user agent must resolve the
URL given by the href
attribute of that element,
relative to that element, and if that is successful, must
navigate a browsing
context to the resulting absolute URL. In the
case of server-side image maps, that absolute URL must
have its hyperlink suffix appended to it before the
navigation is started.
If resolving the URL fails, the user agent may report the error to the user in a user-agent-specific manner, may navigate to an error page to report the error, or may ignore the error and do nothing.
If the user indicated a specific browsing context when following the hyperlink, or if the user agent is configured to follow hyperlinks by navigating a particular browsing context, then that must be the browsing context that is navigated.
Otherwise, if the element is an a
or
area
element that has a target
attribute, then the
browsing context that is navigated must be chosen by
applying the rules for choosing a browsing context given a
browsing context name, using the value of the target
attribute as the
browsing context name. If these rules result in the creation of a
new browsing context, it must be navigated with
replacement enabled.
Otherwise, if the hyperlink is a sidebar hyperlink and the user agent implements a feature that can be considered a secondary browsing context, such a secondary browsing context may be selected as the browsing context to be navigated.
Otherwise, if the element is an a
or
area
element with no target
attribute, but the
Document
contains a base
element with a
target
attribute, then the
browsing context that is navigated must be chosen by applying
the rules for choosing a browsing context given a browsing
context name, using the value of the target
attribute of the first such
base
element as the browsing context name. If these
rules result in the creation of a new browsing context,
it must be navigated with replacement enabled.
Otherwise, the browsing context that must be navigated is the same browsing context as the one which the element itself is in.
The navigation must be done with the browsing
context that contains the Document
object with
which the element in question is associated as the source
browsing context.
The following table summarizes the link types that are defined by this specification. This table is non-normative; the actual definitions for the link types are given in the next few sections.
In this section, the term referenced document refers to the resource identified by the element representing the link, and the term current document refers to the resource within which the element representing the link finds itself.
To determine which link types apply to a link
,
a
, or area
element, the element's rel
attribute must be split on spaces. The resulting tokens are the link
types that apply to that element.
Except where otherwise specified, a keyword must not be specified
more than once per rel
attribute.
The link types that contain no U+003A COLON characters (:), including all those defined in this specification, are ASCII case-insensitive values, and must be compared as such.
Thus, rel="next"
is the
same as rel="NEXT"
.
Link type | Effect on... | Brief description | |
---|---|---|---|
link |
a and area |
||
alternate |
Hyperlink | Hyperlink | Gives alternate representations of the current document. |
author |
Hyperlink | Hyperlink | Gives a link to the current document's author. |
bookmark |
not allowed | Hyperlink | Gives the permalink for the nearest ancestor section. |
external |
not allowed | Hyperlink | Indicates that the referenced document is not part of the same site as the current document. |
help |
Hyperlink | Hyperlink | Provides a link to context-sensitive help. |
icon |
External Resource | not allowed | Imports an icon to represent the current document. |
license |
Hyperlink | Hyperlink | Indicates that the main content of the current document is covered by the copyright license described by the referenced document. |
next |
Hyperlink | Hyperlink | Indicates that the current document is a part of a series, and that the next document in the series is the referenced document. |
nofollow |
not allowed | Annotation | Indicates that the current document's original author or publisher does not endorse the referenced document. |
noreferrer |
not allowed | Annotation | Requires that the user agent not send an HTTP Referer (sic) header if the user follows the hyperlink. |
pingback |
External Resource | not allowed | Gives the address of the pingback server that handles pingbacks to the current document. |
prefetch |
External Resource | External Resource | Specifies that the target resource should be preemptively cached. |
prev |
Hyperlink | Hyperlink | Indicates that the current document is a part of a series, and that the previous document in the series is the referenced document. |
search |
Hyperlink | Hyperlink | Gives a link to a resource that can be used to search through the current document and its related pages. |
sidebar |
Hyperlink | Hyperlink | Specifies that the referenced document, if retrieved, is intended to be shown in the browser's sidebar (if it has one). |
stylesheet |
External Resource | not allowed | Imports a stylesheet. |
tag |
Hyperlink | Hyperlink | Gives a tag (identified by the given address) that applies to the current document. |
Some of the types described below list synonyms for these values. These are to be handled as specified by user agents, but must not be used in documents.
alternate
"The alternate
keyword may be
used with link
, a
, and area
elements.
The meaning of this keyword depends on the values of the other attributes.
link
element and the rel
attribute also contains the
keyword stylesheet
The alternate
keyword
modifies the meaning of the stylesheet
keyword in the way
described for that keyword. The alternate
keyword does not create a
link of its own.
alternate
keyword is
used with the type
attribute set to the value application/rss+xml
or the value application/atom+xml
The keyword creates a hyperlink referencing a syndication feed (though not necessarily syndicating exactly the same content as the current page).
The first link
, a
, or area
element in the document (in tree order) with the alternate
keyword used with the type
attribute set to the value
application/rss+xml
or the value application/atom+xml
must be treated as the default
syndication feed for the purposes of feed autodiscovery.
The following link
element gives the syndication
feed for the current page:
<link rel="alternate" type="application/atom+xml" href="data.xml">
The following extract offers various different syndication feeds:
<p>You can access the planets database using Atom feeds:</p> <ul> <li><a href="recently-visited-planets.xml" rel="alternate" type="application/atom+xml">Recently Visited Planets</a></li> <li><a href="known-bad-planets.xml" rel="alternate" type="application/atom+xml">Known Bad Planets</a></li> <li><a href="unexplored-planets.xml" rel="alternate" type="application/atom+xml">Unexplored Planets</a></li> </ul>
The keyword creates a hyperlink referencing an alternate representation of the current document.
The nature of the referenced document is given by the media
, hreflang
, and type
attributes.
If the alternate
keyword is
used with the media
attribute, it indicates that the referenced document is intended for
use with the media specified.
If the alternate
keyword is
used with the hreflang
attribute, and that attribute's value differs from the root
element's language, it indicates that the
referenced document is a translation.
If the alternate
keyword is
used with the type
attribute, it indicates that the referenced document is a
reformulation of the current document in the specified format.
The media
, hreflang
, and type
attributes can be combined
when specified with the alternate
keyword.
For example, the following link is a French translation that uses the PDF format:
<link rel=alternate type=application/pdf hreflang=fr href=manual-fr>
This relationship is transitive — that is, if a document
links to two other documents with the link type "alternate
", then, in addition to
implying that those documents are alternative representations of
the first document, it is also implying that those two documents
are alternative representations of each other.
author
"The author
keyword may be
used with link
, a
, and area
elements. This keyword creates a hyperlink.
For a
and area
elements, the author
keyword indicates that the
referenced document provides further information about the author of
the nearest article
element ancestor of the element
defining the hyperlink, if there is one, or of the page as a whole,
otherwise.
For link
elements, the author
keyword indicates that the
referenced document provides further information about the author
for the page as a whole.
The "referenced document" can be, and often is, a
mailto:
URL giving the e-mail address of the
author. [MAILTO]
Synonyms: For historical reasons, user agents
must also treat link
, a
, and
area
elements that have a rev
attribute with the value "made
" as having the author
keyword specified as a link
relationship.
bookmark
"The bookmark
keyword may be
used with a
and area
elements. This
keyword creates a hyperlink.
The bookmark
keyword gives a
permalink for the nearest ancestor article
element of
the linking element in question, or of the section the linking element is most
closely associated with, if there are no ancestor
article
elements.
The following snippet has three permalinks. A user agent could determine which permalink applies to which part of the spec by looking at where the permalinks are given.
... <body> <h1>Example of permalinks</h1> <div id="a"> <h2>First example</h2> <p><a href="a.html" rel="bookmark">This</a> permalink applies to only the content from the first H2 to the second H2. The DIV isn't exactly that section, but it roughly corresponds to it.</p> </div> <h2>Second example</h2> <article id="b"> <p><a href="b.html" rel="bookmark">This</a> permalink applies to the outer ARTICLE element (which could be, e.g., a blog post).</p> <article id="c"> <p><a href="c.html" rel="bookmark">This</a> permalink applies to the inner ARTICLE element (which could be, e.g., a blog comment).</p> </article> </article> </body> ...
external
"The external
keyword may be
used with a
and area
elements. This
keyword creates a hyperlink.
The external
keyword indicates
that the link is leading to a document that is not part of the site
that the current document forms a part of.
help
"The help
keyword may be used with
link
, a
, and area
elements. This keyword creates a hyperlink.
For a
and area
elements, the help
keyword indicates that the referenced
document provides further help information for the parent of the
element defining the hyperlink, and its children.
In the following example, the form control has associated context-sensitive help. The user agent could use this information, for example, displaying the referenced document if the user presses the "Help" or "F1" key.
<p><label> Topic: <input name=topic> <a href="help/topic.html" rel="help">(Help)</a></label></p>
For link
elements, the help
keyword indicates that the referenced
document provides help for the page as a whole.
icon
"The icon
keyword may be used with
link
elements. This keyword creates an external resource link.
The specified resource is an icon representing the page or site, and should be used by the user agent when representing the page in the user interface.
Icons could be auditory icons, visual icons, or other kinds of
icons. If multiple icons are provided, the user
agent must select the most appropriate icon according to the type
, media
, and sizes
attributes. If there are
multiple equally appropriate icons, user agents must use the last
one declared in tree order. If the user agent tries to
use an icon but that icon is determined, upon closer examination, to
in fact be inappropriate (e.g. because it uses an unsupported
format), then the user agent must try the next-most-appropriate icon
as determined by the attributes.
There is no default type for resources given by the icon
keyword. However, for the purposes of
determining the type of the
resource, user agents must expect the resource to be an image.
The sizes
attribute gives the sizes of icons for visual media.
If specified, the attribute must have a value that is an
unordered set of unique space-separated tokens, which
are ASCII case-insensitive. The values must all be
either an ASCII case-insensitive match for the string
"any
", or a value that
consists of two valid
non-negative integers that do not have a leading U+0030 DIGIT
ZERO (0) character and that are separated by a single U+0078 LATIN
SMALL LETTER X or U+0058 LATIN CAPITAL LETTER X character.
The keywords represent icon sizes.
To parse and process the attribute's value, the user agent must first split the attribute's value on spaces, and must then parse each resulting keyword to determine what it represents.
The any
keyword
represents that the resource contains a scalable icon, e.g. as
provided by an SVG image.
Other keywords must be further parsed as follows to determine what they represent:
If the keyword doesn't contain exactly one U+0078 LATIN SMALL LETTER X or U+0058 LATIN CAPITAL LETTER X character, then this keyword doesn't represent anything. Abort these steps for that keyword.
Let width string be the string before
the "x
" or "X
".
Let height string be the string after
the "x
" or "X
".
If either width string or height string start with a U+0030 DIGIT ZERO (0) character or contain any characters other than characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), then this keyword doesn't represent anything. Abort these steps for that keyword.
Apply the rules for parsing non-negative integers to width string to obtain width.
Apply the rules for parsing non-negative integers to height string to obtain height.
The keyword represents that the resource contains a bitmap icon with a width of width device pixels and a height of height device pixels.
The keywords specified on the sizes
attribute must not represent
icon sizes that are not actually available in the linked
resource.
If the attribute is not specified, then the user agent must assume that the given icon is appropriate, but less appropriate than an icon of a known and appropriate size.
In the absence of a link
with the icon
keyword, for Document
s
obtained over HTTP or HTTPS, user agents may instead attempt to
fetch and use an icon with the absolute
URL obtained by resolving the URL "/favicon.ico
" against the document's
address, as if the page had declared that icon using the
icon
keyword.
The following snippet shows the top part of an application with several icons.
<!DOCTYPE HTML> <html> <head> <title>lsForums — Inbox</title> <link rel=icon href=favicon.png sizes="16x16" type="image/png"> <link rel=icon href=windows.ico sizes="32x32 48x48" type="image/vnd.microsoft.icon"> <link rel=icon href=mac.icns sizes="128x128 512x512 8192x8192 32768x32768"> <link rel=icon href=iphone.png sizes="57x57" type="image/png"> <link rel=icon href=gnome.svg sizes="any" type="image/svg+xml"> <link rel=stylesheet href=lsforums.css> <script src=lsforums.js></script> <meta name=application-name content="lsForums"> </head> <body> ...
license
"The license
keyword may be used
with link
, a
, and area
elements. This keyword creates a hyperlink.
The license
keyword indicates
that the referenced document provides the copyright license terms
under which the main content of the current document is
provided.
This specification does not specify how to distinguish between the main content of a document and content that is not deemed to be part of that main content. The distinction should be made clear to the user.
Consider a photo sharing site. A page on that site might describe and show a photograph, and the page might be marked up as follows:
<!DOCTYPE HTML> <html> <head> <title>Exampl Pictures: Kissat</title> <link rel="stylesheet" href="/style/default"> </head> <body> <h1>Kissat</h1> <nav> <a href="../">Return to photo index</a> </nav> <figure> <img src="/pix/39627052_fd8dcd98b5.jpg"> <figcaption>Kissat</figcaption> </figure> <p>One of them has six toes!</p> <p><small><a rel="license" href="http://www.opensource.org/licenses/mit-license.php">MIT Licensed</a></small></p> <footer> <a href="/">Home</a> | <a href="../">Photo index</a> <p><small>© copyright 2009 Exampl Pictures. All Rights Reserved.</small></p> </footer> </body> </html>
In this case the license
applies to just the photo (the main content of the document), not
the whole document. In particular not the design of the page
itself, which is covered by the copyright given at the bottom of
the document. This could be made clearer in the styling
(e.g. making the license link prominently positioned near the
photograph, while having the page copyright in light small text at
the foot of the page.
Synonyms: For historical reasons, user agents
must also treat the keyword "copyright
" like
the license
keyword.
nofollow
"The nofollow
keyword may be
used with a
and area
elements. This
keyword does not create a hyperlink, but annotates any other hyperlinks
created by the element (the implied hyperlink, if no other keywords
create one).
The nofollow
keyword indicates
that the link is not endorsed by the original author or publisher of
the page, or that the link to the referenced document was included
primarily because of a commercial relationship between people
affiliated with the two pages.
noreferrer
"The noreferrer
keyword may be
used with a
and area
elements. This
keyword does not create a hyperlink, but annotates any other hyperlinks
created by the element (the implied hyperlink, if no other keywords
create one).
It indicates that no referrer information is to be leaked when following the link.
If a user agent follows a link defined by an a
or
area
element that has the noreferrer
keyword, the user agent
must not include a Referer
(sic)
HTTP header (or
equivalent for other protocols) in the request.
This keyword also causes the opener
attribute to remain null if the
hyperlink creates a new browsing context.
pingback
"The pingback
keyword may be
used with link
elements. This keyword creates an external resource link.
For the semantics of the pingback
keyword, see the Pingback 1.0
specification. [PINGBACK]
prefetch
"The prefetch
keyword may be
used with link
, a
, and area
elements. This keyword creates an external resource link.
The prefetch
keyword indicates
that preemptively fetching and caching the specified resource is
likely to be beneficial, as it is highly likely that the user will
require this resource.
There is no default type for resources given by the prefetch
keyword.
search
"The search
keyword may be used
with link
, a
, and area
elements. This keyword creates a hyperlink.
The search
keyword indicates that
the referenced document provides an interface specifically for
searching the document and its related resources.
OpenSearch description documents can be used with
link
elements and the search
link type to enable user agents to
autodiscover search interfaces. [OPENSEARCH]
sidebar
"The sidebar
keyword may be used
with link
, a
, and area
elements. This keyword creates a hyperlink.
The sidebar
keyword indicates
that the referenced document, if retrieved, is intended to be shown
in a secondary browsing context (if possible), instead
of in the current browsing context.
A hyperlink with the sidebar
keyword specified is a sidebar hyperlink.
stylesheet
"The stylesheet
keyword may be
used with link
elements. This keyword creates an external resource link that
contributes to the styling processing model.
The specified resource is a resource that describes how to present the document. Exactly how the resource is to be processed depends on the actual type of the resource.
If the alternate
keyword is
also specified on the link
element, then the link
is an alternative stylesheet; in this case, the title
attribute must be specified on the
link
element, with a non-empty value.
The default type for resources given by the stylesheet
keyword is text/css
.
The appropriate time to obtain the resource is when the external resource link is created or when its element is inserted into a document, whichever happens last. If the resource is an alternative stylesheet then the user agent may defer obtaining the resource until it is part of the preferred style sheet set. [CSSOM]
Quirk: If the document has been set to
quirks mode, has the same origin as the
URL of the external resource, and
the Content-Type metadata of the
external resource is not a supported style sheet type, the user
agent must instead assume it to be text/css
.
tag
"The tag
keyword may be used
with link
, a
, and area
elements. This keyword creates a hyperlink.
The tag
keyword indicates that the
tag that the referenced document represents applies to the
current document.
Since it indicates that the tag applies to the current document, it would be inappropriate to use this keyword in the markup of a tag cloud, which lists the popular tag across a set of pages.
Some documents form part of a sequence of documents.
A sequence of documents is one where each document can have a previous sibling and a next sibling. A document with no previous sibling is the start of its sequence, a document with no next sibling is the end of its sequence.
A document may be part of multiple sequences.
next
"The next
keyword may be used with
link
, a
, and area
elements. This keyword creates a hyperlink.
The next
keyword indicates that the
document is part of a sequence, and that the link is leading to the
document that is the next logical document in the sequence.
prev
"The prev
keyword may be used with
link
, a
, and area
elements. This keyword creates a hyperlink.
The prev
keyword indicates that the
document is part of a sequence, and that the link is leading to the
document that is the previous logical document in the sequence.
Synonyms: For historical reasons, user agents
must also treat the keyword "previous
" like
the prev
keyword.
Extensions to the predefined set of link types may be registered in the Microformats wiki existing-rel-values page. [MFREL]
Anyone is free to edit the Microformats wiki existing-rel-values page at any time to add a type. Extension types must be specified with the following information:
The actual value being defined. The value should not be confusingly similar to any other defined value (e.g. differing only in case).
If the value contains a U+003A COLON character (:), it must also be an absolute URL.
link
One of the following:
link
elements.link
element;
it creates a hyperlink.link
element;
it creates an external resource link.a
and area
One of the following:
a
and
area
elements.a
and
area
elements; it creates a
hyperlink.a
and
area
elements; it creates an external resource
link.a
and
area
elements; it annotates other hyperlinks created by the element.A short non-normative description of what the keyword's meaning is.
A link to a more detailed description of the keyword's semantics and requirements. It could be another page on the Wiki, or a link to an external page.
A list of other keyword values that have exactly the same processing requirements. Authors should not use the values defined to be synonyms, they are only intended to allow user agents to support legacy content. Anyone may remove synonyms that are not used in practice; only names that need to be processed as synonyms for compatibility with legacy content are to be registered in this way.
One of the following:
If a keyword is found to be redundant with existing values, it should be removed and listed as a synonym for the existing value.
If a keyword is registered in the "proposed" state for a period of a month or more without being used or specified, then it may be removed from the registry.
If a keyword is added with the "proposed" status and found to be redundant with existing values, it should be removed and listed as a synonym for the existing value. If a keyword is added with the "proposed" status and found to be harmful, then it should be changed to "discontinued" status.
Anyone can change the status at any time, but should only do so in accordance with the definitions above.
Conformance checkers must use the information given on the Microformats wiki existing-rel-values page to establish if a value is allowed or not: values defined in this specification or marked as "proposed" or "ratified" must be accepted when used on the elements for which they apply as described in the "Effect on..." field, whereas values marked as "discontinued" or not listed in either this specification or on the aforementioned page must be rejected as invalid. Conformance checkers may cache this information (e.g. for performance reasons or to avoid the use of unreliable network connectivity).
When an author uses a new type not defined by either this specification or the Wiki page, conformance checkers should offer to add the value to the Wiki, with the details described above, with the "proposed" status.
Types defined as extensions in the Microformats
wiki existing-rel-values page with the status "proposed" or
"ratified" may be used with the rel
attribute
on link
, a
, and area
elements
in accordance to the "Effect on..." field. [MFREL]
The main content of a page — not including headers and footers, navigation links, sidebars, advertisements, and so forth — can be marked up in a variety of ways, depending on the needs of the author.
The simplest solution is to not mark up the main content at all,
and just leave it as implicit. Another way to think of this is that
the body
elements marks up the main content of the
page, and the bits that aren't main content are excluded through the
use of more appropriate elements like aside
and
nav
.
Here is a short Web page marked up along this minimalistic
school of thought. The main content is highlighted. Notice how all
the other content in the body
is marked up
with elements to indicate that it's not part of the main content,
in this case header
, nav
, and
footer
.
<!DOCTYPE HTML> <html> <head> <title> My Toys </title> </head> <body> <header> <h1>My toys</h1> </header> <nav> <p><a href="/">Home</a></p> <p><a href="/contact">Contact</a></p> </nav> <p>I really like my chained book and my telephone. I'm not such a fan of my big ball.</p> <p>Another toy I like is my mirror.</p> <footer> <p>© copyright 2010 by the boy</p> </footer> </body> </html>
If the main content is an independent unit of content that one
could imagine syndicating independently, then the
article
element would be appropriate to mark up the
main content of the document.
The document in the previous example is here recast as a blog post:
<!DOCTYPE HTML> <html> <head> <title> The Boy Blog: My Toys </title> </head> <body> <header> <h1>The Boy Blog</h1> </header> <nav> <p><a href="/">Home</a></p> <p><a href="/contact">Contact</a></p> </nav> <article> <header> <h1>My toys</h1> <p>Published <time pubdate datetime="2010-08-04">August 4th</time></p> </header> <p>I really like my chained book and my telephone. I'm not such a fan of my big ball.</p> <p>Another toy I like is my mirror.</p> </article> <footer> <p>© copyright 2010 by the boy</p> </footer> </body> </html>
If the main content is not an independent unit of content so much
as a section of a larger work, for instance a chapter, then the
section
element would be appropriate to mark up the
main content of the document.
Here is the same document, case as a chapter in an online book:
<!DOCTYPE HTML> <html> <head> <title> Chapter 2: My Toys — The Book of the Boy </title> </head> <body> <header> <h1>Chapter 2: My Toys</h1> </header> <nav> <p><a href="/">Front Page</a></p> <p><a href="/toc">Table of Contents</a></p> <p><a href="/c1">Chapter 1</a> — <a href="/c3">Chapter 3</a></p> </nav> <section> <p>I really like my chained book and my telephone. I'm not such a fan of my big ball.</p> <p>Another toy I like is my mirror.</p> </section> <footer> <p>© copyright 2010 by the boy</p> </footer> </body> </html>
If neither article
nor section
would be
appropriate, but the main content still needs an explicit element,
for example for styling purposes, then the div
element
can be used.
This is the same as the original example, but using
div
for the main content instead of leaving it
implied:
<!DOCTYPE HTML> <html> <head> <title> My Toys </title> <style> body > div { background: navy; color: yellow; } </style> </head> <body> <header> <h1>My toys</h1> </header> <nav> <p><a href="/">Home</a></p> <p><a href="/contact">Contact</a></p> </nav> <div> <p>I really like my chained book and my telephone. I'm not such a fan of my big ball.</p> <p>Another toy I like is my mirror.</p> </div> <footer> <p>© copyright 2010 by the boy</p> </footer> </body> </html>
This specification does not provide a machine-readable way of
describing bread-crumb navigation menus. Authors are encouraged to
just use a series of links in a paragraph. The nav
element can be used to mark the section containing these
paragraphs as being navigation blocks.
In the following example, the current page can be reached via two paths.
<nav> <p> <a href="/">Main</a> > <a href="/products/">Products</a> > <a href="/products/dishwashers/">Dishwashers</a> > <a>Second hand</a> </p> <p> <a href="/">Main</a> > <a href="/second-hand/">Second hand</a> > <a>Dishwashers</a> </p> </nav>
This specification does not define any markup
specifically for marking up lists of keywords that apply to a group
of pages (also known as tag clouds). In general, authors are
encouraged to either mark up such lists using ul
elements with explicit inline counts that are then hidden and turned
into a presentational effect using a style sheet, or to use SVG.
Here, three tags are included in a short tag cloud:
<style> @media screen, print, handheld, tv { /* should be ignored by non-visual browsers */ .tag-cloud > li > span { display: none; } .tag-cloud > li { display: inline; } .tag-cloud-1 { font-size: 0.7em; } .tag-cloud-2 { font-size: 0.9em; } .tag-cloud-3 { font-size: 1.1em; } .tag-cloud-4 { font-size: 1.3em; } .tag-cloud-5 { font-size: 1.5em; } } </style> ... <ul class="tag-cloud"> <li class="tag-cloud-4"><a title="28 instances" href="/t/apple">apple</a> <span>(popular)</span> <li class="tag-cloud-2"><a title="6 instances" href="/t/kiwi">kiwi</a> <span>(rare)</span> <li class="tag-cloud-5"><a title="41 instances" href="/t/pear">pear</a> <span>(very popular)</span> </ul>
The actual frequency of each tag is given using the title
attribute. A CSS style sheet is
provided to convert the markup into a cloud of differently-sized
words, but for user agents that do not support CSS or are not
visual, the markup contains annotations like "(popular)" or
"(rare)" to categorize the various tags by frequency, thus enabling
all users to benefit from the information.
The ul
element is used (rather than
ol
) because the order is not particularly important:
while the list is in fact ordered alphabetically, it would convey
the same information if ordered by, say, the length of the tag.
The tag
rel
-keyword is not used
on these a
elements because they do not represent tags
that apply to the page itself; they are just part of an index
listing the tags themselves.
This specification does not define a specific element for marking up conversations, meeting minutes, chat transcripts, dialogues in screenplays, instant message logs, and other situations where different players take turns in discourse.
Instead, authors are encouraged to mark up conversations using
p
elements and punctuation. Authors who need to mark
the speaker for styling purposes are encouraged to use
span
or b
. Paragraphs with their text
wrapped in the i
element can be used for marking up
stage directions.
This example demonstrates this using an extract from Abbot and Costello's famous sketch, Who's on first:
<p> Costello: Look, you gotta first baseman? <p> Abbott: Certainly. <p> Costello: Who's playing first? <p> Abbott: That's right. <p> Costello becomes exasperated. <p> Costello: When you pay off the first baseman every month, who gets the money? <p> Abbott: Every dollar of it.
The following extract shows how an IM conversation log could be marked up.
<p> <time>14:22</time> <b>egof</b> I'm not that nerdy, I've only seen 30% of the star trek episodes <p> <time>14:23</time> <b>kaj</b> if you know what percentage of the star trek episodes you have seen, you are inarguably nerdy <p> <time>14:23</time> <b>egof</b> it's unarguably <p> <time>14:23</time> <i>* kaj blinks</i> <p> <time>14:24</time> <b>kaj</b> you are not helping your case
HTML does not have a dedicated mechanism for marking up footnotes. Here are the recommended alternatives.
For short inline annotations, the title
attribute should be used.
In this example, two parts of a dialogue are annotated with
footnote-like content using the title
attribute.
<p> <b>Customer</b>: Hello! I wish to register a complaint. Hello. Miss? <p> <b>Shopkeeper</b>: <span title="Colloquial pronunciation of 'What do you'" >Watcha</span> mean, miss? <p> <b>Customer</b>: Uh, I'm sorry, I have a cold. I wish to make a complaint. <p> <b>Shopkeeper</b>: Sorry, <span title="This is, of course, a lie.">we're closing for lunch</span>.
For longer annotations, the a
element should be
used, pointing to an element later in the document. The convention
is that the contents of the link be a number in square brackets.
In this example, a footnote in the dialogue links to a paragraph below the dialogue. The paragraph then reciprocally links back to the dialogue, allowing the user to return to the location of the footnote.
<p> Announcer: Number 16: The <i>hand</i>. <p> Interviewer: Good evening. I have with me in the studio tonight Mr Norman St John Polevaulter, who for the past few years has been contradicting people. Mr Polevaulter, why <em>do</em> you contradict people? <p> Norman: I don't. <sup><a href="#fn1" id="r1">[1]</a></sup> <p> Interviewer: You told me you did! ... <section> <p id="fn1"><a href="#r1">[1]</a> This is, naturally, a lie, but paradoxically if it were true he could not say so without contradicting the interviewer and thus making it false.</p> </section>
For side notes, longer annotations that apply to entire sections
of the text rather than just specific words or sentences, the
aside
element should be used.
In this example, a sidebar is given after a dialogue, giving it some context.
<p> <span class="speaker">Customer</span>: I will not buy this record, it is scratched. <p> <span class="speaker">Shopkeeper</span>: I'm sorry? <p> <span class="speaker">Customer</span>: I will not buy this record, it is scratched. <p> <span class="speaker">Shopkeeper</span>: No no no, this's'a tobacconist's. <aside> <p>In 1970, the British Empire lay in ruins, and foreign nationalists frequented the streets — many of them Hungarians (not the streets — the foreign nationals). Sadly, Alexander Yalt has been publishing incompetently-written phrase books. </aside>
For figures or tables, footnotes can be included in the relevant
figcaption
or caption
element, or in
surrounding prose.
In this example, a table has cells with footnotes
that are given in prose. A figure
element is used to
give a single legend to the combination of the table and its
footnotes.
<figure> <figcaption>Table 1. Alternative activities for knights.</figcaption> <table> <tr> <th> Activity <th> Location <th> Cost <tr> <td> Dance <td> Wherever possible <td> £0<sup><a href="#fn1">1</a></sup> <tr> <td> Routines, chorus scenes<sup><a href="#fn2">2</a></sup> <td> Undisclosed <td> Undisclosed <tr> <td> Dining<sup><a href="#fn3">3</a></sup> <td> Camelot <td> Cost of ham, jam, and spam<sup><a href="#fn4">4</a></sup> </table> <p id="fn1">1. Assumed.</p> <p id="fn2">2. Footwork impeccable.</p> <p id="fn3">3. Quality described as "well".</p> <p id="fn4">4. A lot.</p> </figure>
Attribute and element names of HTML elements in HTML documents must be treated as ASCII case-insensitive.
Classes from the class
attribute
of HTML elements in documents that are in quirks
mode must be treated as ASCII
case-insensitive.
Attribute selectors on an HTML element in an HTML document must treat the values of attributes with the following names as ASCII case-insensitive, with one exception as noted below:
accept
accept-charset
align
alink
axis
bgcolor
charset
checked
clear
codetype
color
compact
declare
defer
dir
direction
disabled
enctype
face
frame
hreflang
http-equiv
lang
language
link
media
method
multiple
nohref
noresize
noshade
nowrap
readonly
rel
rev
rules
scope
scrolling
selected
shape
target
text
type
(except as specified below)
valign
valuetype
vlink
All other attribute values on HTML elements must be treated as case-sensitive.
The exception to the list above is the type
attribute on ol
elements, which must be treated as case-sensitive.
There are a number of dynamic selectors that can be used with HTML. This section defines when these selectors match HTML elements.
:link
:visited
All a
elements that have an href
attribute, all
area
elements that have an href
attribute, and all
link
elements that have an href
attribute, must match one of
:link
and :visited
.
Other specifications might apply more specific rules regarding how these elements are to match these pseudo-elements, to mitigate some privacy concerns that apply with straightforward implementations of this requirement.
:active
The :active
pseudo-class
is defined to match an element while
an element is being activated by the user
. For the
purposes of defining the :active
pseudo-class only, an HTML
user agent must consider an element as being activated if
it is:
An element falling into one of the following categories between the time the user begins to indicate an intent to trigger the element's activation behavior and either the time the user stops indicating an intent to trigger the element's activation behavior, or the time the element's activation behavior has finished running, which ever comes first:
a
elements that have an href
attributearea
elements that have an href
attributelink
elements that have an href
attributebutton
elements that are not disabledinput
elements whose type
attribute is in the Submit Button, Image Button, Reset Button, or Button statecommand
elements that do not have a disabled
attributeFor example, if the user is using a keyboard
to push a button
element by pressing the space bar,
the element would match this pseudo-class in between the time
that the element received the keydown
event and the time the
element received the keyup
event.
An element that the user indicates using a pointing device while that pointing device is in the "down" state (e.g. for a mouse, between the time the mouse button is pressed and the time it is depressed).
An element that has a descendant that is currently matching
the :active
pseudo-class.
:enabled
The :enabled
pseudo-class
must match any element falling into one of the following
categories:
a
elements that have an href
attributearea
elements that have an href
attributelink
elements that have an href
attributebutton
elements that are not disabledinput
elements whose type
attribute are not in the
Hidden state and that
are not disabledselect
elements that are not disabledtextarea
elements that are not disabledoptgroup
elements that are not disabledoption
elements that are not disabledcommand
elements that do not have a disabled
attributeli
elements that are children of
menu
elements, and that have a child element that
defines a command, if the
first such element's Disabled State facet
is false (not disabled)fieldset
elements that do not have a disabled
attribute:disabled
The :disabled
pseudo-class must match any element falling into one of the
following categories:
button
elements that are disabledinput
elements whose type
attribute are not in the
Hidden state and that
are disabledselect
elements that are disabledtextarea
elements that are disabledoptgroup
elements that are disabledoption
elements that are disabledcommand
elements that have a disabled
attributeli
elements that are children of
menu
elements, and that have a child element that
defines a command, if the
first such element's Disabled State facet
is true (disabled)fieldset
elements that have a disabled
attribute:checked
The :checked
pseudo-class
must match any element falling into one of the following
categories:
input
elements whose type
attribute is in the Checkbox state and whose
checkedness state is
trueinput
elements whose type
attribute is in the Radio Button state and whose
checkedness state is
trueoption
elements whose selectedness is
truecommand
elements whose type
attribute is in the Checkbox state
and that have a checked
attributecommand
elements whose type
attribute is in the Radio state and that
have a checked
attribute:indeterminate
The :indeterminate
pseudo-class must match any element falling into one of the
following categories:
:default
The :default
pseudo-class
must match any element falling into one of the following
categories:
button
elements that are their form's
default buttoninput
elements whose type
attribute is in the Submit Button or Image Button state, and that
are their form's default buttoninput
elements to which the checked
attribute applies and
that have a checked
attributeoption
elements that have a selected
attribute:valid
The :valid
pseudo-class
must match all elements that are candidates for constraint validation
and that satisfy their
constraints.
:invalid
The :invalid
pseudo-class
must match all elements that are candidates for constraint validation
but that do not satisfy their
constraints.
:in-range
The :in-range
pseudo-class must match all elements that are candidates for
constraint validation, have range limitations,
and that are neither suffering from an underflow nor
suffering from an overflow.
:out-of-range
The :out-of-range
pseudo-class must match all elements that are candidates for
constraint validation, have range limitations,
and that are either suffering from an underflow or
suffering from an overflow.
:required
The :required
pseudo-class must match any element falling into one of the
following categories:
:optional
The :optional
pseudo-class must match any element falling into one of the
following categories:
:read-only
:read-write
The :read-write
pseudo-class must match any element falling into one of the
following categories:
input
elements to which the readonly
attribute applies,
but that are not immutable
(i.e. that do not have the readonly
attribute specified
and that are not disabled)textarea
elements that do not have a readonly
attribute, and
that are not disabledinput
elemenst nor textarea
elementsThe :read-only
pseudo-class must match all other HTML elements.
:ltr
The :ltr
pseudo-class must
match all elements whose directionality is 'ltr'.
:rtl
The :rtl
pseudo-class must
match all elements whose directionality is 'rtl'.
Another section of this specification defines the
target element used with the :target
pseudo-class.
This specification does not define when an element
matches the :hover
, :focus
, or :lang()
dynamic pseudo-classes, as
those are all defined in sufficient detail in a language-agnostic
fashion in the Selectors specification. [SELECTORS]
This section describes features that apply most directly to Web browsers. Having said that, except where specified otherwise, the requirements defined in this section do apply to all user agents, whether they are Web browsers or not.
A browsing context is an environment in which
Document
objects are presented to the user.
A tab or window in a Web browser typically contains
a browsing context, as does an iframe
or frame
s in a
frameset
.
Each browsing context has a corresponding
WindowProxy
object.
A browsing context has a session
history, which lists the Document
objects that
that browsing context has presented, is presenting, or
will present. At any time, one Document
in each
browsing context is designated the active
document.
Each Document
is associated with a
Window
object. A browsing context's
WindowProxy
object forwards everything to the
browsing context's active document's
Window
object.
In general, there is a 1-to-1 mapping from the
Window
object to the Document
object. In
one particular case, a Window
can be reused for the
presentation of a second Document
in the same
browsing context, such that the mapping is then
2-to-1. This occurs when a browsing context is navigated from the initial
about:blank
Document
to another, with
replacement enabled.
A Document
does not necessarily have a
browsing context associated with it. In particular,
data mining tools are likely to never instantiate browsing
contexts.
A browsing context can have a creator browsing context, the browsing context that was responsible for its creation. If a browsing context has a parent browsing context, then that is its creator browsing context. Otherwise, if the browsing context has an opener browsing context, then that is its creator browsing context. Otherwise, the browsing context has no creator browsing context.
If a browsing context A has a
creator browsing context, then the
Document
that was the active document of
that creator browsing context at the time A was created is the creator
Document
.
When a browsing context is first created, it must be
created with a single Document
in its session history,
whose address is
about:blank
, which is marked as being an HTML document, and whose character encoding is
UTF-8. The Document
must have a single child
html
node, which itself has a single child
body
node.
If the browsing context is created specifically to be immediately navigated, then that initial navigation will have replacement enabled.
The origin of the
about:blank
Document
is set when the
Document
is created. If the new browsing
context has a creator browsing context, then the
origin of the about:blank
Document
is the origin of the
creator Document
. Otherwise, the
origin of the about:blank
Document
is a globally unique identifier assigned when
the new browsing context is created.
Certain elements (for example, iframe
elements) can
instantiate further browsing
contexts. These are called nested browsing contexts. If a browsing context P has a Document
s D
with an element E that nests another browsing
context C inside it, then C
is said to be nested
through D, and E is
said to be the browsing context container of C. If the browsing context container
element E is in the Document
D,
then P is said to be the parent browsing
context of C and C is
said to be a child browsing context of P. Otherwise, the nested browsing
context C has no parent browsing
context.
A browsing context A is said to be an ancestor of a browsing context B if there exists a browsing context A' that is a child browsing context of A and that is itself an ancestor of B, or if there is a browsing context P that is a child browsing context of A and that is the parent browsing context of B.
A browsing context that is not a nested browsing context has no parent browsing context, and is the top-level browsing context of all the browsing contexts for which it is an ancestor browsing context.
The transitive closure of parent browsing contexts for a nested browsing context gives the list of ancestor browsing contexts.
The list of the descendant browsing contexts of a
Document
d is the (ordered) list
returned by the following algorithm:
Let list be an empty list.
For each child browsing context of d that is nested through an element that is in the Document
d, in the tree order of the elements
nesting those browsing
contexts, run these substeps:
Append that child browsing context to the list list.
Append the list of the descendant browsing contexts of the active document of that child browsing context to the list list.
Return the constructed list.
A Document
is said to be fully active
when it is the active document of its browsing
context, and either its browsing context is a top-level
browsing context, or it has a parent browsing
context and the Document
through which it is nested is itself fully
active.
Because they are nested through an element, child browsing contexts are always tied to
a specific Document
in their parent browsing
context. User agents must not allow the user to interact with
child browsing contexts
of elements that are in Document
s that are not
themselves fully active.
A nested browsing context can have a seamless
browsing context flag set, if it is embedded through an
iframe
element with a seamless
attribute.
A nested browsing context can in some
cases be taken out of its parent browsing context (e.g.
if an iframe
element is removed from its
Document
). In such a situation, the nested
browsing context has no parent browsing context,
but it still has the same browsing context container
and is still nested
through that element's Document
. Such a
nested browsing context is not a
top-level browsing context, and cannot contain
Document
s that are fully active.
Furthermore, if a browsing context container (such as
an iframe
) is moved to another Document
,
then the parent browsing context of its nested
browsing context will change.
top
Returns the WindowProxy
for the top-level browsing context.
parent
Returns the WindowProxy
for the parent browsing context.
frameElement
Returns the Element
for the browsing context container.
Returns null if there isn't one.
Throws a SECURITY_ERR
exception in cross-origin situations.
The top
IDL attribute on
the Window
object of a Document
in a
browsing context b must return the
WindowProxy
object of its top-level browsing
context (which would be its own WindowProxy
object if it was a top-level browsing context itself),
if it has one, or its own WindowProxy
object otherwise
(e.g. if it was a detached nested browsing
context).
The parent
IDL
attribute on the Window
object of a
Document
in a browsing context b must return the WindowProxy
object of
the parent browsing context, if there is one (i.e. if
b is a child browsing context), or
the WindowProxy
object of the browsing
context b itself, otherwise (i.e. if it
is a top-level browsing context or a detached
nested browsing context).
The frameElement
IDL attribute on the Window
object of a
Document
d, on getting, must run
the following algorithm:
If d is not a Document
in a
nested browsing context, return null and abort these
steps.
If the browsing context container's
Document
does not have the same effective script origin as the
entry script, then throw a SECURITY_ERR
exception.
Otherwise, return the browsing context container for b.
It is possible to create new browsing contexts that are related to a top-level browsing context without being nested through an element. Such browsing contexts are called auxiliary browsing contexts. Auxiliary browsing contexts are always top-level browsing contexts.
An auxiliary browsing context has an opener browsing context, which is the browsing context from which the auxiliary browsing context was created.
The opener
IDL
attribute on the Window
object, on getting, must return
the WindowProxy
object of the browsing
context from which the current browsing context
was created (its opener browsing context), if there is
one, if it is still available, and if the current browsing
context has not disowned its opener. On setting, if
the new value is null then the current browsing context
must disown its opener; if
the new value is anything else then the user agent must ignore the
new value.
User agents may support secondary browsing contexts, which are browsing contexts that form part of the user agent's interface, apart from the main content area.
A browsing context A is allowed to navigate a second browsing context B if one of the following conditions is true:
An element has a browsing context scope origin if its
Document
's browsing context is a
top-level browsing context or if all of its
Document
's ancestor browsing contexts all have active documents whose
origin are the same origin as the
element's Document
's origin. If an element
has a browsing context scope origin, then its value is
the origin of the element's Document
.
Each browsing context is defined as having a list of one or more directly reachable browsing contexts. These are:
The transitive closure of all the browsing contexts that are directly reachable browsing contexts forms a unit of related browsing contexts.
Each unit of related browsing contexts is then
further divided into the smallest number of groups such that every
member of each group has an active document with an
effective script origin that, through appropriate
manipulation of the document.domain
attribute, could
be made to be the same as other members of the group, but could not
be made the same as members of any other group. Each such group is a
unit of related similar-origin browsing contexts.
Each unit of related similar-origin browsing contexts can have a entry script which is used to obtain, amongst other things, the script's base URL to resolve relative URLs used in scripts running in that unit of related similar-origin browsing contexts. Initially, there is no entry script. It is changed by the jump to a code entry-point algorithm.
There is at most one event loop per unit of related similar-origin browsing contexts.
Browsing contexts can have a browsing context name. By default, a browsing context has no name (its name is not set).
A valid browsing context name is any string with at least one character that does not start with a U+005F LOW LINE character. (Names starting with an underscore are reserved for special keywords.)
A valid browsing context name or keyword is any string
that is either a valid browsing context name or that is
an ASCII case-insensitive match for one of: _blank
, _self
, _parent
, or _top
.
The rules for choosing a browsing context given a browsing context name are as follows. The rules assume that they are being applied in the context of a browsing context.
If the given browsing context name is the empty string or _self
, then the chosen browsing context must be
the current one.
If the given browsing context name is _self
, then this is an explicit
self-navigation override, which overrides the behavior of
the seamless browsing context flag set by the seamless
attribute on
iframe
elements.
If the given browsing context name is _parent
, then the chosen browsing context must be
the parent browsing context of the current
one, unless there isn't one, in which case the chosen browsing
context must be the current browsing context.
If the given browsing context name is _top
, then the chosen browsing context must be the
top-level browsing context of the current one, if
there is one, or else the current browsing context.
If the given browsing context name is not _blank
and there exists a browsing context whose
name is the same as the
given browsing context name, and the current browsing context is
allowed to navigate that browsing context, and the
user agent determines that the two browsing contexts are related
enough that it is ok if they reach each other, then that browsing
context must be the chosen one. If there are multiple matching
browsing contexts, the user agent should select one in some
arbitrary consistent manner, such as the most recently opened,
most recently focused, or more closely related.
If the browsing context is chosen by this step to be the current browsing context, then this is also an explicit self-navigation override.
Otherwise, a new browsing context is being requested, and what happens depends on the user agent's configuration and/or abilities:
The user agent may offer to create a new top-level browsing context or reuse an existing top-level browsing context. If the user picks one of those options, then the designated browsing context must be the chosen one (the browsing context's name isn't set to the given browsing context name). Otherwise (if the user agent doesn't offer the option to the user, or if the user declines to allow a browsing context to be used) there must not be a chosen browsing context.
noreferrer
keywordA new top-level browsing context must be
created. If the given browsing context name is not _blank
, then the new top-level browsing context's
name must be the given browsing context name (otherwise, it has
no name). The chosen browsing context must be this new browsing
context.
If it is immediately navigated, then the navigation will be done with replacement enabled.
noreferrer
keyword doesn't
applyA new auxiliary browsing context must be
created, with the opener browsing context being the
current one. If the given browsing context name is not _blank
, then the new auxiliary browsing context's
name must be the given browsing context name (otherwise, it has
no name). The chosen browsing context must be this new browsing
context.
If it is immediately navigated, then the navigation will be done with replacement enabled.
The chosen browsing context is the current browsing context.
There must not be a chosen browsing context.
User agent implementors are encouraged to provide a way for users to configure the user agent to always reuse the current browsing context.
Window
object[ReplaceableNamedProperties] interface Window { // the current browsing context readonly attribute WindowProxy window; readonly attribute WindowProxy self; readonly attribute Document document; attribute DOMString name; [PutForwards=href] readonly attribute Location location; readonly attribute History history; [Replaceable] readonly attribute BarProp locationbar; [Replaceable] readonly attribute BarProp menubar; [Replaceable] readonly attribute BarProp personalbar; [Replaceable] readonly attribute BarProp scrollbars; [Replaceable] readonly attribute BarProp statusbar; [Replaceable] readonly attribute BarProp toolbar; void close(); void stop(); void focus(); void blur(); // other browsing contexts [Replaceable] readonly attribute WindowProxy frames; [Replaceable] readonly attribute unsigned long length; readonly attribute WindowProxy top; attribute WindowProxy opener; readonly attribute WindowProxy parent; readonly attribute Element frameElement; WindowProxy open(in optional DOMString url, in optional DOMString target, in optional DOMString features, in optional DOMString replace); getter WindowProxy (in unsigned long index); getter any (in DOMString name); // the user agent readonly attribute Navigator navigator; readonly attribute ApplicationCache applicationCache; // user prompts void alert(in DOMString message); boolean confirm(in DOMString message); DOMString prompt(in DOMString message, in optional DOMString default); void print(); any showModalDialog(in DOMString url, in optional any argument); // event handler IDL attributes attribute Function onabort; attribute Function onafterprint; attribute Function onbeforeprint; attribute Function onbeforeunload; attribute Function onblur; attribute Function oncanplay; attribute Function oncanplaythrough; attribute Function onchange; attribute Function onclick; attribute Function oncontextmenu; attribute Function oncuechange; attribute Function ondblclick; attribute Function ondrag; attribute Function ondragend; attribute Function ondragenter; attribute Function ondragleave; attribute Function ondragover; attribute Function ondragstart; attribute Function ondrop; attribute Function ondurationchange; attribute Function onemptied; attribute Function onended; attribute Function onerror; attribute Function onfocus; attribute Function onhashchange; attribute Function oninput; attribute Function oninvalid; attribute Function onkeydown; attribute Function onkeypress; attribute Function onkeyup; attribute Function onload; attribute Function onloadeddata; attribute Function onloadedmetadata; attribute Function onloadstart; attribute Function onmessage; attribute Function onmousedown; attribute Function onmousemove; attribute Function onmouseout; attribute Function onmouseover; attribute Function onmouseup; attribute Function onmousewheel; attribute Function onoffline; attribute Function ononline; attribute Function onpause; attribute Function onplay; attribute Function onplaying; attribute Function onpagehide; attribute Function onpageshow; attribute Function onpopstate; attribute Function onprogress; attribute Function onratechange; attribute Function onreadystatechange; attribute Function onredo; attribute Function onreset; attribute Function onresize; attribute Function onscroll; attribute Function onseeked; attribute Function onseeking; attribute Function onselect; attribute Function onshow; attribute Function onstalled; attribute Function onstorage; attribute Function onsubmit; attribute Function onsuspend; attribute Function ontimeupdate; attribute Function onundo; attribute Function onunload; attribute Function onvolumechange; attribute Function onwaiting; }; Window implements EventTarget;
window
frames
self
These attributes all return window.
document
Returns the active document.
defaultView
Returns the Window
object of the active document.
The window
, frames
, and self
IDL attributes must all
return the Window
object's browsing
context's WindowProxy
object.
The document
IDL
attribute must return the Document
object of the
Window
object's Document
's browsing
context's active document.
The defaultView
IDL
attribute of the HTMLDocument
interface must return the
Document
's browsing context's
WindowProxy
object, if there is one, or null
otherwise.
User agents must raise a
SECURITY_ERR
exception whenever any of the members of a
Window
object are accessed by scripts whose
effective script origin is not the same as the
Window
object's Document
's effective
script origin, with the following exceptions:
location
object
postMessage()
method
frames
attribute
When a script whose effective script origin is not
the same as the Window
object's Document
's
effective script origin attempts to access that
Window
object's methods or attributes, the user agent
must act as if any changes to the Window
object's
properties, getters, setters, etc, were not present.
For members that return objects (including function objects),
each distinct effective script origin that is not the
same as the Window
object's Document
's
effective script origin must be provided with a
separate set of objects. These objects must have the prototype chain
appropriate for the script for which the objects are created (not
those that would be appropriate for scripts whose script's
global object is the Window
object in
question).
open
( [ url [, target [, features [, replace ] ] ] ] )Opens a window to show url (defaults to
about:blank
), and returns it. The target argument gives the name of the new
window. If a window exists with that name already, it is
reused. The replace attribute, if true, means
that whatever page is currently open in that window will be
removed from the window's session history. The features argument is ignored.
name
[ = value ]Returns the name of the window.
Can be set, to change the name.
close
()Closes the window.
stop
()Cancels the document load.
The open()
method on
Window
objects provides a mechanism for navigating an existing browsing
context or opening and navigating an auxiliary browsing
context.
The method has four arguments, though they are all optional.
The first argument, url, must be a
valid non-empty URL for a page to load in the browsing
context. If no arguments are provided, or if the first argument is
the empty string, then the url argument defaults
to "about:blank
". The argument must be resolved to an absolute
URL (or an error), relative to the entry
script's base URL,
when the method is invoked.
The second argument, target, specifies the
name of the browsing
context that is to be navigated. It must be a valid browsing
context name or keyword. If fewer than two arguments are
provided, then the target argument defaults to the
value "_blank
".
The third argument, features, has no defined effect and is mentioned for historical reasons only. User agents may interpret this argument as instructions to set the size and position of the browsing context, but are encouraged to instead ignore the argument entirely.
The fourth argument, replace, specifies whether or not the new page will replace the page currently loaded in the browsing context, when target identifies an existing browsing context (as opposed to leaving the current page in the browsing context's session history). When three or fewer arguments are provided, replace defaults to false.
When the method is invoked, the user agent must first select a browsing context to navigate by applying the rules for choosing a browsing context given a browsing context name using the target argument as the name and the browsing context of the script as the context in which the algorithm is executed, unless the user has indicated a preference, in which case the browsing context to navigate may instead be the one indicated by the user.
For example, suppose there is a user agent that
supports control-clicking a link to open it in a new tab. If a user
clicks in that user agent on an element whose onclick
handler uses the window.open()
API to open a page in an
iframe, but, while doing so, holds the control key down, the user
agent could override the selection of the target browsing context to
instead target a new tab.
Then, the user agent must navigate the selected browsing context to the absolute URL (or error) obtained from resolving url earlier. If the replace is true or if the browsing context was just created as part of the rules for choosing a browsing context given a browsing context name, then replacement must be enabled. The navigation must be done with the browsing context of the entry script as the source browsing context.
The method must return the WindowProxy
object of the
browsing context that was navigated, or null if no
browsing context was navigated.
The name
attribute of
the Window
object must, on getting, return the current
name of the browsing context, and, on setting, set the
name of the browsing context to the new value.
The name gets reset when the browsing context is navigated to another domain.
The close()
method on Window
objects should, if the corresponding
browsing context A is an
auxiliary browsing context that was created by a script
(as opposed to by an action of the user), and if the browsing context of the
script that invokes the method
is allowed to navigate the browsing
context A, close the browsing
context A (and may discard it too).
The stop()
method
on Window
objects should, if there is an existing
attempt to navigate the browsing context
and that attempt is not currently running the unload a
document algorithm, cancel that navigation and any associated instances of
the fetch algorithm. Otherwise, it must
do nothing.
length
Returns the number of child browsing contexts.
Returns the indicated child browsing context.
The length
IDL
attribute on the Window
interface must return the
number of child browsing
contexts that are nested through elements that are in the Document
that is the
active document of that Window
object, if
that Window
's browsing context shares the
same event loop as the script's browsing
context of the entry script accessing the IDL
attribute; otherwise, it must return zero.
The supported property indices on the
Window
object at any instant are the numbers in the
range 0 .. n-1, where n is the number returned by the length
IDL attribute. If n is zero then there are no supported property
indices.
To determine the value of an indexed
property index of a Window
object, the user agent must return the WindowProxy
object of the indexth child browsing
context of the Document
that is nested through
an element that is in the
Document
, sorted in the tree order
of the elements nesting those browsing contexts.
These properties are the dynamic nested browsing context properties.
Window
objectReturns the indicated element or collection of elements.
The Window
interface supports named properties. The supported
property names at any moment consist of:
name
content attribute
for all a
, applet
, area
,
embed
, form
, frame
,
frameset
, iframe
, img
, and
object
elements in the active document
that have a name
content attribute, andid
content
attribute of any HTML element in
the active document with an id
content attribute.It is possible that this will change. Browser vendors are considering limiting this behaviour to quirks mode. Read more...
When the Window
object is indexed for property retrieval using a name name, then the user agent must return the value
obtained using the following steps:
Let elements be the list of named elements with the name name in the active document.
There will be at least one such element, by definition.
If elements contains an iframe
element, then return the WindowProxy
object of the
nested browsing context represented by the first such
iframe
element in tree order, and abort
these steps.
Otherwise, if elements has only one element, return that element and abort these steps.
Otherwise return an HTMLCollection
rooted at the
Document
node, whose filter matches only named elements with
the name name.
Named elements with the name name, for the purposes of the above algorithm, are those that are either:
A browsing context has a strong reference to each of
its Document
s and its WindowProxy
object,
and the user agent itself has a strong reference to its top-level browsing
contexts.
A Document
has a strong reference to its
Window
object.
A Window
object has a strong reference to its
Document
object through its document
attribute. Thus, references
from other scripts to either of those objects will keep both
alive. Similarly, both Document
and Window
objects have implied strong
references to the WindowProxy
object.
Each script has a strong reference to its browsing context and its document.
When a browsing context is to discard a
Document
, the user agent must run the following
steps:
Set the Document
's salvageable state to
false.
Run any unloading document cleanup steps for
the Document
that are defined by this specification
and other applicable specifications.
Remove any tasks
associated with the Document
in any task
source, without running those tasks.
Discard
all the child browsing
contexts of the Document
.
Lose the strong reference from the Document
's
browsing context to the
Document
.
Whenever a Document
object is discarded, it is also removed from
the list of the worker's Document
s of each
worker whose list contains that Document
.
When a browsing context is
discarded, the strong reference from the user agent itself to
the browsing context must be severed, and all the
Document
objects for all the entries in the
browsing context's session history must be discarded as well.
User agents may discard top-level browsing contexts at any time (typically,
in response to user requests, e.g. when a user closes a window
containing one or more top-level browsing contexts). Other browsing contexts must be discarded
once their WindowProxy
object is eligible for garbage
collection.
To allow Web pages to integrate with Web browsers, certain Web browser interface elements are exposed in a limited way to scripts in Web pages.
Each interface element is represented by a BarProp
object:
interface BarProp { attribute boolean visible; };
locationbar
. visible
Returns true if the location bar is visible; otherwise, returns false.
menubar
. visible
Returns true if the menu bar is visible; otherwise, returns false.
personalbar
. visible
Returns true if the personal bar is visible; otherwise, returns false.
scrollbars
. visible
Returns true if the scroll bars are visible; otherwise, returns false.
statusbar
. visible
Returns true if the status bar is visible; otherwise, returns false.
toolbar
. visible
Returns true if the toolbar is visible; otherwise, returns false.
The visible attribute, on getting, must return either true or a value determined by the user agent to most accurately represent the visibility state of the user interface element that the object represents, as described below. On setting, the new value must be discarded.
The following BarProp
objects exist for each
Document
object in a browsing
context. Some of the user interface elements represented by
these objects might have no equivalent in some user agents; for
those user agents, except when otherwise specified, the object must
act as if it was present and visible (i.e. its visible
attribute must return
true).
BarProp
objectBarProp
objectBarProp
objectBarProp
objectBarProp
objectvisible
attribute may return false).BarProp
objectvisible
attribute may return false).The locationbar
attribute must return the location bar BarProp
object.
The menubar
attribute must return the menu bar BarProp
object.
The personalbar
attribute must return the personal bar BarProp
object.
The scrollbars
attribute must return the scrollbar BarProp
object.
The statusbar
attribute
must return the status bar BarProp
object.
The toolbar
attribute must return the toolbar BarProp
object.
WindowProxy
objectAs mentioned earlier, each browsing context has a
WindowProxy
object. This object is unusual
in that all operations that would be performed on it must be
performed on the Window
object of the browsing
context's active document instead. It is thus
indistinguishable from that Window
object in every way
until the browsing context is navigated.
There is no WindowProxy
interface object.
The WindowProxy
object allows scripts
to act as if each browsing context had a single
Window
object, while still keeping separate
Window
objects for each Document
.
In the following example, the variable x is
set to the WindowProxy
object returned by the window
accessor on the global object. All
of the expressions following the assignment return true, because in
every respect, the WindowProxy
object acts like the
underlying Window
object.
var x = window; x instanceof Window; // true x === this; // true
The origin of a resource and the effective script origin of a resource are both either opaque identifiers or tuples consisting of a scheme component, a host component, a port component, and optionally extra data.
The extra data could include the certificate of the site when using encrypted connections, to ensure that if the site's secure certificate changes, the origin is considered to change as well.
These characteristics are defined as follows:
The origin and effective script origin of the URL is whatever is returned by the following algorithm:
Let url be the URL for which the origin is being determined.
Parse url.
If url identifies a resource that is its own trust domain (e.g. it identifies an e-mail on an IMAP server or a post on an NNTP server) then return a globally unique identifier specific to the resource identified by url, so that if this algorithm is invoked again for URLs that identify the same resource, the same identifier will be returned.
If url does not use a server-based naming authority, or if parsing url failed, or if url is not an absolute URL, then return a new globally unique identifier.
Let scheme be the <scheme> component of url, converted to ASCII lowercase.
If the UA doesn't support the protocol given by scheme, then return a new globally unique identifier.
If scheme is "file
", then the user agent may return a
UA-specific value.
Let host be the <host> component of url.
Apply the IDNA ToASCII algorithm to host, with both the AllowUnassigned and UseSTD3ASCIIRules flags set. Let host be the result of the ToASCII algorithm.
If ToASCII fails to convert one of the components of the string, e.g. because it is too long or because it contains invalid characters, then return a new globally unique identifier. [RFC3490]
Let host be the result of converting host to ASCII lowercase.
If there is no <port> component, then let port be the default port for the protocol given by scheme. Otherwise, let port be the <port> component of url.
Return the tuple (scheme, host, port).
In addition, if the URL is in fact associated with
a Document
object that was created by parsing the
resource obtained from fetching URL, and this was
done over a secure connection, then the server's secure
certificate may be added to the origin as additional data.
The origin and effective script origin of a script are determined from another resource, called the owner:
script
elementDocument
to which the
script
element belongs.Document
to which the
attribute node belongs.javascript:
URL that was returned as the
location of an HTTP redirect (or equivalent in
other protocols)javascript:
URL.javascript:
URL in an attributeDocument
of the element on
which the attribute is found.javascript:
URL in a style sheetjavascript:
URL to which a browsing
context is being navigated,
the URL having been provided by the user (e.g. by using a
bookmarklet)Document
of the browsing
context's active document.javascript:
URL to which a browsing
context is being navigated,
the URL having been declared in markupDocument
of the element
(e.g. an a
or area
element) that
declared the URL.javascript:
URL to which a browsing
context is being navigated,
the URL having been provided by scriptThe origin of the script is then equal to the origin of the owner, and the effective script origin of the script is equal to the effective script origin of the owner.
Document
objects and imagesDocument
is in a
browsing context whose sandboxed origin
browsing context flag was set when the
Document
was createdDocument
was generated from a resource
labeled as text/html-sandboxed
Document
is created.Document
or image was generated from a
javascript:
URLjavascript:
URL.Document
or image was served over the
network and has an address that uses a URL scheme with a
server-based naming authorityDocument
or the URL of the image, as
appropriate.Document
or image was generated from a
data:
URL that was returned as the location of an HTTP redirect
(or equivalent
in other protocols)data:
URL.Document
or image was generated from a
data:
URL found in another Document
or in a
scriptDocument
or script that initiated the navigation to that URL.Document
has the address
"about:blank
"Document
is the origin it was
assigned when its browsing context was created.Document
is an iframe
srcdoc
documentDocument
is the
origin of the Document
's browsing
context's browsing context container's
Document
.Document
or image was obtained in some
other manner (e.g. a data:
URL typed in by the user, a
Document
created using the createDocument()
API, etc)Document
or image is created.When a Document
is created, its effective
script origin is initialized to the origin of
the Document
. However, the document.domain
attribute can
be used to change it.
audio
and video
elementsIf value of the media element's currentSrc
attribute is the
empty string, the origin is the same as the
origin of the element's Document
's
origin.
Otherwise, the origin is equal to the
origin of the absolute URL given by the
media element's currentSrc
attribute.
The origin of a downloadable Web font is equal to the origin of the absolute URL used to obtain the font (after any redirects). [CSSFONTS]
The origin of a locally installed system font is
equal to the origin of the Document
in
which that font is being used.
Other specifications can override the above definitions by
themselves specifying the origin of a particular URL, script,
Document
, or image.
The Unicode serialization of an origin is the string obtained by applying the following algorithm to the given origin:
If the origin in question is not a
scheme/host/port tuple, then return the literal string "null
" and abort these steps.
Otherwise, let result be the scheme part of the origin tuple.
Append the string "://
" to result.
Apply the IDNA ToUnicode algorithm to each component of the host part of the origin tuple, and append the results — each component, in the same order, separated by U+002E FULL STOP characters (.) — to result. [RFC3490]
If the port part of the origin tuple gives a port that is different from the default port for the protocol given by the scheme part of the origin tuple, then append a U+003A COLON character (:) and the given port, in base ten, to result.
Return result.
The ASCII serialization of an origin is the string obtained by applying the following algorithm to the given origin:
If the origin in question is not a
scheme/host/port tuple, then return the literal string "null
" and abort these steps.
Otherwise, let result be the scheme part of the origin tuple.
Append the string "://
" to result.
Apply the IDNA ToASCII algorithm the host part of the origin tuple, with both the AllowUnassigned and UseSTD3ASCIIRules flags set, and append the results result.
If ToASCII fails to convert one of the components of the string, e.g. because it is too long or because it contains invalid characters, then return the empty string and abort these steps. [RFC3490]
If the port part of the origin tuple gives a port that is different from the default port for the protocol given by the scheme part of the origin tuple, then append a U+003A COLON character (:) and the given port, in base ten, to result.
Return result.
Two origins are said to be the same origin if the following algorithm returns true:
Let A be the first origin being compared, and B be the second origin being compared.
If A and B are both opaque identifiers, and their value is equal, then return true.
Otherwise, if either A or B or both are opaque identifiers, return false.
If A and B have scheme components that are not identical, return false.
If A and B have host components that are not identical, return false.
If A and B have port components that are not identical, return false.
If either A or B have additional data, but that data is not identical for both, return false.
Return true.
domain
[ = domain ]Returns the current domain used for security checks.
Can be set to a value that removes subdomains, to change the effective script origin to allow pages on other subdomains of the same domain (if they do the same thing) to access each other.
The domain
attribute on Document
objects must be initialized to
the document's domain, if it has one, and the empty
string otherwise. If the value is an IPv6 address, then the square
brackets from the host portion of the <host> component must be omitted from
the attribute's value.
On getting, the attribute must return its current value, unless
the Document
has no browsing context, in
which case it must return the empty string.
On setting, the user agent must run the following algorithm:
If the Document
has no browsing
context, throw a SECURITY_ERR
exception and
abort these steps.
If the new value is an IP address, let new value be the new value. Otherwise, apply the IDNA ToASCII algorithm to the new value, with both the AllowUnassigned and UseSTD3ASCIIRules flags set, and let new value be the result of the ToASCII algorithm.
If ToASCII fails to convert one of the components of the
string, e.g. because it is too long or because it contains invalid
characters, then throw a SECURITY_ERR
exception and abort
these steps. [RFC3490]
If new value is not exactly equal to the
current value of the document.domain
attribute, then
run these substeps:
If the current value is an IP address, throw a
SECURITY_ERR
exception and abort these steps.
If new value, prefixed by a U+002E FULL
STOP (.), does not exactly match the end of the current value,
throw a SECURITY_ERR
exception and abort these
steps.
If new value matches a suffix in the
Public Suffix List, or, if new value,
prefixed by a U+002E FULL STOP (.), matches the end of a
suffix in the Public Suffix List, then throw a
SECURITY_ERR
exception and abort these steps. [PSL]
Suffixes must be compared after applying the IDNA ToASCII algorithm to them, with both the AllowUnassigned and UseSTD3ASCIIRules flags set, in an ASCII case-insensitive manner. [RFC3490]
Release the storage mutex.
Set the attribute's value to new value.
Set the host part of the effective script origin
tuple of the Document
to new
value.
Set the port part of the effective script origin
tuple of the Document
to "manual override" (a value
that, for the purposes of comparing
origins, is identical to "manual override" but not
identical to any other value).
The domain of a
Document
is the host part of the document's
origin, if that is a scheme/host/port tuple. If it
isn't, then the document does not have a domain.
The domain
attribute is used to enable pages on different hosts of a domain to
access each others' DOMs.
Do not use the document.domain
attribute when
using shared hosting. If an untrusted third party is able to host an
HTTP server at the same IP address but on a different port, then the
same-origin protection that normally protects two different sites on
the same host will fail, as the ports are ignored when comparing
origins after the document.domain
attribute has
been used.
The sequence of Document
s in a browsing
context is its session history.
History
objects provide a representation of the
pages in the session history of browsing contexts. Each browsing
context, including nested browsing contexts, has a distinct session
history.
Each Document
object in a browsing
context's session history is associated with a
unique instance of the History
object, although they
all must model the same underlying session history.
The history
attribute
of the Window
interface must return the object
implementing the History
interface for that
Window
object's Document
.
History
objects represent their browsing
context's session history as a flat list of session history entries. Each
session history entry consists of either a
URL or a state object, or both, and may in addition have a title, a
Document
object, form data, a scroll position, and
other information associated with it.
This does not imply that the user interface need be linear. See the notes below.
Titles associated with session history entries need not have any relation
with the current title
of the
Document
. The title of a session history
entry is intended to explain the state of the document at
that point, so that the user can navigate the document's
history.
URLs without associated state objects are added to the session history as the user (or script) navigates from page to page.
A state object is an object representing a user interface state.
Pages can add state objects between their entry in the session history and the next ("forward") entry. These are then returned to the script when the user (or script) goes back in the history, thus enabling authors to use the "navigation" metaphor even in one-page applications.
State objects are intended to
be used for two main purposes: first, storing a preparsed
description of the state in the URL so that in the
simple case an author doesn't have to do the parsing (though one
would still need the parsing for handling URLs passed around by users, so it's only a minor
optimization), and second, so that the author can store state that
one wouldn't store in the URL because it only applies to the current
Document
instance and it would have to be reconstructed
if a new Document
were opened.
An example of the latter would be something like keeping track of
the precise coordinate from which a popup div
was made
to animate, so that if the user goes back, it can be made to animate
to the same location. Or alternatively, it could be used to keep a
pointer into a cache of data that would be fetched from the server
based on the information in the URL, so that when going
back and forward, the information doesn't have to be fetched
again.
At any point, one of the entries in the session history is the
current entry. This is the entry representing the
active document of the browsing
context. The current entry is usually an entry
for the location of the
Document
. However, it can also be one of the entries
for state objects added to the
history by that document.
An entry with persisted user state is one that also has user-agent defined state. This specification does not specify what kind of state can be stored.
For example, some user agents might want to persist the scroll position, or the values of form controls.
Entries that consist of state
objects share the same Document
as the entry for
the page that was active when they were added.
Contiguous entries that differ just by fragment identifier also
share the same Document
.
All entries that share the same
Document
(and that are therefore merely different
states of one particular document) are contiguous by definition.
User agents may discard
the Document
objects of entries other than the
current entry that are not referenced from any script,
reloading the pages afresh when the user or script navigates back to
such pages. This specification does not specify when user agents
should discard Document
objects and when they should
cache them.
Entries that have had their Document
objects
discarded must, for the purposes of the algorithms given below, act
as if they had not. When the user or script navigates back or
forwards to a page which has no in-memory DOM objects, any other
entries that shared the same Document
object with it
must share the new object as well.
History
interfaceinterface History { readonly attribute long length; readonly attribute any state; void go(in optional long delta); void back(); void forward(); void pushState(in any data, in DOMString title, in optional DOMString url); void replaceState(in any data, in DOMString title, in optional DOMString url); };
history
. length
Returns the number of entries in the joint session history.
history
. state
Returns the current state object.
history
. go
( [ delta ] )Goes back or forward the specified number of steps in the joint session history.
A zero delta will reload the current page.
If the delta is out of range, does nothing.
history
. back
()Goes back one step in the joint session history.
If there is no previous page, does nothing.
history
. forward
()Goes forward one step in the joint session history.
If there is no next page, does nothing.
history
. pushState
(data, title [, url ] )Pushes the given data onto the session history, with the given title, and, if provided, the given URL.
history
. replaceState
(data, title [, url ] )Updates the current entry in the session history to have the given data, title, and, if provided, URL.
The joint session history of a History
object is the union of all the session
histories of all browsing
contexts of all the fully active
Document
objects that share the History
object's top-level browsing context, with all the
entries that are current entries
in their respective session
histories removed except for the current entry of the
joint session history.
The current entry of the joint session history is the entry that most recently became a current entry in its session history.
Entries in the joint session history are ordered chronologically by the time they were added to their respective session histories. (Since all these browsing contexts by definition share an event loop, there is always a well-defined sequential order in which their session histories had their entries added.) Each entry has an index; the earliest entry has index 0, and the subsequent entries are numbered with consecutively increasing integers (1, 2, 3, etc).
The length
attribute of the History
interface must return the
number of entries in the joint session history.
The actual entries are not accessible from script.
The state
attribute of the History
interface must return the last
value it was set to by the user agent. Initially, its value must be
null.
When the go(delta)
method is invoked, if the
argument to the method was omitted or has the value zero, the user
agent must act as if the location.reload()
method was
called instead. Otherwise, the user agent must traverse the
history by a delta whose value is the value of the method's
argument.
When the back()
method is invoked, the user agent must traverse the history by
a delta −1.
When the forward()
method is
invoked, the user agent must traverse the history by a
delta +1.
To traverse the history by a delta delta, the user agent must queue a task to run the following steps. The task source for the queued task is the history traversal task source.
Let delta be the argument to the method.
If the index of the current entry of the joint session history plus delta is less than zero or greater than or equal to the number of items in the joint session history, then abort these steps.
Let specified entry be the entry in the joint session history whose index is the sum of delta and the index of the current entry of the joint session history.
Let specified browsing context be the browsing context of the specified entry.
If the specified browsing context's
active document is not the same Document
as the Document
of the specified
entry, then run these substeps:
Prompt to unload the active document of the specified browsing context. If the user refused to allow the document to be unloaded, then abort these steps.
Unload the active document of the specified browsing context with the recycle parameter set to false.
Traverse the history of the specified browsing context to the specified entry.
When the user navigates through a browsing context, e.g. using a browser's back and forward buttons, the user agent must traverse the history by a delta equivalent to the action specified by the user.
The pushState(data, title, url)
method adds a state object entry to
the history.
The replaceState(data, title, url)
method updates the state object,
title, and optionally the URL of the current
entry in the history.
When either of these methods is invoked, the user agent must run the following steps:
Let clone data be a structured clone of the specified data. If this throws an exception, then rethrow that exception and abort these steps.
If a third argument is specified, run these substeps:
SECURITY_ERR
exception
and abort these steps.SECURITY_ERR
exception and abort these
steps.SECURITY_ERR
exception and abort
these steps. (This prevents sandboxed content from spoofing other
pages on the same origin.)For the purposes of the comparisons in the above substeps, the <path> and <query> components can only be the same if the URLs are both hierarchical URLs.
If the method invoked was the pushState()
method:
Remove all the entries in the browsing context's session history after the current entry. If the current entry is the last entry in the session history, then no entries are removed.
This doesn't necessarily have to affect the user agent's user interface.
Remove any tasks queued by the history traversal task source.
If appropriate, update the current entry to reflect any state that the user agent wishes to persist. The entry is then said to be an entry with persisted user state.
Add a state object entry to the session history, after the current entry, with cloned data as the state object, the given title as the title, and, if the third argument is present, the absolute URL that was found earlier in this algorithm as the URL of the entry.
Update the current entry to be this newly added entry.
Otherwise, if the method invoked was the replaceState()
method:
Update the current entry in the session history so that cloned data is the entry's new state object, the given title is the new title, and, if the third argument is present, the absolute URL that was found earlier in this algorithm is the entry's new URL.
If the third argument is present, set the document's current address to the absolute URL that was found earlier in this algorithm.
Since this is neither a navigation of the browsing
context nor a history
traversal, it does not cause a hashchange
event to be fired.
Set history.state
to
another structured clone of the specified data.
The title is purely advisory. User agents might use the title in the user interface.
User agents may limit the number of state objects added to the
session history per page. If a page hits the UA-defined limit, user
agents must remove the entry immediately after the first entry for
that Document
object in the session history after
having added the new entry. (Thus the state history acts as a FIFO
buffer for eviction, but as a LIFO buffer for navigation.)
Consider a game where the user can navigate along a line, such that the user is always at some coordinate, and such that the user can bookmark the page corresponding to a particular coordinate, to return to it later.
A static page implementing the x=5 position in such a game could look like the following:
<!DOCTYPE HTML> <!-- this is http://example.com/line?x=5 --> <title>Line Game - 5</title> <p>You are at coordinate 5 on the line.</p> <p> <a href="?x=6">Advance to 6</a> or <a href="?x=4">retreat to 4</a>? </p>
The problem with such a system is that each time the user clicks, the whole page has to be reloaded. Here instead is another way of doing it, using script:
<!DOCTYPE HTML> <!-- this starts off as http://example.com/line?x=5 --> <title>Line Game - 5</title> <p>You are at coordinate <span id="coord">5</span> on the line.</p> <p> <a href="?x=6" onclick="go(1); return false;">Advance to 6</a> or <a href="?x=4" onclick="go(-1); return false;">retreat to 4</a>? </p> <script> var currentPage = 5; // prefilled by server function go(d) { setupPage(currentPage + d); history.pushState(currentPage, document.title, '?x=' + currentPage); } onpopstate = function(event) { setupPage(event.state); } function setupPage(page) { currentPage = page; document.title = 'Line Game - ' + currentPage; document.getElementById('coord').textContent = currentPage; document.links[0].href = '?x=' + (currentPage+1); document.links[0].textContent = 'Advance to ' + (currentPage+1); document.links[1].href = '?x=' + (currentPage-1); document.links[1].textContent = 'retreat to ' + (currentPage-1); } </script>
In systems without script, this still works like the previous example. However, users that do have script support can now navigate much faster, since there is no network access for the same experience. Furthermore, contrary to the experience the user would have with just a naïve script-based approach, bookmarking and navigating the session history still work.
In the example above, the data argument to
the pushState()
method
is the same information as would be sent to the server, but in a
more convenient form, so that the script doesn't have to parse the
URL each time the user navigates.
Applications might not use the same title for a session
history entry as the value of the document's
title
element at that time. For example, here is a
simple page that shows a block in the title
element.
Clearly, when navigating backwards to a previous state the user
does not go back in time, and therefore it would be inappropriate
to put the time in the session history title.
<!DOCTYPE HTML> <TITLE>Line</TITLE> <SCRIPT> setInterval(function () { document.title = 'Line - ' + new Date(); }, 1000); var i = 1; function inc() { set(i+1); history.pushState(i, 'Line - ' + i); } function set(newI) { i = newI; document.forms.F.I.value = newI; } </SCRIPT> <BODY ONPOPSTATE="set(event.state)"> <FORM NAME=F> State: <OUTPUT NAME=I>1</OUTPUT> <INPUT VALUE="Increment" TYPE=BUTTON ONCLICK="inc()"> </FORM>
Location
interfaceEach Document
object in a browsing
context's session history is associated with a unique
instance of a Location
object.
location
[ = value ]location
[ = value ]Returns a Location
object with the current page's location.
Can be set, to navigate to another page.
The location
attribute
of the HTMLDocument
interface must return the
Location
object for that Document
object,
if it is in a browsing context, and null otherwise.
The location
attribute of the Window
interface must return the
Location
object for that Window
object's
Document
.
Location
objects provide a representation of their document's current
address, and allow the current entry of the
browsing context's session history to be changed, by
adding or replacing entries in the history
object.
interface Location { stringifier attribute DOMString href; void assign(in DOMString url); void replace(in DOMString url); void reload(); // URL decomposition IDL attributes attribute DOMString protocol; attribute DOMString host; attribute DOMString hostname; attribute DOMString port; attribute DOMString pathname; attribute DOMString search; attribute DOMString hash; // resolving relative URLs DOMString resolveURL(in DOMString url); };
href
[ = value ]Returns the current page's location.
Can be set, to navigate to another page.
assign
(url)Navigates to the given page.
replace
(url)Removes the current page from the session history and navigates to the given page.
reload
()Reloads the current page.
resolveURL
(url)Resolves the given relative URL to an absolute URL.
The href
attribute must return the current address of the associated
Document
object, as an absolute URL.
On setting, if the Location
object's associated
Document
object has completely loaded,
then the user agent must act as if the assign()
method had been called
with the new value as its argument. Otherwise, the user agent must
act as if the replace()
method had been called with the new value as its argument.
When the assign(url)
method is invoked, the UA must
resolve the argument, relative to
the entry script's base
URL, and if that is successful, must
navigate the
browsing context to the specified url. If the browsing context's
session history contains only one
Document
, and that was the about:blank
Document
created when the browsing context
was created, then the navigation must be done with replacement
enabled.
When the replace(url)
method is invoked, the UA must
resolve the argument, relative to
the entry script's base
URL, and if that is successful,
navigate the
browsing context to the specified url with replacement enabled.
Navigation for the assign()
and replace()
methods must be done
with the browsing
context of the script that invoked the method as the
source browsing context.
If the resolving step of the
assign()
and replace()
methods is not
successful, then the user agent must instead throw a
SYNTAX_ERR
exception.
When the reload()
method is
invoked, the user agent must run the appropriate steps from the
following list:
resize
event in response to the user
resizing the browsing contextRepaint the browsing context and abort these steps.
iframe
srcdoc
documentReprocess the
iframe
attributes of the browsing
context's browsing context container.
Perform an overridden reload.
Navigate the browsing context to the document's current address with replacement enabled. The source browsing context must be the browsing context being navigated.
When a user requests that the current page of a browsing
context be reloaded through a user interface element, the
user agent should navigate the
browsing context to the same resource as
Document
, with replacement enabled. In the
case of non-idempotent methods (e.g. HTTP POST), the user agent
should prompt the user to confirm the operation first, since
otherwise transactions (e.g. purchases or database modifications)
could be repeated. User agents may allow the user to explicitly
override any caches when reloading. If browsing
context's active document's reload
override flag is set, then the user agent may instead perform
an overridden reload rather than the navigation
described in this paragraph.
The Location
interface also has the complement of
URL decomposition IDL attributes, protocol
, host
, port
, hostname
, pathname
, search
, and hash
. These must follow the rules given for URL
decomposition IDL attributes, with the input being the current address of the
associated Document
object, as an absolute
URL (same as the href
attribute), and the common setter
action being the same as setting the href
attribute to the new output
value.
The resolveURL(url)
method must resolve its url argument, relative
to the entry script's base URL, and if that succeeds, return the resulting
absolute URL. If it fails, it must throw a
SYNTAX_ERR
exception instead.
User agents must raise a
SECURITY_ERR
exception whenever any of the members of a
Location
object are accessed by scripts whose
effective script origin is not the same as the Location
object's associated
Document
's effective script origin, with
the following exceptions:
href
setter, if the
script is running in a browsing context that is
allowed to navigate the browsing context with which
the Location
object is associated
replace()
method,
if the script is running in a browsing context that is
allowed to navigate the browsing context with which
the Location
object is associated
This section is non-normative.
The History
interface is not meant to place
restrictions on how implementations represent the session history to
the user.
For example, session history could be implemented in a tree-like
manner, with each page having multiple "forward" pages. This
specification doesn't define how the linear list of pages in the
history
object are derived from the
actual session history as seen from the user's perspective.
Similarly, a page containing two iframe
s has a history
object distinct from the
iframe
s' history
objects, despite the fact that typical Web browsers present the user
with just one "Back" button, with a session history that interleaves
the navigation of the two inner frames and the outer page.
Security: It is suggested that to avoid letting
a page "hijack" the history navigation facilities of a UA by abusing
pushState()
, the UA
provide the user with a way to jump back to the previous page
(rather than just going back to the previous state). For example,
the back button could have a drop down showing just the pages in the
session history, and not showing any of the states. Similarly, an
aural browser could have two "back" commands, one that goes back to
the previous state, and one that jumps straight back to the previous
page.
In addition, a user agent could ignore calls to pushState()
that are invoked on
a timer, or from event listeners that are not triggered in response
to a clear user action, or that are invoked in rapid succession.
Certain actions cause the browsing context to navigate to a new resource. Navigation always involves source browsing context, which is the browsing context which was responsible for starting the navigation.
For example, following a hyperlink, form submission, and the window.open()
and location.assign()
methods can all
cause a browsing context to navigate.
A user agent may provide various ways for the user to explicitly cause a browsing context to navigate, in addition to those defined in this specification.
When a browsing context is navigated to a new resource, the user agent must run the following steps:
Release the storage mutex.
If the source browsing context is not the same as the browsing context being navigated, and the source browsing context is not one of the ancestor browsing contexts of the browsing context being navigated, and the browsing context being navigated is not both a top-level browsing context and one of the ancestor browsing contexts of the source browsing context, and the source browsing context had its sandboxed navigation browsing context flag set when its active document was created, then abort these steps.
Otherwise, if the browsing context being navigated is a top-level browsing context, and is one of the ancestor browsing contexts of the source browsing context, and the source browsing context had its sandboxed top-level navigation browsing context flag set when its active document was created, then abort these steps.
In both cases, the user agent may additionally offer to open the new resource in a new top-level browsing context or in the top-level browsing context of the source browsing context, at the user's option, in which case the user agent must navigate that designated top-level browsing context to the new resource as if the user had requested it independently.
If the source browsing context is the same as the browsing context being navigated, and this browsing context has its seamless browsing context flag set, and the browsing context being navigated was not chosen using an explicit self-navigation override, then find the nearest ancestor browsing context that does not have its seamless browsing context flag set, and continue these steps as if that browsing context was the one that was going to be navigated instead.
If there is a preexisting attempt to navigate the browsing context, and the source browsing context is the same as the browsing context being navigated, and that attempt is currently running the unload a document algorithm, and the origin of the URL of the resource being loaded in that navigation is not the same origin as the origin of the URL of the resource being loaded in this navigation, then abort these steps without affecting the preexisting attempt to navigate the browsing context.
If a task queued by the traverse the history by a delta algorithm is running the unload a document algorithm for the active document of the browsing context being navigated, then abort these steps without affecting the unload a document algorithm or the aforementioned history traversal task.
If there is a preexisting attempt to navigate the
browsing context, and either that attempt has not yet
matured (i.e. it has
not passed the point of making its Document
the
active document), or that navigation's resource is not
to be fetched using HTTP GET or equivalent, or its
resource's absolute URL differs from this attempt's by
more than the presence, absence, or value of the <fragment> component, then cancel
that preexisting attempt to navigate the browsing
context.
Cancel any preexisting attempt to navigate the browsing context.
If the new resource is to be handled using a mechanism that does not affect the browsing context, e.g. ignoring the navigation request altogether because the specified scheme is not one of the supported protocols, then abort these steps and proceed with that mechanism instead.
Prompt to
unload the Document
object. If the user
refused to allow the document to be unloaded, then
these steps must be aborted.
Abort the active document of the browsing context.
If the new resource is to be handled by displaying some sort of inline content, e.g. an error message because the specified scheme is not one of the supported protocols, or an inline prompt to allow the user to select a registered handler for the given scheme, then display the inline content and abort these steps.
In the case of a registered handler being used, the algorithm will be reinvoked with a new URL to handle the request.
If the resource has already been obtained (e.g. because it is
being used to populate an object
element's new
child browsing context), then skip this step.
Otherwise:
If the new resource is to be fetched using HTTP GET or equivalent, and there are relevant application caches that are identified by a URL with the same origin as the URL in question, and that have this URL as one of their entries, excluding entries marked as foreign, then get the resource from the most appropriate application cache of those that match.
For example, imagine an HTML page with an associated application cache displaying an image and a form, where the image is also used by several other application caches. If the user right-clicks on the image and chooses "View Image", then the user agent could decide to show the image from any of those caches, but it is likely that the most useful cache for the user would be the one that was used for the aforementioned HTML page. On the other hand, if the user submits the form, and the form does a POST submission, then the user agent will not use an application cache at all; the submission will be made to the network.
Otherwise, fetch the new resource, with the manual redirect flag set.
If the resource is being fetched using a method other than one equivalent to HTTP's GET, or, if the navigation algorithm was invoked as a result of the form submission algorithm, then the fetching algorithm must be invoked from the origin of the active document of the source browsing context, if any.
If the browsing context being navigated is a
child browsing context for an iframe
or
object
element, then the fetching
algorithm must be invoked from the iframe
or
object
element's browsing context scope
origin, if it has one.
The fetch algorithm must delay the load event of the browsing context.
At this point, unless this step has already been reached once before in the execution of this instance of the algorithm, the user agents must return to whatever algorithm invoked the navigation steps and must continue these steps asynchronously.
If fetching the resource results in a redirect, and either the URL of the target of the redirect has the same origin as the original resource, or the resource is being obtained using the POST method or a safe method (in HTTP terms), return to the step labeled "fragment identifiers" with the new resource.
Otherwise, if fetching the resource results in a redirect but the URL of the target of the redirect does not have the same origin as the original resource and the resource is being obtained using a method that is neither the POST method nor a safe method (in HTTP terms), then abort these steps. The user agent may indicate to the user that the navigation has been aborted for security reasons.
Wait for one or more bytes to be available or for the user agent to establish that the resource in question is empty. During this time, the user agent may allow the user to cancel this navigation attempt or start other navigation attempts.
If the resource was not fetched from an application cache, and was to be fetched using HTTP GET or equivalent, and its URL matches the fallback namespace of one or more relevant application caches, and the most appropriate application cache of those that match does not have an entry in its online whitelist that has the same origin as the resource's URL and that is a prefix match for the resource's URL, and the user didn't cancel the navigation attempt during the previous step, and the navigation attempt failed (e.g. the server returned a 4xx or 5xx status code or equivalent, or there was a DNS error), then:
Let candidate be the fallback resource specified for the fallback namespace in question. If multiple application caches match, the user agent must use the fallback of the most appropriate application cache of those that match.
If candidate is not marked as foreign, then the user agent must discard the failed load and instead continue along these steps using candidate as the resource. The document's address, if appropriate, will still be the originally requested URL, not the fallback URL, but the user agent may indicate to the user that the original page load failed, that the page used was a fallback resource, and what the URL of the fallback resource actually is.
If the document's out-of-band metadata (e.g. HTTP headers), not counting any type information (such as the Content-Type HTTP header), requires some sort of processing that will not affect the browsing context, then perform that processing and abort these steps.
Such processing might be triggered by, amongst other things, the following:
HTTP 401 responses that do not include a challenge recognized by the user agent must be processed as if they had no challenge, e.g. rendering the entity body as if the response had been 200 OK.
User agents may show the entity body of an HTTP 401 response even when the response do include a recognized challenge, with the option to login being included in a non-modal fashion, to enable the information provided by the server to be used by the user before authenticating. Similarly, user agents should allow the user to authenticate (in a non-modal fashion) against authentication challenges included in other responses such as HTTP 200 OK responses, effectively allowing resources to present HTTP login forms without requiring their use.
Let type be the sniffed type of the resource.
If the user agent has been configured to process resources of the given type using some mechanism other than rendering the content in a browsing context, then skip this step. Otherwise, if the type is one of the following types, jump to the appropriate entry in the following list, and process the resource as described there:
text/html
"text/html-sandboxed
"+xml
"application/xml
"text/xml
"text/plain
"Setting the document's
address: If there is no override URL, then any
Document
created by these steps must have its address set to the
URL that was originally to be fetched, ignoring any other data that was
used to obtain the resource (e.g. the entity body in the case of a
POST submission is not part of the document's
address, nor is the URL of the fallback resource in the
case of the original load having failed and that URL having been
found to match a fallback
namespace). However, if there is an override
URL, then any Document
created by these steps
must have its address
set to that URL instead.
An override URL
is set when dereferencing a
javascript:
URL.
Creating a new
Document
object: When a Document
is created as part of the above steps, a new Window
object must be created and associated with the
Document
, with one exception: if the browsing
context's only entry in its session history is
the about:blank
Document
that was added
when the browsing context was created, and navigation
is occurring with replacement enabled, and that
Document
has the same origin as the new
Document
, then the Window
object of that
Document
must be used instead, and the document
attribute of the
Window
object must be changed to point to the new
Document
instead.
Otherwise, the document's type is such that the resource will not affect the browsing context, e.g. because the resource is to be handed to an external application. Process the resource appropriately.
Some of the sections below, to which the above algorithm defers
in certain cases, require the user agent to update the session
history with the new page. When a user agent is required to do
this, it must queue a task (associated with the
Document
object of the current entry, not
the new one) to run the following steps:
Unload the
Document
object of the current entry,
with the recycle parameter set to
false.
Replace the Document
of the entry being
updated, and any other entries that referenced the same
document as that entry, with the new
Document
.
Traverse the history to the new entry.
This can only happen if the entry being updated
is no the current entry, and can never happen with
replacement enabled. (It happens when the user
tried to traverse to a session history entry that no longer had
a Document
object.)
Remove all the entries in the browsing context's session history after the current entry. If the current entry is the last entry in the session history, then no entries are removed.
This doesn't necessarily have to affect the user agent's user interface.
Remove any tasks queued by the history traversal task source.
Append a new entry at the end of the History
object representing the new resource and its
Document
object and related state.
Traverse the history to the new entry. If the navigation was initiated with replacement enabled, then the traversal must itself be initiated with replacement enabled.
The navigation algorithm has now matured.
Fragment identifier loop: Spin the event loop for a user-agent-defined amount of time, as desired by the user agent implementor. (This is intended to allow the user agent to optimize the user experience in the face of performance concerns.)
If the Document
object has no parser, or its
parser has stopped parsing, or
the user agent has reason to believe the user is no longer
interested in scrolling to the fragment identifier, then abort
these steps.
Scroll to the fragment identifier given in the document's current address. If this fails to find an indicated part of the document, then return to the fragment identifier loop step.
The task source for this task is the networking task source.
When an HTML document is to be loaded in a browsing
context, the user agent must queue a task to
create a Document
object, mark it as being
an HTML document, create an
HTML parser, and associate it with the document. Each
task that the networking
task source places on the task queue while the
fetching algorithm runs must then fill
the parser's input stream with the fetched bytes and
cause the HTML parser to perform the appropriate
processing of the input stream.
The input stream converts bytes into characters for use in the tokenizer. This process relies, in part, on character encoding information found in the real Content-Type metadata of the resource; the "sniffed type" is not used for this purpose.
When no more bytes are available, the user agent must queue
a task for the parser to process the implied EOF character,
which eventually causes a load
event
to be fired.
After creating the Document
object, but before any
script execution, certainly before the parser stops, the user agent must update the session
history with the new page.
Application cache selection happens in the HTML parser.
The task source for the two tasks mentioned in this section must be the networking task source.
When faced with displaying an XML file inline, user agents must
first create a Document
object, following
the requirements of the XML and Namespaces in XML recommendations,
RFC 3023, DOM3 Core, and other relevant specifications. [XML] [XMLNS] [RFC3023] [DOMCORE]
The actual HTTP headers and other metadata, not the headers as mutated or implied by the algorithms given in this specification, are the ones that must be used when determining the character encoding according to the rules given in the above specifications. Once the character encoding is established, the document's character encoding must be set to that character encoding.
If the root element, as parsed according to the XML
specifications cited above, is found to be an html
element with an attribute manifest
whose value is not the
empty string, then, as soon as the element is inserted into the document, the user
agent must resolve the value of
that attribute relative to that element, and if that is successful,
must run the application cache
selection algorithm with the resulting absolute
URL with any <fragment> component removed as
the manifest URL, and passing in the newly-created
Document
. Otherwise, if the attribute is absent, its
value is the empty string, or resolving its value fails, then as
soon as the root element is inserted into the document, the user agent must run
the application cache selection
algorithm with no manifest, and passing in the
Document
.
Because the processing of the manifest
attribute happens
only once the root element is parsed, any URLs referenced by
processing instructions before the root element (such as <?xml-stylesheet?>
and <?xbl?>
PIs) will be fetched from the network and
cannot be cached.
User agents may examine the namespace of the root
Element
node of this Document
object to
perform namespace-based dispatch to alternative processing tools,
e.g. determining that the content is actually a syndication feed and
passing it to a feed handler. If such processing is to take place,
abort the steps in this section, and jump to the next step (labeled
"non-document content") in the navigate steps
above.
Otherwise, then, with the newly created Document
,
the user agents must update the session history with the new
page. User agents may do this before the complete document
has been parsed (thus achieving incremental rendering), and
must do this before any scripts are to be executed.
Error messages from the parse process (e.g. XML namespace
well-formedness errors) may be reported inline by mutating the
Document
.
When a plain text document is to be loaded in a browsing
context, the user agent should queue a task to
create a Document
object, mark it as being
an HTML document, create an
HTML parser, associate it with the document, act as if
the tokenizer had emitted a start tag token with the tag name "pre"
followed by a single U+000A LINE FEED (LF) character, and switch the HTML parser's tokenizer
to the PLAINTEXT state. Each task that the networking task
source places on the task queue while the fetching algorithm runs must then fill the
parser's input stream with the fetched bytes and cause
the HTML parser to perform the appropriate processing
of the input stream.
The rules for how to convert the bytes of the plain text document into actual characters, and the rules for actually rendering the text to the user, are defined in RFC 2046, RFC 3676, and subsequent versions thereof. [RFC2046] [RFC3676]
The document's character encoding must be set to the character encoding used to decode the document.
Upon creation of the Document
object, the user agent
must run the application cache
selection algorithm with no manifest, and passing in the
newly-created Document
.
When no more bytes are available, the user agent must queue
a task for the parser to process the implied EOF character,
which eventually causes a load
event
to be fired.
After creating the Document
object, but potentially
before the page has finished parsing, the user agent must
update the session history with the new page.
User agents may add content to the head
element of
the Document
, e.g. linking to a style sheet or an XBL
binding, providing script, giving the document a title
,
etc.
In particular, if the user agent supports the Format=Flowed
feature of RFC 3676 then the user
agent would need to apply extra styling to cause the text to wrap
correctly and to handle the quoting feature. This could be performed
using, e.g., an XBL binding or a CSS extension.
The task source for the two tasks mentioned in this section must be the networking task source.
When an image resource is to be loaded in a browsing
context, the user agent should create a
Document
object, mark it as being an HTML document, append an
html
element to the Document
, append a
head
element and a body
element to the
html
element, append an img
to the
body
element, and set the src
attribute of the img
element to the address of the image.
Then, the user agent must act as if it had stopped parsing.
Upon creation of the Document
object, the user agent
must run the application cache
selection algorithm with no manifest, and passing in the
newly-created Document
.
After creating the Document
object, but potentially
before the page has finished fully loading, the user agent must
update the session history with the new page.
User agents may add content to the head
element of
the Document
, or attributes to the img
element, e.g. to link to a style sheet or an XBL binding, to provide
a script, to give the document a title
, etc.
When a resource that requires an external resource to be rendered
is to be loaded in a browsing context, the user agent
should create a Document
object, mark it
as being an HTML document,
append an html
element to the Document
,
append a head
element and a body
element
to the html
element, append an embed
to
the body
element, and set the src
attribute of the
embed
element to the address of the resource.
Then, the user agent must act as if it had stopped parsing.
Upon creation of the Document
object, the user agent
must run the application cache
selection algorithm with no manifest, and passing in the
newly-created Document
.
After creating the Document
object, but potentially
before the page has finished fully loading, the user agent must
update the session history with the new page.
User agents may add content to the head
element of
the Document
, or attributes to the embed
element, e.g. to link to a style sheet or an XBL binding, or to give
the document a title
.
When the user agent is to display a user agent page inline in a
browsing context, the user agent should create a
Document
object, mark it as being an HTML document, and then either
associate that Document
with a custom rendering that is
not rendered using the normal Document
rendering rules,
or mutate that Document
until it represents the content
the user agent wants to render.
Once the page has been set up, the user agent must act as if it had stopped parsing.
Upon creation of the Document
object, the user agent
must run the application cache
selection algorithm with no manifest, passing in the
newly-created Document
.
After creating the Document
object, but potentially
before the page has been completely set up, the user agent must
update the session history with the new page.
When a user agent is supposed to navigate to a fragment identifier, then the user agent must queue a task to run the following steps:
Remove all the entries in the browsing context's session history after the current entry. If the current entry is the last entry in the session history, then no entries are removed.
This doesn't necessarily have to affect the user agent's user interface.
Remove any tasks queued by the history traversal task source.
Append a new entry at the end of the History
object representing the new resource and its Document
object and related state. Its URL must be set to the
address to which the user agent was navigating. The title must be left
unset.
Traverse the history to the new entry. This will scroll to the fragment identifier given in what is now the document's current address.
If the scrolling fails because the relevant ID has not yet been parsed, then the original navigation algorithm will take care of the scrolling instead, as the last few steps of its update the session history with the new page algorithm.
When the user agent is required to scroll to the fragment identifier, it must change the scrolling position of the document using the scroll an element into view algorithm defined in the CSSOM View specification, or perform some other action, such that the indicated part of the document is brought to the user's attention. If there is no indicated part, then the user agent must not scroll anywhere. [CSSOMVIEW]
The indicated part of the document is the one that the
fragment identifier, if any, identifies. The semantics of the
fragment identifier in terms of mapping it to a specific DOM Node is
defined by the specification that defines the MIME type
used by the Document
(for example, the processing of
fragment identifiers for XML MIME
types is the responsibility of RFC3023). [RFC3023]
For HTML documents (and HTML MIME types), the following processing model must be followed to determine what the indicated part of the document is.
Parse the URL, and let fragid be the <fragment> component of the URL.
If fragid is the empty string, then the indicated part of the document is the top of the document; stop the algorithm here.
Let decoded fragid be the result of expanding any sequences of percent-encoded octets in fragid that are valid UTF-8 sequences into Unicode characters as defined by UTF-8. If any percent-encoded octets in that string are not valid UTF-8 sequences, then skip this step and the next one.
If this step was not skipped and there is an element in the DOM that has an ID exactly equal to decoded fragid, then the first such element in tree order is the indicated part of the document; stop the algorithm here.
If there is an a
element in the DOM that has a
name
attribute whose value is
exactly equal to fragid (not decoded fragid), then the first such element in tree
order is the indicated part of the document; stop the
algorithm here.
If fragid is an ASCII
case-insensitive match for the string top
, then the indicated part of the
document is the top of the document; stop the algorithm
here.
Otherwise, there is no indicated part of the document.
For the purposes of the interaction of HTML with Selectors' :target
pseudo-class, the
target element is the indicated part of the
document, if that is an element; otherwise there is no
target element. [SELECTORS]
When a user agent is required to traverse the history to a specified entry, optionally with replacement enabled, the user agent must act as follows.
This algorithm is not just invoked when explicitly going back or forwards in the session history — it is also invoked in other situations, for example when navigating a browsing context, as part of updating the session history with the new page.
If there is no longer a Document
object for the
entry in question, the user agent must
navigate
the browsing context to the location for that entry to perform an
entry update of that entry, and abort these steps. The
"navigate" algorithm reinvokes this "traverse"
algorithm to complete the traversal, at which point there
is a Document
object and so this step gets
skipped. The navigation must be done using the same source
browsing context as was used the first time this entry was
created. (This can never happen with replacement
enabled.)
If the current entry's title was not set by the
pushState()
or replaceState()
methods,
then set its title to the value returned by the document.title
IDL
attribute.
If appropriate, update the current entry in the
browsing context's Document
object's
History
object to reflect any state that the user
agent wishes to persist. The entry is then said to be an
entry with persisted user state.
If the specified entry has a different
Document
object than the current entry
then the user agent must run the following substeps:
Document
of the specified entry is not the
same as the origin
of the Document
of the current entry,
then the following sub-sub-steps must be run:
Document
objects with the same
origin as the active document and
that are contiguous with the current entry.Document
object the
active document of the browsing
context.Document
objects with the same origin
as the new active document, and that are
contiguous with the specified entry, must be cleared.If the specified entry's
Document
has any input
elements whose
resulting autocompletion state is off, invoke the reset algorithm of each
of those elements.
If the current document readiness of the
specified entry's Document
is "complete",
queue a task to fire a pageshow
event at the
Window
object of that Document
, but
with its target
set to the
Document
object (and the currentTarget
set to the
Window
object), using the
PageTransitionEvent
interface, with the persisted
attribute set to true. This event must not bubble, must not be
cancelable, and has no default action.
Set the document's current address to the URL of the specified entry.
If the specified entry has a URL whose fragment
identifier differs from that of the current entry's
when compared in a case-sensitive manner, and the two
share the same Document
object, then let hash changed be true, and let old
URL be the URL of the current entry and new URL be the URL of the specified entry.
Otherwise, let hash changed be false.
If the traversal was initiated with replacement enabled, remove the entry immediately before the specified entry in the session history.
If the specified entry is not an entry with persisted user state, but its URL has a fragment identifier, scroll to the fragment identifier.
If the entry is an entry with persisted user state, the user agent may update aspects of the document and its rendering, for instance the scroll position or values of form fields, that it had previously recorded.
This can even include updating the dir
attribute of textarea
elements or input
elements whose type
attribute is in either the
Text state or the Search state, if the
persisted state includes the directionality of user input in such
controls.
If the entry is a state object entry, let state be a structured clone of that state object. Otherwise, let state be null.
Set history.state
to state.
Fire a popstate
event at
the Window
object of the Document
, using
the PopStateEvent
interface, with the state
attribute set to the
value of state. This event must bubble but not
be cancelable and has no default action.
If hash changed is true, then fire a
hashchange
event at the
browsing context's Window
object, using
the HashChangeEvent
interface, with the oldURL
attribute set to
old URL and the newURL
attribute set to
new URL. This event must bubble but not be
cancelable and has no default action.
The current entry is now the specified entry.
The task source for the tasks mentioned above is the DOM manipulation task source.
The popstate
event
is fired in certain cases when navigating to a session history
entry.
interface PopStateEvent : Event { readonly attribute any state; void initPopStateEvent(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in any stateArg); };
state
Returns a copy of the information that was provided to pushState()
or replaceState()
.
The initPopStateEvent()
method must initialize the event in a manner analogous to the
similarly-named method in the DOM Events interfaces. [DOMEVENTS]
The state
attribute represents the context information for the event, or null,
if the state represented is the initial state of the
Document
.
The hashchange
event is fired when navigating to a session history
entry whose URL differs from that of the
previous one only in the fragment identifier.
interface HashChangeEvent : Event { readonly attribute DOMString oldURL; readonly attribute DOMString newURL; void initHashChangeEvent(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in DOMString oldURLArg, in DOMString newURLArg); };
oldURL
Returns the URL of the session history entry that was previously current.
newURL
Returns the URL of the session history entry that is now current.
The initHashChangeEvent()
method must initialize the event in a manner analogous to the
similarly-named method in the DOM Events interfaces. [DOMEVENTS]
The oldURL
attribute represents context information for the event, specifically
the URL of the session history entry that was traversed
from.
The newURL
attribute represents context information for the event, specifically
the URL of the session history entry that was traversed
to.
The pageshow
event
is fired when traversing to a session history
entry.
The pagehide
event is fired when traversing from a session history
entry.
interface PageTransitionEvent : Event { readonly attribute boolean persisted; void initPageTransitionEvent(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in boolean persistedArg); };
persisted
Returns false if the page is newly being loaded (and the load
event will fire). Otherwise, returns true.
The initPageTransitionEvent()
method must initialize the event in a manner analogous to the
similarly-named method in the DOM Events interfaces. [DOMEVENTS]
The persisted
attribute represents the context information for the event.
A Document
has a salvageable state, which
is initially true.
When a user agent is to prompt to unload a document, it must run the following steps.
Let event be a new
BeforeUnloadEvent
event object with the name beforeunload
, which does not
bubble but is cancelable.
Release the storage mutex.
If any event listeners were triggered by the earlier
dispatch step, then set the Document
's salvageable state to
false.
If the returnValue
attribute of the event object is not the empty
string, or if the event was canceled, then the user agent should
ask the user to confirm that they wish to unload the document.
The prompt shown by the user agent may include the string of
the returnValue
attribute, or some leading subset thereof. (A user agent may want
to truncate the string to 1024 characters for display, for
instance.)
The user agent must pause while waiting for the user's response.
If the user did not confirm the page navigation, then the user agent refused to allow the document to be unloaded.
If this algorithm was invoked by another instance of the "prompt to unload a document" algorithm (i.e. through the steps below that invoke this algorithm for all descendant browsing contexts), then abort these steps here.
Let descendants be the list of the
descendant browsing contexts of the
Document
.
If descendants is not an empty list, then for each browsing context b in descendants run the following substeps:
Prompt to unload the active document of the browsing context b. If the user refused to allow the document to be unloaded, then the user implicitly also refused to allow this document to be unloaded; abort these steps.
If salvageable state of the active document of the browsing context b is false, then set the salvageable state of this document to false also.
When a user agent is to unload a document, it must run
the following steps. These steps are passed an argument, recycle, which is either true or false, indicating
whether the Document
object is going to be
re-used. (This is set by the document.open()
method.)
Fire a pagehide
event at
the Window
object of the Document
, but
with its target
set to the
Document
object (and the currentTarget
set to the
Window
object), using the
PageTransitionEvent
interface, with the persisted
attribute set to true. This event must not bubble, must not be
cancelable, and has no default action.
Unload event: Fire a simple event named
unload
at the
Document
's Window
object.
Release the storage mutex.
If any event listeners were triggered by the earlier
unload event step, then set the Document
object's salvageable state to
false.
Run any unloading document cleanup steps for
Document
that are defined by this specification and
other applicable specifications.
If this algorithm was invoked by another instance of the "unload a document" algorithm (i.e. through the steps below that invoke this algorithm for all descendant browsing contexts), then abort these steps here.
Let descendants be the list of the
descendant browsing contexts of the
Document
.
If descendants is not an empty list, then for each browsing context b in descendants run the following substeps:
Unload the active document of the browsing context b with the recycle parameter set to false.
If salvageable state of the active document of the browsing context b is false, then set the salvageable state of this document to false also.
If salvageable and recycle are both false, then the
Document
's browsing context must discard the
Document
.
This specification defines the following unloading document cleanup steps. Other specifications can define more.
Close the WebSocket connection of any
WebSocket
objects that were created by the WebSocket()
constructor visible on the
Document
's Window
object. If this
affected any WebSocket
objects, the set
Document
's salvageable state to
false.
[WEBSOCKET]
If the Document
's salvageable state is
false, empty the Document
's Window
's
list of active timeouts and its list of active
intervals.
interface BeforeUnloadEvent : Event { attribute DOMString returnValue; };
returnValue
[ = value ]Returns the current return value of the event (the message to show the user).
Can be set, to update the message.
There are no BeforeUnloadEvent
-specific
initialization methods.
The returnValue
attribute represents the message to show the user. When the event is
created, the attribute must be set to the empty string. On getting,
it must return the last value it was set to. On setting, the
attribute must be set to the new value.
If a Document
is aborted, the user agent must run the following
steps:
Abort the active documents of every child browsing context.
Cancel any instances of the fetch
algorithm in the context of this Document
, discarding
any tasks queued for them, and discarding any further data
received from the network for them.
If the Document
has an active
parser, then abort that
parser.
User agents may allow users to explicitly invoke the abort a document algorithm for a
Document
. If the user does so, then, if that
Document
is an active document, the user
agent should queue a task to fire a simple
event named abort
at that
Document
's Window
object before invoking
the abort algorithm.
This section is non-normative.
In order to enable users to continue interacting with Web applications and documents even when their network connection is unavailable — for instance, because they are traveling outside of their ISP's coverage area — authors can provide a manifest which lists the files that are needed for the Web application to work offline and which causes the user's browser to keep a copy of the files for use offline.
To illustrate this, consider a simple clock applet consisting of
an HTML page "clock.html
", a CSS style sheet
"clock.css
", and a JavaScript script "clock.js
".
Before adding the manifest, these three files might look like this:
<!-- clock.html --> <!DOCTYPE HTML> <html> <head> <title>Clock</title> <script src="clock.js"></script> <link rel="stylesheet" href="clock.css"> </head> <body> <p>The time is: <output id="clock"></output></p> </body> </html>
/* clock.css */ output { font: 2em sans-serif; }
/* clock.js */ setTimeout(function () { document.getElementById('clock').value = new Date(); }, 1000);
If the user tries to open the "clock.html
"
page while offline, though, the user agent (unless it happens to
have it still in the local cache) will fail with an error.
The author can instead provide a manifest of the three files:
CACHE MANIFEST clock.html clock.css clock.js
With a small change to the HTML file, the manifest (served as
text/cache-manifest
) is linked to the application:
<!-- clock.html --> <!DOCTYPE HTML> <html manifest="clock.appcache"> <head> <title>Clock</title> <script src="clock.js"></script> <link rel="stylesheet" href="clock.css"> </head> <body> <p>The time is: <output id="clock"></output></p> </body> </html>
Now, if the user goes to the page, the browser will cache the files and make them available even when the user is offline.
Authors are encouraged to include the main page in the manifest also, but in practice the page that referenced the manifest is automatically cached even if it isn't explicitly mentioned.
HTTP cache headers and restrictions on caching pages
served over TLS (encrypted, using https:
) are
overridden by manifests. Thus, pages will not expire from an
application cache before the user agent has updated it, and even
applications served over TLS can be made to work offline.
This section is non-normative.
When the user visits a page that declares a manifest, the browser will try to update the cache. It does this by fetching a copy of the manifest and, if the manifest has changed since the user agent last saw it, redownloading all the resources it mentions and caching them anew.
As this is going on, a number of events get fired on the
ApplicationCache
object to keep the script updated as
to the state of the cache update, so that the user can be notified
appropriately. The events are as follows:
Event name | Interface | Dispatched when... | Next events |
---|---|---|---|
checking
| Event
| The user agent is checking for an update, or attempting to download the manifest for the first time. This is always the first event in the sequence. | noupdate , downloading , obsolete , error
|
noupdate
| Event
| The manifest hadn't changed. | Last event in sequence. |
downloading
| Event
| The user agent has found an update and is fetching it, or is downloading the resources listed by the manifest for the first time. | progress , error , cached , updateready
|
progress
| ProgressEvent
| The user agent is downloading resources listed by the manifest. | progress , error , cached , updateready
|
cached
| Event
| The resources listed in the manifest have been downloaded, and the application is now cached. | Last event in sequence. |
updateready
| Event
| The resources listed in the manifest have been newly redownloaded, and the script can use swapCache() to switch to the new cache.
| Last event in sequence. |
obsolete
| Event
| The manifest was found to have become a 404 or 410 page, so the application cache is being deleted. | Last event in sequence. |
error
| Event
| The manifest was a 404 or 410 page, so the attempt to cache the application has been aborted. | Last event in sequence. |
The manifest hadn't changed, but the page referencing the manifest failed to download properly. | |||
A fatal error occurred while fetching the resources listed in the manifest. | |||
The manifest changed while the update was being run. | The user agent will try fetching the files again momentarily. |
An application cache is a set of cached resources consisting of:
One or more resources (including their out-of-band metadata, such as HTTP headers, if any), identified by URLs, each falling into one (or more) of the following categories:
These are documents that were added to the
cache because a browsing context was navigated to that document and the
document indicated that this was its cache, using the manifest
attribute.
This is the resource corresponding to the URL
that was given in a master entry's html
element's
manifest
attribute. The
manifest is fetched and processed during the application
cache download process. All the master entries have the
same origin as the manifest.
These are the resources that were listed in the cache's manifest in an explicit section.
These are the resources that were listed in the cache's manifest in a fallback section.
Explicit entries
and Fallback
entries can be marked as foreign, which means that
they have a manifest
attribute but that it doesn't point at this cache's manifest.
A URL in the list can be flagged with multiple different types, and thus an entry can end up being categorized as multiple entries. For example, an entry can be a manifest entry and an explicit entry at the same time, if the manifest is listed within the manifest.
Zero or more fallback namespaces, each of which is mapped to a fallback entry.
These are URLs used as prefix match patterns for resources that are to be fetched from the network if possible, or to be replaced by the corresponding fallback entry if not. Each namespace URL has the same origin as the manifest.
Zero or more URLs that form the online whitelist namespaces.
These are used as prefix match patterns, and declare URLs that the user agent will never load from the cache but will instead always attempt to obtain from the network.
An online whitelist wildcard flag, which is either open or blocking.
The open state indicates that any URL not listed as cached is to be implicitly treated as being in the online whitelist namespaces; the blocking state indicates that URLs not listed explicitly in the manifest are to be treated as unavailable.
Each application cache has a completeness flag, which is either complete or incomplete.
An application cache group is a group of application caches, identified by the absolute URL of a resource manifest which is used to populate the caches in the group.
An application cache is newer than another if it was created after the other (in other words, application caches in an application cache group have a chronological order).
Only the newest application cache in an application cache group can have its completeness flag set to incomplete; the others are always all complete.
Each application cache group has an update status, which is one of the following: idle, checking, downloading.
A relevant application cache is an application cache that is the newest in its group to be complete.
Each application cache group has a list of pending master
entries. Each entry in this list consists of a resource and a
corresponding Document
object. It is used during the
application cache download process to ensure that new
master entries are cached even if the application cache
download process was already running for their
application cache group when they were loaded.
An application cache group can be marked as obsolete, meaning that it must be ignored when looking at what application cache groups exist.
A cache host is a Document
or a
SharedWorkerGlobalScope
object. A cache
host can be associated with an application
cache.
[WEBWORKERS]
A Document
initially is not associated with an
application cache, but can become associated with one
early during the page load process, when steps in the parser and in the navigation sections cause cache selection to occur.
A SharedWorkerGlobalScope
can be associated with an
application cache when it is created.
[WEBWORKERS]
Each cache host has an associated
ApplicationCache
object.
Multiple application caches in different application cache groups can contain the same resource, e.g. if the manifests all reference that resource. If the user agent is to select an application cache from a list of relevant application caches that contain a resource, the user agent must use the application cache that the user most likely wants to see the resource from, taking into account the following:
A URL matches a fallback namespace if there exists a relevant application cache whose manifest's URL has the same origin as the URL in question, and that has a fallback namespace that is a prefix match for the URL being examined. If multiple fallback namespaces match the same URL, the longest one is the one that matches. A URL looking for a fallback namespace can match more than one application cache at a time, but only matches one namespace in each cache.
If a manifest http://example.com/app1/manifest
declares that
http://example.com/resources/images
is a
fallback namespace, and the user navigates to HTTP://EXAMPLE.COM:80/resources/images/cat.png
,
then the user agent will decide that the application cache
identified by http://example.com/app1/manifest
contains a
namespace with a match for that URL.
This section is non-normative.
This example manifest requires two images and a style sheet to be cached and whitelists a CGI script.
CACHE MANIFEST # the above line is required # this is a comment # there can be as many of these anywhere in the file # they are all ignored # comments can have spaces before them # but must be alone on the line # blank lines are ignored too # these are files that need to be cached they can either be listed # first, or a "CACHE:" header could be put before them, as is done # lower down. images/sound-icon.png images/background.png # note that each file has to be put on its own line # here is a file for the online whitelist -- it isn't cached, and # references to this file will bypass the cache, always hitting the # network (or trying to, if the user is offline). NETWORK: comm.cgi # here is another set of files to cache, this time just the CSS file. CACHE: style/default.css
It could equally well be written as follows:
CACHE MANIFEST NETWORK: comm.cgi CACHE: style/default.css images/sound-icon.png images/background.png
Offline application cache manifests can use absolute paths or even absolute URLs:
CACHE MANIFEST /main/home /main/app.js /settings/home /settings/app.js http://img.example.com/logo.png http://img.example.com/check.png http://img.example.com/cross.png
The following manifest defines a catch-all error page that is displayed for any page on the site while the user is offline. It also specifies that the online whitelist wildcard flag is open, meaning that accesses to resources on other sites will not be blocked. (Resources on the same site are already not blocked because of the catch-all fallback namespace.)
So long as all pages on the site reference this manifest, they will get cached locally as they are fetched, so that subsequent hits to the same page will load the page immediately from the cache. Until the manifest is changed, those pages will not be fetched from the server again. When the manifest changes, then all the files will be redownloaded.
Subresources, such as style sheets, images, etc, would only be cached using the regular HTTP caching semantics, however.
CACHE MANIFEST FALLBACK: / /offline.html NETWORK: *
Manifests must be served using the
text/cache-manifest
MIME type. All
resources served using the text/cache-manifest
MIME type must follow the syntax of application cache
manifests, as described in this section.
An application cache manifest is a text file, whose text is encoded using UTF-8. Data in application cache manifests is line-based. Newlines must be represented by U+000A LINE FEED (LF) characters, U+000D CARRIAGE RETURN (CR) characters, or U+000D CARRIAGE RETURN (CR) U+000A LINE FEED (LF) pairs. [RFC3629]
This is a willful violation of RFC
2046, which requires all text/*
types to only
allow CRLF line breaks. This requirement, however, is outdated; the
use of CR, LF, and CRLF line breaks is commonly supported and indeed
sometimes CRLF is not supported by text editors. [RFC2046]
The first line of an application cache manifest must consist of the string "CACHE", a single U+0020 SPACE character, the string "MANIFEST", and either a U+0020 SPACE character, a U+0009 CHARACTER TABULATION (tab) character, a U+000A LINE FEED (LF) character, or a U+000D CARRIAGE RETURN (CR) character. The first line may optionally be preceded by a U+FEFF BYTE ORDER MARK (BOM) character. If any other text is found on the first line, it is ignored.
Subsequent lines, if any, must all be one of the following:
Blank lines must consist of zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION (tab) characters only.
Comment lines must consist of zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION (tab) characters, followed by a single U+0023 NUMBER SIGN character (#), followed by zero or more characters other than U+000A LINE FEED (LF) and U+000D CARRIAGE RETURN (CR) characters.
Comments must be on a line on their own. If they were to be included on a line with a URL, the "#" would be mistaken for part of a fragment identifier.
Section headers change the current section. There are three possible section headers:
CACHE:
FALLBACK:
NETWORK:
Section header lines must consist of zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION (tab) characters, followed by one of the names above (including the U+003A COLON character (:)) followed by zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION (tab) characters.
Ironically, by default, the current section is the explicit section.
The format that data lines must take depends on the current section.
When the current section is the explicit section, data lines must consist of zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION (tab) characters, a valid URL identifying a resource other than the manifest itself, and then zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION (tab) characters.
When the current section is the fallback section, data lines must consist of zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION (tab) characters, a valid URL identifying a resource other than the manifest itself, one or more U+0020 SPACE and U+0009 CHARACTER TABULATION (tab) characters, another valid URL identifying a resource other than the manifest itself, and then zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION (tab) characters.
When the current section is the online whitelist section, data lines must consist of zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION (tab) characters, either a single U+002A ASTERISK character (*) or a valid URL identifying a resource other than the manifest itself, and then zero or more U+0020 SPACE and U+0009 CHARACTER TABULATION (tab) characters.
Manifests may contain sections more than once. Sections may be empty.
If the manifest's <scheme>
is https:
or another scheme intended for
encrypted data transfer, then all URLs in explicit sections
must have the same origin as the manifest itself.
URLs that are to be fallback pages associated with fallback namespaces, and those namespaces themselves, must be given in fallback sections, with the namespace being the first URL of the data line, and the corresponding fallback page being the second URL. All the other pages to be cached must be listed in explicit sections.
Fallback namespaces and fallback entries must have the same origin as the manifest itself.
A fallback namespace must not be listed more than once.
Namespaces that the user agent is to put into the online whitelist must all be specified in online whitelist sections. (This is needed for any URL that the page is intending to use to communicate back to the server.) To specify that all URLs are automatically whitelisted in this way, a U+002A ASTERISK character (*) may be specified as one of the URLs.
Authors should not include namespaces in the online whitelist for which another namespace in the online whitelist is a prefix match.
Relative URLs must be given relative to the manifest's own URL. All URLs in the manifest must have the same <scheme> as the manifest itself (either explicitly or implicitly, through the use of relative URLs).
URLs in manifests must not have fragment identifiers (i.e. the U+0023 NUMBER SIGN character isn't allowed in URLs in manifests).
Fallback namespaces and namespaces in the online whitelist are matched by prefix match.
When a user agent is to parse a manifest, it means that the user agent must run the following steps:
The user agent must decode the byte stream corresponding with the manifest to be parsed as UTF-8, with error handling.
Let base URL be the absolute URL representing the manifest.
Let explicit URLs be an initially empty list of absolute URLs for explicit entries.
Let fallback URLs be an initially empty mapping of fallback namespaces to absolute URLs for fallback entries.
Let online whitelist namespaces be an initially empty list of absolute URLs for an online whitelist.
Let online whitelist wildcard flag be blocking.
Let input be the decoded text of the manifest's byte stream.
Let position be a pointer into input, initially pointing at the first character.
If position is pointing at a U+FEFF BYTE ORDER MARK (BOM) character, then advance position to the next character.
If the characters starting from position are "CACHE", followed by a U+0020 SPACE character, followed by "MANIFEST", then advance position to the next character after those. Otherwise, this isn't a cache manifest; abort this algorithm with a failure while checking for the magic signature.
If the character at position is neither a U+0020 SPACE character, a U+0009 CHARACTER TABULATION (tab) character, U+000A LINE FEED (LF) character, nor a U+000D CARRIAGE RETURN (CR) character, then this isn't a cache manifest; abort this algorithm with a failure while checking for the magic signature.
This is a cache manifest. The algorithm cannot fail beyond this point (though bogus lines can get ignored).
Collect a sequence of characters that are not U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters, and ignore those characters. (Extra text on the first line, after the signature, is ignored.)
Let mode be "explicit".
Start of line: If position is past the end of input, then jump to the last step. Otherwise, collect a sequence of characters that are U+000A LINE FEED (LF), U+000D CARRIAGE RETURN (CR), U+0020 SPACE, or U+0009 CHARACTER TABULATION (tab) characters.
Now, collect a sequence of characters that are not U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters, and let the result be line.
Drop any trailing U+0020 SPACE and U+0009 CHARACTER TABULATION (tab) characters at the end of line.
If line is the empty string, then jump back to the step labeled "start of line".
If the first character in line is a U+0023 NUMBER SIGN character (#), then jump back to the step labeled "start of line".
If line equals "CACHE:" (the word "CACHE" followed by a U+003A COLON character (:)), then set mode to "explicit" and jump back to the step labeled "start of line".
If line equals "FALLBACK:" (the word "FALLBACK" followed by a U+003A COLON character (:)), then set mode to "fallback" and jump back to the step labeled "start of line".
If line equals "NETWORK:" (the word "NETWORK" followed by a U+003A COLON character (:)), then set mode to "online whitelist" and jump back to the step labeled "start of line".
If line ends with a U+003A COLON character (:), then set mode to "unknown" and jump back to the step labeled "start of line".
This is either a data line or it is syntactically incorrect.
Let position be a pointer into line, initially pointing at the start of the string.
Let tokens be a list of strings, initially empty.
While position doesn't point past the end of line:
Let current token be an empty string.
While position doesn't point past the end of line and the character at position is neither a U+0020 SPACE nor a U+0009 CHARACTER TABULATION (tab) character, add the character at position to current token and advance position to the next character in input.
Add current token to the tokens list.
While position doesn't point past the end of line and the character at position is either a U+0020 SPACE or a U+0009 CHARACTER TABULATION (tab) character, advance position to the next character in input.
Process tokens as follows:
Resolve the first item in tokens, relative to base URL; ignore the rest.
If this fails, then jump back to the step labeled "start of line".
If the resulting absolute URL has a different
<scheme> component than
the manifest's URL (compared in an ASCII
case-insensitive manner), then jump back to the step
labeled "start of line". If the manifest's <scheme> is https:
or another scheme intended for encrypted
data transfer, and the resulting absolute URL does
not have the same origin as the manifest's URL,
then jump back to the step labeled "start of line".
Drop the <fragment> component of the resulting absolute URL, if it has one.
Add the resulting absolute URL to the explicit URLs.
Let part one be the first token in tokens, and let part two be the second token in tokens.
Resolve part one and part two, relative to base URL.
If either fails, then jump back to the step labeled "start of line".
If the absolute URL corresponding to either part one or part two does not have the same origin as the manifest's URL, then jump back to the step labeled "start of line".
Drop any <fragment> components of the resulting absolute URLs.
If the absolute URL corresponding to part one is already in the fallback URLs mapping as a fallback namespace, then jump back to the step labeled "start of line".
Otherwise, add the absolute URL corresponding to part one to the fallback URLs mapping as a fallback namespace, mapped to the absolute URL corresponding to part two as the fallback entry.
If the first item in tokens is a U+002A ASTERISK character (*), then set online whitelist wildcard flag to open and jump back to the step labeled "start of line".
Otherwise, resolve the first item in tokens, relative to base URL; ignore the rest.
If this fails, then jump back to the step labeled "start of line".
If the resulting absolute URL has a different <scheme> component than the manifest's URL (compared in an ASCII case-insensitive manner), then jump back to the step labeled "start of line".
Drop the <fragment> component of the resulting absolute URL, if it has one.
Add the resulting absolute URL to the online whitelist namespaces.
Do nothing. The line is ignored.
Jump back to the step labeled "start of line". (That step jumps to the next, and last, step when the end of the file is reached.)
Return the explicit URLs list, the fallback URLs mapping, the online whitelist namespaces, and the online whitelist wildcard flag.
The resource that declares the manifest (with the manifest
attribute) will always
get taken from the cache, whether it is listed in the cache or not,
even if it is listed in an online whitelist
namespace.
If a resource is listed in the explicit section or as a fallback entry in the fallback section, the resource will always be taken from the cache, regardless of any other matching entries in the fallback namespaces or online whitelist namespaces.
When a fallback namespace and an online whitelist namespace overlap, the online whitelist namespace has priority.
The online whitelist wildcard flag is applied last, only for URLs that match neither the online whitelist namespace nor the fallback namespace and that are not listed in the explicit section.
When the user agent is required (by other parts of this specification) to start the application cache download process for an absolute URL purported to identify a manifest, or for an application cache group, potentially given a particular cache host, and potentially given a master resource, the user agent must run the steps below. These steps are always run asynchronously, in parallel with the event loop tasks.
Some of these steps have requirements that only apply if the user agent shows caching progress. Support for this is optional. Caching progress UI could consist of a progress bar or message panel in the user agent's interface, or an overlay, or something else. Certain events fired during the application cache download process allow the script to override the display of such an interface. The goal of this is to allow Web applications to provide more seamless update mechanisms, hiding from the user the mechanics of the application cache mechanism. User agents may display user interfaces independent of this, but are encouraged to not show prominent update progress notifications for applications that cancel the relevant events.
These events are delayed until after the load
event has fired.
The application cache download process steps are as follows:
Optionally, wait until the permission to start the application cache download process has been obtained from the user and until the user agent is confident that the network is available. This could include doing nothing until the user explicitly opts-in to caching the site, or could involve prompting the user for permission. The algorithm might never get past this point. (This step is particularly intended to be used by user agents running on severely space-constrained devices or in highly privacy-sensitive environments).
Atomically, so as to avoid race conditions, perform the following substeps:
Pick the appropriate substeps:
Let manifest URL be that absolute URL.
If there is no application cache group identified by manifest URL, then create a new application cache group identified by manifest URL. Initially, it has no application caches. One will be created later in this algorithm.
Let manifest URL be the absolute URL of the manifest used to identify the application cache group to be updated.
If that application cache group is obsolete, then abort this instance of the application cache download process. This can happen if another instance of this algorithm found the manifest to be 404 or 410 while this algorithm was waiting in the first step above.
Let cache group be the application cache group identified by manifest URL.
If these steps were invoked with a master resource, then add
the resource, along with the resource's Document
, to
cache group's list of pending master
entries.
If these steps were invoked with a cache
host, and the status of cache group is checking or
downloading, then queue a post-load task to
fire a simple event named checking
that is
cancelable at the ApplicationCache
singleton of that
cache host. The default action of this event must
be, if the user agent shows caching progress, the
display of some sort of user interface indicating to the user
that the user agent is checking to see if it can download the
application.
If these steps were invoked with a cache
host, and the status of cache group is downloading, then also
queue a post-load task to fire a simple
event named downloading
that is
cancelable at the ApplicationCache
singleton of that
cache host. The default action of this event must
be, if the user agent shows caching progress, the
display of some sort of user interface indicating to the user the
application is being downloaded.
If the status of the cache group is either checking or downloading, then abort this instance of the application cache download process, as an update is already in progress.
Set the status of cache group to checking.
For each cache host associated with an
application cache in cache
group, queue a post-load task to fire a
simple event that is cancelable named checking
at the
ApplicationCache
singleton of the cache
host. The default action of these events must be, if the
user agent shows caching progress, the display of
some sort of user interface indicating to the user that the user
agent is checking for the availability of updates.
The remainder of the steps run asynchronously.
If cache group already has an application cache in it, then this is an upgrade attempt. Otherwise, this is a cache attempt.
If this is a cache
attempt, then this algorithm was invoked with a cache
host; queue a post-load task to fire a
simple event named checking
that is cancelable
at the ApplicationCache
singleton of that cache
host. The default action of this event must be, if the user
agent shows caching progress, the display of some sort
of user interface indicating to the user that the user agent is
checking for the availability of updates.
Fetching the manifest: Fetch the resource from manifest URL with the synchronous flag set, and let manifest be that resource.
If the resource is labeled with the MIME type
text/cache-manifest
, parse manifest according to the rules for parsing manifests, obtaining a list of
explicit entries,
fallback entries
and the fallback
namespaces that map to them, entries for the online whitelist,
and a value for the online whitelist
wildcard flag.
If fetching the manifest fails due to a 404 or 410 response or equivalent, then run these substeps:
Mark cache group as obsolete. This cache group no longer exists for any purpose other
than the processing of Document
objects already
associated with an application cache in the cache group.
Let task list be an empty list of tasks.
For each cache host associated with an
application cache in cache
group, create a task to
fire a simple event named obsolete
that is
cancelable at the ApplicationCache
singleton of the
cache host, and append it to task
list. The default action of these events must be, if the
user agent shows caching progress, the display of
some sort of user interface indicating to the user that the
application is no longer available for offline use.
For each entry in cache group's list of pending master
entries, create a task
to fire a simple event that is cancelable named
error
(not obsolete
!) at the
ApplicationCache
singleton of the cache
host the Document
for this entry, if there
still is one, and append it to task list. The
default action of this event must be, if the user agent
shows caching progress, the display of some sort of
user interface indicating to the user that the user agent failed
to save the application for offline use.
If cache group has an application cache whose completeness flag is incomplete, then discard that application cache.
If appropriate, remove any user interface indicating that an update for this cache is in progress.
Let the status of cache group be idle.
For each task in task list, queue that task as a post-load task.
Abort the application cache download process.
Otherwise, if fetching the manifest fails in some other
way (e.g. the server returns another 4xx or 5xx response or equivalent, or
there is a DNS error, or the connection times out, or the user
cancels the download, or the parser for manifests fails when
checking the magic signature), or if the server returned a
redirect, or if the resource is labeled with a MIME
type other than text/cache-manifest
, then run
the cache failure steps.
If this is an upgrade attempt and the newly downloaded manifest is byte-for-byte identical to the manifest found in the newest application cache in cache group, or the server reported it as "304 Not Modified" or equivalent, then run these substeps:
Let cache be the newest application cache in cache group.
Let task list be an empty list of tasks.
For each entry in cache group's list of pending master entries, wait for the resource for this entry to have either completely downloaded or failed.
If the download failed (e.g. the connection times out, or the
user cancels the download), then create a task to fire a simple
event that is cancelable named error
at the
ApplicationCache
singleton of the cache
host the Document
for this entry, if there
still is one, and append it to task list. The
default action of this event must be, if the user agent
shows caching progress, the display of some sort of
user interface indicating to the user that the user agent failed
to save the application for offline use.
Otherwise, associate the Document
for this entry
with cache; store the resource for this
entry in cache, if it isn't already there,
and categorize its entry as a master entry. If the
resource's URL has a <fragment> component, it must
be removed from the entry in cache
(application caches never include fragment identifiers).
HTTP caching rules, such as Cache-Control: no-store
, are ignored for the
purposes of the application cache download
process.
For each cache host associated with an
application cache in cache
group, create a task to
fire a simple event that is cancelable named noupdate
at the
ApplicationCache
singleton of the cache
host, and append it to task list. The
default action of these events must be, if the user agent
shows caching progress, the display of some sort of
user interface indicating to the user that the application is up
to date.
Empty cache group's list of pending master entries.
If appropriate, remove any user interface indicating that an update for this cache is in progress.
Let the status of cache group be idle.
For each task in task list, queue that task as a post-load task.
Abort the application cache download process.
Let new cache be a newly created application cache in cache group. Set its completeness flag to incomplete.
For each entry in cache group's list of pending master
entries, associate the Document
for this entry
with new cache.
Set the status of cache group to downloading.
For each cache host associated with an
application cache in cache group,
queue a post-load task to fire a simple
event that is cancelable named downloading
at the
ApplicationCache
singleton of the cache
host. The default action of these events must be, if the
user agent shows caching progress, the display of some
sort of user interface indicating to the user that a new version is
being downloaded.
Let file list be an empty list of URLs with flags.
Add all the URLs in the list of explicit entries obtained by parsing manifest to file list, each flagged with "explicit entry".
Add all the URLs in the list of fallback entries obtained by parsing manifest to file list, each flagged with "fallback entry".
If this is an upgrade attempt, then add all the URLs of master entries in the newest application cache in cache group whose completeness flag is complete to file list, each flagged with "master entry".
If any URL is in file list more than once, then merge the entries into one entry for that URL, that entry having all the flags that the original entries had.
For each URL in file list, run the following steps. These steps may be run in parallel for two or more of the URLs at a time.
If the resource URL being processed was flagged as neither an "explicit entry" nor or a "fallback entry", then the user agent may skip this URL.
This is intended to allow user agents to expire resources not listed in the manifest from the cache. Generally, implementors are urged to use an approach that expires lesser-used resources first.
For each cache host associated with an
application cache in cache
group, queue a post-load task to fire an event
with the name progress
, which does not
bubble, which is cancelable, and which uses the
ProgressEvent
interface, at the
ApplicationCache
singleton of the cache
host. The lengthComputable
attribute must be set to true, the total
attribute must be
set to the number of files in file list, and
the loaded
attribute must be set to the number of number of files in file list that have been either downloaded or
skipped so far. The default action of these events must be, if
the user agent shows caching progress, the display
of some sort of user interface indicating to the user that a file
is being downloaded in preparation for updating the
application. [PROGRESS]
Fetch the resource, from the origin of the URL manifest URL, with the synchronous flag set and the manual redirect flag set. If this is an upgrade attempt, then use the newest application cache in cache group as an HTTP cache, and honor HTTP caching semantics (such as expiration, ETags, and so forth) with respect to that cache. User agents may also have other caches in place that are also honored.
If the resource in question is already being downloaded for other reasons then the existing download process can sometimes be used for the purposes of this step, as defined by the fetching algorithm.
An example of a resource that might already
be being downloaded is a large image on a Web page that is being
seen for the first time. The image would get downloaded to
satisfy the img
element on the page, as well as
being listed in the cache manifest. According to the rules for
fetching that image only need be
downloaded once, and it can be used both for the cache and for
the rendered Web page.
If the previous step fails (e.g. the server returns a 4xx or 5xx response or equivalent, or there is a DNS error, or the connection times out, or the user cancels the download), or if the server returned a redirect, then run the first appropriate step from the following list:
Run the cache failure steps.
Redirects are fatal because they are either indicative of a network problem (e.g. a captive portal); or would allow resources to be added to the cache under URLs that differ from any URL that the networking model will allow access to, leaving orphan entries; or would allow resources to be stored under URLs different than their true URLs. All of these situations are bad.
Skip this resource. It is dropped from the cache.
Copy the resource and its metadata from the newest application cache in cache group whose completeness flag is complete, and act as if that was the fetched resource, ignoring the resource obtained from the network.
User agents may warn the user of these errors as an aid to development.
These rules make errors for resources listed in the manifest fatal, while making it possible for other resources to be removed from caches when they are removed from the server, without errors, and making non-manifest resources survive server-side errors.
Otherwise, the fetching succeeded. Store the resource in the new cache.
If the user agent is not able to store the resource (e.g. because of quota restrictions), the user agent may prompt the user or try to resolve the problem in some other manner (e.g. automatically pruning content in other caches). If the problem cannot be resolved, the user agent must run the cache failure steps.
If the URL being processed was flagged as an "explicit entry" in file list, then categorize the entry as an explicit entry.
If the URL being processed was flagged as a "fallback entry" in file list, then categorize the entry as a fallback entry.
If the URL being processed was flagged as an "master entry" in file list, then categorize the entry as a master entry.
As an optimization, if the resource is an HTML or XML file
whose root element is an html
element with a manifest
attribute whose value
doesn't match the manifest URL of the application cache being
processed, then the user agent should mark the entry as being
foreign.
For each cache host associated with an
application cache in cache group,
queue a post-load task to fire an event with the name
progress
, which does
not bubble, which is cancelable, and which uses the
ProgressEvent
interface, at the
ApplicationCache
singleton of the cache
host. The lengthComputable
attribute must be set to true, the total
and the loaded
attributes must be
set to the number of number of files in file
list. The default action of these events must be, if the user
agent shows caching progress, the display of some sort
of user interface indicating to the user that all the files have
been downloaded. [PROGRESS]
Store the list of fallback namespaces, and the URLs of the fallback entries that they map to, in new cache.
Store the URLs that form the new online whitelist in new cache.
Store the value of the new online whitelist wildcard flag in new cache.
For each entry in cache group's list of pending master entries, wait for the resource for this entry to have either completely downloaded or failed.
If the download failed (e.g. the connection times out, or the user cancels the download), then run these substeps:
Unassociate the Document
for this entry from
new cache.
Queue a post-load task to fire a simple
event that is cancelable named error
at the
ApplicationCache
singleton of the
Document
for this entry, if there still is one. The
default action of this event must be, if the user agent
shows caching progress, the display of some sort of
user interface indicating to the user that the user agent failed
to save the application for offline use.
If this is a cache attempt and this entry is the last entry in cache group's list of pending master entries, then run these further substeps:
Discard cache group and its only application cache, new cache.
If appropriate, remove any user interface indicating that an update for this cache is in progress.
Abort the application cache download process.
Otherwise, remove this entry from cache group's list of pending master entries.
Otherwise, store the resource for this entry in new cache, if it isn't already there, and categorize its entry as a master entry.
Fetch the resource from manifest URL again, with the synchronous flag set, and let second manifest be that resource.
If the previous step failed for any reason, or if the fetching attempt involved a redirect, or if second manifest and manifest are not byte-for-byte identical, then schedule a rerun of the entire algorithm with the same parameters after a short delay, and run the cache failure steps.
Otherwise, store manifest in new cache, if it's not there already, and categorize its entry as the manifest.
Set the completeness flag of new cache to complete.
Let task list be an empty list of tasks.
If this is a cache
attempt, then for each cache host associated
with an application cache in cache
group, create a task to
fire a simple event that is cancelable named cached
at the
ApplicationCache
singleton of the cache
host, and append it to task list. The
default action of these events must be, if the user agent
shows caching progress, the display of some sort of
user interface indicating to the user that the application has
been cached and that they can now use it offline.
Otherwise, it is an upgrade attempt. For each
cache host associated with an application
cache in cache group, create a task to fire a simple
event that is cancelable named updateready
at the
ApplicationCache
singleton of the cache
host, and append it to task list. The
default action of these events must be, if the user agent
shows caching progress, the display of some sort of
user interface indicating to the user that a new version is
available and that they can activate it by reloading the page.
If appropriate, remove any user interface indicating that an update for this cache is in progress.
Set the update status of cache group to idle.
For each task in task list, queue that task as a post-load task.
The cache failure steps are as follows:
Let task list be an empty list of tasks.
For each entry in cache group's list of pending master entries, run the following further substeps. These steps may be run in parallel for two or more entries at a time.
Wait for the resource for this entry to have either completely downloaded or failed.
Unassociate the Document
for this entry from
its application cache, if it has one.
Create a task to
fire a simple event that is cancelable named error
at the
ApplicationCache
singleton of the
Document
for this entry, if there still is one, and
append it to task list. The default action of
these events must be, if the user agent shows caching
progress, the display of some sort of user interface
indicating to the user that the user agent failed to save the
application for offline use.
For each cache host still associated with an
application cache in cache group,
create a task to fire a
simple event that is cancelable named error
at the
ApplicationCache
singleton of the cache
host, and append it to task list. The
default action of these events must be, if the user agent
shows caching progress, the display of some sort of
user interface indicating to the user that the user agent failed to
save the application for offline use.
Empty cache group's list of pending master entries.
If cache group has an application cache whose completeness flag is incomplete, then discard that application cache.
If appropriate, remove any user interface indicating that an update for this cache is in progress.
Let the status of cache group be idle.
If this was a cache attempt, discard cache group altogether.
For each task in task list, queue that task as a post-load task.
Abort the application cache download process.
Attempts to fetch resources as part of the application cache download process may be done with cache-defeating semantics, to avoid problems with stale or inconsistent intermediary caches.
User agents may invoke the application cache download process, in the background, for any application cache, at any time (with no cache host). This allows user agents to keep caches primed and to update caches even before the user visits a site.
Each Document
has a list of pending application
cache download process tasks that is used to delay events
fired by the algorithm above until the document's load
event has fired. When the
Document
is created, the list must be empty.
When the steps above say to queue a post-load task
task, where task is a task that dispatches an event on a
target ApplicationCache
object target, the user agent must run the appropriate steps
from the following list:
Document
is
ready for post-load tasksQueue the task task.
Add task to target's
Document
's list of pending application cache
download process tasks.
The task source for these tasks is the networking task source.
When the application cache
selection algorithm algorithm is invoked with a
Document
document and optionally a
manifest URL manifest URL, the user
agent must run the first applicable set of steps from the following
list:
Mark the entry for the resource from which document was taken in the application cache from which it was loaded as foreign.
Restart the current navigation from the top of the navigation algorithm, undoing any changes that were made as part of the initial load (changes can be avoided by ensuring that the step to update the session history with the new page is only ever completed after this application cache selection algorithm is run, though this is not required).
The navigation will not result in the same resource being loaded, because "foreign" entries are never picked during navigation.
User agents may notify the user of the inconsistency between the cache manifest and the document's own metadata, to aid in application development.
Associate document with the application cache from which it was loaded. Invoke, in the background, the application cache download process for that application cache's application cache group, with document as the cache host.
Invoke, in the background, the application cache download process for manifest URL, with document as the cache host and with the resource from which document was parsed as the master resource.
The Document
is not associated with any
application cache.
If there was a manifest URL, the user agent may report to the user that it was ignored, to aid in application development.
When a cache host is associated with an application cache whose completeness flag is complete, any and all loads for resources related to that cache host other than those for child browsing contexts must go through the following steps instead of immediately invoking the mechanisms appropriate to that resource's scheme:
If the resource is not to be fetched using the HTTP GET mechanism or equivalent, or if its URL has a different <scheme> component than the application cache's manifest, then fetch the resource normally and abort these steps.
If the resource's URL is a master entry, the manifest, an explicit entry, or a fallback entry in the application cache, then get the resource from the cache (instead of fetching it), and abort these steps.
If there is an entry in the application cache's online whitelist that has the same origin as the resource's URL and that is a prefix match for the resource's URL, then fetch the resource normally and abort these steps.
If the resource's URL has the same origin as the manifest's URL, and there is a fallback namespace f in the application cache that is a prefix match for the resource's URL, then:
Fetch the resource normally. If this results in a redirect to a resource with another origin (indicative of a captive portal), or a 4xx or 5xx status code or equivalent, or if there were network errors (but not if the user canceled the download), then instead get, from the cache, the resource of the fallback entry corresponding to the fallback namespace f. Abort these steps.
If the application cache's online whitelist wildcard flag is open, then fetch the resource normally and abort these steps.
Fail the resource load as if there had been a generic network error.
The above algorithm ensures that so long as the online whitelist wildcard flag is blocking, resources that are not present in the manifest will always fail to load (at least, after the application cache has been primed the first time), making the testing of offline applications simpler.
As a general rule, user agents should not expire application caches, except on request from the user, or after having been left unused for an extended period of time.
Application caches and cookies have similar implications with respect to privacy (e.g. if the site can identify the user when providing the cache, it can store data in the cache that can be used for cookie resurrection). Implementors are therefore encouraged to expose application caches in a manner related to HTTP cookies, allowing caches to be expunged together with cookies and other origin-specific data.
For example, a user agent could have a "delete site-specific data" feature that clears all cookies, application caches, local storage, databases, etc, from an origin all at once.
User agents should consider applying constraints on disk usage of application caches, and care should be taken to ensure that the restrictions cannot be easily worked around using subdomains.
User agents should allow users to see how much space each domain is using, and may offer the user the ability to delete specific application caches.
How quotas are presented to the user is not defined by this specification. User agents are encouraged to provide features such as allowing a user to indicate that certain sites are trusted to use more than the default quota, e.g. by asynchronously presenting a user interface while a cache is being updated, or by having an explicit whitelist in the user agent's configuration interface.
interface ApplicationCache { // update status const unsigned short UNCACHED = 0; const unsigned short IDLE = 1; const unsigned short CHECKING = 2; const unsigned short DOWNLOADING = 3; const unsigned short UPDATEREADY = 4; const unsigned short OBSOLETE = 5; readonly attribute unsigned short status; // updates void update(); void swapCache(); // events attribute Function onchecking; attribute Function onerror; attribute Function onnoupdate; attribute Function ondownloading; attribute Function onprogress; attribute Function onupdateready; attribute Function oncached; attribute Function onobsolete; }; ApplicationCache implements EventTarget;
applicationCache
(In a window.) Returns the ApplicationCache
object that applies to the active document of that Window
.
applicationCache
(In a shared worker.) Returns the ApplicationCache
object that applies to the current shared worker.
[WEBWORKERS]
status
Returns the current status of the application cache, as given by the constants defined below.
update
()Invokes the application cache download process.
Throws an INVALID_STATE_ERR
exception if there is no application cache to update.
swapCache
()Switches to the most recent application cache, if there is a
newer one. If there isn't, throws an
INVALID_STATE_ERR
exception.
This does not cause previously-loaded resources to be reloaded; for example, images do not suddenly get reloaded and style sheets and scripts do not get reparsed or reevaluated. The only change is that subsequent requests for cached resources will obtain the newer copies.
There is a one-to-one mapping from cache
hosts to ApplicationCache
objects. The applicationCache
attribute on Window
objects must return the
ApplicationCache
object associated with the
Window
object's active document. The applicationCache
attribute on SharedWorkerGlobalScope
objects must
return the ApplicationCache
object associated with the
worker.
[WEBWORKERS]
A Window
or
SharedWorkerGlobalScope
object has an associated
ApplicationCache
object even if that cache
host has no actual application cache.
The status
attribute, on getting, must return the current state of the
application cache that the
ApplicationCache
object's cache host is
associated with, if any. This must be the appropriate value from the
following list:
UNCACHED
(numeric value 0)The ApplicationCache
object's cache
host is not associated with an application
cache at this time.
IDLE
(numeric value 1)The ApplicationCache
object's cache
host is associated with an application cache
whose application cache group's update status is
idle, and that application cache is the newest cache in its
application cache group, and the application
cache group is not marked as obsolete.
CHECKING
(numeric value 2)The ApplicationCache
object's cache
host is associated with an application cache
whose application cache group's update status is
checking.
DOWNLOADING
(numeric value 3)The ApplicationCache
object's cache
host is associated with an application cache
whose application cache group's update status is
downloading.
UPDATEREADY
(numeric value 4)The ApplicationCache
object's cache
host is associated with an application cache
whose application cache group's update status is
idle, and whose application cache group is not
marked as obsolete,
but that application cache is not the newest cache in its
group.
OBSOLETE
(numeric value 5)The ApplicationCache
object's cache
host is associated with an application cache
whose application cache group is marked as obsolete.
If the update()
method is
invoked, the user agent must invoke the application cache
download process, in the background, for the application
cache with which the ApplicationCache
object's
cache host is associated, but without giving that
cache host to the algorithm. If there is no such
application cache, or if it is marked as obsolete, then the method
must raise an INVALID_STATE_ERR
exception instead.
If the swapCache()
method
is invoked, the user agent must run the following steps:
Check that ApplicationCache
object's
cache host is associated with an application
cache. If it is not, then raise an
INVALID_STATE_ERR
exception and abort these
steps.
Let cache be the application
cache with which the ApplicationCache
object's
cache host is associated. (By definition, this is the
same as the one that was found in the previous step.)
If cache's application cache
group is marked as obsolete, then unassociate
the ApplicationCache
object's cache host
from cache and abort these steps. (Resources
will now load from the network instead of the cache.)
Check that there is an application cache in the same
application cache group as cache
whose completeness
flag is complete and that is newer than cache. If there is not, then raise an
INVALID_STATE_ERR
exception and abort these
steps.
Let new cache be the newest application cache in the same application cache group as cache whose completeness flag is complete.
Unassociate the ApplicationCache
object's
cache host from cache and instead
associate it with new cache.
The following are the event handlers (and their
corresponding event handler
event types) that must be supported, as IDL attributes, by
all objects implementing the ApplicationCache
interface:
Event handler | Event handler event type |
---|---|
onchecking | checking
|
onerror | error
|
onnoupdate | noupdate
|
ondownloading | downloading
|
onprogress | progress
|
onupdateready | updateready
|
oncached | cached
|
onobsolete | obsolete
|
[Supplemental, NoInterfaceObject] interface NavigatorOnLine { readonly attribute boolean onLine; };
navigator
. onLine
Returns false if the user agent is definitely offline (disconnected from the network). Returns true if the user agent might be online.
The events online
and offline
are fired when the value of
this attribute changes.
The navigator.onLine
attribute must return false if the user agent will not contact the
network when the user follows links or when a script requests a
remote page (or knows that such an attempt would fail), and must
return true otherwise.
When the value that would be returned by the navigator.onLine
attribute of a
Window
or WorkerGlobalScope
changes from
true to false, the user agent must queue a task to
fire a simple event named offline
at the
Window
or WorkerGlobalScope
object.
On the other hand, when the value that would be returned by the
navigator.onLine
attribute
of a Window
or WorkerGlobalScope
changes
from false to true, the user agent must queue a task to
fire a simple event named online
at the
Window
or WorkerGlobalScope
object.
The task source for these tasks is the networking task source.
This attribute is inherently unreliable. A computer can be connected to a network without having Internet access.
In this example, an indicator is updated as the browser goes online and offline.
<!DOCTYPE HTML> <html> <head> <title>Online status</title> <script> function updateIndicator() { document.getElementById('indicator').textContext = navigator.onLine ? 'online' : 'offline'; } </script> </head> <body onload="updateIndicator()" ononline="updateIndicator()" onoffline="updateIndicator()"> <p>The network is: <span id="indicator">(state unknown)</span> </body> </html>
Various mechanisms can cause author-provided executable code to run in the context of a document. These mechanisms include, but are probably not limited to:
script
elements.javascript:
URLs (e.g. the src
attribute of img
elements, or an @import
rule in a CSS
style
element block).addEventListener()
, by explicit event handler
content attributes, by event handler IDL
attributes, or otherwise.Scripting is enabled in a browsing context when all of the following conditions are true:
Scripting is disabled in a browsing context when any of the above conditions are false (i.e. when scripting is not enabled).
Scripting is enabled for a
node if the Document
object of the node (the
node itself, if it is itself a Document
object) has an
associated browsing context, and scripting is enabled in that
browsing context.
Scripting is disabled for a node if there is no such browsing context, or if scripting is disabled in that browsing context.
A script has:
The characteristics of the script execution environment depend on the language, and are not defined by this specification.
In JavaScript, the script execution environment consists of the interpreter, the stack of execution contexts, the global code and function code and the Function objects resulting, and so forth.
Each code entry-point represents a block of executable code that the script exposes to other scripts and to the user agent.
Each Function object in a JavaScript script execution environment has a corresponding code entry-point, for instance.
The main program code of the script, if any, is the initial code entry-point. Typically, the code corresponding to this entry-point is executed immediately after the script is parsed.
In JavaScript, this corresponds to the execution context of the global code.
An object that provides the APIs that the code can use.
This is typically a Window
object. In JavaScript, this corresponds to the global
object.
When a script's global object is an empty object, it can't do anything that interacts with the environment.
If the script's global object is a
Window
object, then in JavaScript, the ThisBinding of
the global execution context for this script must be the
Window
object's WindowProxy
object,
rather than the global object. [ECMA262]
This is a willful violation of the
JavaScript specification current at the time of writing
(ECMAScript edition 5, as defined in section 10.4.1.1 Initial
Global Execution Context, step 3). The JavaScript specification
requires that the this
keyword in the global
scope return the global object, but this is not compatible with
the security design prevalent in implementations as specified
herein. [ECMA262]
A browsing context that is assigned responsibility for actions taken by the script.
When a script creates and navigates a new top-level browsing
context, the opener
attribute of the new browsing context's
Window
object will be set to the script's
browsing context's WindowProxy
object.
A Document
that is assigned responsibility for
actions taken by the script.
When a script fetches a resource, the current address of the
script's document will be used to set the Referer
(sic) header.
A character encoding, set when the script is created, used to encode URLs. If the character encoding is set from another source, e.g. a document's character encoding, then the script's URL character encoding must follow the source, so that if the source's changes, so does the script's.
A URL, set when the script is created, used to resolve relative URLs. If the base URL is set from another source, e.g. a document base URL, then the script's base URL must follow the source, so that if the source's changes, so does the script's.
When a user agent is to jump to a code entry-point for a script, for example to invoke an event listener defined in that script, the user agent must run the following steps:
If the script's global object is a
Window
object whose Document
object is
not fully active, then abort these steps without doing
anything. The callback is not fired.
Set the entry script to be the script being invoked.
Make the script execution environment for the script execute the code for the given code entry-point.
Set the entry script back to whatever it was when this algorithm started.
This algorithm is not invoked by one script calling another.
When the specification says that a script is to be created, given some script source, its scripting language, a global object, a browsing context, a URL character encoding, and a base URL, the user agent must run the following steps:
If scripting is disabled for browsing context passed to this algorithm, then abort these steps, as if the script did nothing but return void.
Set up a script execution environment as appropriate for the scripting language.
Parse/compile/initialize the source of the script using the script execution environment, as appropriate for the scripting language, and thus obtain the list of code entry-points for the script. If the semantics of the scripting language and the given source code are such that there is executable code to be immediately run, then the initial code entry-point is the entry-point for that code.
Set up the script's global object, the script's browsing context, the script's document, the script's URL character encoding, and the script's base URL from the settings passed to this algorithm.
If all the steps above succeeded (in particular, if the script was compiled successfully), Jump to the script's initial code entry-point.
Otherwise, report the error using the onerror
event handler of the script's global
object. If the error is still not handled after this, then
the error may be reported to the user.
When the user agent is to create an impotent script, given some script source, its scripting language, and a browsing context, the user agent must create a script, using the given script source and scripting language, using a new empty object as the global object, and using the given browsing context as the browsing context. The URL character encoding and base URL for the resulting script are not important as no APIs are exposed to the script.
When the specification says that a script is to be created from a node node, given some script source and its scripting language, the user agent must create a script, using the given script source and scripting language, and using the script settings determined from the node node.
The script settings determined from the node node are computed as follows:
Let document be the
Document
of node (or node itself if it is a
Document
).
The browsing context is the browsing context of document.
The global object is the Window
object of
document.
The URL character encoding is the character encoding of document. (This is a reference, not a copy.)
The base URL is the base URL of document. (This is a reference, not a copy.)
User agents may impose resource limitations on scripts, for
example CPU quotas, memory limits, total execution time limits, or
bandwidth limitations. When a script exceeds a limit, the user agent
may either throw a QUOTA_EXCEEDED_ERR
exception, abort
the script without an exception, prompt the user, or throttle script
execution.
For example, the following script never terminates. A user agent could, after waiting for a few seconds, prompt the user to either terminate the script or let it continue.
<script> while (true) { /* loop */ } </script>
User agents are encouraged to allow users to disable scripting
whenever the user is prompted either by a script (e.g. using the
window.alert()
API) or because of a
script's actions (e.g. because it has exceeded a time limit).
If scripting is disabled while a script is executing, the script should be terminated immediately.
Whenever an uncaught runtime script error occurs in one of the
scripts associated with a Document
, the user agent must
report the error using the onerror
event handler of the script's global
object. If the error is still not handled after this, then
the error may be reported to the user.
When the user agent is required to report an error error using the event handler onerror, it must run these steps, after which the error is either handled or not handled:
Function
The function must be invoked with three arguments. The three
arguments passed to the function are all DOMString
s;
the first must give the message that the UA is considering
reporting, the second must give the absolute URL of
the resource in which the error occurred, and the third must give
the line number in that resource on which the error occurred.
If the function returns false, then the error is handled. Otherwise, the error is not handled.
Any uncaught exceptions thrown or errors caused by this function may be reported to the user immediately after the error that the function was called for; the report an error algorithm must not be used to handle exceptions thrown or errors caused by this function.
The error is not handled.
To coordinate events, user interaction, scripts, rendering, networking, and so forth, user agents must use event loops as described in this section.
There must be at least one event loop per user agent, and at most one event loop per unit of related similar-origin browsing contexts.
When there is more than one event loop for a unit of related browsing contexts, complications arise when a browsing context in that group is navigated such that it switches from one unit of related similar-origin browsing contexts to another. This specification does not currently describe how to handle these complications.
An event loop always has at least one browsing context. If an event loop's browsing contexts all go away, then the event loop goes away as well. A browsing context always has an event loop coordinating its activities.
Other specifications can define new kinds of event loops that aren't associated with browsing contexts; in particular, the Web Workers specification does so.
An event loop has one or more task queues. A task queue is an ordered list of tasks, which can be:
Asynchronously dispatching an Event
object at a
particular EventTarget
object is a task.
Not all events are dispatched using the task queue, many are dispatched synchronously during other tasks.
The HTML parser tokenizing one or more bytes, and then processing any resulting tokens, is typically a task.
Calling a callback asynchronously is a task.
When an algorithm fetches a resource, if the fetching occurs asynchronously then the processing of the resource once some or all of the resource is available is a task.
Some elements have tasks that trigger in response to DOM manipulation, e.g. when that element is inserted into the document.
When a user agent is to queue a task, it must add the given task to one of the task queues of the relevant event loop. All the tasks from one particular task source (e.g. the callbacks generated by timers, the events dispatched for mouse movements, the tasks queued for the parser) must always be added to the same task queue, but tasks from different task sources may be placed in different task queues.
For example, a user agent could have one task queue for mouse and key events (the user interaction task source), and another for everything else. The user agent could then give keyboard and mouse events preference over other tasks three quarters of the time, keeping the interface responsive but not starving other task queues, and never processing events from any one task source out of order.
Each task that is queued onto a task queue of
an event loop defined by this specification is
associated with a Document
; if the task was queued in
the context of an element, then it is the element's
Document
; if the task was queued in the context of a
browsing context, then it is the browsing
context's active document at the time the task
was queued; if the task was queued by or for a script then the document is the
script's document.
A user agent is required to have one storage mutex. This mutex is used to control access to shared state like cookies. At any one point, the storage mutex is either free, or owned by a particular event loop or instance of the fetching algorithm.
Whenever a script calls into a plugin, and whenever a plugin calls into a script, the user agent must release the storage mutex.
An event loop must continually run through the following steps for as long as it exists:
Run the oldest task on one
of the event loop's task
queues, ignoring tasks whose associated
Document
s are not fully active. The user
agent may pick any task queue.
If the storage mutex is now owned by the event loop, release it so that it is once again free.
Remove that task from its task queue.
If necessary, update the rendering or user interface of any
Document
or browsing context to reflect
the current state.
Return to the first step of the event loop.
When the user agent is to provide a stable state, if any asynchronously-running algorithms are awaiting a stable state, then the user agent must run their synchronous section and then resume running their asynchronous algorithm (if appropriate).
A synchronous section never mutates the DOM, runs any script, or has any other side-effects.
Steps in synchronous sections are marked with ⌛.
When an algorithm says to spin the event loop until a condition goal is met, the user agent must run the following steps:
Let task source be the task source of the currently running task.
Stop the currently running task, allowing the event loop to resume, but continue these steps asynchronously.
This causes the event loop to move on to the second step of its processing model (defined above).
Wait until the condition goal is met.
Queue a task to continue running these steps, using the task source task source. Wait until this task runs before continuing these steps.
Return to the caller.
Some of the algorithms in this specification, for historical reasons, require the user agent to pause while running a task until a condition goal is met. This means running the following steps:
If any asynchronously-running algorithms are awaiting a stable state, then run their synchronous section and then resume running their asynchronous algorithm. (See the event loop processing model definition above for details.)
If necessary, update the rendering or user interface of any
Document
or browsing context to reflect
the current state.
Wait until the condition goal is met. While a user agent has a paused task, the corresponding event loop must not run further tasks, and any script in the currently running task must block. User agents should remain responsive to user input while paused, however, albeit in a reduced capacity since the event loop will not be doing anything.
When a user agent is to obtain the storage mutex as part of running a task, it must run through the following steps:
If the storage mutex is already owned by this task's event loop, then abort these steps.
Otherwise, pause until the storage mutex can be taken by the event loop.
Take ownership of the storage mutex.
The following task sources are used by a number of mostly unrelated features in this and other specifications.
This task source is used for features that react to DOM manipulations, such as things that happen asynchronously when an element is inserted into the document.
This task source is used for features that react to user interaction, for example keyboard or mouse input.
Asynchronous events sent in response to user input (e.g. click
events) must be dispatched using
tasks queued with the user interaction task
source. [DOMEVENTS]
This task source is used for features that trigger in response to network activity.
This task source is used to queue calls to history.back()
and similar
APIs.
javascript:
URL schemeWhen a URL using the javascript:
scheme is dereferenced, the user agent must run
the following steps:
Let the script source be the string obtained using the
content retrieval operation defined for javascript:
URLs. [JSURL]
Use the appropriate step from the following list:
javascript:
URL, and the source browsing context for that
navigation, if any, has scripting disabledLet result be void.
javascript:
URL, and the active document of that browsing
context has the same origin as the script given by
that URLLet address be the address of the active document of the browsing context being navigated.
If address is about:blank
,
and the browsing context being navigated has a
creator browsing context, then let address be the address of the creator
Document
instead.
Create a
script from the Document
node of the
active document, using the aforementioned script
source, and assuming the scripting language is JavaScript.
Let result be the return value of the initial code entry-point of this script. If an exception was raised, let result be void instead. (The result will be void also if scripting is disabled.)
When it comes time to set the document's address in the navigation algorithm, use address as the override URL.
Let result be void.
If the result of executing the script is void (there is no return value), then the URL must be treated in a manner equivalent to an HTTP resource with an HTTP 204 No Content response.
Otherwise, the URL must be treated in a manner equivalent to an
HTTP resource with a 200 OK response whose Content-Type metadata is
text/html
and whose response body is the return value
converted to a string value.
Certain contexts, in particular img
elements, ignore the Content-Type
metadata.
So for example a javascript:
URL for a
src
attribute of an
img
element would be evaluated in the context of an
empty object as soon as the attribute is set; it would then be
sniffed to determine the image type and decoded as an image.
A javascript:
URL in an href
attribute of an a
element would only be evaluated when the link was followed.
The src
attribute of an
iframe
element would be evaluated in the context of
the iframe
's own browsing context; once
evaluated, its return value (if it was not void) would replace that
browsing context's document, thus changing the
variables visible in that browsing context.
Many objects can have event handlers specified. These act as bubbling event listeners for the object on which they are specified.
An event handler can either
have the value null or be set to a Function
object. Initially, event handlers must be set to
null.
Event handlers are exposed in one or two ways.
The first way, common to all event handlers, is as an event handler IDL attribute.
The second way is as an event handler content attribute. Event handlers
on HTML elements and some of the event handlers on
Window
objects are exposed in this way.
Event handler IDL attributes, on setting, must set the corresponding event handler to their new value, and on getting, must return whatever the current value of the corresponding event handler is (possibly null).
If an event handler IDL attribute exposes an event handler of an object that doesn't exist, it must always return null on getting and must do nothing on setting.
This can happen in particular for event handler IDL attribute on
body
elements that do not have corresponding
Window
objects.
Certain event handler IDL attributes have additional
requirements, in particular the onmessage
attribute of
MessagePort
objects.
Event handler content attributes, when specified, must
contain valid JavaScript code which, when parsed, would match the
FunctionBody
production after automatic
semicolon insertion. [ECMA262]
When an event
handler content attribute is set, if the element is owned by
a Document
that is in a browsing context,
and scripting is enabled for
that browsing context, the user agent must run the
following steps to create a script after setting the content
attribute to its new value:
Set the corresponding event handler to null.
Set up a script execution environment for JavaScript.
Let body be the event handler content attribute's new value.
If body is not parsable as FunctionBody or if parsing detects an early error then abort these steps.
FunctionBody is defined in ECMAScript edition 5 section 13 Function Definition. Early error is defined in ECMAScript edition 5 section 16 Errors. [ECMA262]
If body begins with a Directive Prologue that contains a Use Strict Directive then let strict be true, otherwise let strict be false.
The terms "Directive Prologue" and "Use Strict Directive" are defined in ECMAScript edition 5 section 14.1 Directive Prologues and the Use Strict Directive. [ECMA262]
Using the script execution environment created above, create a function object (as defined in ECMAScript edition 5 section 13.2 Creating Function Objects), with:
Document
, the
global environment).NewObjectEnvironment() is defined in ECMAScript edition 5 section 10.2.2.3 NewObjectEnvironment (O, E). [ECMA262]
Let this new function be the only entry in the script's list of code entry-points.
Set up the script's global object, the script's browsing context, the script's document, the script's URL character encoding, and the script's base URL from the script settings determined from the node on which the attribute is being set.
Set the corresponding event handler to the aforementioned function.
When an event handler content attribute is removed, the user agent must set the corresponding event handler to null.
When an event handler content attribute is set on an
element owned by a Document
that is not in a
browsing context, the corresponding event handler is
not changed.
All event handlers on an object, whether an element
or some other object, and whether set to null or to a
Function
object, must be registered as event listeners
on the object when it is created, as if the addEventListener()
method on the object's EventTarget
interface had been
invoked, with the event type (type
argument) equal to the type corresponding to the event handler (the
event handler event type), the listener set to be a
target and bubbling phase listener (useCapture argument set to
false), and the event listener itself (listener argument) set to do
nothing while the event handler's value is not a
Function
object, and set to invoke the call()
callback of the
Function
object associated with the event handler
otherwise.
Event handlers therefore always fire before event listeners
attached using addEventListener()
.
The listener argument is emphatically not the event handler itself.
The interfaces implemented by the event object do not influence whether an event handler is triggered or not.
When an event handler's
Function
object is invoked, its call()
callback must be invoked
with one argument, set to the Event
object of the event
in question.
The handler's return value must then be processed as follows:
mouseover
If the return value is a boolean with the value true, then the event must be canceled.
BeforeUnloadEvent
objectIf the return value is a string, and the event object's
returnValue
attribute's value is the empty string, then set the returnValue
attribute's value to the return value.
If the return value is a boolean with the value false, then the event must be canceled.
The Function
interface represents a function in the
scripting language being used. It is represented in IDL as
follows:
[Callback=FunctionOnly, NoInterfaceObject] interface Function { any call(in any... arguments); };
The call(...)
method is the object's callback.
In JavaScript, any Function
object implements this interface.
If the Function
object is a JavaScript Function
, then when it is invoked by the user agent,
the user agent must set the thisArg (as defined
by ECMAScript edition 5 section 10.4.3 Entering Function Code) to
the event handler's object. [ECMA262]
For example, the following document fragment:
<body onload="alert(this)" onclick="alert(this)">
...leads to an alert saying "[object Window]
" when the document is loaded,
and an alert saying "[object HTMLBodyElement]
" whenever the user
clicks something in the page.
The return value of the function affects whether the event is
canceled or not: as described above, if
the return value is false, the event is canceled (except for mouseover
events, where the return
value has to be true to cancel the event). With beforeunload
events, the value is
instead used to determine the message to show the user.
Document
objects, and Window
objectsThe following are the event handlers (and their
corresponding event handler
event types) that must be supported by all HTML
elements, as both content attributes and IDL attributes, and
on Document
and Window
objects, as IDL
attributes.
Event handler | Event handler event type |
---|---|
onabort | abort
|
oncanplay | canplay
|
oncanplaythrough | canplaythrough
|
onchange | change
|
onclick | click
|
oncontextmenu | contextmenu
|
oncuechange | cuechange
|
ondblclick | dblclick
|
ondrag | drag
|
ondragend | dragend
|
ondragenter | dragenter
|
ondragleave | dragleave
|
ondragover | dragover
|
ondragstart | dragstart
|
ondrop | drop
|
ondurationchange | durationchange
|
onemptied | emptied
|
onended | ended
|
oninput | input
|
oninvalid | invalid
|
onkeydown | keydown
|
onkeypress | keypress
|
onkeyup | keyup
|
onloadeddata | loadeddata
|
onloadedmetadata | loadedmetadata
|
onloadstart | loadstart
|
onmousedown | mousedown
|
onmousemove | mousemove
|
onmouseout | mouseout
|
onmouseover | mouseover
|
onmouseup | mouseup
|
onmousewheel | mousewheel
|
onpause | pause
|
onplay | play
|
onplaying | playing
|
onprogress | progress
|
onratechange | ratechange
|
onreadystatechange | readystatechange
|
onreset | reset
|
onseeked | seeked
|
onseeking | seeking
|
onselect | select
|
onshow | show
|
onstalled | stalled
|
onsubmit | submit
|
onsuspend | suspend
|
ontimeupdate | timeupdate
|
onvolumechange | volumechange
|
onwaiting | waiting
|
The following are the event handlers (and their
corresponding event handler
event types) that must be supported by all HTML
elements other than body
, as both content
attributes and IDL attributes, and on Document
objects,
as IDL attributes:
Event handler | Event handler event type |
---|---|
onblur | blur
|
onerror | error
|
onfocus | focus
|
onload | load
|
onscroll | scroll
|
The following are the event handlers (and their
corresponding event handler
event types) that must be supported by Window
objects, as IDL attributes on the Window
object, and
with corresponding content attributes and IDL attributes exposed on
the body
and frameset
elements:
Event handler | Event handler event type |
---|---|
onafterprint | afterprint
|
onbeforeprint | beforeprint
|
onbeforeunload | beforeunload
|
onblur | blur
|
onerror | error
|
onfocus | focus
|
onhashchange | hashchange
|
onload | load
|
onmessage | message
|
onoffline | offline
|
ononline | online
|
onpagehide | pagehide
|
onpageshow | pageshow
|
onpopstate | popstate
|
onredo | redo
|
onresize | resize
|
onscroll | scroll
|
onstorage | storage
|
onundo | undo
|
onunload | unload
|
The onerror
handler is also used for reporting script errors.
Certain operations and methods are defined as firing events on
elements. For example, the click()
method on the HTMLElement
interface is defined as
firing a click
event on the
element. [DOMEVENTS]
Firing a simple event named e means that an event with the name e, which does not bubble (except where otherwise
stated) and is not cancelable (except where otherwise stated), and
which uses the Event
interface, must be dispatched at
the given target.
Firing a synthetic
mouse event named e means that an event
with the name e, which does not bubble (except
where otherwise stated) and is not cancelable (except where
otherwise stated), and which uses the MouseEvent
interface, must be dispatched at the given target. The event object
must have its screenX
, screenY
, clientX
, clientY
, and button
attributes
set to 0, its ctrlKey
, shiftKey
, altKey
, and metaKey
attributes set according to the current
state of the key input device, if any (false for any keys that are
not available), its detail
attribute set to 1,
and its relatedTarget
attribute set to null.
The getModifierState()
method on the object
must return values appropriately describing the state of the key
input device at the time the event is created.
Firing a click
event means firing a synthetic mouse event named click
, which bubbles and is
cancelable.
The default action of these events is to do nothing except where otherwise stated.
Window
objectWhen an event is dispatched at a DOM node in a
Document
in a browsing context, if the
event is not a load
event, the user
agent must also dispatch the event to the Window
, as
follows:
Window
object before propagating to any of the nodes,
as if the Window
object was the parent of the
Document
in the dispatch chain.Window
object at the end of the phase, unless bubbling
has been prevented, again as if the Window
object was
the parent of the Document
in the dispatch chain.The atob()
and btoa()
methods allow authors to
transform content to and from the base64 encoding.
[Supplemental, NoInterfaceObject] interface WindowBase64 { DOMString btoa(in DOMString btoa); DOMString atob(in DOMString atob); }; Window implements WindowBase64;
In these APIs, for mnemonic purposes, the "b" can be considered to stand for "binary", and the "a" for "ASCII". In practice, though, for primarily historical reasons, both the input and output of these functions are Unicode strings.
btoa
( data )Takes the input data, in the form of a Unicode string containing only characters in the range U+0000 to U+00FF, each representing a binary byte with values 0x00 to 0xFF respectively, and converts it to its base64 representation, which it returns.
Throws an INVALID_CHARACTER_ERR
exception if the
input string contains any out-of-range characters.
atob
( data )Takes the input data, in the form of a Unicode string containing base64-encoded binary data, decodes it, and returns a string consisting of characters in the range U+0000 to U+00FF, each representing a binary byte with values 0x00 to 0xFF respectively, corresponding to that binary data.
Throws an INVALID_CHARACTER_ERR
exception if the
input string is not valid base64 data.
The WindowBase64
interface adds to the
Window
interface and the WorkerUtils
interface (part of Web Workers).
The btoa()
method must throw an INVALID_CHARACTER_ERR
exception if
the method's first argument contains any character whose code point
is greater than U+00FF. Otherwise, the user agent must convert that
argument to a sequence of octets whose nth octet
is the eight-bit representation of the code point of the nth character of the argument, and then must apply
the base64 algorithm to that sequence of octets, and return the
result. [RFC4648]
The atob()
method must run the following steps to parse the string passed in
the method's first argument:
Let input be the string being parsed.
Let position be a pointer into input, initially pointing at the start of the string.
If the length of input divides by 4 leaving no remainder, then: if input ends with one or two U+003D EQUALS SIGN (=) characters, remove them from input.
If the length of input divides by 4
leaving a remainder of 1, throw an
INVALID_CHARACTER_ERR
exception and abort these
steps.
If input contains a character that is not
in the following list of characters and character ranges, throw an
INVALID_CHARACTER_ERR
exception and abort these
steps:
Let output be a string, initially empty.
Let buffer be a buffer that can have bits appended to it, initially empty.
While position does not point past the end of input, run these substeps:
Find the character pointed to by position in the first column of the following table. Let n be the number given in the second cell of the same row.
Character | Number |
---|---|
A | 0 |
B | 1 |
C | 2 |
D | 3 |
E | 4 |
F | 5 |
G | 6 |
H | 7 |
I | 8 |
J | 9 |
K | 10 |
L | 11 |
M | 12 |
N | 13 |
O | 14 |
P | 15 |
Q | 16 |
R | 17 |
S | 18 |
T | 19 |
U | 20 |
V | 21 |
W | 22 |
X | 23 |
Y | 24 |
Z | 25 |
a | 26 |
b | 27 |
c | 28 |
d | 29 |
e | 30 |
f | 31 |
g | 32 |
h | 33 |
i | 34 |
j | 35 |
k | 36 |
l | 37 |
m | 38 |
n | 39 |
o | 40 |
p | 41 |
q | 42 |
r | 43 |
s | 44 |
t | 45 |
u | 46 |
v | 47 |
w | 48 |
x | 49 |
y | 50 |
z | 51 |
0 | 52 |
1 | 53 |
2 | 54 |
3 | 55 |
4 | 56 |
5 | 57 |
6 | 58 |
7 | 59 |
8 | 60 |
9 | 61 |
+ | 62 |
/ | 63 |
Append to buffer the six bits corresponding to number, most significant bit first.
If buffer has accumulated 24 bits, interpret them as three 8-bit big-endian numbers. Append the three characters with code points equal to those numbers to output, in the same order, and then empty buffer.
Advance position by one character.
If buffer is not empty, it contains either 12 or 18 bits. If it contains 12 bits, discard the last four and interpret the remaining eight as an 8-bit big-endian number. If it contains 18 bits, discard the last two and interpret the remaining 16 as two 8-bit big-endian numbers. Append the one or two characters with code points equal to those one or two numbers to output, in the same order.
The discarded bits mean that, for instance, atob("YQ")
and atob("YR")
both return "a
".
Return output.
Some base64 encoders add newlines or other
whitespace to their output. The atob()
method throws an
exception if its input contains characters other than those
described by the regular expression bracket expression [+/=0-9A-Za-z]
, so other characters need to be
removed before atob()
is
used for decoding.
The setTimeout()
and setInterval()
methods allow authors to schedule timer-based callbacks.
[Supplemental, NoInterfaceObject] interface WindowTimers { long setTimeout(in any handler, in optional any timeout, in any... args); void clearTimeout(in long handle); long setInterval(in any handler, in optional any timeout, in any... args); void clearInterval(in long handle); }; Window implements WindowTimers;
setTimeout
( handler [, timeout [, arguments ] ] )Schedules a timeout to run handler after timeout milliseconds. Any arguments are passed straight through to the handler.
setTimeout
( code [, timeout ] )Schedules a timeout to compile and run code after timeout milliseconds.
clearTimeout
( handle )Cancels the timeout set with setTimeout()
identified by handle.
setInterval
( handler [, timeout [, arguments ] ] )Schedules a timeout to run handler every timeout milliseconds. Any arguments are passed straight through to the handler.
setInterval
( code [, timeout ] )Schedules a timeout to compile and run code every timeout milliseconds.
clearInterval
( handle )Cancels the timeout set with setInterval()
identified by handle.
This API does not guarantee that timers will fire exactly on schedule. Delays due to CPU load, other tasks, etc, are to be expected.
The WindowTimers
interface adds to the
Window
interface and the WorkerUtils
interface (part of Web Workers).
Each object that implements the WindowTimers
interface has a list of active timeouts and a list
of active intervals. Each entry in these lists is identified
by a number, which must be unique within its list for the lifetime
of the object that implements the WindowTimers
interface.
The setTimeout()
method must run the following steps:
Let handle be a user-agent-defined integer that is greater than zero that will identify the timeout to be set by this call.
Add an entry to the list of active timeouts for handle.
Get the timed task handle in the list of active timeouts, and let task be the result.
Get the timeout, and let timeout be the result.
If the currently running task is a task that was created by the
setTimeout()
method, and timeout is less than 4, then
increase timeout to 4.
Return handle, and then continue running this algorithm asynchronously.
If the method context is a Window
object, wait until the Document
associated with the
method context has been fully active for
a further timeout milliseconds (not
necessarily consecutively).
Otherwise, if the method context is a
WorkerUtils
object, wait until timeout milliseconds have passed with the worker
not suspended (not necessarily consecutively).
Otherwise, act as described in the specification that defines
that the WindowTimers
interface is implemented by
some other object.
Wait until any invocations of this algorithm started before this one whose timeout is equal to or less than this one's have completed.
Optionally, wait a further user-agent defined length of time.
This is intended to allow user agents to pad timeouts as needed to optimise the power usage of the device. For example, some processors have a low-power mode where the granularity of timers is reduced; on such platforms, user agents can slow timers down to fit this schedule instead of requiring the processor to use the more accurate mode with its associated higher power usage.
The clearTimeout()
method must clear the entry identified as handle
from the list of active timeouts of the
WindowTimers
object on which the method was invoked,
where handle is the argument passed to the
method, if any. (If handle does not identify an
entry in the list of active timeouts of the
WindowTimers
object on which the method was invoked,
the method does nothing.)
The setInterval()
method must run the following steps:
Let handle be a user-agent-defined integer that is greater than zero that will identify the interval to be set by this call.
Add an entry to the list of active intervals for handle.
Get the timed task handle in the list of active intervals, and let task be the result.
Get the timeout, and let timeout be the result.
If timeout is less than 10, then increase timeout to 10.
Return handle, and then continue running this algorithm asynchronously.
Wait: If the method context is a
Window
object, wait until the Document
associated with the method context has been fully
active for a further interval
milliseconds (not necessarily consecutively).
Otherwise, if the method context is a
WorkerUtils
object, wait until interval milliseconds have passed with the worker
not suspended (not necessarily consecutively).
Otherwise, act as described in the specification that defines
that the WindowTimers
interface is implemented by
some other object.
Optionally, wait a further user-agent defined length of time.
This is intended to allow user agents to pad timeouts as needed to optimise the power usage of the device. For example, some processors have a low-power mode where the granularity of timers is reduced; on such platforms, user agents can slow timers down to fit this schedule instead of requiring the processor to use the more accurate mode with its associated higher power usage.
Return to the step labeled wait.
The clearInterval()
method must clear the entry identified as handle
from the list of active intervals of the
WindowTimers
object on which the method was invoked,
where handle is the argument passed to the
method, if any. (If handle does not identify an
entry in the list of active intervals of the
WindowTimers
object on which the method was invoked,
the method does nothing.)
The method context, when referenced by the algorithms
in this section, is the object on which the method for which the
algorithm is running is implemented (a Window
or
WorkerUtils
object).
When the above methods are invoked and try to get the timed task handle in list list, they must run the following steps:
If the first argument to the invoked method is an object that has an internal [[Call]] method, then return a task that checks if the entry for handle in list has been cleared, and if it has not, calls the aforementioned [[Call]] method with as its arguments the third and subsequent arguments to the invoked method (if any), and with an undefined thisArg, and abort these steps. [ECMA262]
Setting thisArg to undefined
means that the function code will be executed with the this
keyword bound to the WindowProxy
or the WorkerGlobalScope
object, as if the code was
running in the global scope.
Otherwise, continue with the remaining steps.
Apply the ToString() abstract operation to the first argument to the method, and let script source be the result. [ECMA262]
Let script language be JavaScript.
If the method context is a Window
object, let global object be the method
context, let browsing context be the
browsing context with which global
object is associated, let character
encoding be the character encoding of the Document
associated with global object (this is a reference, not a copy), and let
base URL be the base URL of the Document
associated with
global object (this is
a reference, not a copy).
Otherwise, if the method context is a
WorkerUtils
object, let global
object, browsing context, document, character encoding,
and base URL be the script's global
object, script's browsing context,
script's document, script's URL character
encoding, and script's base URL (respectively)
of the script that the
run a worker algorithm created when it created the
method context.
Otherwise, act as described in the specification that defines
that the WindowTimers
interface is implemented by
some other object.
Return a task that checks if the entry for handle in list has been cleared, and if it has not, creates a script using script source as the script source, scripting language as the scripting language, global object as the global object, browsing context as the browsing context, document as the document, character encoding as the URL character encoding, and base URL as the base URL.
When the above methods are to get the timeout, they must run the following steps:
Let timeout be the second argument to the method, or zero if the argument was omitted.
Apply the ToString() abstract operation to timeout, and let timeout be the result. [ECMA262]
Apply the ToNumber() abstract operation to timeout, and let timeout be the result. [ECMA262]
If timeout is an Infinity value, a Not-a-Number (NaN) value, or negative, let timeout be zero.
Round timeout down to the nearest integer, and let timeout be the result.
Return timeout.
The task source for these tasks is the timer task source.
alert
(message)Displays a modal alert with the given message, and waits for the user to dismiss it.
A call to the navigator.yieldForStorageUpdates()
method is implied when this method is invoked.
confirm
(message)Displays a modal OK/Cancel prompt with the given message, waits for the user to dismiss it, and returns true if the user clicks OK and false if the user clicks Cancel.
A call to the navigator.yieldForStorageUpdates()
method is implied when this method is invoked.
prompt
(message [, default] )Displays a modal text field prompt with the given message, waits for the user to dismiss it, and returns the value that the user entered. If the user cancels the prompt, then returns null instead. If the second argument is present, then the given value is used as a default.
A call to the navigator.yieldForStorageUpdates()
method is implied when this method is invoked.
The alert(message)
method, when invoked, must
release the storage mutex and show the given message to the user. The user agent may make the
method wait for the user to acknowledge the message before
returning; if so, the user agent must pause while the
method is waiting.
The confirm(message)
method, when invoked, must
release the storage mutex and show the given message to the user, and ask the user to respond with
a positive or negative response. The user agent must then
pause as the method waits for the user's response. If
the user responds positively, the method must return true, and if
the user responds negatively, the method must return false.
The prompt(message, default)
method, when invoked, must release the storage mutex,
show the given message to the user, and ask the
user to either respond with a string value or abort. The user agent
must then pause as the method waits for the user's
response. The second argument is optional. If the second argument
(default) is present, then the response must be
defaulted to the value given by default. If the
user aborts, then the method must return null; otherwise, the method
must return the string that the user responded with.
print
()Prompts the user to print the page.
A call to the navigator.yieldForStorageUpdates()
method is implied when this method is invoked.
The print()
method,
when invoked, must run the printing steps.
User agents should also run the printing steps whenever the user asks for the opportunity to obtain a physical form (e.g. printed copy), or the representation of a physical form (e.g. PDF copy), of a document.
The printing steps are as follows:
The user agent may display a message to the user and/or may abort these steps.
For instance, a kiosk browser could silently
ignore any invocations of the print()
method.
For instance, a browser on a mobile device could detect that there are no printers in the vicinity and display a message saying so before continuing to offer a "save to PDF" option.
The user agent must fire a simple event named
beforeprint
at the
Window
object of the Document
that is
being printed, as well as any nested browsing contexts in it.
The beforeprint
event can be used
to annotate the printed copy, for instance adding the time at
which the document was printed.
The user agent must release the storage mutex.
The user agent should offer the user the opportunity to obtain a physical form (or the representation of a physical form) of the document. The user agent may wait for the user to either accept or decline before returning; if so, the user agent must pause while the method is waiting. Even if the user agent doesn't wait at this point, the user agent must use the state of the relevant documents as they are at this point in the algorithm if and when it eventually creates the alternate form.
The user agent must fire a simple event named
afterprint
at the
Window
object of the Document
that is
being printed, as well as any nested browsing contexts in it.
The afterprint
event can be used
to revert annotations added in the earlier event, as well as
showing post-printing UI. For instance, if a page is walking the
user through the steps of applying for a home loan, the script
could automatically advance to the next step after having printed
a form or other.
showModalDialog
(url [, argument] )Prompts the user with the given page, waits for that page to close, and returns the return value.
A call to the navigator.yieldForStorageUpdates()
method is implied when this method is invoked.
The showModalDialog(url, argument)
method, when invoked, must
cause the user agent to run the following steps:
Resolve url relative to the entry script's base URL.
If this fails, then throw a SYNTAX_ERR
exception
and abort these steps.
Release the storage mutex.
If the user agent is configured such that this invocation of
showModalDialog()
is
somehow disabled, then return the empty string and abort these
steps.
User agents are expected to disable this method in certain cases to avoid user annoyance (e.g. as part of their popup blocker feature). For instance, a user agent could require that a site be white-listed before enabling this method, or the user agent could be configured to only allow one modal dialog at a time.
Let the list of background browsing contexts be a list of all the browsing contexts that:
Window
object on which the showModalDialog()
method was
called, and thatshowModalDialog()
method at
the time the method was called,...as well as any browsing contexts that are nested inside any of the browsing contexts matching those conditions.
Disable the user interface for all the browsing contexts in the list of background browsing contexts. This should prevent the user from navigating those browsing contexts, causing events to be sent to those browsing context, or editing any content in those browsing contexts. However, it does not prevent those browsing contexts from receiving events from sources other than the user, from running scripts, from running animations, and so forth.
Create a new auxiliary browsing context, with the
opener browsing context being the browsing context of
the Window
object on which the showModalDialog()
method was
called. The new auxiliary browsing context has no name.
This browsing context's
Document
s' Window
objects all implement
the WindowModal
interface.
Let the dialog arguments of the new browsing context be set to the value of argument, or the 'undefined' value if the argument was omitted.
Let the dialog arguments' origin be the
origin of the script that called the showModalDialog()
method.
Navigate the new browsing context to the absolute URL that resulted from resolving url earlier, with replacement enabled, and with the browsing context of the script that invoked the method as the source browsing context.
Spin the event loop until the new browsing context is closed. (The user agent must allow the user to indicate that the browsing context is to be closed.)
Reenable the user interface for all the browsing contexts in the list of background browsing contexts.
Return the auxiliary browsing context's return value.
The Window
objects of Document
s hosted
by browsing contexts created
by the above algorithm must also implement the
WindowModal
interface.
When this happens, the members of the
WindowModal
interface, in JavaScript environments,
appear to actually be part of the Window
interface
(e.g. they are on the same prototype chain as the window.alert()
method).
[NoInterfaceObject] interface WindowModal { readonly attribute any dialogArguments; attribute DOMString returnValue; };
dialogArguments
Returns the argument argument that was
passed to the showModalDialog()
method.
returnValue
[ = value ]Returns the current return value for the window.
Can be set, to change the value that will be returned by the
showModalDialog()
method.
Such browsing contexts have associated dialog
arguments, which are stored along with the dialog
arguments' origin. These values are set by the showModalDialog()
method in the
algorithm above, when the browsing context is created, based on the
arguments provided to the method.
The dialogArguments
IDL attribute, on getting, must check whether its browsing context's
active document's origin is the same as the dialog arguments'
origin. If it is, then the browsing context's dialog
arguments must be returned unchanged. Otherwise, if the
dialog arguments are an object, then the empty string
must be returned, and if the dialog arguments are not
an object, then the stringification of the dialog
arguments must be returned.
These browsing contexts also have an associated return value. The return value of a browsing context must be initialized to the empty string when the browsing context is created.
The returnValue
IDL attribute, on getting, must return the return value
of its browsing context, and on setting, must set the return
value to the given new value.
The window.close()
method can be used to
close the browsing context.
Navigator
objectThe navigator
attribute of the Window
interface must return an
instance of the Navigator
interface, which represents
the identity and state of the user agent (the client), and allows
Web pages to register themselves as potential protocol and content
handlers:
interface Navigator { // objects implementing this interface also implement the interfaces given below }; Navigator implements NavigatorID; Navigator implements NavigatorOnLine; Navigator implements NavigatorContentUtils; Navigator implements NavigatorStorageUtils;
These interfaces are defined separately so that other
specifications can re-use parts of the Navigator
interface.
[Supplemental, NoInterfaceObject] interface NavigatorID { readonly attribute DOMString appName; readonly attribute DOMString appVersion; readonly attribute DOMString platform; readonly attribute DOMString userAgent; };
In certain cases, despite the best efforts of the entire industry, Web browsers have bugs and limitations that Web authors are forced to work around.
This section defines a collection of attributes that can be used to determine, from script, the kind of user agent in use, in order to work around these issues.
Client detection should always be limited to detecting known current versions; future versions and unknown versions should always be assumed to be fully compliant.
navigator
. appName
Returns the name of the browser.
navigator
. appVersion
Returns the version of the browser.
navigator
. platform
Returns the name of the platform.
navigator
. userAgent
Returns the complete User-Agent header.
appName
Must return either the string "Netscape
" or the full name of the browser, e.g. "Mellblom Browsernator
".
appVersion
Must return either the string "4.0
" or a string representing the version of the browser in detail, e.g. "1.0 (VMS; en-US) Mellblomenator/9000
".
platform
Must return either the empty string or a string representing the platform on which the browser is executing, e.g. "MacIntel
", "Win32
", "FreeBSD i386
", "WebTV OS
".
userAgent
Must return the string used for the value of the "User-Agent
" header in HTTP requests, or the empty string if no such header is ever sent.
Any information in this API that varies from user to user can be used to profile the user. In fact, if enough such information is available, a user can actually be uniquely identified. For this reason, user agent implementors are strongly urged to include as little information in this API as possible.
[Supplemental, NoInterfaceObject] interface NavigatorContentUtils { // content handler registration void registerProtocolHandler(in DOMString scheme, in DOMString url, in DOMString title); void registerContentHandler(in DOMString mimeType, in DOMString url, in DOMString title); };
The registerProtocolHandler()
method allows Web sites to register themselves as possible handlers
for particular schemes. For example, an online telephone messaging
service could register itself as a handler of the sms:
scheme ([RFC5724]), so that if the user
clicks on such a link, he is given the opportunity to use that Web
site. Analogously, the registerContentHandler()
method allows Web sites to register themselves as possible handlers
for content in a particular MIME type. For example, the
same online telephone messaging service could register itself as a
handler for text/directory
files ([RFC2425]), so that if the user has no
native application capable of handling vCards ([RFC2426]), his Web browser can instead
suggest he use that site to view contact information stored on
vCards that he opens.
navigator
. registerProtocolHandler
(scheme, url, title)navigator
. registerContentHandler
(mimeType, url, title)Registers a handler for the given scheme or content type, at the given URL, with the given title.
The string "%s
" in the URL is used as a
placeholder for where to put the URL of the content to be
handled.
Throws a SECURITY_ERR
exception if the user agent
blocks the registration (this might happen if trying to register
as a handler for "http", for instance).
Throws a SYNTAX_ERR
if the "%s
" string is missing in the URL.
User agents may, within the constraints described in this section, do whatever they like when the methods are called. A UA could, for instance, prompt the user and offer the user the opportunity to add the site to a shortlist of handlers, or make the handlers his default, or cancel the request. UAs could provide such a UI through modal UI or through a non-modal transient notification interface. UAs could also simply silently collect the information, providing it only when relevant to the user.
User agents should keep track of which sites have registered handlers (even if the user has declined such registrations) so that the user is not repeatedly prompted with the same request.
The arguments to the methods have the following meanings and corresponding implementation requirements:
registerProtocolHandler()
only)A scheme, such as ftp
or sms
. The
scheme must be compared in an ASCII case-insensitive
manner by user agents for the purposes of comparing with the
scheme part of URLs that they consider against the list of
registered handlers.
The scheme value, if it contains a colon
(as in "ftp:
"), will never match anything, since
schemes don't contain colons.
This feature is not intended to be used with non-standard protocols.
registerContentHandler()
only)A MIME type, such as
model/vnd.flatland.3dml
or
application/vnd.google-earth.kml+xml
. The MIME
type must be compared in an ASCII
case-insensitive manner by user agents for the purposes of
comparing with MIME types of documents that they consider against
the list of registered handlers.
User agents must compare the given values only to the MIME type/subtype parts of content types, not to the complete type including parameters. Thus, if mimeType values passed to this method include characters such as commas or whitespace, or include MIME parameters, then the handler being registered will never be used.
The type is compared to the MIME type used by the user agent after the sniffing algorithms have been applied.
A string used to build the URL of the page that will handle the requests.
When the user agent uses this URL, it must replace the first
occurrence of the exact literal string "%s
"
with an escaped version of the absolute URL of the
content in question (as defined below), then resolve the resulting URL, relative to the base URL of the entry
script at the time the registerContentHandler()
or registerProtocolHandler()
methods were invoked, and then navigate an appropriate browsing context to the
resulting URL using the GET method (or equivalent for
non-HTTP URLs).
To get the escaped version of the absolute URL of the content in question, the user agent must replace every character in that absolute URL that doesn't match the <query> production defined in RFC 3986 by the percent-encoded form of that character. [RFC3986]
If the user had visited a site at http://example.com/
that made the following
call:
navigator.registerContentHandler('application/x-soup', 'soup?url=%s', 'SoupWeb™')
...and then, much later, while visiting http://www.example.net/
, clicked on a link such
as:
<a href="chickenkïwi.soup">Download our Chicken Kïwi soup!</a>
...then, assuming this chickenkïwi.soup
file
was served with the MIME type
application/x-soup
, the UA might navigate to the
following URL:
http://example.com/soup?url=http://www.example.net/chickenk%C3%AFwi.soup
This site could then fetch the chickenkïwi.soup
file and do whatever it is that it does with soup (synthesize it
and ship it to the user, or whatever).
A descriptive title of the handler, which the UA might use to remind the user what the site in question is.
User agents should raise SECURITY_ERR
exceptions if
the methods are called with scheme or mimeType values that the UA deems to be
"privileged". For example, a site attempting to register a handler
for http
URLs or text/html
content in a
Web browser would likely cause an exception to be raised.
User agents must raise a SYNTAX_ERR
exception if the
url argument passed to one of these methods does
not contain the exact literal string "%s
", or if resolving the url
argument with the first occurrence of the string "%s
" removed, relative to the entry
script's base URL, is
not successful.
User agents must not raise any other exceptions (other than binding-specific exceptions, such as for an incorrect number of arguments in an JavaScript implementation).
This section does not define how the pages registered by these methods are used, beyond the requirements on how to process the url value (see above). To some extent, the processing model for navigating across documents defines some cases where these methods are relevant, but in general UAs may use this information wherever they would otherwise consider handing content to native plugins or helper applications.
UAs must not use registered content handlers to handle content that was returned as part of a non-GET transaction (or rather, as part of any non-idempotent transaction), as the remote site would not be able to fetch the same data.
These mechanisms can introduce a number of concerns, in particular privacy concerns.
Hijacking all Web usage. User agents should not
allow schemes that are key to its normal operation, such as
http
or https
, to be rerouted through
third-party sites. This would allow a user's activities to be
trivially tracked, and would allow user information, even in secure
connections, to be collected.
Hijacking defaults. It is strongly recommended that user agents do not automatically change any defaults, as this could lead the user to send data to remote hosts that the user is not expecting. New handlers registering themselves should never automatically cause those sites to be used.
Registration spamming. User agents should
consider the possibility that a site will attempt to register a
large number of handlers, possibly from multiple domains (e.g. by
redirecting through a series of pages each on a different domain,
and each registering a handler for video/mpeg
—
analogous practices abusing other Web browser features have been
used by pornography Web sites for many years). User agents should
gracefully handle such hostile attempts, protecting the user.
Misleading titles. User agents should not rely
wholly on the title argument to the methods when
presenting the registered handlers to the user, since sites could
easily lie. For example, a site hostile.example.net
could claim that it was registering the "Cuddly Bear Happy Content
Handler". User agents should therefore use the handler's domain in
any UI along with any title.
Hostile handler metadata. User agents should protect against typical attacks against strings embedded in their interface, for example ensuring that markup or escape characters in such strings are not executed, that null bytes are properly handled, that over-long strings do not cause crashes or buffer overruns, and so forth.
Leaking Intranet URLs. The mechanism described in this section can result in secret Intranet URLs being leaked, in the following manner:
No actual confidential file data is leaked in this manner, but
the URLs themselves could contain confidential information. For
example, the URL could be
http://www.corp.example.com/upcoming-aquisitions/the-sample-company.egf
,
which might tell the third party that Example Corporation is
intending to merge with The Sample Company. Implementors might wish
to consider allowing administrators to disable this feature for
certain subdomains, content types, or schemes.
Leaking secure URLs. User agents should not send
HTTPS URLs to third-party sites registered as content handlers, in
the same way that user agents do not send Referer
(sic) HTTP headers from secure
sites to third-party sites.
Leaking credentials. User agents must never send username or password information in the URLs that are escaped and included sent to the handler sites. User agents may even avoid attempting to pass to Web-based handlers the URLs of resources that are known to require authentication to access, as such sites would be unable to access the resources in question without prompting the user for credentials themselves (a practice that would require the user to know whether to trust the third-party handler, a decision many users are unable to make or even understand).
This section is non-normative.
A simple implementation of this feature for a desktop Web browser might work as follows.
The registerContentHandler()
method could display a modal dialog box:
In this dialog box, "Kittens at work" is the title of the page
that invoked the method, "http://kittens.example.org/" is the URL of
that page, "application/x-meowmeow" is the string that was passed to
the registerContentHandler()
method as its first argument (mimeType),
"http://kittens.example.org/?show=%s" was the second argument (url), and "Kittens-at-work displayer" was the third
argument (title).
If the user clicks the Cancel button, then nothing further happens. If the user clicks the "Trust" button, then the handler is remembered.
When the user then attempts to fetch a URL that uses the "application/x-meowmeow" MIME type, then it might display a dialog as follows:
In this dialog, the third option is the one that was primed by the site registering itself earlier.
If the user does select that option, then the browser, in accordance with the requirements described in the previous two sections, will redirect the user to "http://kittens.example.org/?show=data%3Aapplication/x-meowmeow;base64,S2l0dGVucyBhcmUgdGhlIGN1dGVzdCE%253D".
The registerProtocolHandler()
method would work equivalently, but for schemes instead of unknown
content types.
[Supplemental, NoInterfaceObject] interface NavigatorStorageUtils { void yieldForStorageUpdates(); };
navigator
. yieldForStorageUpdates
()If a script uses the document.cookie
API, or the
localStorage
API, the
browser will block other scripts from accessing cookies or storage
until the first script finishes.
[WEBSTORAGE]
Calling the navigator.yieldForStorageUpdates()
method tells the user agent to unblock any other scripts that may
be blocked, even though the script hasn't returned.
Values of cookies and items in the Storage
objects
of localStorage
attributes
can change after calling this method, whence its name.
[WEBSTORAGE]
The yieldForStorageUpdates()
method, when invoked, must, if the storage mutex is
owned by the event loop of the task that resulted in the method being
called, release the storage mutex so that it is once
again free. Otherwise, it must do nothing.
hidden
attributeAll HTML elements may have the hidden
content attribute set. The hidden
attribute is a boolean
attribute. When specified on an element, it indicates that
the element is not yet, or is no longer, relevant. User agents should not render elements that have the
hidden
attribute
specified.
In the following skeletal example, the attribute is used to hide the Web game's main screen until the user logs in:
<h1>The Example Game</h1> <section id="login"> <h2>Login</h2> <form> ... <!-- calls login() once the user's credentials have been checked --> </form> <script> function login() { // switch screens document.getElementById('login').hidden = true; document.getElementById('game').hidden = false; } </script> </section> <section id="game" hidden> ... </section>
The hidden
attribute must not be
used to hide content that could legitimately be shown in another
presentation. For example, it is incorrect to use hidden
to hide panels in a tabbed dialog,
because the tabbed interface is merely a kind of overflow
presentation — one could equally well just show all the form
controls in one big page with a scrollbar. It is similarly incorrect
to use this attribute to hide content just from one presentation
— if something is marked hidden
, it is hidden from all
presentations, including, for instance, screen readers.
Elements that are not hidden
should not link to or refer to elements that are hidden
.
For example, it would be incorrect to use the href
attribute to link to a
section marked with the hidden
attribute. If the content is not applicable or relevant, then there
is no reason to link to it.
It would similarly be incorrect to use the ARIA aria-describedby
attribute to
refer to descriptions that are themselves hidden
. Hiding a section means that it
is not applicable or relevant to anyone at the current time, so
clearly it cannot be a valid description of content the user can
interact with.
Elements in a section hidden by the hidden
attribute are still active,
e.g. scripts and form controls in such sections still execute
and submit respectively. Only their presentation to the user
changes.
The hidden
IDL
attribute must reflect the content attribute of the
same name.
click
()Acts as if the element was clicked.
Each element has a click in progress flag, initially set to false.
The click()
method must
run these steps:
If the element's click in progress flag is set to true, then abort these steps.
Set the click in progress flag on the element to true.
If the element has a defined activation behavior,
run synthetic click activation steps on the
element. Otherwise, fire a click
event at
the element.
Set the click in progress flag on the element to false.
When an element is focused, key events received by the document must be targeted at that element. There may be no element focused; when no element is focused, key events received by the document must be targeted at the body element.
User agents may track focus for each browsing
context or Document
individually, or may support
only one focused element per top-level browsing context
— user agents should follow platform conventions in this
regard.
Which elements within a top-level browsing context currently have focus must be independent of whether or not the top-level browsing context itself has the system focus.
When an element is focused, the element matches the
CSS :focus
pseudo-class.
tabindex
attributeThe tabindex
content attribute specifies whether the element is focusable,
whether it can be reached using sequential focus navigation, and the
relative order of the element for the purposes of sequential focus
navigation. The name "tab index" comes from the common use of the
"tab" key to navigate through the focusable elements. The term
"tabbing" refers to moving forward through the focusable elements
that can be reached using sequential focus navigation.
The tabindex
attribute, if
specified, must have a value that is a valid
integer.
If the attribute is specified, it must be parsed using the rules for parsing integers. The attribute's values have the following meanings:
The user agent should follow platform conventions to determine if the element is to be focusable and, if so, whether the element can be reached using sequential focus navigation, and if so, what its relative order should be.
The user agent must allow the element to be focused, but should not allow the element to be reached using sequential focus navigation.
The user agent must allow the element to be focused, should allow the element to be reached using sequential focus navigation, and should follow platform conventions to determine the element's relative order.
The user agent must allow the element to be focused, should allow the element to be reached using sequential focus navigation, and should place the element in the sequential focus navigation order so that it is:
tabindex
attribute has been
omitted or whose value, when parsed, returns an error,tabindex
attribute has a value equal
to or less than zero,tabindex
attribute has a value
greater than zero but less than the value of the tabindex
attribute on the
element,tabindex
attribute has a value equal
to the value of the tabindex
attribute on the element but that is earlier in the document in
tree order than the element,tabindex
attribute has a value equal
to the value of the tabindex
attribute on the element but that is later in the document in
tree order than the element, andtabindex
attribute has a value
greater than the value of the tabindex
attribute on the
element.An element is specially focusable if the tabindex
attribute's definition above
defines the element to be focusable.
An element that is specially focusable but does not otherwise have an activation behavior defined has an activation behavior that does nothing.
This means that an element that is only focusable
because of its tabindex
attribute
will fire a click
event in response
to a non-mouse activation (e.g. hitting the "enter" key while the
element is focused).
The tabIndex
IDL
attribute must reflect the value of the tabindex
content attribute. Its default
value is 0 for elements that are focusable and −1 for
elements that are not focusable.
An element is focusable if the user agent's default
behavior allows it to be focusable or if the element is
specially focusable, but only if the element is either
being rendered or is a
descendant of a canvas
element that
represents embedded content.
User agents should make the following elements focusable, unless platform conventions dictate otherwise:
a
elements that have an href
attributelink
elements that have an href
attributebutton
elements that are not disabledinput
elements whose type
attribute are not in the
Hidden state and that
are not disabledselect
elements that are not disabledtextarea
elements that are not disabledcommand
elements that do not have a disabled
attributedraggable
attribute set, if that would enable the user agent to allow the
user to begin a drag operations for those elements without the use
of a pointing deviceIn addition, each shape that is generated for an
area
element should be focusable, unless
platform conventions dictate otherwise. (A single area
element can correspond to multiple shapes, since image maps can be
reused with multiple images on a page.)
The user agent may also make part of a details
element's rendering focusable, to enable the element to be opened or
closed using keyboard input. However, this is distinct from the
details
or summary
element being
focusable.
The focusing steps are as follows:
If the element is not in a
Document
, or if the element's
Document
has no browsing context, or if
the element's Document
's browsing context
has no top-level browsing context, then abort these
steps.
If focusing the element will remove the focus from another element, then run the unfocusing steps for that element.
Make the element the currently focused element in its top-level browsing context.
Some elements, most notably area
, can correspond
to more than one distinct focusable area. If a particular area was
indicated when the element was focused, then that is the area that
must get focus; otherwise, e.g. when using the focus()
method, the first such region in
tree order is the one that must be focused.
The user agent may apply relevant platform-specific conventions for focusing widgets.
For example, some platforms select the contents of a text field when that field is focused.
Fire a simple event named focus
at the element.
User agents must synchronously run the focusing steps for an element whenever the user moves the focus to a focusable element.
The unfocusing steps are as follows:
If the element is an input
element, and the
change
event applies to the
element, and the element does not have a defined activation
behavior, and the user has changed the element's value or its list of selected files
while the control was focused without committing that change, then
fire a simple event that bubbles named change
at the element.
Unfocus the element.
Fire a simple event named blur
at the element.
When an element that is focused stops being a focusable element, or stops being focused without another element being explicitly focused in its stead, the user agent should synchronously run the focusing steps for the body element, if there is one; if there is not, then the user agent should synchronously run the unfocusing steps for the affected element only.
For example, this might happen because the
element is removed from its Document
, or has a hidden
attribute added. It would also
happen to an input
element when the element gets disabled.
activeElement
Returns the currently focused element.
hasFocus
()Returns true if the document has focus; otherwise, returns false.
focus
()Focuses the window. Use of this method is discouraged. Allow the user to control window focus instead.
blur
()Unfocuses the window. Use of this method is discouraged. Allow the user to control window focus instead.
The activeElement
attribute on HTMLDocument
objects must return the
element in the document that is focused. If no element in the
Document
is focused, this must return the body
element.
The hasFocus()
method
on HTMLDocument
objects must return true if the
Document
's browsing context is focused,
and all its ancestor
browsing contexts are also focused, and the top-level
browsing context has the system focus. If the
Document
has no browsing context or if its
browsing context has no top-level browsing
context, then the method will always return false.
The focus()
method on the Window
object, when invoked, provides a
hint to the user agent that the script believes the user might be
interested in the contents of the browsing context of
the Window
object on which the method was invoked.
User agents are encouraged to have this focus()
method trigger some kind of
notification.
The blur()
method
on the Window
object, when invoked, provides a hint to
the user agent that the script believes the user probably is not
currently interested in the contents of the browsing
context of the Window
object on which the method
was invoked, but that the contents might become interesting again in
the future.
User agents are encouraged to ignore calls to this blur()
method entirely.
Historically the focus()
and blur()
methods actually affected the
system focus, but hostile sites widely abuse this behavior to the
user's detriment.
focus
()Focuses the element.
blur
()Unfocuses the element. Use of this method is discouraged. Focus another element instead.
Do not use this method to hide the focus ring if you find the focus ring unsightly. Instead, use a CSS rule to override the 'outline' property.
For example, to hide the outline from links, you could use:
:link:focus, :visited:focus { outline: none; }
The focus()
method,
when invoked, must run the following algorithm:
If the element is marked as locked for focus, then abort these steps.
If the element is not focusable, then abort these steps.
Mark the element as locked for focus.
If the element is not already focused, run the focusing steps for the element.
Unmark the element as locked for focus.
The blur()
method, when
invoked, should run the focusing steps for the
body element, if there is one; if there is not, then it
should run the unfocusing steps for the element on
which the method was called instead. User agents may selectively or
uniformly ignore calls to this method for usability reasons.
For example, if the blur()
method is unwisely being used to
remove the focus ring for aesthetics reasons, the page would become
unusable by keyboard users. Ignoring calls to this method would thus
allow keyboard users to interact with the page.
This section is non-normative.
Each element that can be activated or focused can be assigned a
single key combination to activate it, using the accesskey
attribute.
The exact shortcut is determined by the user agent, based on
information about the user's keyboard, what keyboard shortcuts
already exist on the platform, and what other shortcuts have been
specified on the page, using the information provided in the accesskey
attribute as a guide.
In order to ensure that a relevant keyboard shortcut is available
on a wide variety of input devices, the author can provide a number
of alternatives in the accesskey
attribute.
Each alternative consists of a single character, such as a letter or digit.
User agents can provide users with a list of the keyboard
shortcuts, but authors are encouraged to do so also. The accessKeyLabel
IDL attribute
returns a string representing the actual key combination assigned by
the user agent.
accesskey
attributeAll HTML elements may have the accesskey
content attribute set. The
accesskey
attribute's value is
used by the user agent as a guide for creating a keyboard shortcut
that activates or focuses the element.
If specified, the value must be an ordered set of unique space-separated tokens that are case-sensitive, each of which must be exactly one Unicode code point in length.
In the following example, a variety of links are given with access keys so that keyboard users familiar with the site can more quickly navigate to the relevant pages:
<nav> <p> <a title="Consortium Activities" accesskey="A" href="/Consortium/activities">Activities</a> | <a title="Technical Reports and Recommendations" accesskey="T" href="/TR/">Technical Reports</a> | <a title="Alphabetical Site Index" accesskey="S" href="/Consortium/siteindex">Site Index</a> | <a title="About This Site" accesskey="B" href="/Consortium/">About Consortium</a> | <a title="Contact Consortium" accesskey="C" href="/Consortium/contact">Contact</a> </p> </nav>
In the following example, the search field is given two possible access keys, "s" and "0" (in that order). A user agent on a device with a full keyboard might pick Ctrl+Alt+S as the shortcut key, while a user agent on a small device with just a numeric keypad might pick just the plain unadorned key 0:
<form action="/search"> <label>Search: <input type="search" name="q" accesskey="s 0"></label> <input type="submit"> </form>
In the following example, a button has possible access keys described. A script then tries to update the button's label to advertise the key combination the user agent selected.
<input type=submit accesskey="N @ 1" value="Compose"> ... <script> function labelButton(button) { if (button.accessKeyLabel) button.value += ' (' + button.accessKeyLabel + ')'; } var inputs = document.getElementsByTagName('input'); for (var i = 0; i < inputs.length; i += 1) { if (inputs[i].type == "submit") labelButton(inputs[i]); } </script>
On one user agent, the button's label might become "Compose (⌘N)". On another, it might become "Compose (Alt+⇧+1)". If the user agent doesn't assign a key, it will be just "Compose". The exact string depends on what the assigned access key is, and on how the user agent represents that key combination.
An element's assigned access key is a key combination
derived from the element's accesskey
content attribute.
Initially, an element must not have an assigned access
key.
Whenever an element's accesskey
attribute is set, changed,
or removed, the user agent must update the element's assigned
access key by running the following steps:
If the element has no accesskey
attribute, then skip to the
fallback step below.
Otherwise, split the attribute's value on spaces, and let keys be the resulting tokens.
For each value in keys in turn, in the order the tokens appeared in the attribute's value, run the following substeps:
If the value is not a string exactly one Unicode code point in length, then skip the remainder of these steps for this value.
If the value does not correspond to a key on the system's keyboard, then skip the remainder of these steps for this value.
If the user agent can find a combination of modifier keys that, with the key that corresponds to the value given in the attribute, can be used as a shortcut key, then the user agent may assign that combination of keys as the element's assigned access key and abort these steps.
Fallback: Optionally, the user agent may assign a key combination of its choosing as the element's assigned access key and then abort these steps.
If this step is reached, the element has no assigned access key.
Once a user agent has selected and assigned an access key for an
element, the user agent should not change the element's
assigned access key unless the accesskey
content attribute is changed
or the element is moved to another Document
.
When the user presses the key combination corresponding to the assigned access key for an element, if the element defines a command, and the command's Hidden State facet is false (visible), and the command's Disabled State facet is also false (enabled), then the user agent must trigger the Action of the command.
User agents may expose elements that have an accesskey
attribute in other ways as
well, e.g. in a menu displayed in response to a specific key
combination.
The accessKey
IDL
attribute must reflect the accesskey
content attribute.
The accessKeyLabel
IDL
attribute must return a string that represents the element's
assigned access key, if any. If the element does not
have one, then the IDL attribute must return the empty string.
contenteditable
attributeThe contenteditable
attribute is an enumerated attribute whose keywords are
the empty string, true
, and false
. The empty string and the true
keyword map to the true state. The false
keyword maps to the false state. In
addition, there is a third state, the inherit state, which is
the missing value default (and the invalid value
default).
The true state indicates that the element is editable. The inherit state indicates that the element is editable if its parent is. The false state indicates that the element is not editable.
Specifically, if an HTML
element has a contenteditable
attribute set to
the true state, or it has its contenteditable
attribute set to
the inherit state and if its nearest ancestor HTML element with the contenteditable
attribute set to
a state other than the inherit state has its attribute set to the
true state, or if it and its ancestors all have their contenteditable
attribute set to
the inherit state but the Document
has designMode
enabled, then the
UA must treat the element as editable (as described
below).
Otherwise, either the HTML
element has a contenteditable
attribute set to
the false state, or its contenteditable
attribute is set
to the inherit state and its nearest ancestor HTML element with the contenteditable
attribute set to
a state other than the inherit state has its attribute set to the
false state, or all its ancestors have their contenteditable
attribute set to
the inherit state and the Document
itself has designMode
disabled; either
way, the element is not editable.
contentEditable
[ = value ]Returns "true
", "false
", or "inherit
", based
on the state of the contenteditable
attribute.
Can be set, to change that state.
Throws a SYNTAX_ERR
exception if the new value
isn't one of those strings.
isContentEditable
Returns true if the element is editable; otherwise, returns false.
The contentEditable
IDL
attribute, on getting, must return the string "true
" if the content attribute is set to the true
state, "false
" if the content attribute is set
to the false state, and "inherit
"
otherwise. On setting, if the new value is an ASCII
case-insensitive match for the string "inherit
" then the content attribute must be removed,
if the new value is an ASCII case-insensitive match for
the string "true
" then the content attribute
must be set to the string "true
", if the new
value is an ASCII case-insensitive match for the string
"false
" then the content attribute must be set
to the string "false
", and otherwise the
attribute setter must raise a SYNTAX_ERR
exception.
The isContentEditable
IDL attribute, on getting, must return true if the element is
editable, and false otherwise.
If an element is editable and its parent element is not, or if an element is editable and it has no parent element, then the element is an editing host. Editable elements can be nested. Editing hosts are typically focusable and typically form part of the tab order. An editing host can contain non-editable sections, these are handled as described below. An editing host can contain non-editable sections that contain further editing hosts.
When an editing host has focus, it must have a caret position that specifies where the current editing position is. It may also have a selection.
How the caret and selection are represented depends entirely on the UA.
There are several actions that the user agent should allow the user to perform while the user is interacting with an editing host. How exactly each action is triggered is not defined for every action, but when it is not defined, suggested key bindings are provided to guide implementors.
User agents must allow users to move the caret to any
position within an editing host, even into nested editable
elements. This could be triggered as the default action of keydown
events with various key
identifiers and as the default action of mousedown
events.
User agents must allow users to change the selection within
an editing host, even into nested editable elements. User agents
may prevent selections from being made in ways that cross from
editable elements into non-editable elements (e.g. by making each
non-editable descendant atomically selectable, but not allowing
text selection within them). This could be triggered as the default
action of keydown
events with
various key identifiers and as the default action of mousedown
events.
This action must be triggered as the default action of a
textInput
event, and may be
triggered by other commands as well. It must cause the user agent
to insert the specified text (given by the event object's data
attribute in the case of the textInput
event) at the caret.
If the caret is positioned somewhere where phrasing
content is not allowed (e.g. inside an empty ol
element), then the user agent must not insert the text directly at
the caret position. In such cases the behavior is UA-dependent,
but user agents must not, in response to a request to insert text,
generate a DOM that is less conformant than the DOM prior to the
request.
User agents should allow users to insert new paragraphs into elements that contains only content other than paragraphs.
UAs should offer a way for the user to request that the
current paragraph be broken at the caret, e.g. as the default
action of a keydown
event whose
identifier is the "Enter" key and that has no modifiers set.
The exact behavior is UA-dependent, but user agents must not, in response to a request to break a paragraph, generate a DOM that is less conformant than the DOM prior to the request.
UAs should offer a way for the user to request an explicit
line break at the caret position without breaking the paragraph,
e.g. as the default action of a keydown
event whose identifier is the
"Enter" key and that has a shift modifier set. Line separators are
typically found within a poem verse or an address. To insert a line
break, the user agent must insert a br
element.
If the caret is positioned somewhere where phrasing
content is not allowed (e.g. in an empty ol
element), then the user agent must not insert the br
element directly at the caret position. In such cases the behavior
is UA-dependent, but user agents must not, in response to a request
to insert a line separator, generate a DOM that is less conformant
than the DOM prior to the request.
UAs should offer a way for the user to delete text and
elements, including non-editable descendants, e.g. as the default
action of keydown
events whose
identifiers are "U+0008" or "U+007F".
Five edge cases in particular need to be considered carefully when implementing this feature: backspacing at the start of an element, backspacing when the caret is immediately after an element, forward-deleting at the end of an element, forward-deleting when the caret is immediately before an element, and deleting a selection whose start and end points do not share a common parent node.
In any case, the exact behavior is UA-dependent, but user agents must not, in response to a request to delete text or an element, generate a DOM that is less conformant than the DOM prior to the request.
UAs should offer the user the ability to mark text and paragraphs with semantics that HTML can express.
UAs should similarly offer a way for the user to insert empty semantic elements to subsequently fill by entering text manually.
UAs should also offer a way to remove those semantics from marked up text, and to remove empty semantic element that have been inserted.
In response to a request from a user to mark text up in italics,
user agents should use the i
element to represent the
semantic. The em
element should be used only if the
user agent is sure that the user means to indicate stress
emphasis.
In response to a request from a user to mark text up in bold,
user agents should use the b
element to represent the
semantic. The strong
element should be used only if
the user agent is sure that the user means to indicate
importance.
The exact behavior is UA-dependent, but user agents must not, in response to a request to wrap semantics around some text or to insert or remove a semantic element, generate a DOM that is less conformant than the DOM prior to the request.
UAs should offer a way for the user to move images and other non-editable parts around the content within an editing host. This may be done using the drag and drop mechanism. User agents must not, in response to a request to move non-editable elements nested inside editing hosts, generate a DOM that is less conformant than the DOM prior to the request.
When an editable form control is edited, the
changes must be reflected in both its current value and
its default value. For input
elements this means
updating the defaultValue
IDL attribute as
well as the value
IDL
attribute; for select
elements it means updating the
option
elements' defaultSelected
IDL
attribute as well as the selected
IDL attribute; for
textarea
elements this means updating the defaultValue
IDL attribute
as well as the value
IDL
attribute. (Updating the default*
IDL
attributes causes content attributes to be updated as well.)
User agents may perform several commands per user request; for example if the user selects a block of text and hits Enter, the UA might interpret that as a request to delete the content of the selection followed by a request to break the paragraph at that position.
User agents may add DOM changes entries to the
undo transaction history of the editing
host's Document
object each time an action is
triggered.
All of the actions defined above, whether triggered by the user
or programmatically (e.g. by execCommand()
commands),
must fire mutation events as appropriate.
Documents have a designMode
, which
can be either enabled or disabled.
designMode
[ = value ]Returns "on
" if the document is editable,
and "off
" if it isn't.
Can be set, to change the document's current state.
The designMode
IDL
attribute on the Document
object takes two values,
"on
" and "off
". When it
is set, the new value must be compared in an ASCII
case-insensitive manner to these two values. If it matches
the "on
" value, then designMode
must be enabled,
and if it matches the "off
" value, then designMode
must be
disabled. Other values must be ignored.
When designMode
is
enabled, the IDL attribute must return the value "on
", and when it is disabled, it must return the
value "off
".
The last state set must persist until the document is destroyed
or the state is changed. Initially, documents must have their designMode
disabled.
User agents can support the checking of spelling and grammar of
editable text, either in form controls (such as the value of
textarea
elements), or in elements in an editing
host (using contenteditable
).
For each element, user agents must establish a default behavior, either through defaults or through preferences expressed by the user. There are three possible default behaviors for each element:
The spellcheck
attribute is an enumerated attribute whose keywords are
the empty string, true
and false
. The empty string and the true
keyword map to the true state. The false
keyword maps to the false state. In
addition, there is a third state, the default state, which is
the missing value default (and the invalid value
default).
The true state indicates that the element is to have its
spelling and grammar checked. The default state indicates
that the element is to act according to a default behavior, possibly
based on the parent element's own spellcheck
state. The false
state indicates that the element is not to be checked.
spellcheck
[ = value ]Returns true if the element is to have its spelling and grammar checked; otherwise, returns false.
Can be set, to override the default and set the spellcheck
content attribute.
The spellcheck
IDL
attribute, on getting, must return true if the element's spellcheck
content attribute is in
the true state, or if the element's spellcheck
content attribute is in
the default state and the element's default behavior is true-by-default, or
if the element's spellcheck
content attribute is in the default state and the element's
default behavior is
inherit-by-default
and the element's parent element's spellcheck
IDL attribute would return
true; otherwise, if none of those conditions applies, then the
attribute must instead return false.
The spellcheck
IDL attribute is not affected by user preferences that override the
spellcheck
content attribute,
and therefore might not reflect the actual spellchecking state.
On setting, if the new value is true, then the element's spellcheck
content attribute must be
set to the literal string "true
", otherwise it
must be set to the literal string "false
".
User agents must only consider the following pieces of text as checkable for the purposes of this feature:
input
elements to which the readonly
attribute applies,
whose type
attributes are not
in the Password
state, and that are not immutable (i.e. that do not
have the readonly
attribute specified and that are not disabled).textarea
elements that do not have a
readonly
attribute and
that are not disabled.For text that is part of a text node, the element
with which the text is associated is the element that is the
immediate parent of the first character of the word, sentence, or
other piece of text. For text in attributes, it is the attribute's
element. For the values of input
and
textarea
elements, it is the element itself.
To determine if a word, sentence, or other piece of text in an applicable element (as defined above) is to have spelling- and/or grammar-checking enabled, the UA must use the following algorithm:
spellcheck
content
attribute, then: if that attribute is in the true state,
then checking is enabled; otherwise, if that attribute is in the
false state, then checking is disabled.spellcheck
content attribute that is
not in the default state, then: if the nearest such
ancestor's spellcheck
content
attribute is in the true state, then checking is enabled;
otherwise, checking is disabled.If the checking is enabled for a word/sentence/text, the user
agent should indicate spelling and/or grammar errors in that
text. User agents should take into account the other semantics given
in the document when suggesting spelling and grammar
corrections. User agents may use the language of the element to
determine what spelling and grammar rules to use, or may use the
user's preferred language settings. UAs should use
input
element attributes such as pattern
to ensure that the
resulting value is valid, where possible.
If checking is disabled, the user agent should not indicate spelling or grammar errors for that text.
The element with ID "a" in the following example would be the one used to determine if the word "Hello" is checked for spelling errors. In this example, it would not be.
<div contenteditable="true"> <span spellcheck="false" id="a">Hell</span><em>o!</em> </div>
The element with ID "b" in the following example would have
checking enabled (the leading space character in the attribute's
value on the input
element causes the attribute to be
ignored, so the ancestor's value is used instead, regardless of the
default).
<p spellcheck="true"> <label>Name: <input spellcheck=" false" id="b"></label> </p>
This specification does not define the user interface for spelling and grammar checkers. A user agent could offer on-demand checking, could perform continuous checking while the checking is enabled, or could use other interfaces.
This section defines an event-based drag-and-drop mechanism.
This specification does not define exactly what a drag-and-drop operation actually is.
On a visual medium with a pointing device, a drag operation could
be the default action of a mousedown
event that is followed by a
series of mousemove
events, and
the drop could be triggered by the mouse being released.
On media without a pointing device, the user would probably have to explicitly indicate his intention to perform a drag-and-drop operation, stating what he wishes to drag and where he wishes to drop it, respectively.
However it is implemented, drag-and-drop operations must have a starting point (e.g. where the mouse was clicked, or the start of the selection or element that was selected for the drag), may have any number of intermediate steps (elements that the mouse moves over during a drag, or elements that the user picks as possible drop points as he cycles through possibilities), and must either have an end point (the element above which the mouse button was released, or the element that was finally selected), or be canceled. The end point must be the last element selected as a possible drop point before the drop occurs (so if the operation is not canceled, there must be at least one element in the middle step).
This section is non-normative.
To make an element draggable is simple: give the element a draggable
attribute, and set an event
listener for dragstart
that
stores the data being dragged.
The event handler typically needs to check that it's not a text
selection that is being dragged, and then needs to store data into
the DataTransfer
object and set the allowed effects
(copy, move, link, or some combination).
For example:
<p>What fruits do you like?</p> <ol ondragstart="dragStartHandler(event)"> <li draggable="true" data-value="fruit-apple">Apples</li> <li draggable="true" data-value="fruit-orange">Oranges</li> <li draggable="true" data-value="fruit-pear">Pears</li> </ol> <script> var internalDNDType = 'text/x-example'; // set this to something specific to your site function dragStartHandler(event) { if (event.target instanceof HTMLLIElement) { // use the element's data-value="" attribute as the value to be moving: event.dataTransfer.setData(internalDNDType, event.target.dataset.value); event.dataTransfer.effectAllowed = 'move'; // only allow moves } else { event.preventDefault(); // don't allow selection to be dragged } } </script>
To accept a drop, the drop target has to have a dropzone
attribute and listen to the
drop
event.
The value of the dropzone
attribute specifies what kind of data to accept (e.g. "s:text/plain
" to accept any text strings, or
"f:image/png
" to accept a PNG image file) and what kind
of feedback to give (e.g. "move
" to indicate that the
data will be moved).
Instead of using the dropzone
attribute, a drop target can
handle the dragenter
event (to
report whether or not the drop target is to accept the drop) and the
dragover
event (to specify what
feedback is to be shown to the user).
The drop
event allows the actual
drop to be performed. This event needs to be canceled, so that the
dropEffect
attribute's value can be used by the source (otherwise it's
reset).
For example:
<p>Drop your favorite fruits below:</p> <ol dropzone="move s:text/x-example" ondrop="dropHandler(event)"> <-- don't forget to change the "text/x-example" type to something specific to your site --> </ol> <script> var internalDNDType = 'text/x-example'; // set this to something specific to your site function dropHandler(event) { var li = document.createElement('li'); var data = event.dataTransfer.getData(internalDNDType); if (data == 'fruit-apple') { li.textContent = 'Apples'; } else if (data == 'fruit-orange') { li.textContent = 'Oranges'; } else if (data == 'fruit-pear') { li.textContent = 'Pears'; } else { li.textContent = 'Unknown Fruit'; } event.target.appendChild(li); } </script>
To remove the original element (the one that was dragged) from
the display, the dragend
event
can be used.
For our example here, that means updating the original markup to handle that event:
<p>What fruits do you like?</p> <ol ondragstart="dragStartHandler(event)" ondragend="dragEndHandler(event)"> ...as before... </ol> <script> function dragStartHandler(event) { // ...as before... } function dragEndHandler(event) { // remove the dragged element event.target.parentNode.removeChild(event.target); } </script>
The data that underlies a drag-and-drop operation, known as the drag data store, consists of the following information:
A drag data store item list, which is a list of items representing the dragged data, each consisting of the following information:
The kind of data:
Text.
Binary data with a file name.
A Unicode string giving the type or format of the data, generally given by a MIME type. Some values that are not MIME types are special-cased for legacy reasons. The API does not enforce the use of MIME types; other values can be used as well. In all cases, however, the values are all converted to ASCII lowercase by the API.
Strings that contain space characters cannot be used with the dropzone
attribute, so authors are
encouraged to use only MIME types
or custom strings (without spaces).
There is a limit of one Plain Unicode string item per item type string.
A Unicode or binary string, in some cases with a file name (itself a Unicode string), as per the drag data item kind.
The drag data store item list is ordered in the order that the items were added to the list; most recently added last.
The following information, used to generate the UI feedback during the drag:
A drag data store mode, which is one of the following:
For the dragstart
event.
New data can be added to the drag data store.
For the drop
event. The list of
items representing dragged data can be read, including the data.
No new data can be added.
For all other events. The formats and kinds in the drag data store list of items representing dragged data can be enumerated, but the data itself is unavailable and no new data can be added.
A drag data store allowed effects state, which is a string.
When a drag data store is created, it must be initialized such that its
drag data store item list is empty, it has no
drag data store default feedback, its drag data
store elements list is empty, it has no drag data store
bitmap / drag data store hot spot coordinate,
its drag data store mode is protected mode, and its drag data
store allowed effects state is the string "uninitialized
".
DataTransfer
interfaceDataTransfer
objects are used to expose the
drag data store that underlies a drag-and-drop
operation.
interface DataTransfer { attribute DOMString dropEffect; attribute DOMString effectAllowed; readonly attribute DataTransferItems items; void setDragImage(in Element image, in long x, in long y); void addElement(in Element element); /* old interface */ readonly attribute DOMStringList types; DOMString getData(in DOMString format); void setData(in DOMString format, in DOMString data); void clearData(in optional DOMString format); readonly attribute FileList files; };
dropEffect
[ = value ]Returns the kind of operation that is currently selected. If
the kind of operation isn't one of those that is allowed by the
effectAllowed
attribute, then the operation will fail.
Can be set, to change the selected operation.
The possible values are "none
", "copy
", "link
", and "move
".
effectAllowed
[ = value ]Returns the kinds of operations that are to be allowed.
Can be set, to change the allowed operations.
The possible values are "none
", "copy
", "copyLink
", "copyMove
", "link
", "linkMove
", "move
", "all
", and "uninitialized
",
items
Returns a DataTransferItems
object, with the drag data.
setDragImage
(element, x, y)Uses the given element to update the drag feedback, replacing any previously specified feedback.
addElement
(element)Adds the given element to the list of elements used to render the drag feedback.
types
Returns a DOMStringList
listing the formats that
were set in the dragstart
event. In addition, if any files are being dragged, then one of
the types will be the string "Files
".
getData
(format)Returns the specified data. If there is no such data, returns the empty string.
setData
(format, data)Adds the specified data.
clearData
( [ format ] )Removes the data of the specified formats. Removes all data if the argument is omitted.
files
Returns a FileList
of the files being dragged, if any.
DataTransfer
objects are used during the drag-and-drop events, and are only valid while
those events are being dispatched.
A DataTransfer
object is associated with a
drag data store while it is valid.
The dropEffect
attribute controls the drag-and-drop feedback that the user is given
during a drag-and-drop operation. When the DataTransfer
object is created, the dropEffect
attribute is
set to a string value. On getting, it must return its current value.
On setting, if the new value is one of "none
",
"copy
", "link
", or
"move
", then the attribute's current value
must be set to the new value. Other values must be ignored.
The effectAllowed
attribute is used in the drag-and-drop processing model to
initialize the dropEffect
attribute
during the dragenter
and dragover
events. When the
DataTransfer
object is created, the effectAllowed
attribute is set to a string value. On getting, it must return its
current value. On setting, if the new value is one of "none
", "copy
", "copyLink
", "copyMove
", "link
", "linkMove
", "move
", "all
", or "uninitialized
", then the attribute's current value
must be set to the new value. Other values must be ignored.
The items
attribute must return a DataTransferItems
object
associated with the DataTransfer
object. The same
object must be returned each time.
The setDragImage(element, x, y)
method must run the following
steps:
If the DataTransfer
object is no longer
associated with a drag data store, abort these steps.
Nothing happens.
If the drag data store's mode is not in the read/write mode, abort these steps. Nothing happens.
If the element argument is an
img
element, then set the drag data store
bitmap to the element's image (at its intrinsic size);
otherwise, set the drag data store bitmap to an image
generated from the given element (the exact mechanism for doing so
is not currently specified).
Set the drag data store hot spot coordinate to the given x, y coordinate.
The addElement(element)
method is an alternative way of
specifying how the user agent is to render the drag feedback. The method
must run the following steps:
If the DataTransfer
object is no longer
associated with a drag data store, abort these steps.
Nothing happens.
If the drag data store's mode is not in the read/write mode, abort these steps. Nothing happens.
Add the given element to the element's drag data store elements list.
The difference between setDragImage()
and
addElement()
is
that the latter automatically generates the image based on the
current rendering of the elements added (potentially keeping it
updated as the drag continues, e.g. if the elements include an
actively playing video), whereas the former uses the exact specified
image at the time the method is invoked.
The types
attribute must return a live DOMStringList
giving the strings that the following steps would produce. The same
object must be returned each time.
Start with an empty list L.
If the DataTransfer
object is no longer
associated with a drag data store, the
DOMStringList
is empty. Abort these steps; return the
empty list L.
For each item in the drag data store item list whose kind is Plain Unicode string, add an entry to the list L consisting of the item's type string.
If there are any items in the drag data store item
list whose kind
is File, then add an entry to the list L
consisting of the string "Files
". (This value
can be distinguished from the other values because it is not
lowercase.)
The strings produced by these steps are those in the list L.
The getData(format)
method
must run the following steps:
If the DataTransfer
object is no longer
associated with a drag data store, return the empty
string and abort these steps.
If the drag data store's mode is in the protected mode, return the empty string and abort these steps.
Let format be the first argument, converted to ASCII lowercase.
Let convert-to-URL be false.
If format equals "text
", change it to "text/plain
".
If format equals "url
", change it to "text/uri-list
" and set convert-to-URL to true.
If there is no item in the drag data store item list whose kind is Plain Unicode string and whose type string is equal to format, return the empty string and abort these steps.
Let result be the data of the item in the drag data store item list whose kind is Plain Unicode string and whose type string is equal to format.
If convert-to-URL is true, then parse
result as appropriate for text/uri-list
data, and then set result to the first URL from the list, if any, or
the empty string otherwise. [RFC2483]
Return result.
The setData(format, data)
method
must run the following steps:
If the DataTransfer
object is no longer
associated with a drag data store, abort these steps.
Nothing happens.
If the drag data store's mode is not the read/write mode, abort these steps. Nothing happens.
Let format be the first argument, converted to ASCII lowercase.
If format equals "text
", change it to "text/plain
".
If format equals "url
", change it to "text/uri-list
".
Remove the item in the drag data store item list whose kind is Plain Unicode string and whose type string is equal to format, if there is one.
Add an item to the drag data store item list whose kind is Plain Unicode string, whose type string is equal to format, and whose data is the string given by the method's second argument.
The clearData()
method must run the following steps:
If the DataTransfer
object is no longer
associated with a drag data store, abort these steps.
Nothing happens.
If the drag data store's mode is not the read/write mode, abort these steps. Nothing happens.
If the method was called with no arguments, remove each item in the drag data store item list whose kind is Plain Unicode string, and abort these steps.
Let format be the first argument, converted to ASCII lowercase.
If format equals "text
", change it to "text/plain
".
If format equals "url
", change it to "text/uri-list
".
Remove the item in the drag data store item list whose kind is Plain Unicode string and whose type string is equal to format, if there is one.
The clearData()
method does
not affect whether any files were included in the drag, so the types
attribute's list might
still not be empty after calling clearData()
(it would
still contain the "Files
" string if any files
were included in the drag).
The files
attribute must return a live FileList
sequence consisting of File
objects representing the
files found by the following steps. The same object must be returned
each time. Furthermore, for a given FileList
object and
a given underlying file, the same File
object must be
used each time.
Start with an empty list L.
If the DataTransfer
object is no longer
associated with a drag data store, the
FileList
is empty. Abort these steps; return the
empty list L.
If the drag data store's mode is in the protected mode, abort these steps; return the empty list L.
For each item in the drag data store item list whose kind is File , add the item's data (the file, in particular its name and contents, as well as its type) to the list L.
The files found by these steps are those in the list L.
This version of the API does not expose the types of the files during the drag.
DataTransferItems
interfaceEach DataTransfer
object is associated with a
DataTransferItems
object.
interface DataTransferItems { readonly attribute unsigned long length; getter DataTransferItem (in unsigned long index); deleter void (in unsigned long index); void clear(); DataTransferItem add(in DOMString data, in DOMString type); DataTransferItem add(in File data);};
length
Returns the number of items in the drag data store.
Returns the DataTransferItem
object representing the indexth entry in the drag data store.
delete
items[index]Removes the indexth entry in the drag data store.
clear
()Removes all the entries in the drag data store.
add
(data)add
(data, type)Adds a new entry for the given data to the drag data store. If the data is plain text then a type string has to be provided also.
While the DataTransferItems
object's
DataTransfer
object is associated with a drag
data store, the DataTransferItems
object's
mode is the same as the drag data store mode.
When the DataTransferItems
object's
DataTransfer
object is not associated with a
drag data store, the DataTransferItems
object's mode is the disabled mode. The drag
data store referenced in this section (which is used only
when the DataTransferItems
object is not in the
disabled mode) is the drag data store with which
the DataTransferItems
object's
DataTransfer
object is associated.
The length
attribute must return zero if the object is in the disabled
mode; otherwise it must return the number of items in the
drag data store item list.
When a DataTransferItems
object is not in the
disabled mode, its supported property indices
are the numbers in the range
0 .. n-1,
where n is the number of items in the drag
data store item list.
To determine the value of
an indexed property i of a
DataTransferItems
object, the user agent must return a
DataTransferItem
object representing the ith item in the drag data store. The
same object must be returned each time a particular item is obtained
from this DataTransferItems
object. The
DataTransferItem
object must be associated with the
same DataTransfer
object as the
DataTransferItems
object when it is first created.
To delete an
existing indexed property i of a
DataTransferItems
object, the user agent must run these
steps:
If the DataTransferItems
object is not in the
read/write mode, throw an
INVALID_STATE_ERR
exception and abort these
steps.
Remove the ith item from the drag data store.
The clear
method,
if the DataTransferItems
object is in the read/write mode, must remove all the
items from the drag data store. Otherwise, it must do
nothing.
The add()
method
must run the following steps:
If the DataTransferItems
object is not in the
read/write mode, return null and
abort these steps.
Jump to the appropriate set of steps from the following list:
If there is already an item in the drag data store item
list whose kind is Plain Unicode string and whose type string is
equal to the value of the method's second argument,
converted to ASCII lowercase, then throw a
NOT_SUPPORTED_ERR
exception and abort these
steps.
Otherwise, add an item to the drag data store item list whose kind is Plain Unicode string, whose type string is equal to the value of the method's second argument, converted to ASCII lowercase, and whose data is the string given by the method's first argument.
File
Add an item to the drag data store item list
whose kind is
File, whose type string is the type
of the File
,
converted to ASCII lowercase, and whose data is the
same as the File
's data.
Determine the value
of the indexed property corresponding to the newly added
item, and return that value (a newly created
DataTransferItem
object).
DataTransferItem
interfaceEach DataTransferItem
object is associated with a
DataTransfer
object.
interface DataTransferItem {
readonly attribute DOMString kind;
readonly attribute DOMString type;
void getAsString(in FunctionStringCallback callback); File getAsFile();};
[Callback=FunctionOnly, NoInterfaceObject]
interface FunctionStringCallback {
void handleEvent(in DOMString data);
};
kind
Returns the drag data item kind, one of: "string", "file".
type
Returns the drag data item type string.
getAsString
(callback)Invokes the callback with the string data as the argument, if the drag data item kind is Plain Unicode string.
getAsFile
()Returns a File
object, if the drag data item kind is File.
While the DataTransferItem
object's
DataTransfer
object is associated with a drag
data store and that drag data store's drag
data store item list still contains the item that the
DataTransferItem
object represents, the
DataTransferItem
object's mode is the same as
the drag data store mode. When the
DataTransferItem
object's DataTransfer
object is not associated with a drag data
store, or if the item that the DataTransferItem
object represents has been removed from the relevant drag data
store item list, the DataTransferItem
object's
mode is the disabled mode. The drag data
store referenced in this section (which is used only when the
DataTransferItem
object is not in the disabled
mode) is the drag data store with which the
DataTransferItem
object's DataTransfer
object is associated.
The kind
attribute
must return the empty string if the DataTransferItem
object is in the disabled mode; otherwise it must return the
string given in the cell from the second column of the following
table from the row whose cell in the first column contains the
drag data item kind of the item represented by the
DataTransferItem
object:
Kind | String |
---|---|
Plain Unicode string | "string "
|
File | "file "
|
The type
attribute
must return the empty string if the DataTransferItem
object is in the disabled mode; otherwise it must return
the drag data item type string of the item represented
by the DataTransferItem
object.
The getAsString(callback)
method must run the following
steps:
If the callback is null, abort these steps.
If the DataTransferItem
object is not in the read/write mode or the read-only mode, abort these steps. The
callback is never invoked.
If the drag data item kind is not Plain Unicode string, abort these steps. The callback is never invoked.
Otherwise, queue a task to invoke callback, passing the actual data of the item
represented by the DataTransferItem
object as the
argument.
The getAsFile()
method must run the following steps:
If the DataTransferItem
object is not in the read/write mode or the read-only mode, return null and abort
these steps.
If the drag data item kind is not File, then return null and abort these steps.
Return a new File
object representing the
actual data of the item represented by the
DataTransferItem
object.
DragEvent
interfaceThe drag-and-drop processing model involves several events. They
all use the DragEvent
interface.
interface DragEvent : MouseEvent { readonly attribute DataTransfer dataTransfer; void initDragEvent(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in any dummyArg, in long detailArg, in long screenXArg, in long screenYArg, in long clientXArg, in long clientYArg, in boolean ctrlKeyArg, in boolean altKeyArg, in boolean shiftKeyArg, in boolean metaKeyArg, in unsigned short buttonArg, in EventTarget relatedTargetArg, in DataTransfer dataTransferArg); };
dataTransfer
Returns the DataTransfer
object for the event.
The initDragEvent()
method must initialize the event in a manner analogous to the
similarly-named method in the DOM Events interfaces, except that the
dummyArg argument must be ignored. [DOMEVENTS]
The dataTransfer
attribute of the DragEvent
interface represents the
context information for the event.
When a user agent is required to fire a DND event named e at an element, using a particular drag data store, the user agent must run the following steps:
If e is dragstart
, set the drag data
store mode to the read/write
mode.
If e is drop
, set the drag data store
mode to the read-only
mode.
Let dataTransfer be a newly created
DataTransfer
object associated with the given
drag data store.
Set the effectAllowed
attribute to the drag data store's drag data
store allowed effects state.
Set the dropEffect
attribute to
"none
" if e is dragstart
, drag
, or dragleave
; to the value
corresponding to the current drag operation if e is drop
or dragend
; and to a value based on the
effectAllowed
attribute's value and to the drag-and-drop source, as given by the
following table, otherwise (i.e. if e is dragenter
or dragover
):
effectAllowed |
dropEffect |
---|---|
"none " |
"none " |
"copy ", "copyLink ", "copyMove ", "all " |
"copy " |
"link ", "linkMove " |
"link " |
"move " |
"move " |
"uninitialized " when what is being dragged is a selection from a text field |
"move " |
"uninitialized " when what is being dragged is a selection |
"copy " |
"uninitialized " when what is being dragged is an a element with an href attribute |
"link " |
Any other case | "copy " |
Create a DragEvent
object and initialize it to
have the given name e, to bubble, to be
cancelable unless e is dragleave
or dragend
, and to have the detail
attribute set to zero,
the mouse and key attributes set according to the state of the
input devices as they would be for user interaction events, the
relatedTarget
attribute set to null, and the
dataTransfer
attribute set to dataTransfer, the
DataTransfer
object created above.
If there is no relevant pointing device, the object must have
its screenX
, screenY
,
clientX
, clientY
, and
button
attributes set to 0.
Dispatch the newly created DragEvent
object at
the specified target element.
Set the drag data store allowed effects state
to the current value of dataTransfer's effectAllowed
attribute.
Set the drag data store mode back to the protected mode if it was changed in the first step.
Break the association between dataTransfer and the drag data store.
When the user attempts to begin a drag operation, the user agent must run the following steps. User agents must act as if these steps were run even if the drag actually started in another document or application and the user agent was not aware that the drag was occuring until it intersected with a document under the user agent's purview.
Determine what is being dragged, as follows:
If the drag operation was invoked on a selection, then it is the selection that is being dragged.
Otherwise, if the drag operation was invoked on a
Document
, it is the first element, going up the
ancestor chain, starting at the node that the user tried to drag,
that has the IDL attribute draggable
set to true. If there is no
such element, then nothing is being dragged; abort these steps,
the drag-and-drop operation is never started.
Otherwise, the drag operation was invoked outside the user agent's purview. What is being dragged is defined by the document or application where the drag was started.
img
elements and a
elements with an href
attribute have their draggable
attribute set to true by default.
Create a drag data store. All the DND events fired subsequently by the steps in this section must use this drag data store.
Establish which DOM node is the source node, as follows:
If it is a selection that is being dragged, then the source node is the text node that the user started the drag on (typically the text node that the user originally clicked). If the user did not specify a particular node, for example if the user just told the user agent to begin a drag of "the selection", then the source node is the first text node containing a part of the selection.
Otherwise, if it is an element that is being dragged, then the source node is the element that is being dragged.
Otherwise, the source node is part of another document or application. When this specification requires that an event be dispatched at the source node in this case, the user agent must instead follow the platform-specific conventions relevant to that situation.
Multiple events are fired on the source node during the course of the drag-and-drop operation.
Determine the list of dragged nodes, as follows:
If it is a selection that is being dragged, then the list of dragged nodes contains, in tree order, every node that is partially or completely included in the selection (including all their ancestors).
Otherwise, the list of dragged nodes contains only the source node, if any.
If it is a selection that is being dragged, then add an item to the drag data store item list, with its properties set as follows:
text/plain
"Otherwise, if any files are being dragged, then add one item per file to the drag data store item list, with their properties set as follows:
application/octet-stream
" otherwise.Dragging files can currently only happen from outside a browsing context, for example from a file system manager application.
If the drag initiated outside of the application, the user agent must add items to the drag data store item list as appropriate for the data being dragged, honoring platform conventions where appropriate; however, if the platform conventions do not use MIME types to label dragged data, the user agent must make a best-effort attempt to map the types to MIME types, and, in any case, all the drag data item type strings must be converted to ASCII lowercase.
Run the following substeps:
Let urls be an empty list of absolute URLs.
For each node in the list of dragged nodes:
If urls is still empty, abort these substeps.
Let url string be the result of concatenating the strings in urls, in the order they were added, separated by a U+000D CARRIAGE RETURN U+000A LINE FEED character pair (CRLF).
Add one item to the drag data store item list, with its properties set as follows:
text/uri-list
If it is an element that is being dragged, then set the drag data store elements list to contain just the source node.
Otherwise, update the drag data store default feedback as appropriate for the user agent (if the user is dragging the selection, then the selection would likely be the basis for this feedback; if the drag began outside the user agent, then the platform conventions for determining the drag feedback should be used).
Script can use the addElement()
method to
add further elements to the list of what is being dragged. (This
list is only used for rendering the drag feedback.)
Fire a DND event named dragstart
at the source
node.
If the event is canceled, then the drag-and-drop operation should not occur; abort these steps.
Since events with no event listeners registered are, almost by definition, never canceled, drag-and-drop is always available to the user if the author does not specifically prevent it.
Initiate the drag-and-drop operation in a manner consistent with platform conventions, and as described below.
The drag-and-drop feedback must be generated from the first of the following sources that is available:
From the moment that the user agent is to initiate the drag-and-drop operation, until the end of the drag-and-drop operation, device input events (e.g. mouse and keyboard events) must be suppressed. In addition, the user agent must track all DOM changes made during the drag-and-drop operation, and add them to its undo transaction history as one atomic operation once the drag-and-drop operation has ended.
During the drag operation, the element directly indicated by the user as the drop target is called the immediate user selection. (Only elements can be selected by the user; other nodes must not be made available as drop targets.) However, the immediate user selection is not necessarily the current target element, which is the element currently selected for the drop part of the drag-and-drop operation.
The immediate user selection changes as the user selects different elements (either by pointing at them with a pointing device, or by selecting them in some other way). The current target element changes when the immediate user selection changes, based on the results of event listeners in the document, as described below.
Both the current target element and the immediate user selection can be null, which means no target element is selected. They can also both be elements in other (DOM-based) documents, or other (non-Web) programs altogether. (For example, a user could drag text to a word-processor.) The current target element is initially null.
In addition, there is also a current drag operation,
which can take on the values "none
", "copy
", "link
", and "move
". Initially, it has the value "none
". It is updated by the user agent as described
in the steps below.
User agents must, as soon as the drag operation is initiated and every 350ms (±200ms) thereafter for as long as the drag operation is ongoing, queue a task to perform the following steps in sequence:
If the user agent is still performing the previous iteration of the sequence (if any) when the next iteration becomes due, abort these steps for this iteration (effectively "skipping missed frames" of the drag-and-drop operation).
Fire a DND event named drag
event at the source
node. If this event is canceled, the user agent must set
the current drag operation to "none
" (no drag operation).
If the drag
event was not
canceled and the user has not ended the drag-and-drop operation,
check the state of the drag-and-drop operation, as follows:
If the user is indicating a different immediate user selection than during the last iteration (or if this is the first iteration), and if this immediate user selection is not the same as the current target element, then update the current target element as follows:
Set the current target element to null also.
Set the current target element to the immediate user selection.
Fire a DND event named dragenter
at the
immediate user selection.
If the event is canceled, then set the current target element to the immediate user selection.
Otherwise, run the appropriate step from the following list:
textarea
, or an input
element whose type
attribute is in the Text state) or an
editable element, and the drag data store
item list has an item with the drag data item
type string "text/plain
" and the
drag data item kind Plain Unicode stringSet the current target element to the immediate user selection anyway.
dropzone
attribute
that matches the
drag data storeSet the current target element to the immediate user selection anyway.
Leave the current target element unchanged.
Fire a DND event named dragenter
at the body
element, and set the current target
element to the body element, regardless
of whether that event was canceled or not.
If the body element is null,
then the event will be fired at the Document
object (as required by the definition of the body
element), but the current target element
would be set to null, not the Document
object.
If the previous step caused the current target
element to change, and if the previous target element was
not null or a part of a non-DOM document, then fire a DND
event named dragleave
at the previous target
element.
If the current target element is a DOM element,
then fire a DND event named dragover
at this current
target element.
If the dragover
event is
not canceled, run the appropriate step from the following
list:
textarea
, or an input
element
whose type
attribute is in
the Text state) or an
editable element, and the drag data store
item list has an item with the drag data item type
string "text/plain
" and the drag data
item kind Plain Unicode stringSet the current drag operation to either
"copy
" or "move
",
as appropriate given the platform conventions.
dropzone
attribute
that matches the
drag data store and specifies an
operationSet the current drag operation to the
operation specified by the
dropzone
attribute of the
current target element.
dropzone
attribute
that matches the
drag data store and does not specify an
operationSet the current drag operation to "copy
".
Reset the current drag operation to "none
".
Otherwise (if the dragover
event is
canceled), set the current drag operation based on
the values of the effectAllowed
and
dropEffect
attributes of the DragEvent
object's dataTransfer
object as
they stood after the event dispatch finished, as per the
following table:
effectAllowed |
dropEffect |
Drag operation |
---|---|---|
"uninitialized ", "copy ", "copyLink ", "copyMove ", or "all " |
"copy " |
"copy " |
"uninitialized ", "link ", "copyLink ", "linkMove ", or "all " |
"link " |
"link " |
"uninitialized ", "move ", "copyMove ", "linkMove ", or "all " |
"move " |
"move " |
Any other case | "none " |
Otherwise, if the current target element is not a DOM element, use platform-specific mechanisms to determine what drag operation is being performed (none, copy, link, or move), and set the current drag operation accordingly.
Update the drag feedback (e.g. the mouse cursor) to match the current drag operation, as follows:
Drag operation | Feedback |
---|---|
"copy " |
Data will be copied if dropped here. |
"link " |
Data will be linked if dropped here. |
"move " |
Data will be moved if dropped here. |
"none " |
No operation allowed, dropping here will cancel the drag-and-drop operation. |
Otherwise, if the user ended the drag-and-drop operation (e.g.
by releasing the mouse button in a mouse-driven drag-and-drop
interface), or if the drag
event
was canceled, then this will be the last iteration. Run the
following steps, then stop the drag-and-drop operation:
If the current drag operation is "none
" (no drag operation), or, if the user ended
the drag-and-drop operation by canceling it (e.g. by hitting the
Escape key), or if the current target
element is null, then the drag operation failed. Run
these substeps:
Let dropped be false.
If the current target element is a DOM
element, fire a DND event named dragleave
at it; otherwise, if
it is not null, use platform-specific conventions for drag
cancellation.
Otherwise, the drag operation was as success; run these substeps:
Let dropped be true.
If the current target element is a DOM
element, fire a DND event named drop
at it; otherwise, use
platform-specific conventions for indicating a drop.
If the event is canceled, set the current drag
operation to the value of the dropEffect
attribute
of the DragEvent
object's dataTransfer
object
as it stood after the event dispatch finished.
Otherwise, the event is not canceled; perform the event's default action, which depends on the exact target as follows:
textarea
, or an input
element whose type
attribute is in the Text state) or an
editable element, and the drag data store
item list has an item with the drag data item
type string "text/plain
" and the
drag data item kind Plain Unicode stringInsert the actual data of the first item in the
drag data store item list to have a drag data item type
string of "text/plain
" and a drag data item kind
that is Plain Unicode string into the text field or
editable element in a manner consistent with
platform-specific conventions (e.g. inserting it at the
current mouse cursor position, or inserting it at the end of
the field).
Reset the current drag operation to
"none
".
Fire a DND event named dragend
at the source
node.
Run the appropriate steps from the following list as the
default action of the dragend
event:
textarea
, or an input
element
whose type
attribute is in
the Text state), and
dropped is true, and the current drag
operation is "move
", and the
source of the drag-and-drop operation is a selection in the
DOMtextarea
, or an input
element
whose type
attribute is in
the Text state), and
dropped is true, and the current drag
operation is "move
", and the
source of the drag-and-drop operation is a selection in a text
fieldUser agents are encouraged to consider how to react to drags near the edge of scrollable regions. For example, if a user drags a link to the bottom of the viewport on a long page, it might make sense to scroll the page so that the user can drop the link lower on the page.
This model is independent of which
Document
object the nodes involved are from; the events
are fired as described above and the rest of the processing model
runs as described above, irrespective of how many documents are
involved in the operation.
This section is non-normative.
The following events are involved in the drag-and-drop model.
Event Name | Target | Cancelable? | Drag data store mode | dropEffect |
Default Action |
---|---|---|---|---|---|
dragstart |
Source node | ✓ Cancelable | Read/write mode | "none " |
Initiate the drag-and-drop operation |
drag |
Source node | ✓ Cancelable | Protected mode | "none " |
Continue the drag-and-drop operation |
dragenter |
Immediate user selection or the body element | ✓ Cancelable | Protected mode | Based on effectAllowed value |
Reject immediate user selection as potential target element |
dragleave |
Previous target element | — | Protected mode | "none " |
None |
dragover |
Current target element | ✓ Cancelable | Protected mode | Based on effectAllowed value |
Reset the current drag operation to "none" |
drop |
Current target element | ✓ Cancelable | Read-only mode | Current drag operation | Varies |
dragend |
Source node | — | Protected mode | Current drag operation | Varies |
Not shown in the above table: all these events bubble, and the
effectAllowed
attribute always has the value it had after the previous event was
fired, defaulting to "uninitialized
" in the
dragstart
event.
draggable
attributeAll HTML elements may have the draggable
content attribute set. The
draggable
attribute is an
enumerated attribute. It has three states. The first
state is true and it has the keyword true
. The second state is false and it has
the keyword false
. The third state is
auto; it has no keywords but it is the missing value
default.
The true state means the element is draggable; the false state means that it is not. The auto state uses the default behavior of the user agent.
draggable
[ = value ]Returns true if the element is draggable; otherwise, returns false.
Can be set, to override the default and set the draggable
content attribute.
The draggable
IDL
attribute, whose value depends on the content attribute's in the way
described below, controls whether or not the element is
draggable. Generally, only text selections are draggable, but
elements whose draggable
IDL
attribute is true become draggable as well.
If an element's draggable
content attribute has the state true, the draggable
IDL attribute must return
true.
Otherwise, if the element's draggable
content attribute has the
state false, the draggable
IDL attribute must return
false.
Otherwise, the element's draggable
content attribute has the
state auto. If the element is an img
element,
or, if the element is an a
element with an href
content attribute, the draggable
IDL attribute must return
true.
Otherwise, the draggable
DOM
must return false.
If the draggable
IDL attribute
is set to the value false, the draggable
content attribute must be
set to the literal value false
. If the draggable
IDL attribute is set to the
value true, the draggable
content attribute must be set to the literal value true
.
dropzone
attributeAll HTML elements may have the dropzone
content attribute set. When
specified, its value must be an unordered set of unique
space-separated tokens that are ASCII
case-insensitive. The allowed values are the following:
copy
Indicates that dropping an accepted item on the element will result in a copy of the dragged data.
move
Indicates that dropping an accepted item on the element will result in the dragged data being moved to the new location.
link
Indicates that dropping an accepted item on the element will result in a link to the original data.
s:
")Indicates that items with the drag data item kind Plain Unicode string and the drag data item type string set to a value that matches the remainder of the keyword are accepted.
f:
")Indicates that items with the drag data item kind File and the drag data item type string set to a value that matches the remainder of the keyword are accepted.
The dropzone
content
attribute's values must not have more than one of the three feedback
values (copy
, move
, and link
) specified. If none are
specified, the copy
value is
implied.
A dropzone
attribute matches a drag data store if
the dropzone
processing
steps result in a match.
A dropzone
attribute specifies an operation if
the dropzone
processing
steps result in a specified operation. The specified
operation is as given by those steps.
The dropzone
processing
steps are as follows. They either result in a match or not,
and separate from this result either in a specified operation or
not, as defined below.
Let value be the value of the dropzone
attribute.
Let keywords be the result of splitting value on spaces.
Let matched be false.
Let operation be unspecified.
For each value in keywords, if any, in the order that they were found in value, run the following steps.
Let keyword be the keyword.
If keyword is one of "copy
", "move
", or "link
", then: run the following
substeps:
If operation is still unspecified, then let operation be the string given by keyword.
Skip to the step labeled end of keyword below.
If keyword is shorter than three characters in length, then skip to the step labeled end of keyword below.
If the second character in keyword is not a U+003A COLON character (:), then skip to the step labeled end of keyword below.
Let kind code be the first character in keyword, converted to ASCII lowercase.
Jump to the appropriate step from the list below, based on the value of kind code:
Let kind be Plain Unicode string.
Let kind be File.
Skip to the step labeled end of keyword below.
Let type be the string consisting of all but the first two characters of keyword, converted to ASCII lowercase.
If there exist any items in the drag data store item list whose drag data item kind is the kind given in kind and whose drag data item type is type, then let matched be true.
End of keyword: Go on to the next keyword, if any, or the next step in the overall algorithm, if there are no more.
The algorithm results in a match if matched is true, and does not otherwise.
The algorithm results in a specified operation if operation is not unspecified. The specified operation, if one is specified, is the one given by operation.
The dropzone
IDL
attribute must reflect the content attribute of the
same name.
In this example, a div
element is made into a drop
target for image files using the dropzone
attribute. Images dropped
into the target are then displayed.
<div dropzone="copy f:image/png f:image/gif f:image/jpeg" ondrop="receive(event, this)"> <p>Drop an image here to have it displayed.</p> </div> <script> function receive(event, element) { var data = event.dataTransfer.items; for (var i = 0; i < data.length; i += 1) { if ((data[i].kind == 'file') && (data[i].type.match('^image/'))) { var img = new Image(); img.src = window.createObjectURL(data[i].getAsFile()); element.appendChild(img); } } } </script>
User agents must not make the data added to the
DataTransfer
object during the dragstart
event available to scripts
until the drop
event, because
otherwise, if a user were to drag sensitive information from one
document to a second document, crossing a hostile third document in
the process, the hostile document could intercept the data.
For the same reason, user agents must consider a drop to be
successful only if the user specifically ended the drag operation
— if any scripts end the drag operation, it must be considered
unsuccessful (canceled) and the drop
event must not be fired.
User agents should take care to not start drag-and-drop operations in response to script actions. For example, in a mouse-and-window environment, if a script moves a window while the user has his mouse button depressed, the UA would not consider that to start a drag. This is important because otherwise UAs could cause data to be dragged from sensitive sources and dropped into hostile documents without the user's consent.
execCommand
(commandId [, showUI [, value ] ] )Runs the action specified by the first argument, as described in the list below. The second and third arguments sometimes affect the action. (If they don't they are ignored.)
queryCommandEnabled
(commandId)Returns whether the given command is enabled, as described in the list below.
queryCommandIndeterm
(commandId)Returns whether the given command is indeterminate, as described in the list below.
queryCommandState
(commandId)Returns the state of the command, as described in the list below.
queryCommandSupported
(commandId)Returns true if the command is supported; otherwise, returns false.
queryCommandValue
(commandId)Returns the value of the command, as described in the list below.
The execCommand(commandId, showUI, value)
method on the
HTMLDocument
interface allows scripts to perform
actions on the current selection or at the current caret position.
Generally, these commands would be used to implement editor UI, for
example having a "delete" button on a toolbar.
There are three variants to this method, with one, two, and three arguments respectively. The showUI and value parameters, even if specified, are ignored except where otherwise stated.
When execCommand()
is invoked, the user agent must run the following steps:
A document is ready for editing host commands if it has a selection that is entirely within an editing host, or if it has no selection but its caret is inside an editing host.
The queryCommandEnabled(commandId)
method, when invoked, must
return true if the condition listed below under "Enabled When" for
the given commandId is true, and false
otherwise.
The queryCommandIndeterm(commandId)
method, when invoked, must
return true if the condition listed below under "Indeterminate When"
for the given commandId is true, and false
otherwise.
The queryCommandState(commandId)
method, when invoked, must
return the value expressed below under "State" for the given commandId.
The queryCommandSupported(commandId)
method, when invoked, must
return true if the given commandId is in the
list below, and false otherwise.
The queryCommandValue(commandId)
method, when invoked, must
return the value expressed below under "Value" for the given commandId.
The possible values for commandId, and their corresponding meanings, are as follows. These values must be compared to the argument in an ASCII case-insensitive manner.
bold
b
element (or, again,
unwrapped, or have that semantic inserted or removed, as defined by
the UA).b
element. False otherwise.true
"
if the expression given for the "State" above is true, the string
"false
" otherwise.createLink
a
element (or, again,
unwrapped, or have that semantic inserted or removed, as defined by
the UA). If the user agent creates an a
element or
modifies an existing a
element, then if the showUI argument is present and has the value false,
then the value of the value argument must be
used as the URL of the link. Otherwise, the user agent
should prompt the user for the URL of the link.false
".delete
false
".formatBlock
formatBlock
candidate, does nothing.Action: The user agent must run the following steps:
If the value argument wasn't specified, abort these steps without doing anything.
If the value argument has a leading U+003C LESS-THAN SIGN character (<) and a trailing U+003E GREATER-THAN SIGN character (>), then remove the first and last characters from value.
If value is (now) an ASCII
case-insensitive match for the tag name of an element
defined by this specification that is defined to be a
formatBlock
candidate, then,
for every position in the selection, take the nearest
formatBlock
candidate
ancestor element of that position that contains only
phrasing content, and, if that element is
editable, is not an editing host, and
has a parent element whose content model allows that parent to
contain any flow content, replace it with an
element in the HTML namespace whose name is value, and move all the children that were in it
to the new element, and copy all the attributes that were on it
to the new element.
If there is no selection, then, where in the description above refers to the selection, the user agent must act as if the selection was an empty range (with just one position) at the caret position.
false
".forwardDelete
false
".insertImage
img
element (or, again,
unwrapped, or have that semantic inserted or removed, as defined by
the UA). If the user agent creates an img
element or
modifies an existing img
element, then if the showUI argument is present and has the value false,
then the value of the value argument must be
used as the URL of the image. Otherwise, the user
agent should prompt the user for the URL of the image.false
".insertHTML
Action: The user agent must run the following steps:
If the document is an XML
document, then throw an INVALID_ACCESS_ERR
exception and abort these steps.
If the value argument wasn't specified, abort these steps without doing anything.
If there is a selection, act as if the user had requested that the selection be deleted.
Invoke the HTML fragment parsing algorithm
with an arbitrary orphan body
element owned by the
same Document
as the context element
and with the value argument as input.
Insert the nodes returned by the previous step into the document at the location of the caret, firing any mutation events as appropriate.
false
".insertLineBreak
false
".insertOrderedList
ol
element (or unwrapped, or, if
there is no selection, have that semantic inserted or removed
— the exact behavior is UA-defined).false
".insertUnorderedList
ul
element (or unwrapped, or, if
there is no selection, have that semantic inserted or removed
— the exact behavior is UA-defined).false
".insertParagraph
false
".insertText
false
".italic
i
element (or, again,
unwrapped, or have that semantic inserted or removed, as defined by
the UA).i
element. False otherwise.true
"
if the expression given for the "State" above is true, the string
"false
" otherwise.redo
false
".selectAll
false
".subscript
sub
element (or, again,
unwrapped, or have that semantic inserted or removed, as defined by
the UA).sub
element. False otherwise.true
"
if the expression given for the "State" above is true, the string
"false
" otherwise.superscript
sup
element (or unwrapped, or, if
there is no selection, have that semantic inserted or removed
— the exact behavior is UA-defined).sup
element. False otherwise.true
"
if the expression given for the "State" above is true, the string
"false
" otherwise.undo
false
".unlink
a
elements that have href
attributes and that are partially
or completely included in the current selection.a
element that has an href
attribute.false
".unselect
false
".vendorID-customCommandID
vendorID-customCommandID
so as to prevent clashes between extensions from different vendors
and future additions to this specification.false
".This section only describes the rules for resources labeled with an HTML MIME type. Rules for XML resources are discussed in the section below entitled "The XHTML syntax".
This section only applies to documents, authoring tools, and markup generators. In particular, it does not apply to conformance checkers; conformance checkers must use the requirements given in the next section ("parsing HTML documents").
Documents must consist of the following parts, in the given order:
html
element.The various types of content mentioned above are described in the next few sections.
In addition, there are some restrictions on how character encoding declarations are to be serialized, as discussed in the section on that topic.
Space characters before the root html
element, and
space characters at the start of the html
element and
before the head
element, will be dropped when the
document is parsed; space characters after the root
html
element will be parsed as if they were at the end
of the body
element. Thus, space characters around the
root element do not round-trip.
It is suggested that newlines be inserted after the DOCTYPE,
after any comments that are before the root element, after the
html
element's start tag (if it is not omitted), and after any comments
that are inside the html
element but before the
head
element.
Many strings in the HTML syntax (e.g. the names of elements and their attributes) are case-insensitive, but only for characters in the ranges U+0041 to U+005A (LATIN CAPITAL LETTER A to LATIN CAPITAL LETTER Z) and U+0061 to U+007A (LATIN SMALL LETTER A to LATIN SMALL LETTER Z). For convenience, in this section this is just referred to as "case-insensitive".
A DOCTYPE is a required preamble.
DOCTYPEs are required for legacy reasons. When omitted, browsers tend to use a different rendering mode that is incompatible with some specifications. Including the DOCTYPE in a document ensures that the browser makes a best-effort attempt at following the relevant specifications.
A DOCTYPE must consist of the following components, in this order:
<!DOCTYPE
".html
".In other words, <!DOCTYPE html>
,
case-insensitively.
For the purposes of HTML generators that cannot output HTML
markup with the short DOCTYPE "<!DOCTYPE
html>
", a DOCTYPE legacy string may be inserted
into the DOCTYPE (in the position defined above). This string must
consist of:
SYSTEM
".about:legacy-compat
".In other words, <!DOCTYPE html SYSTEM
"about:legacy-compat">
or <!DOCTYPE html SYSTEM
'about:legacy-compat'>
, case-insensitively except for the
part in single or double quotes.
The DOCTYPE legacy string should not be used unless the document is generated from a system that cannot output the shorter string.
To help authors transition from HTML4 and XHTML1, an obsolete permitted DOCTYPE string can be inserted into the DOCTYPE (in the position defined above). This string must consist of:
PUBLIC
".Public identifier | System identifier |
---|---|
-//W3C//DTD HTML 4.0//EN
| |
-//W3C//DTD HTML 4.0//EN
| http://www.w3.org/TR/REC-html40/strict.dtd
|
-//W3C//DTD HTML 4.01//EN
| |
-//W3C//DTD HTML 4.01//EN
| http://www.w3.org/TR/html4/strict.dtd
|
-//W3C//DTD XHTML 1.0 Strict//EN
| http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd
|
-//W3C//DTD XHTML 1.1//EN
| http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd
|
A DOCTYPE containing an obsolete permitted DOCTYPE string is an obsolete permitted DOCTYPE. Authors should not use obsolete permitted DOCTYPEs, as they are unnecessarily long.
There are five different kinds of elements: void elements, raw text elements, RCDATA elements, foreign elements, and normal elements.
area
, base
, br
,
col
, command
, embed
,
hr
, img
, input
,
keygen
, link
, meta
,
param
, source
, track
,
wbr
script
, style
textarea
, title
Tags are used to delimit the start and end of elements in the markup. Raw text, RCDATA, and normal elements have a start tag to indicate where they begin, and an end tag to indicate where they end. The start and end tags of certain normal elements can be omitted, as described later. Those that cannot be omitted must not be omitted. Void elements only have a start tag; end tags must not be specified for void elements. Foreign elements must either have a start tag and an end tag, or a start tag that is marked as self-closing, in which case they must not have an end tag.
The contents of the element must be placed between just after the start tag (which might be implied, in certain cases) and just before the end tag (which again, might be implied in certain cases). The exact allowed contents of each individual element depend on the content model of that element, as described earlier in this specification. Elements must not contain content that their content model disallows. In addition to the restrictions placed on the contents by those content models, however, the five types of elements have additional syntactic requirements.
Void elements can't have any contents (since there's no end tag, no content can be put between the start tag and the end tag).
Raw text elements can have text, though it has restrictions described below.
RCDATA elements can have text and character references, but the text must not contain an ambiguous ampersand. There are also further restrictions described below.
Foreign elements whose start tag is marked as self-closing can't have any contents (since, again, as there's no end tag, no content can be put between the start tag and the end tag). Foreign elements whose start tag is not marked as self-closing can have text, character references, CDATA sections, other elements, and comments, but the text must not contain the character U+003C LESS-THAN SIGN (<) or an ambiguous ampersand.
The HTML syntax does not support namespace declarations, even in foreign elements.
For instance, consider the following HTML fragment:
<p> <svg> <metadata> <!-- this is invalid --> <cdr:license xmlns:cdr="http://www.example.com/cdr/metadata" name="MIT"/> </metadata> </svg> </p>
The innermost element, cdr:license
, is
actually in the SVG namespace, as the "xmlns:cdr
" attribute has no effect (unlike in
XML). In fact, as the comment in the fragment above says, the
fragment is actually non-conforming. This is because the SVG
specification does not define any elements called "cdr:license
" in the SVG namespace.
Normal elements can have text, character references, other elements, and comments, but the text must not contain the character U+003C LESS-THAN SIGN (<) or an ambiguous ampersand. Some normal elements also have yet more restrictions on what content they are allowed to hold, beyond the restrictions imposed by the content model and those described in this paragraph. Those restrictions are described below.
Tags contain a tag name, giving the element's name. HTML elements all have names that only use characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER Z, and U+0041 LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z. In the HTML syntax, tag names, even those for foreign elements, may be written with any mix of lower- and uppercase letters that, when converted to all-lowercase, matches the element's tag name; tag names are case-insensitive.
Start tags must have the following format:
End tags must have the following format:
Attributes for an element are expressed inside the element's start tag.
Attributes have a name and a value. Attribute names must consist of one or more characters other than the space characters, U+0000 NULL, U+0022 QUOTATION MARK ("), U+0027 APOSTROPHE ('), U+003E GREATER-THAN SIGN (>), U+002F SOLIDUS (/), and U+003D EQUALS SIGN (=) characters, the control characters, and any characters that are not defined by Unicode. In the HTML syntax, attribute names, even those for foreign elements, may be written with any mix of lower- and uppercase letters that are an ASCII case-insensitive match for the attribute's name.
Attribute values are a mixture of text and character references, except with the additional restriction that the text cannot contain an ambiguous ampersand.
Attributes can be specified in four different ways:
Just the attribute name. The value is implicitly the empty string.
In the following example, the disabled
attribute is given with
the empty attribute syntax:
<input disabled>
If an attribute using the empty attribute syntax is to be followed by another attribute, then there must be a space character separating the two.
The attribute name, followed by zero or more space characters, followed by a single U+003D EQUALS SIGN character, followed by zero or more space characters, followed by the attribute value, which, in addition to the requirements given above for attribute values, must not contain any literal space characters, any U+0022 QUOTATION MARK characters ("), U+0027 APOSTROPHE characters ('), U+003D EQUALS SIGN characters (=), U+003C LESS-THAN SIGN characters (<), U+003E GREATER-THAN SIGN characters (>), or U+0060 GRAVE ACCENT characters (`), and must not be the empty string.
In the following example, the value
attribute is given
with the unquoted attribute value syntax:
<input value=yes>
If an attribute using the unquoted attribute syntax is to be followed by another attribute or by the optional U+002F SOLIDUS character (/) allowed in step 6 of the start tag syntax above, then there must be a space character separating the two.
The attribute name, followed by zero or more space characters, followed by a single U+003D EQUALS SIGN character, followed by zero or more space characters, followed by a single U+0027 APOSTROPHE character ('), followed by the attribute value, which, in addition to the requirements given above for attribute values, must not contain any literal U+0027 APOSTROPHE characters ('), and finally followed by a second single U+0027 APOSTROPHE character (').
In the following example, the type
attribute is given with the
single-quoted attribute value syntax:
<input type='checkbox'>
If an attribute using the single-quoted attribute syntax is to be followed by another attribute, then there must be a space character separating the two.
The attribute name, followed by zero or more space characters, followed by a single U+003D EQUALS SIGN character, followed by zero or more space characters, followed by a single U+0022 QUOTATION MARK character ("), followed by the attribute value, which, in addition to the requirements given above for attribute values, must not contain any literal U+0022 QUOTATION MARK characters ("), and finally followed by a second single U+0022 QUOTATION MARK character (").
In the following example, the name
attribute is given with the
double-quoted attribute value syntax:
<input name="be evil">
If an attribute using the double-quoted attribute syntax is to be followed by another attribute, then there must be a space character separating the two.
There must never be two or more attributes on the same start tag whose names are an ASCII case-insensitive match for each other.
When a foreign element has one of the namespaced attributes given by the local name and namespace of the first and second cells of a row from the following table, it must be written using the name given by the third cell from the same row.
Local name | Namespace | Attribute name |
---|---|---|
actuate | XLink namespace | xlink:actuate
|
arcrole | XLink namespace | xlink:arcrole
|
href | XLink namespace | xlink:href
|
role | XLink namespace | xlink:role
|
show | XLink namespace | xlink:show
|
title | XLink namespace | xlink:title
|
type | XLink namespace | xlink:type
|
base | XML namespace | xml:base
|
lang | XML namespace | xml:lang
|
space | XML namespace | xml:space
|
xmlns | XMLNS namespace | xmlns
|
xlink | XMLNS namespace | xmlns:xlink
|
No other namespaced attribute can be expressed in the HTML syntax.
Certain tags can be omitted.
Omitting an element's start tag does not mean the element
is not present; it is implied, but it is still there. An HTML
document always has a root html
element, even if the
string <html>
doesn't appear anywhere in
the markup.
An html
element's start tag may be omitted if the
first thing inside the html
element is not a comment.
An html
element's end
tag may be omitted if the html
element is not
immediately followed by a comment.
A head
element's start tag may be omitted if the
element is empty, or if the first thing inside the
head
element is an element.
A head
element's end
tag may be omitted if the head
element is not
immediately followed by a space character or a comment.
A body
element's start tag may be omitted if the
element is empty, or if the first thing inside the body
element is not a space character or a comment, except if the first thing
inside the body
element is a script
or
style
element.
A body
element's end
tag may be omitted if the body
element is not
immediately followed by a comment.
A li
element's end
tag may be omitted if the li
element is
immediately followed by another li
element or if there
is no more content in the parent element.
A dt
element's end
tag may be omitted if the dt
element is
immediately followed by another dt
element or a
dd
element.
A dd
element's end
tag may be omitted if the dd
element is
immediately followed by another dd
element or a
dt
element, or if there is no more content in the
parent element.
A p
element's end
tag may be omitted if the p
element is
immediately followed by an address
,
article
, aside
, blockquote
,
dir
, div
, dl
,
fieldset
, footer
, form
,
h1
, h2
, h3
, h4
,
h5
, h6
, header
,
hgroup
, hr
, menu
,
nav
, ol
, p
, pre
,
section
, table
, or ul
,
element, or if there is no more content in the parent element and
the parent element is not an a
element.
An rt
element's end
tag may be omitted if the rt
element is
immediately followed by an rt
or rp
element, or if there is no more content in the parent element.
An rp
element's end
tag may be omitted if the rp
element is
immediately followed by an rt
or rp
element, or if there is no more content in the parent element.
An optgroup
element's end tag may be omitted if the
optgroup
element is immediately followed by
another optgroup
element, or if there is no
more content in the parent element.
An option
element's end
tag may be omitted if the option
element is
immediately followed by another option
element, or if
it is immediately followed by an optgroup
element, or
if there is no more content in the parent element.
A colgroup
element's start tag may be omitted if the
first thing inside the colgroup
element is a
col
element, and if the element is not immediately
preceded by another colgroup
element whose end tag has been omitted. (It can't be
omitted if the element is empty.)
A colgroup
element's end tag may be omitted if the
colgroup
element is not immediately followed by a
space character or a comment.
A thead
element's end
tag may be omitted if the thead
element is
immediately followed by a tbody
or tfoot
element.
A tbody
element's start tag may be omitted if the
first thing inside the tbody
element is a
tr
element, and if the element is not immediately
preceded by a tbody
, thead
, or
tfoot
element whose end
tag has been omitted. (It can't be omitted if the element is
empty.)
A tbody
element's end
tag may be omitted if the tbody
element is
immediately followed by a tbody
or tfoot
element, or if there is no more content in the parent element.
A tfoot
element's end
tag may be omitted if the tfoot
element is
immediately followed by a tbody
element, or if there is
no more content in the parent element.
A tr
element's end
tag may be omitted if the tr
element is
immediately followed by another tr
element, or if there
is no more content in the parent element.
A td
element's end
tag may be omitted if the td
element is
immediately followed by a td
or th
element, or if there is no more content in the parent element.
A th
element's end
tag may be omitted if the th
element is
immediately followed by a td
or th
element, or if there is no more content in the parent element.
However, a start tag must never be omitted if it has any attributes.
For historical reasons, certain elements have extra restrictions beyond even the restrictions given by their content model.
A table
element must not contain tr
elements, even though these elements are technically allowed inside
table
elements according to the content models
described in this specification. (If a tr
element is
put inside a table
in the markup, it will in fact imply
a tbody
start tag before it.)
A single newline may be
placed immediately after the start
tag of pre
and textarea
elements. This does not affect the processing of the element. The
otherwise optional newline
must be included if the element's contents themselves start
with a newline (because
otherwise the leading newline in the contents would be treated like
the optional newline, and ignored).
The text in raw text and
RCDATA elements must not contain any occurrences of the
string "</
" (U+003C LESS-THAN SIGN, U+002F
SOLIDUS) followed by characters that case-insensitively match the
tag name of the element followed by one of U+0009 CHARACTER
TABULATION (tab), U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D
CARRIAGE RETURN (CR), U+0020 SPACE, U+003E GREATER-THAN SIGN (>), or
U+002F SOLIDUS (/).
Text is allowed inside elements, attribute values, and comments. Text must consist of Unicode characters. Text must not contain U+0000 characters. Text must not contain permanently undefined Unicode characters (noncharacters). Text must not contain control characters other than space characters. Extra constraints are placed on what is and what is not allowed in text based on where the text is to be put, as described in the other sections.
Newlines in HTML may be represented either as U+000D CARRIAGE RETURN (CR) characters, U+000A LINE FEED (LF) characters, or pairs of U+000D CARRIAGE RETURN (CR), U+000A LINE FEED (LF) characters in that order.
Where character references are allowed, a character reference of a U+000A LINE FEED (LF) character (but not a U+000D CARRIAGE RETURN (CR) character) also represents a newline.
In certain cases described in other sections, text may be mixed with character references. These can be used to escape characters that couldn't otherwise legally be included in text.
Character references must start with a U+0026 AMPERSAND character (&). Following this, there are three possible kinds of character references:
The numeric character reference forms described above are allowed to reference any Unicode code point other than U+0000, U+000D, permanently undefined Unicode characters (noncharacters), and control characters other than space characters.
An ambiguous ampersand is a U+0026 AMPERSAND character (&) that is followed by one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER Z, and U+0041 LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z, followed by a U+003B SEMICOLON character (;), where these characters do not match any of the names given in the named character references section.
CDATA sections must consist of the following components, in this order:
<![CDATA[
".]]>
".]]>
".CDATA sections can only be used in foreign content (MathML or
SVG). In this example, a CDATA section is used to escape the
contents of an ms
element:
<p>You can add a string to a number, but this stringifies the number:</p> <math> <ms><![CDATA[x<y]]></ms> <mo>+</mo> <mn>3</mn> <mo>=</mo> <ms><![CDATA[x<y3]]></ms> </math>
Comments must start with the
four character sequence U+003C LESS-THAN SIGN, U+0021 EXCLAMATION
MARK, U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS (<!--
). Following this sequence, the comment may
have text, with the additional
restriction that the text must not start with a single U+003E
GREATER-THAN SIGN character (>), nor start with a U+002D
HYPHEN-MINUS character (-) followed by a U+003E GREATER-THAN SIGN
(>) character, nor contain two consecutive U+002D HYPHEN-MINUS
characters (--
), nor end with a U+002D
HYPHEN-MINUS character (-). Finally, the comment must be ended by
the three character sequence U+002D HYPHEN-MINUS, U+002D
HYPHEN-MINUS, U+003E GREATER-THAN SIGN (-->
).
This section only applies to user agents, data mining tools, and conformance checkers.
The rules for parsing XML documents into DOM trees are covered by the next section, entitled "The XHTML syntax".
For HTML documents, user agents must use the parsing rules described in this section to generate the DOM trees. Together, these rules define what is referred to as the HTML parser.
While the HTML syntax described in this specification bears a close resemblance to SGML and XML, it is a separate language with its own parsing rules.
Some earlier versions of HTML (in particular from HTML2 to HTML4) were based on SGML and used SGML parsing rules. However, few (if any) web browsers ever implemented true SGML parsing for HTML documents; the only user agents to strictly handle HTML as an SGML application have historically been validators. The resulting confusion — with validators claiming documents to have one representation while widely deployed Web browsers interoperably implemented a different representation — has wasted decades of productivity. This version of HTML thus returns to a non-SGML basis.
Authors interested in using SGML tools in their authoring pipeline are encouraged to use XML tools and the XML serialization of HTML.
This specification defines the parsing rules for HTML documents, whether they are syntactically correct or not. Certain points in the parsing algorithm are said to be parse errors. The error handling for parse errors is well-defined: user agents must either act as described below when encountering such problems, or must abort processing at the first error that they encounter for which they do not wish to apply the rules described below.
Conformance checkers must report at least one parse error condition to the user if one or more parse error conditions exist in the document and must not report parse error conditions if none exist in the document. Conformance checkers may report more than one parse error condition if more than one parse error condition exists in the document. Conformance checkers are not required to recover from parse errors.
Parse errors are only errors with the syntax of HTML. In addition to checking for parse errors, conformance checkers will also verify that the document obeys all the other conformance requirements described in this specification.
For the purposes of conformance checkers, if a resource is determined to be in the HTML syntax, then it is an HTML document.
The input to the HTML parsing process consists of a stream of
Unicode characters, which is passed through a
tokenization stage followed by a tree
construction stage. The output is a Document
object.
Implementations that do not
support scripting do not have to actually create a DOM
Document
object, but the DOM tree in such cases is
still used as the model for the rest of the specification.
In the common case, the data handled by the tokenization stage
comes from the network, but it can also come from script running in the user
agent, e.g. using the document.write()
API.
There is only one set of states for the tokenizer stage and the tree construction stage, but the tree construction stage is reentrant, meaning that while the tree construction stage is handling one token, the tokenizer might be resumed, causing further tokens to be emitted and processed before the first token's processing is complete.
In the following example, the tree construction stage will be called upon to handle a "p" start tag token while handling the "script" end tag token:
... <script> document.write('<p>'); </script> ...
To handle these cases, parsers have a script nesting level, which must be initially set to zero, and a parser pause flag, which must be initially set to false.
The stream of Unicode characters that comprises the input to the tokenization stage will be initially seen by the user agent as a stream of bytes (typically coming over the network or from the local file system). The bytes encode the actual characters according to a particular character encoding, which the user agent must use to decode the bytes into characters.
For XML documents, the algorithm user agents must use to determine the character encoding is given by the XML specification. This section does not apply to XML documents. [XML]
In some cases, it might be impractical to unambiguously determine the encoding before parsing the document. Because of this, this specification provides for a two-pass mechanism with an optional pre-scan. Implementations are allowed, as described below, to apply a simplified parsing algorithm to whatever bytes they have available before beginning to parse the document. Then, the real parser is started, using a tentative encoding derived from this pre-parse and other out-of-band metadata. If, while the document is being loaded, the user agent discovers an encoding declaration that conflicts with this information, then the parser can get reinvoked to perform a parse of the document with the real encoding.
User agents must use the following algorithm (the encoding sniffing algorithm) to determine the character encoding to use when decoding a document in the first pass. This algorithm takes as input any out-of-band metadata available to the user agent (e.g. the Content-Type metadata of the document) and all the bytes available so far, and returns an encoding and a confidence. The confidence is either tentative, certain, or irrelevant. The encoding used, and whether the confidence in that encoding is tentative or certain, is used during the parsing to determine whether to change the encoding. If no encoding is necessary, e.g. because the parser is operating on a stream of Unicode characters and doesn't have to use an encoding at all, then the confidence is irrelevant.
If the user has explicitly instructed the user agent to override the document's character encoding with a specific encoding, optionally return that encoding with the confidence certain and abort these steps.
If the transport layer specifies an encoding, and it is supported, return that encoding with the confidence certain, and abort these steps.
The user agent may wait for more bytes of the resource to be available, either in this step or at any later step in this algorithm. For instance, a user agent might wait 500ms or 1024 bytes, whichever came first. In general preparsing the source to find the encoding improves performance, as it reduces the need to throw away the data structures used when parsing upon finding the encoding information. However, if the user agent delays too long to obtain data to determine the encoding, then the cost of the delay could outweigh any performance improvements from the preparse.
The authoring conformance requirements for character encoding declarations limit them to only appearing in the first 1024 bytes. User agents are therefore encouraged to use the preparse algorithm below (part of these steps) on the first 1024 bytes, but not to stall beyond that.
For each of the rows in the following table, starting with the first one and going down, if there are as many or more bytes available than the number of bytes in the first column, and the first bytes of the file match the bytes given in the first column, then return the encoding given in the cell in the second column of that row, with the confidence certain, and abort these steps:
Bytes in Hexadecimal | Encoding |
---|---|
FE FF | Big-endian UTF-16 |
FF FE | Little-endian UTF-16 |
EF BB BF | UTF-8 |
This step looks for Unicode Byte Order Marks (BOMs).
Otherwise, the user agent will have to search for explicit character encoding information in the file itself. This should proceed as follows:
Let position be a pointer to a byte in the input stream, initially pointing at the first byte. If at any point during these substeps the user agent either runs out of bytes or decides that scanning further bytes would not be efficient, then skip to the next step of the overall character encoding detection algorithm. User agents may decide that scanning any bytes is not efficient, in which case these substeps are entirely skipped.
Now, repeat the following "two" steps until the algorithm aborts (either because user agent aborts, as described above, or because a character encoding is found):
If position points to:
Advance the position pointer so that it points at the first 0x3E byte which is preceded by two 0x2D bytes (i.e. at the end of an ASCII '-->' sequence) and comes after the 0x3C byte that was found. (The two 0x2D bytes can be the same as the those in the '<!--' sequence.)
Advance the position pointer so that it points at the next 0x09, 0x0A, 0x0C, 0x0D, 0x20, or 0x2F byte (the one in sequence of characters matched above).
Let attribute list be an empty list of strings.
Let got pragma be false.
Let need pragma be null.
Let charset be the null value (which, for the purposes of this algorithm, is distinct from an unrecognised encoding or the empty string).
Attributes: Get an attribute and its value. If no attribute was sniffed, then jump to the processing step below.
If the attribute's name is already in attribute list, then return to the step labeled attributes.
Add the attribute's name to attribute list.
Run the appropriate step from the following list, if one applies:
http-equiv
"If the attribute's value is "content-type
", then set got
pragma to true.
content
"Apply the algorithm for extracting an encoding
from a meta
element, giving the
attribute's value as the string to parse. If an encoding is
returned, and if charset is still set
to null, let charset be the encoding
returned, and set need pragma to
true.
charset
"Let charset be the encoding corresponding to the attribute's value, and set need pragma to false.
Return to the step labeled attributes.
Processing: If need pragma is null, then jump to the second step of the overall "two step" algorithm.
If mode is true but got pragma is false, then jump to the second step of the overall "two step" algorithm.
If charset is a UTF-16 encoding, change the value of charset to UTF-8.
If charset is not a supported character encoding, then jump to the second step of the overall "two step" algorithm.
Return the encoding given by charset, with confidence tentative, and abort all these steps.
Advance the position pointer so that it points at the next 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), 0x20 (ASCII space), or 0x3E (ASCII >) byte.
Repeatedly get an attribute until no further attributes can be found, then jump to the second step in the overall "two step" algorithm.
Advance the position pointer so that it points at the first 0x3E byte (ASCII >) that comes after the 0x3C byte that was found.
Do nothing with that byte.
When the above "two step" algorithm says to get an attribute, it means doing this:
If the byte at position is one of 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), 0x20 (ASCII space), or 0x2F (ASCII /) then advance position to the next byte and redo this substep.
If the byte at position is 0x3E (ASCII >), then abort the "get an attribute" algorithm. There isn't one.
Otherwise, the byte at position is the start of the attribute name. Let attribute name and attribute value be the empty string.
Attribute name: Process the byte at position as follows:
Advance position to the next byte and return to the previous step.
Spaces: If the byte at position is one of 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), or 0x20 (ASCII space) then advance position to the next byte, then, repeat this step.
If the byte at position is not 0x3D (ASCII =), abort the "get an attribute" algorithm. The attribute's name is the value of attribute name, its value is the empty string.
Advance position past the 0x3D (ASCII =) byte.
Value: If the byte at position is one of 0x09 (ASCII TAB), 0x0A (ASCII LF), 0x0C (ASCII FF), 0x0D (ASCII CR), or 0x20 (ASCII space) then advance position to the next byte, then, repeat this step.
Process the byte at position as follows:
Process the byte at position as follows:
Advance position to the next byte and return to the previous step.
For the sake of interoperability, user agents should not use a pre-scan algorithm that returns different results than the one described above. (But, if you do, please at least let us know, so that we can improve this algorithm and benefit everyone...)
If the user agent has information on the likely encoding for this page, e.g. based on the encoding of the page when it was last visited, then return that encoding, with the confidence tentative, and abort these steps.
The user agent may attempt to autodetect the character encoding from applying frequency analysis or other algorithms to the data stream. Such algorithms may use information about the resource other than the resource's contents, including the address of the resource. If autodetection succeeds in determining a character encoding, then return that encoding, with the confidence tentative, and abort these steps. [UNIVCHARDET]
The UTF-8 encoding has a highly detectable bit pattern. Documents that contain bytes with values greater than 0x7F which match the UTF-8 pattern are very likely to be UTF-8, while documents with byte sequences that do not match it are very likely not. User-agents are therefore encouraged to search for this common encoding. [PPUTF8] [UTF8DET]
Otherwise, return an implementation-defined or user-specified default character encoding, with the confidence tentative.
In controlled environments or in environments where the
encoding of documents can be prescribed (for example, for user
agents intended for dedicated use in new networks), the
comprehensive UTF-8
encoding is
suggested.
In other environments, the default encoding is typically dependent on the user's locale (an approximation of the languages, and thus often encodings, of the pages that the user is likely to frequent). The following table gives suggested defaults based on the user's locale, for compatibility with legacy content. Locales are identified by BCP 47 language tags. [BCP47]
Locale language | Suggested default encoding |
---|---|
ar | UTF-8 |
be | ISO-8859-5 |
bg | windows-1251 |
cs | ISO-8859-2 |
cy | UTF-8 |
fa | UTF-8 |
he | windows-1255 |
hr | UTF-8 |
hu | ISO-8859-2 |
ja | Windows-31J |
kk | UTF-8 |
ko | windows-949 |
ku | windows-1254 |
lt | windows-1257 |
lv | ISO-8859-13 |
mk | UTF-8 |
or | UTF-8 |
pl | ISO-8859-2 |
ro | UTF-8 |
ru | windows-1251 |
sk | windows-1250 |
sl | ISO-8859-2 |
sr | UTF-8 |
th | windows-874 |
tr | windows-1254 |
uk | windows-1251 |
vi | UTF-8 |
zh-CN | GB18030 |
zh-TW | Big5 |
All other locales | windows-1252 |
The document's character encoding must immediately be set to the value returned from this algorithm, at the same time as the user agent uses the returned value to select the decoder to use for the input stream.
This algorithm is a willful violation of the HTTP specification, which requires that the encoding be assumed to be ISO-8859-1 in the absence of a character encoding declaration to the contrary, and of RFC 2046, which requires that the encoding be assumed to be US-ASCII in the absence of a character encoding declaration to the contrary. This specification's third approach is motivated by a desire to be maximally compatible with legacy content. [HTTP] [RFC2046]
User agents must at a minimum support the UTF-8 and Windows-1252 encodings, but may support more. [RFC3629] [WIN1252]
It is not unusual for Web browsers to support dozens if not upwards of a hundred distinct character encodings.
User agents must support the preferred MIME name of every character encoding they support, and should support all the IANA-registered names and aliases of every character encoding they support. [IANACHARSET]
When comparing a string specifying a character encoding with the name or alias of a character encoding to determine if they are equal, user agents must remove any leading or trailing space characters in both names, and then perform the comparison in an ASCII case-insensitive manner.
When a user agent would otherwise use an encoding given in the first column of the following table to either convert content to Unicode characters or convert Unicode characters to bytes, it must instead use the encoding given in the cell in the second column of the same row. When a byte or sequence of bytes is treated differently due to this encoding aliasing, it is said to have been misinterpreted for compatibility.
Input encoding | Replacement encoding | References |
---|---|---|
EUC-KR | windows-949 | [EUCKR] [WIN949] |
EUC-JP | CP51932 | [EUCJP] [CP51932] |
GB2312 | GBK | [RFC1345] [GBK] |
GB_2312-80 | GBK | [RFC1345] [GBK] |
ISO-8859-1 | windows-1252 | [RFC1345] [WIN1252] |
ISO-8859-9 | windows-1254 | [RFC1345] [WIN1254] |
ISO-8859-11 | windows-874 | [ISO885911] [WIN874] |
KS_C_5601-1987 | windows-949 | [RFC1345] [WIN949] |
Shift_JIS | Windows-31J | [SHIFTJIS] [WIN31J] |
TIS-620 | windows-874 | [TIS620] [WIN874] |
US-ASCII | windows-1252 | [RFC1345] [WIN1252] |
The requirement to treat certain encodings as other encodings according to the table above is a willful violation of the W3C Character Model specification, motivated by a desire for compatibility with legacy content. [CHARMOD]
When a user agent is to use the UTF-16 encoding but no BOM has been found, user agents must default to UTF-16LE.
The requirement to default UTF-16 to LE rather than BE is a willful violation of RFC 2781, motivated by a desire for compatibility with legacy content. [RFC2781]
User agents must not support the CESU-8, UTF-7, BOCU-1 and SCSU encodings. [CESU8] [UTF7] [BOCU1] [SCSU]
Support for encodings based on EBCDIC is not recommended. This encoding is rarely used for publicly-facing Web content.
Support for UTF-32 is not recommended. This encoding is rarely used, and frequently implemented incorrectly.
This specification does not make any attempt to support EBCDIC-based encodings and UTF-32 in its algorithms; support and use of these encodings can thus lead to unexpected behavior in implementations of this specification.
Given an encoding, the bytes in the input stream must be converted to Unicode characters for the tokenizer, as described by the rules for that encoding, except that the leading U+FEFF BYTE ORDER MARK character, if any, must not be stripped by the encoding layer (it is stripped by the rule below).
Bytes or sequences of bytes in the original byte stream that could not be converted to Unicode code points must be converted to U+FFFD REPLACEMENT CHARACTERs. Specifically, if the encoding is UTF-8, the bytes must be decoded with the error handling defined in this specification.
Bytes or sequences of bytes in the original byte stream that did not conform to the encoding specification (e.g. invalid UTF-8 byte sequences in a UTF-8 input stream) are errors that conformance checkers are expected to report.
Any byte or sequence of bytes in the original byte stream that is misinterpreted for compatibility is a parse error.
One leading U+FEFF BYTE ORDER MARK character must be ignored if any are present.
The requirement to strip a U+FEFF BYTE ORDER MARK character regardless of whether that character was used to determine the byte order is a willful violation of Unicode, motivated by a desire to increase the resilience of user agents in the face of naïve transcoders.
Any occurrences of any characters in the ranges U+0001 to U+0008, U+000E to U+001F, U+007F to U+009F, U+FDD0 to U+FDEF, and characters U+000B, U+FFFE, U+FFFF, U+1FFFE, U+1FFFF, U+2FFFE, U+2FFFF, U+3FFFE, U+3FFFF, U+4FFFE, U+4FFFF, U+5FFFE, U+5FFFF, U+6FFFE, U+6FFFF, U+7FFFE, U+7FFFF, U+8FFFE, U+8FFFF, U+9FFFE, U+9FFFF, U+AFFFE, U+AFFFF, U+BFFFE, U+BFFFF, U+CFFFE, U+CFFFF, U+DFFFE, U+DFFFF, U+EFFFE, U+EFFFF, U+FFFFE, U+FFFFF, U+10FFFE, and U+10FFFF are parse errors. These are all control characters or permanently undefined Unicode characters (noncharacters).
U+000D CARRIAGE RETURN (CR) characters and U+000A LINE FEED (LF) characters are treated specially. Any CR characters that are followed by LF characters must be removed, and any CR characters not followed by LF characters must be converted to LF characters. Thus, newlines in HTML DOMs are represented by LF characters, and there are never any CR characters in the input to the tokenization stage.
The next input character is the first character in the input stream that has not yet been consumed. Initially, the next input character is the first character in the input. The current input character is the last character to have been consumed.
The insertion point is the position (just before a
character or just before the end of the input stream) where content
inserted using document.write()
is actually
inserted. The insertion point is relative to the position of the
character immediately after it, it is not an absolute offset into
the input stream. Initially, the insertion point is
undefined.
The "EOF" character in the tables below is a conceptual character
representing the end of the input stream. If the parser
is a script-created parser, then the end of the
input stream is reached when an explicit "EOF"
character (inserted by the document.close()
method) is
consumed. Otherwise, the "EOF" character is not a real character in
the stream, but rather the lack of any further characters.
When the parser requires the user agent to change the encoding, it must run the following steps. This might happen if the encoding sniffing algorithm described above failed to find an encoding, or if it found an encoding that was not the actual encoding of the file.
The insertion mode is a state variable that controls the primary operation of the tree construction stage.
Initially, the insertion mode is "initial". It can change to "before html", "before head", "in head", "in head noscript", "after head", "in body", "text", "in table", "in table text", "in caption", "in column group", "in table body", "in row", "in cell", "in select", "in select in table", "after body", "in frameset", "after frameset", "after after body", and "after after frameset" during the course of the parsing, as described in the tree construction stage. The insertion mode affects how tokens are processed and whether CDATA sections are supported.
Several of these modes, namely "in head", "in body", "in table", and "in select", are special, in that the other modes defer to them at various times. When the algorithm below says that the user agent is to do something "using the rules for the m insertion mode", where m is one of these modes, the user agent must use the rules described under the m insertion mode's section, but must leave the insertion mode unchanged unless the rules in m themselves switch the insertion mode to a new value.
When the insertion mode is switched to "text" or "in table text", the original insertion mode is also set. This is the insertion mode to which the tree construction stage will return.
When the steps below require the UA to reset the insertion mode appropriately, it means the UA must follow these steps:
select
element,
then switch the insertion mode to "in select" and abort these
steps. (fragment case)td
or
th
element and last is false, then
switch the insertion mode to "in cell" and abort these steps.tr
element, then
switch the insertion mode to "in row" and abort these steps.tbody
,
thead
, or tfoot
element, then switch the
insertion mode to "in table body" and abort these steps.caption
element,
then switch the insertion mode to "in caption" and abort
these steps.colgroup
element,
then switch the insertion mode to "in column group" and
abort these steps. (fragment case)table
element,
then switch the insertion mode to "in table" and abort these
steps.head
element,
then switch the insertion mode to "in body" ("in body"! not "in head"!) and abort
these steps. (fragment case)body
element,
then switch the insertion mode to "in body" and abort these
steps.frameset
element,
then switch the insertion mode to "in frameset" and abort
these steps. (fragment case)html
element,
then switch the insertion mode
to "before
head" Then, abort these steps. (fragment
case)Initially, the stack of open elements is empty. The stack grows downwards; the topmost node on the stack is the first one added to the stack, and the bottommost node of the stack is the most recently added node in the stack (notwithstanding when the stack is manipulated in a random access fashion as part of the handling for misnested tags).
The "before
html" insertion mode creates the
html
root element node, which is then added to the
stack.
In the fragment case, the stack of open
elements is initialized to contain an html
element that is created as part of that algorithm. (The fragment
case skips the "before html" insertion mode.)
The html
node, however it is created, is the topmost
node of the stack. It only gets popped off the stack when the parser
finishes.
The current node is the bottommost node in this stack.
The current table is the last table
element in the stack of open elements, if there is
one. If there is no table
element in the stack of
open elements (fragment case), then the
current table is the first element in the stack
of open elements (the html
element).
Elements in the stack fall into the following categories:
The following elements have varying levels of special
parsing rules: HTML's address
, applet
,
area
, article
, aside
,
base
, basefont
, bgsound
,
blockquote
, body
, br
,
button
, caption
, center
,
col
, colgroup
, command
,
dd
, details
, dir
,
div
, dl
, dt
,
embed
, fieldset
, figcaption
,
figure
, footer
, form
,
frame
, frameset
, h1
,
h2
, h3
, h4
, h5
,
h6
, head
, header
,
hgroup
, hr
, html
,
iframe
, img
, input
,
isindex
, li
, link
,
listing
, marquee
, menu
,
meta
, nav
, noembed
,
noframes
, noscript
, object
,
ol
, p
, param
,
plaintext
, pre
, script
,
section
, select
, style
,
summary
, table
, tbody
,
td
, textarea
, tfoot
,
th
, thead
, title
,
tr
, ul
, wbr
, and
xmp
; MathML's mi
, mo
, mn
, ms
, mtext
, and annotation-xml
; and SVG's foreignObject
, desc
, and
title
.
The following HTML elements are those that end up in the
list of active formatting elements: a
,
b
, big
, code
,
em
, font
, i
,
nobr
, s
, small
,
strike
, strong
, tt
, and
u
.
All other elements found while parsing an HTML document.
The stack of open elements is said to have an element in a specific scope consisting of a list of element types list when the following algorithm terminates in a match state:
Initialize node to be the current node (the bottommost node of the stack).
If node is the target node, terminate in a match state.
Otherwise, if node is one of the element types in list, terminate in a failure state.
Otherwise, set node to the previous
entry in the stack of open elements and return to step
2. (This will never fail, since the loop will always terminate in
the previous step if the top of the stack — an
html
element — is reached.)
The stack of open elements is said to have an element in scope when it has an element in the specific scope consisting of the following element types:
applet
in the HTML namespacecaption
in the HTML namespacehtml
in the HTML namespacetable
in the HTML namespacetd
in the HTML namespaceth
in the HTML namespacemarquee
in the HTML namespaceobject
in the HTML namespacemi
in the MathML namespacemo
in the MathML namespacemn
in the MathML namespacems
in the MathML namespacemtext
in the MathML namespaceannotation-xml
in the MathML namespaceforeignObject
in the SVG namespacedesc
in the SVG namespacetitle
in the SVG namespaceThe stack of open elements is said to have an element in list item scope when it has an element in the specific scope consisting of the following element types:
ol
in the HTML namespaceul
in the HTML namespaceThe stack of open elements is said to have an element in button scope when it has an element in the specific scope consisting of the following element types:
button
in the HTML namespaceThe stack of open elements is said to have an element in table scope when it has an element in the specific scope consisting of the following element types:
html
in the HTML namespacetable
in the HTML namespaceThe stack of open elements is said to have an element in select scope when it has an element in the specific scope consisting of all element types except the following:
optgroup
in the HTML namespaceoption
in the HTML namespaceNothing happens if at any time any of the elements in the
stack of open elements are moved to a new location in,
or removed from, the Document
tree. In particular, the
stack is not changed in this situation. This can cause, amongst
other strange effects, content to be appended to nodes that are no
longer in the DOM.
In some cases (namely, when closing misnested formatting elements), the stack is manipulated in a random-access fashion.
Initially, the list of active formatting elements is empty. It is used to handle mis-nested formatting element tags.
The list contains elements in the formatting
category, and scope markers. The scope markers are inserted when
entering applet
elements, buttons, object
elements, marquees, table cells, and table captions, and are used to
prevent formatting from "leaking" into applet
elements, buttons, object
elements, marquees, and
tables.
The scope markers are unrelated to the concept of an element being in scope.
In addition, each element in the list of active formatting elements is associated with the token for which it was created, so that further elements can be created for that token if necessary.
When the steps below require the UA to push onto the list of active formatting elements an element element, the UA must perform the following steps:
If there are already three elements in the list of active formatting elements after the last list marker, if any, or anywhere in the list if there are no list markers, that have the same tag name, namespace, and attributes as element, then remove the earliest such element from the list of active formatting elements. For these purposes, the attributes must be compared as they were when the elements were created by the parser; two elements have the same attributes if all their parsed attributes can be paired such that the two attributes in each pair have identical names, namespaces, and values (the order of the attributes does not matter).
This is the Noah's Ark clause. But with three per family instead of two.
Add element to the list of active formatting elements.
When the steps below require the UA to reconstruct the active formatting elements, the UA must perform the following steps:
This has the effect of reopening all the formatting elements that were opened in the current body, cell, or caption (whichever is youngest) that haven't been explicitly closed.
The way this specification is written, the list of active formatting elements always consists of elements in chronological order with the least recently added element first and the most recently added element last (except for while steps 8 to 11 of the above algorithm are being executed, of course).
When the steps below require the UA to clear the list of active formatting elements up to the last marker, the UA must perform the following steps:
Initially, the head
element
pointer and the form
element
pointer are both null.
Once a head
element has been parsed (whether
implicitly or explicitly) the head
element pointer gets set to point to this node.
The form
element pointer
points to the last form
element that was opened and
whose end tag has not yet been seen. It is used to make form
controls associate with forms in the face of dramatically bad
markup, for historical reasons.
The scripting flag is set to "enabled" if scripting was enabled for the
Document
with which the parser is associated when the
parser was created, and "disabled" otherwise.
The scripting flag can be enabled even
when the parser was originally created for the HTML fragment
parsing algorithm, even though script
elements
don't execute in that case.
The frameset-ok flag is set to "ok" when the parser is created. It is set to "not ok" after certain tokens are seen.
Implementations must act as if they used the following state machine to tokenize HTML. The state machine must start in the data state. Most states consume a single character, which may have various side-effects, and either switches the state machine to a new state to reconsume the same character, or switches it to a new state (to consume the next character), or repeats the same state (to consume the next character). Some states have more complicated behavior and can consume several characters before switching to another state. In some cases, the tokenizer state is also changed by the tree construction stage.
The exact behavior of certain states depends on the insertion mode and the stack of open elements. Certain states also use a temporary buffer to track progress.
The output of the tokenization step is a series of zero or more of the following tokens: DOCTYPE, start tag, end tag, comment, character, end-of-file. DOCTYPE tokens have a name, a public identifier, a system identifier, and a force-quirks flag. When a DOCTYPE token is created, its name, public identifier, and system identifier must be marked as missing (which is a distinct state from the empty string), and the force-quirks flag must be set to off (its other state is on). Start and end tag tokens have a tag name, a self-closing flag, and a list of attributes, each of which has a name and a value. When a start or end tag token is created, its self-closing flag must be unset (its other state is that it be set), and its attributes list must be empty. Comment and character tokens have data.
When a token is emitted, it must immediately be handled by the
tree construction stage. The tree construction stage
can affect the state of the tokenization stage, and can insert
additional characters into the stream. (For example, the
script
element can result in scripts executing and
using the dynamic markup insertion APIs to insert
characters into the stream being tokenized.)
When a start tag token is emitted with its self-closing flag set, if the flag is not acknowledged when it is processed by the tree construction stage, that is a parse error.
When an end tag token is emitted with attributes, that is a parse error.
When an end tag token is emitted with its self-closing flag set, that is a parse error.
An appropriate end tag token is an end tag token whose tag name matches the tag name of the last start tag to have been emitted from this tokenizer, if any. If no start tag has been emitted from this tokenizer, then no end tag token is appropriate.
Before each step of the tokenizer, the user agent must first check the parser pause flag. If it is true, then the tokenizer must abort the processing of any nested invocations of the tokenizer, yielding control back to the caller.
The tokenizer state machine consists of the states defined in the following subsections.
Consume the next input character:
Attempt to consume a character reference, with no additional allowed character.
If nothing is returned, emit a U+0026 AMPERSAND character (&) token.
Otherwise, emit the character token that was returned.
Finally, switch to the data state.
Consume the next input character:
Attempt to consume a character reference, with no additional allowed character.
If nothing is returned, emit a U+0026 AMPERSAND character (&) token.
Otherwise, emit the character token that was returned.
Finally, switch to the RCDATA state.
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
script
", then switch to the script data
double escaped state. Otherwise, switch to the script
data escaped state. Emit the current input
character as a character token.Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
script
", then switch to the script data
escaped state. Otherwise, switch to the script data
double escaped state. Emit the current input
character as a character token.Consume the next input character:
Consume the next input character:
When the user agent leaves the attribute name state (and before emitting the tag token, if appropriate), the complete attribute's name must be compared to the other attributes on the same token; if there is already an attribute on the token with the exact same name, then this is a parse error and the new attribute must be dropped, along with the value that gets associated with it (if any).
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Attempt to consume a character reference.
If nothing is returned, append a U+0026 AMPERSAND character (&) to the current attribute's value.
Otherwise, append the returned character token to the current attribute's value.
Finally, switch back to the attribute value state that switched into this state.
Consume the next input character:
Consume the next input character:
Consume every character up to and including the first U+003E GREATER-THAN SIGN character (>) or the end of the file (EOF), whichever comes first. Emit a comment token whose data is the concatenation of all the characters starting from and including the character that caused the state machine to switch into the bogus comment state, up to and including the character immediately before the last consumed character (i.e. up to the character just before the U+003E or EOF character), but with any U+0000 NULL characters replaced by U+FFFD REPLACEMENT CHARACTER characters. (If the comment was started by the end of the file (EOF), the token is empty.)
Switch to the data state.
If the end of the file was reached, reconsume the EOF character.
If the next two characters are both U+002D HYPHEN-MINUS characters (-), consume those two characters, create a comment token whose data is the empty string, and switch to the comment start state.
Otherwise, if the next seven characters are an ASCII case-insensitive match for the word "DOCTYPE", then consume those characters and switch to the DOCTYPE state.
Otherwise, if the current node is not an element in the HTML namespace and the next seven characters are an case-sensitive match for the string "[CDATA[" (the five uppercase letters "CDATA" with a U+005B LEFT SQUARE BRACKET character before and after), then consume those characters and switch to the CDATA section state.
Otherwise, this is a parse error. Switch to the bogus comment state. The next character that is consumed, if any, is the first character that will be in the comment.
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
If the six characters starting from the current input character are an ASCII case-insensitive match for the word "PUBLIC", then consume those characters and switch to the after DOCTYPE public keyword state.
Otherwise, if the six characters starting from the current input character are an ASCII case-insensitive match for the word "SYSTEM", then consume those characters and switch to the after DOCTYPE system keyword state.
Otherwise, this is the parse error. Set the DOCTYPE token's force-quirks flag to on. Switch to the bogus DOCTYPE state.
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume the next input character:
Consume every character up to the next occurrence of the three
character sequence U+005D RIGHT SQUARE BRACKET U+005D RIGHT SQUARE
BRACKET U+003E GREATER-THAN SIGN (]]>
), or the
end of the file (EOF), whichever comes first. Emit a series of
character tokens consisting of all the characters consumed except
the matching three character sequence at the end (if one was found
before the end of the file).
Switch to the data state.
If the end of the file was reached, reconsume the EOF character.
This section defines how to consume a character reference. This definition is used when parsing character references in text and in attributes.
The behavior depends on the identity of the next character (the one immediately after the U+0026 AMPERSAND character):
Consume the U+0023 NUMBER SIGN.
The behavior further depends on the character after the U+0023 NUMBER SIGN:
Consume the X.
Follow the steps below, but using the range of characters U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0061 LATIN SMALL LETTER A to U+0066 LATIN SMALL LETTER F, and U+0041 LATIN CAPITAL LETTER A to U+0046 LATIN CAPITAL LETTER F (in other words, 0-9, A-F, a-f).
When it comes to interpreting the number, interpret it as a hexadecimal number.
Follow the steps below, but using the range of characters U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9).
When it comes to interpreting the number, interpret it as a decimal number.
Consume as many characters as match the range of characters given above.
If no characters match the range, then don't consume any characters (and unconsume the U+0023 NUMBER SIGN character and, if appropriate, the X character). This is a parse error; nothing is returned.
Otherwise, if the next character is a U+003B SEMICOLON, consume that too. If it isn't, there is a parse error.
If one or more characters match the range, then take them all and interpret the string of characters as a number (either hexadecimal or decimal as appropriate).
If that number is one of the numbers in the first column of the following table, then this is a parse error. Find the row with that number in the first column, and return a character token for the Unicode character given in the second column of that row.
Number | Unicode character | |
---|---|---|
0x00 | U+FFFD | REPLACEMENT CHARACTER |
0x0D | U+000D | CARRIAGE RETURN (CR) |
0x80 | U+20AC | EURO SIGN (€) |
0x81 | U+0081 | <control> |
0x82 | U+201A | SINGLE LOW-9 QUOTATION MARK (‚) |
0x83 | U+0192 | LATIN SMALL LETTER F WITH HOOK (ƒ) |
0x84 | U+201E | DOUBLE LOW-9 QUOTATION MARK („) |
0x85 | U+2026 | HORIZONTAL ELLIPSIS (…) |
0x86 | U+2020 | DAGGER (†) |
0x87 | U+2021 | DOUBLE DAGGER (‡) |
0x88 | U+02C6 | MODIFIER LETTER CIRCUMFLEX ACCENT (ˆ) |
0x89 | U+2030 | PER MILLE SIGN (‰) |
0x8A | U+0160 | LATIN CAPITAL LETTER S WITH CARON (Š) |
0x8B | U+2039 | SINGLE LEFT-POINTING ANGLE QUOTATION MARK (‹) |
0x8C | U+0152 | LATIN CAPITAL LIGATURE OE (Œ) |
0x8D | U+008D | <control> |
0x8E | U+017D | LATIN CAPITAL LETTER Z WITH CARON (Ž) |
0x8F | U+008F | <control> |
0x90 | U+0090 | <control> |
0x91 | U+2018 | LEFT SINGLE QUOTATION MARK (‘) |
0x92 | U+2019 | RIGHT SINGLE QUOTATION MARK (’) |
0x93 | U+201C | LEFT DOUBLE QUOTATION MARK (“) |
0x94 | U+201D | RIGHT DOUBLE QUOTATION MARK (”) |
0x95 | U+2022 | BULLET (•) |
0x96 | U+2013 | EN DASH (–) |
0x97 | U+2014 | EM DASH (—) |
0x98 | U+02DC | SMALL TILDE (˜) |
0x99 | U+2122 | TRADE MARK SIGN (™) |
0x9A | U+0161 | LATIN SMALL LETTER S WITH CARON (š) |
0x9B | U+203A | SINGLE RIGHT-POINTING ANGLE QUOTATION MARK (›) |
0x9C | U+0153 | LATIN SMALL LIGATURE OE (œ) |
0x9D | U+009D | <control> |
0x9E | U+017E | LATIN SMALL LETTER Z WITH CARON (ž) |
0x9F | U+0178 | LATIN CAPITAL LETTER Y WITH DIAERESIS (Ÿ) |
Otherwise, if the number is in the range 0xD800 to 0xDFFF or is greater than 0x10FFFF, then this is a parse error. Return a U+FFFD REPLACEMENT CHARACTER.
Otherwise, return a character token for the Unicode character whose code point is that number. If the number is in the range 0x0001 to 0x0008, 0x000E to 0x001F, 0x007F to 0x009F, 0xFDD0 to 0xFDEF, or is one of 0x000B, 0xFFFE, 0xFFFF, 0x1FFFE, 0x1FFFF, 0x2FFFE, 0x2FFFF, 0x3FFFE, 0x3FFFF, 0x4FFFE, 0x4FFFF, 0x5FFFE, 0x5FFFF, 0x6FFFE, 0x6FFFF, 0x7FFFE, 0x7FFFF, 0x8FFFE, 0x8FFFF, 0x9FFFE, 0x9FFFF, 0xAFFFE, 0xAFFFF, 0xBFFFE, 0xBFFFF, 0xCFFFE, 0xCFFFF, 0xDFFFE, 0xDFFFF, 0xEFFFE, 0xEFFFF, 0xFFFFE, 0xFFFFF, 0x10FFFE, or 0x10FFFF, then this is a parse error.
Consume the maximum number of characters possible, with the consumed characters matching one of the identifiers in the first column of the named character references table (in a case-sensitive manner).
If no match can be made, then no characters are consumed, and nothing is returned. In this case, if the characters after the U+0026 AMPERSAND character (&) consist of a sequence of one or more characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER Z, and U+0041 LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z, followed by a U+003B SEMICOLON character (;), then this is a parse error.
If the character reference is being consumed as part of an attribute, and the last character matched is not a U+003B SEMICOLON character (;), and the next character is either a U+003D EQUALS SIGN character (=) or in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), U+0041 LATIN CAPITAL LETTER A to U+005A LATIN CAPITAL LETTER Z, or U+0061 LATIN SMALL LETTER A to U+007A LATIN SMALL LETTER Z, then, for historical reasons, all the characters that were matched after the U+0026 AMPERSAND character (&) must be unconsumed, and nothing is returned.
Otherwise, a character reference is parsed. If the last character matched is not a U+003B SEMICOLON character (;), there is a parse error.
Return one or two character tokens for the character(s) corresponding to the character reference name (as given by the second column of the named character references table).
If the markup contains (not in an attribute) the string I'm ¬it; I tell you
, the character
reference is parsed as "not", as in, I'm ¬it;
I tell you
(and this is a parse error). But if the markup
was I'm ∉ I tell you
, the
character reference would be parsed as "notin;", resulting in
I'm ∉ I tell you
(and no parse
error).
The input to the tree construction stage is a sequence of tokens
from the tokenization stage. The tree construction
stage is associated with a DOM Document
object when a
parser is created. The "output" of this stage consists of
dynamically modifying or extending that document's DOM tree.
This specification does not define when an interactive user agent
has to render the Document
so that it is available to
the user, or when it has to begin accepting user input.
As each token is emitted from the tokenizer, the user agent must follow the appropriate steps from the following list:
annotation-xml
element in the MathML namespace and the token is a start tag whose tag name is "svg"The current node is a MathML text integration point if it is one of the following elements:
mi
element in the MathML namespacemo
element in the MathML namespacemn
element in the MathML namespacems
element in the MathML namespacemtext
element in the MathML namespaceThe current node is an HTML integration point if it is one of the following elements:
annotation-xml
element in the MathML namespace whose start tag token had an attribute with the name "encoding" whose value was an ASCII case-insensitive match for the string "text/html
"annotation-xml
element in the MathML namespace whose start tag token had an attribute with the name "encoding" whose value was an ASCII case-insensitive match for the string "application/xhtml+xml
"foreignObject
element in the SVG namespacedesc
element in the SVG namespacetitle
element in the SVG namespaceWhen the steps below require the UA to insert a
character into a node, if that node has a child immediately
before where the character is to be inserted, and that child is a
Text
node, then the character must be appended to that
Text
node; otherwise, a new Text
node
whose data is just that character must be inserted in the
appropriate place.
Here are some sample inputs to the parser and the corresponding number of text nodes that they result in, assuming a user agent that executes scripts.
Input | Number of text nodes |
---|---|
A<script> var script = document.getElementsByTagName('script')[0]; document.body.removeChild(script); </script>B | One text node in the document, containing "AB". |
A<script> var text = document.createTextNode('B'); document.body.appendChild(text); </script>C | Three text nodes; "A" before the script, the script's contents, and "BC" after the script (the parser appends to the text node created by the script). |
A<script> var text = document.getElementsByTagName('script')[0].firstChild; text.data = 'B'; document.body.appendChild(text); </script>C | Two adjacent text nodes in the document, containing "A" and "BC". |
A<table>B<tr>C</tr>D</table> | One text node before the table, containing "ABCD". (This is caused by foster parenting.) |
A<table><tr> B</tr> C</table> | One text node before the table, containing "A B C" (A-space-B-space-C). (This is caused by foster parenting.) |
A<table><tr> B</tr> </em>C</table> | One text node before the table, containing "A BC" (A-space-B-C), and one text node inside the table (as a child of a tbody ) with a single space character. (Space characters separated from non-space characters by non-character tokens are not affected by foster parenting, even if those other tokens then get ignored.)
|
DOM mutation events must not fire
for changes caused by the UA parsing the document. (Conceptually,
the parser is not mutating the DOM, it is constructing it.) This
includes the parsing of any content inserted using document.write()
and document.writeln()
calls. [DOMEVENTS]
Not all of the tag names mentioned below are conformant tag names in this specification; many are included to handle legacy content. They still form part of the algorithm that implementations are required to implement to claim conformance.
The algorithm described below places no limit on the depth of the DOM tree generated, or on the length of tag names, attribute names, attribute values, text nodes, etc. While implementors are encouraged to avoid arbitrary limits, it is recognized that practical concerns will likely force user agents to impose nesting depth constraints.
When the steps below require the UA to create an element for a token in a
particular namespace, the UA must create a node implementing the
interface appropriate for the element type corresponding to the tag
name of the token in the given namespace (as given in the
specification that defines that element, e.g. for an a
element in the HTML namespace, this specification
defines it to be the HTMLAnchorElement
interface), with
the tag name being the name of that element, with the node being in
the given namespace, and with the attributes on the node being those
given in the given token.
The interface appropriate for an element in the HTML
namespace that is not defined in this specification (or
other applicable specifications) is
HTMLUnknownElement
. Element in other namespaces whose
interface is not defined by that namespace's specification must use
the interface Element
.
When a resettable element is created in this manner, its reset algorithm must be invoked once the attributes are set. (This initializes the element's value and checkedness based on the element's attributes.)
When the steps below require the UA to insert an HTML element for a token, the UA must first create an element for the token in the HTML namespace, and then append this node to the current node, and push it onto the stack of open elements so that it is the new current node.
The steps below may also require that the UA insert an HTML element in a particular place, in which case the UA must follow the same steps except that it must insert or append the new node in the location specified instead of appending it to the current node. (This happens in particular during the parsing of tables with invalid content.)
If an element created by the insert an HTML element
algorithm is a form-associated element, and the
form
element pointer is not null,
and the newly created element doesn't have a form
attribute, the user agent must
associate the newly
created element with the form
element pointed to by the
form
element pointer when the
element is inserted, instead of running the reset the form
owner algorithm.
When the steps below require the UA to insert a foreign
element for a token, the UA must first create an element
for the token in the given namespace, and then append this
node to the current node, and push it onto the
stack of open elements so that it is the new
current node. If the newly created element has an xmlns
attribute in the XMLNS namespace
whose value is not exactly the same as the element's namespace, that
is a parse error. Similarly, if the newly created
element has an xmlns:xlink
attribute in the
XMLNS namespace whose value is not the XLink
Namespace, that is a parse error.
When the steps below require the user agent to adjust MathML
attributes for a token, then, if the token has an attribute
named definitionurl
, change its name to definitionURL
(note the case difference).
When the steps below require the user agent to adjust SVG attributes for a token, then, for each attribute on the token whose attribute name is one of the ones in the first column of the following table, change the attribute's name to the name given in the corresponding cell in the second column. (This fixes the case of SVG attributes that are not all lowercase.)
Attribute name on token | Attribute name on element |
---|---|
attributename | attributeName
|
attributetype | attributeType
|
basefrequency | baseFrequency
|
baseprofile | baseProfile
|
calcmode | calcMode
|
clippathunits | clipPathUnits
|
contentscripttype | contentScriptType
|
contentstyletype | contentStyleType
|
diffuseconstant | diffuseConstant
|
edgemode | edgeMode
|
externalresourcesrequired | externalResourcesRequired
|
filterres | filterRes
|
filterunits | filterUnits
|
glyphref | glyphRef
|
gradienttransform | gradientTransform
|
gradientunits | gradientUnits
|
kernelmatrix | kernelMatrix
|
kernelunitlength | kernelUnitLength
|
keypoints | keyPoints
|
keysplines | keySplines
|
keytimes | keyTimes
|
lengthadjust | lengthAdjust
|
limitingconeangle | limitingConeAngle
|
markerheight | markerHeight
|
markerunits | markerUnits
|
markerwidth | markerWidth
|
maskcontentunits | maskContentUnits
|
maskunits | maskUnits
|
numoctaves | numOctaves
|
pathlength | pathLength
|
patterncontentunits | patternContentUnits
|
patterntransform | patternTransform
|
patternunits | patternUnits
|
pointsatx | pointsAtX
|
pointsaty | pointsAtY
|
pointsatz | pointsAtZ
|
preservealpha | preserveAlpha
|
preserveaspectratio | preserveAspectRatio
|
primitiveunits | primitiveUnits
|
refx | refX
|
refy | refY
|
repeatcount | repeatCount
|
repeatdur | repeatDur
|
requiredextensions | requiredExtensions
|
requiredfeatures | requiredFeatures
|
specularconstant | specularConstant
|
specularexponent | specularExponent
|
spreadmethod | spreadMethod
|
startoffset | startOffset
|
stddeviation | stdDeviation
|
stitchtiles | stitchTiles
|
surfacescale | surfaceScale
|
systemlanguage | systemLanguage
|
tablevalues | tableValues
|
targetx | targetX
|
targety | targetY
|
textlength | textLength
|
viewbox | viewBox
|
viewtarget | viewTarget
|
xchannelselector | xChannelSelector
|
ychannelselector | yChannelSelector
|
zoomandpan | zoomAndPan
|
When the steps below require the user agent to adjust
foreign attributes for a token, then, if any of the attributes
on the token match the strings given in the first column of the
following table, let the attribute be a namespaced attribute, with
the prefix being the string given in the corresponding cell in the
second column, the local name being the string given in the
corresponding cell in the third column, and the namespace being the
namespace given in the corresponding cell in the fourth
column. (This fixes the use of namespaced attributes, in particular
lang
attributes in
the XML namespace.)
Attribute name | Prefix | Local name | Namespace |
---|---|---|---|
xlink:actuate | xlink | actuate | XLink namespace |
xlink:arcrole | xlink | arcrole | XLink namespace |
xlink:href | xlink | href | XLink namespace |
xlink:role | xlink | role | XLink namespace |
xlink:show | xlink | show | XLink namespace |
xlink:title | xlink | title | XLink namespace |
xlink:type | xlink | type | XLink namespace |
xml:base | xml | base | XML namespace |
xml:lang | xml | lang | XML namespace |
xml:space | xml | space | XML namespace |
xmlns | (none) | xmlns | XMLNS namespace |
xmlns:xlink | xmlns | xlink | XMLNS namespace |
The generic raw text element parsing algorithm and the generic RCDATA element parsing algorithm consist of the following steps. These algorithms are always invoked in response to a start tag token.
Insert an HTML element for the token.
If the algorithm that was invoked is the generic raw text element parsing algorithm, switch the tokenizer to the RAWTEXT state; otherwise the algorithm invoked was the generic RCDATA element parsing algorithm, switch the tokenizer to the RCDATA state.
Let the original insertion mode be the current insertion mode.
Then, switch the insertion mode to "text".
When the steps below require the UA to generate implied end
tags, then, while the current node is a
dd
element, a dt
element, an
li
element, an option
element, an
optgroup
element, a p
element, an
rp
element, or an rt
element, the UA must
pop the current node off the stack of open
elements.
If a step requires the UA to generate implied end tags but lists an element to exclude from the process, then the UA must perform the above steps as if that element was not in the above list.
Foster parenting happens when content is misnested in tables.
When a node node is to be foster parented, the node node must be inserted into the foster parent element.
The foster parent element is the parent element of the
last table
element in the stack of open
elements, if there is a table
element and it has
such a parent element.
It might have no parent or some other kind parent if a script manipulated the DOM after the element was inserted by the parser.
If there is no table
element in the stack of
open elements (fragment case), then the
foster parent element is the first element in the stack
of open elements (the html
element). Otherwise,
if there is a table
element in the stack of open
elements, but the last table
element in the
stack of open elements has no parent, or its parent
node is not an element, then the foster parent element is the
element before the last table
element in the
stack of open elements.
If the foster parent element is the parent element of the
last table
element in the stack of open
elements, then node must be inserted into
the foster parent element, immediately before the
last table
element in the stack of open
elements; otherwise, node must be
appended to the foster parent element.
When the user agent is to apply the rules for the "initial" insertion mode, the user agent must handle the token as follows:
Ignore the token.
Append a Comment
node to the Document
object with the data
attribute set to the
data given in the comment token.
If the DOCTYPE token's name is not a
case-sensitive match for the string "html
", or the token's public identifier is not
missing, or the token's system identifier is neither missing nor a
case-sensitive match for the string
"about:legacy-compat
", and none of the sets of
conditions in the following list are matched, then there is a
parse error.
html
", the token's
public identifier is the case-sensitive string
"-//W3C//DTD HTML 4.0//EN
", and
the token's system identifier is either missing or the
case-sensitive string "http://www.w3.org/TR/REC-html40/strict.dtd
".html
", the token's
public identifier is the case-sensitive string
"-//W3C//DTD HTML 4.01//EN
", and
the token's system identifier is either missing or the
case-sensitive string "http://www.w3.org/TR/html4/strict.dtd
".html
", the token's
public identifier is the case-sensitive string
"-//W3C//DTD XHTML 1.0 Strict//EN
",
and the token's system identifier is the
case-sensitive string "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd
".html
", the token's
public identifier is the case-sensitive string
"-//W3C//DTD XHTML 1.1//EN
", and
the token's system identifier is the case-sensitive
string "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd
".Conformance checkers may, based on the values (including presence or lack thereof) of the DOCTYPE token's name, public identifier, or system identifier, switch to a conformance checking mode for another language (e.g. based on the DOCTYPE token a conformance checker could recognize that the document is an HTML4-era document, and defer to an HTML4 conformance checker.)
Append a DocumentType
node to the
Document
node, with the name
attribute set to the name given in the DOCTYPE token, or the empty
string if the name was missing; the publicId
attribute set to the public identifier given in the DOCTYPE token,
or the empty string if the public identifier was missing; the
systemId
attribute set to the system
identifier given in the DOCTYPE token, or the empty string if the
system identifier was missing; and the other attributes specific
to DocumentType
objects set to null and empty lists
as appropriate. Associate the DocumentType
node with
the Document
object so that it is returned as the
value of the doctype
attribute of the
Document
object.
Then, if the DOCTYPE token matches
one of the conditions in the following list, then set the
Document
to quirks mode:
html
" (compared case-sensitively). +//Silmaril//dtd html Pro v0r11 19970101//
" -//AdvaSoft Ltd//DTD HTML 3.0 asWedit + extensions//
" -//AS//DTD HTML 3.0 asWedit + extensions//
" -//IETF//DTD HTML 2.0 Level 1//
" -//IETF//DTD HTML 2.0 Level 2//
" -//IETF//DTD HTML 2.0 Strict Level 1//
" -//IETF//DTD HTML 2.0 Strict Level 2//
" -//IETF//DTD HTML 2.0 Strict//
" -//IETF//DTD HTML 2.0//
" -//IETF//DTD HTML 2.1E//
" -//IETF//DTD HTML 3.0//
" -//IETF//DTD HTML 3.2 Final//
" -//IETF//DTD HTML 3.2//
" -//IETF//DTD HTML 3//
" -//IETF//DTD HTML Level 0//
" -//IETF//DTD HTML Level 1//
" -//IETF//DTD HTML Level 2//
" -//IETF//DTD HTML Level 3//
" -//IETF//DTD HTML Strict Level 0//
" -//IETF//DTD HTML Strict Level 1//
" -//IETF//DTD HTML Strict Level 2//
" -//IETF//DTD HTML Strict Level 3//
" -//IETF//DTD HTML Strict//
" -//IETF//DTD HTML//
" -//Metrius//DTD Metrius Presentational//
" -//Microsoft//DTD Internet Explorer 2.0 HTML Strict//
" -//Microsoft//DTD Internet Explorer 2.0 HTML//
" -//Microsoft//DTD Internet Explorer 2.0 Tables//
" -//Microsoft//DTD Internet Explorer 3.0 HTML Strict//
" -//Microsoft//DTD Internet Explorer 3.0 HTML//
" -//Microsoft//DTD Internet Explorer 3.0 Tables//
" -//Netscape Comm. Corp.//DTD HTML//
" -//Netscape Comm. Corp.//DTD Strict HTML//
" -//O'Reilly and Associates//DTD HTML 2.0//
" -//O'Reilly and Associates//DTD HTML Extended 1.0//
" -//O'Reilly and Associates//DTD HTML Extended Relaxed 1.0//
" -//SoftQuad Software//DTD HoTMetaL PRO 6.0::19990601::extensions to HTML 4.0//
" -//SoftQuad//DTD HoTMetaL PRO 4.0::19971010::extensions to HTML 4.0//
" -//Spyglass//DTD HTML 2.0 Extended//
" -//SQ//DTD HTML 2.0 HoTMetaL + extensions//
" -//Sun Microsystems Corp.//DTD HotJava HTML//
" -//Sun Microsystems Corp.//DTD HotJava Strict HTML//
" -//W3C//DTD HTML 3 1995-03-24//
" -//W3C//DTD HTML 3.2 Draft//
" -//W3C//DTD HTML 3.2 Final//
" -//W3C//DTD HTML 3.2//
" -//W3C//DTD HTML 3.2S Draft//
" -//W3C//DTD HTML 4.0 Frameset//
" -//W3C//DTD HTML 4.0 Transitional//
" -//W3C//DTD HTML Experimental 19960712//
" -//W3C//DTD HTML Experimental 970421//
" -//W3C//DTD W3 HTML//
" -//W3O//DTD W3 HTML 3.0//
" -//W3O//DTD W3 HTML Strict 3.0//EN//
" -//WebTechs//DTD Mozilla HTML 2.0//
" -//WebTechs//DTD Mozilla HTML//
" -/W3C/DTD HTML 4.0 Transitional/EN
" HTML
" http://www.ibm.com/data/dtd/v11/ibmxhtml1-transitional.dtd
" -//W3C//DTD HTML 4.01 Frameset//
" -//W3C//DTD HTML 4.01 Transitional//
" Otherwise, if the DOCTYPE token matches one of the conditions
in the following list, then set the Document
to
limited-quirks mode:
-//W3C//DTD XHTML 1.0 Frameset//
" -//W3C//DTD XHTML 1.0 Transitional//
" -//W3C//DTD HTML 4.01 Frameset//
" -//W3C//DTD HTML 4.01 Transitional//
" The system identifier and public identifier strings must be compared to the values given in the lists above in an ASCII case-insensitive manner. A system identifier whose value is the empty string is not considered missing for the purposes of the conditions above.
Then, switch the insertion mode to "before html".
If the document is not an iframe
srcdoc
document,
then this is a parse error; set the
Document
to quirks mode.
In any case, switch the insertion mode to "before html", then reprocess the current token.
When the user agent is to apply the rules for the "before html" insertion mode, the user agent must handle the token as follows:
Parse error. Ignore the token.
Append a Comment
node to the Document
object with the data
attribute set to the
data given in the comment token.
Ignore the token.
Create an element for the token in the HTML
namespace. Append it to the Document
object. Put this element in the stack of open
elements.
If the Document
is being
loaded as part of navigation of a
browsing context, then: if the newly created element
has a manifest
attribute
whose value is not the empty string, then resolve the value of that attribute to an
absolute URL, relative to the newly created element,
and if that is successful, run the application cache selection
algorithm with the resulting absolute URL with
any <fragment> component
removed; otherwise, if there is no such attribute, or its value is
the empty string, or resolving its value fails, run the application cache selection
algorithm with no manifest. The algorithm must be passed
the Document
object.
Switch the insertion mode to "before head".
Act as described in the "anything else" entry below.
Parse error. Ignore the token.
Create an html
element. Append it to the
Document
object. Put this element in the stack
of open elements.
If the Document
is being loaded as part of navigation of a browsing
context, then: run the application cache selection
algorithm with no manifest, passing it the
Document
object.
Switch the insertion mode to "before head", then reprocess the current token.
The root element can end up being removed from the
Document
object, e.g. by scripts; nothing in particular
happens in such cases, content continues being appended to the nodes
as described in the next section.
When the user agent is to apply the rules for the "before head" insertion mode, the user agent must handle the token as follows:
Ignore the token.
Append a Comment
node to the current
node with the data
attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Insert an HTML element for the token.
Set the head
element pointer
to the newly created head
element.
Switch the insertion mode to "in head".
Act as if a start tag token with the tag name "head" and no attributes had been seen, then reprocess the current token.
Parse error. Ignore the token.
Act as if a start tag token with the tag name "head" and no attributes had been seen, then reprocess the current token.
When the user agent is to apply the rules for the "in head" insertion mode, the user agent must handle the token as follows:
Insert the character into the current node.
Append a Comment
node to the current
node with the data
attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
If the element has a charset
attribute, and its value
is either a supported ASCII-compatible character
encoding or a UTF-16 encoding, and the confidence is currently
tentative, then change the encoding to the
encoding given by the value of the charset
attribute.
Otherwise, if the element has an http-equiv
attribute whose
value is an ASCII case-insensitive match for the
string "Content-Type
", and the element has a
content
attribute, and
applying the algorithm for extracting an encoding from a
meta
element to that attribute's value returns
a supported ASCII-compatible character encoding or a
UTF-16 encoding, and the confidence is currently
tentative, then change the encoding to the
extracted encoding.
Follow the generic RCDATA element parsing algorithm.
Follow the generic raw text element parsing algorithm.
Insert an HTML element for the token.
Switch the insertion mode to "in head noscript".
Run these steps:
Mark the element as being "parser-inserted" and unset the element's "force-async" flag.
This ensures that, if the script is external,
any document.write()
calls in the script will execute in-line, instead of blowing the
document away, as would happen in most other cases. It also
prevents the script from executing until the end tag is
seen.
If the parser was originally created for the HTML
fragment parsing algorithm, then mark the
script
element as "already
started". (fragment case)
Append the new element to the current node and push it onto the stack of open elements.
Switch the tokenizer to the script data state.
Let the original insertion mode be the current insertion mode.
Switch the insertion mode to "text".
Pop the current node (which will be the
head
element) off the stack of open
elements.
Switch the insertion mode to "after head".
Act as described in the "anything else" entry below.
Parse error. Ignore the token.
Act as if an end tag token with the tag name "head" had been seen, and reprocess the current token.
When the user agent is to apply the rules for the "in head noscript" insertion mode, the user agent must handle the token as follows:
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Pop the current node (which will be a
noscript
element) from the stack of open
elements; the new current node will be a
head
element.
Switch the insertion mode to "in head".
Process the token using the rules for the "in head" insertion mode.
Act as described in the "anything else" entry below.
Parse error. Ignore the token.
Parse error. Act as if an end tag with the tag name "noscript" had been seen and reprocess the current token.
When the user agent is to apply the rules for the "after head" insertion mode, the user agent must handle the token as follows:
Insert the character into the current node.
Append a Comment
node to the current
node with the data
attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Insert an HTML element for the token.
Set the frameset-ok flag to "not ok".
Switch the insertion mode to "in body".
Insert an HTML element for the token.
Switch the insertion mode to "in frameset".
Push the node pointed to by the head
element pointer onto the
stack of open elements.
Process the token using the rules for the "in head" insertion mode.
Remove the node pointed to by the head
element pointer from the stack
of open elements.
The head
element
pointer cannot be null at this point.
Act as described in the "anything else" entry below.
Parse error. Ignore the token.
Act as if a start tag token with the tag name "body" and no attributes had been seen, then set the frameset-ok flag back to "ok", and then reprocess the current token.
When the user agent is to apply the rules for the "in body" insertion mode, the user agent must handle the token as follows:
Parse error. Ignore the token.
Reconstruct the active formatting elements, if any.
Insert the token's character into the current node.
Reconstruct the active formatting elements, if any.
Insert the token's character into the current node.
Set the frameset-ok flag to "not ok".
Append a Comment
node to the current
node with the data
attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Parse error. For each attribute on the token, check to see if the attribute is already present on the top element of the stack of open elements. If it is not, add the attribute and its corresponding value to that element.
Process the token using the rules for the "in head" insertion mode.
If the second element on the stack of open
elements is not a body
element, or, if the
stack of open elements has only one node on it,
then ignore the token. (fragment case)
Otherwise, set the frameset-ok flag to "not ok";
then, for each attribute on the token, check to see if the
attribute is already present on the body
element (the
second element) on the stack of open elements, and if
it is not, add the attribute and its corresponding value to that
element.
If the second element on the stack of open
elements is not a body
element, or, if the
stack of open elements has only one node on it,
then ignore the token. (fragment case)
If the frameset-ok flag is set to "not ok", ignore the token.
Otherwise, run the following steps:
Remove the second element on the stack of open elements from its parent node, if it has one.
Pop all the nodes from the bottom of the stack of
open elements, from the current node up to,
but not including, the root html
element.
Insert an HTML element for the token.
Switch the insertion mode to "in frameset".
If there is a node in the stack of open elements
that is not either a dd
element, a dt
element, an li
element, a p
element, a
tbody
element, a td
element, a
tfoot
element, a th
element, a
thead
element, a tr
element, the
body
element, or the html
element, then
this is a parse error.
If the stack of open elements does not have a body
element
in scope, this is a parse error; ignore the
token.
Otherwise, if there is a node in the stack of open
elements that is not either a dd
element, a
dt
element, an li
element, an
optgroup
element, an option
element, a
p
element, an rp
element, an
rt
element, a tbody
element, a
td
element, a tfoot
element, a
th
element, a thead
element, a
tr
element, the body
element, or the
html
element, then this is a parse
error.
Switch the insertion mode to "after body".
Act as if an end tag with tag name "body" had been seen, then, if that token wasn't ignored, reprocess the current token.
If the stack of open elements has a p
element in button
scope, then act as if an end tag with the tag name "p" had
been seen.
Insert an HTML element for the token.
If the stack of open elements has a p
element in button
scope, then act as if an end tag with the tag name
"p" had been seen.
If the current node is an element whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6", then this is a parse error; pop the current node off the stack of open elements.
Insert an HTML element for the token.
If the stack of open elements has a p
element in button
scope, then act as if an end tag with the tag name
"p" had been seen.
Insert an HTML element for the token.
If the next token is a U+000A LINE FEED (LF) character
token, then ignore that token and move on to the next
one. (Newlines at the start of pre
blocks are
ignored as an authoring convenience.)
Set the frameset-ok flag to "not ok".
If the form
element
pointer is not null, then this is a parse
error; ignore the token.
Otherwise:
If the stack of open elements has a p
element in button
scope, then act as if an end tag with the tag name
"p" had been seen.
Insert an HTML element for the token, and set the
form
element pointer to
point to the element created.
Run these steps:
Set the frameset-ok flag to "not ok".
Initialize node to be the current node (the bottommost node of the stack).
Loop: If node is an
li
element, then act as if an end tag with the tag
name "li" had been seen, then jump to the last step.
If node is in the special
category, but is not an address
, div
,
or p
element, then jump to the last step.
Otherwise, set node to the previous entry in the stack of open elements and return to the step labeled loop.
This is the last step.
If the stack of open elements has a p
element in button
scope, then act as if an end tag with the tag name
"p" had been seen.
Finally, insert an HTML element for the token.
Run these steps:
Set the frameset-ok flag to "not ok".
Initialize node to be the current node (the bottommost node of the stack).
Loop: If node is a
dd
or dt
element, then act as if an end
tag with the same tag name as node had been
seen, then jump to the last step.
If node is in the special
category, but is not an address
, div
,
or p
element, then jump to the last step.
Otherwise, set node to the previous entry in the stack of open elements and return to the step labeled loop.
This is the last step.
If the stack of open elements has a p
element in button
scope, then act as if an end tag with the tag name
"p" had been seen.
Finally, insert an HTML element for the token.
If the stack of open elements has a p
element in button
scope, then act as if an end tag with the tag name
"p" had been seen.
Insert an HTML element for the token.
Switch the tokenizer to the PLAINTEXT state.
Once a start tag with the tag name "plaintext" has been seen, that will be the last token ever seen other than character tokens (and the end-of-file token), because there is no way to switch out of the PLAINTEXT state.
If the stack of open elements has a button
element in
scope, then this is a parse error;
act as if an end tag with the tag name "button" had been seen,
then reprocess the token.
Otherwise:
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
Set the frameset-ok flag to "not ok".
If the stack of open elements does not have an element in scope with the same tag name as that of the token, then this is a parse error; ignore the token.
Otherwise, run these steps:
If the current node is not an element with the same tag name as that of the token, then this is a parse error.
Pop elements from the stack of open elements until an element with the same tag name as the token has been popped from the stack.
Let node be the element that the
form
element pointer is set
to.
Set the form
element pointer
to null.
If node is null or the stack of open elements does not have node in scope, then this is a parse error; ignore the token.
Otherwise, run these steps:
If the current node is not node, then this is a parse error.
Remove node from the stack of open elements.
If the stack of open elements does not have an element in button scope with the same tag name as that of the token, then this is a parse error; act as if a start tag with the tag name "p" had been seen, then reprocess the current token.
Otherwise, run these steps:
Generate implied end tags, except for elements with the same tag name as the token.
If the current node is not an element with the same tag name as that of the token, then this is a parse error.
Pop elements from the stack of open elements until an element with the same tag name as the token has been popped from the stack.
If the stack of open elements does not have an element in list item scope with the same tag name as that of the token, then this is a parse error; ignore the token.
Otherwise, run these steps:
Generate implied end tags, except for elements with the same tag name as the token.
If the current node is not an element with the same tag name as that of the token, then this is a parse error.
Pop elements from the stack of open elements until an element with the same tag name as the token has been popped from the stack.
If the stack of open elements does not have an element in scope with the same tag name as that of the token, then this is a parse error; ignore the token.
Otherwise, run these steps:
Generate implied end tags, except for elements with the same tag name as the token.
If the current node is not an element with the same tag name as that of the token, then this is a parse error.
Pop elements from the stack of open elements until an element with the same tag name as the token has been popped from the stack.
If the stack of open elements does not have an element in scope whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6", then this is a parse error; ignore the token.
Otherwise, run these steps:
If the current node is not an element with the same tag name as that of the token, then this is a parse error.
Pop elements from the stack of open elements until an element whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6" has been popped from the stack.
Take a deep breath, then act as described in the "any other end tag" entry below.
If the list of active formatting elements contains an element whose tag name is "a" between the end of the list and the last marker on the list (or the start of the list if there is no marker on the list), then this is a parse error; act as if an end tag with the tag name "a" had been seen, then remove that element from the list of active formatting elements and the stack of open elements if the end tag didn't already remove it (it might not have if the element is not in table scope).
In the non-conforming stream
<a href="a">a<table><a href="b">b</table>x
,
the first a
element would be closed upon seeing the
second one, and the "x" character would be inside a link to "b",
not to "a". This is despite the fact that the outer a
element is not in table scope (meaning that a regular
</a>
end tag at the start of the table wouldn't
close the outer a
element). The result is that the
two a
elements are indirectly nested inside each
other — non-conforming markup will often result in
non-conforming DOMs when parsed.
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Push onto the list of active formatting elements that element.
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Push onto the list of active formatting elements that element.
Reconstruct the active formatting elements, if any.
If the stack of open elements has a nobr
element in scope,
then this is a parse error; act as if an end tag with
the tag name "nobr" had been seen, then once again
reconstruct the active formatting elements, if
any.
Insert an HTML element for the token. Push onto the list of active formatting elements that element.
Run these steps:
Let outer loop counter be zero.
Outer loop: If outer loop counter is greater than or equal to eight, then abort these steps.
Increment outer loop counter by one.
Let the formatting element be the last element in the list of active formatting elements that:
If there is no such node, then abort these steps and instead act as described in the "any other end tag" entry below.
Otherwise, if there is such a node, but that node is not in the stack of open elements, then this is a parse error; remove the element from the list, and abort these steps.
Otherwise, if there is such a node, and that node is also in the stack of open elements, but the element is not in scope, then this is a parse error; ignore the token, and abort these steps.
Otherwise, there is a formatting element and that element is in the stack and is in scope. If the element is not the current node, this is a parse error. In any case, proceed with the algorithm as written in the following steps.
Let the furthest block be the topmost node in the stack of open elements that is lower in the stack than the formatting element, and is an element in the special category. There might not be one.
If there is no furthest block, then the UA must skip the subsequent steps and instead just pop all the nodes from the bottom of the stack of open elements, from the current node up to and including the formatting element, and remove the formatting element from the list of active formatting elements.
Let the common ancestor be the element immediately above the formatting element in the stack of open elements.
Let a bookmark note the position of the formatting element in the list of active formatting elements relative to the elements on either side of it in the list.
Let node and last node be the furthest block. Follow these steps:
Let inner loop counter be zero.
Inner loop: If inner loop counter is greater than or equal to three, then abort these steps.
Increment inner loop counter by one.
If the common ancestor node is a
table
, tbody
, tfoot
,
thead
, or tr
element, then,
foster parent whatever last
node ended up being in the previous step, first removing
it from its previous parent node if any.
Otherwise, append whatever last node ended up being in the previous step to the common ancestor node, first removing it from its previous parent node if any.
Create an element for the token for which the formatting element was created.
Take all of the child nodes of the furthest block and append them to the element created in the last step.
Append that new element to the furthest block.
Remove the formatting element from the list of active formatting elements, and insert the new element into the list of active formatting elements at the position of the aforementioned bookmark.
Remove the formatting element from the stack of open elements, and insert the new element into the stack of open elements immediately below the position of the furthest block in that stack.
Jump back to the step labeled outer loop.
Because of the way this algorithm causes elements to change parents, it has been dubbed the "adoption agency algorithm" (in contrast with other possible algorithms for dealing with misnested content, which included the "incest algorithm", the "secret affair algorithm", and the "Heisenberg algorithm").
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
Insert a marker at the end of the list of active formatting elements.
Set the frameset-ok flag to "not ok".
If the stack of open elements does not have an element in scope with the same tag name as that of the token, then this is a parse error; ignore the token.
Otherwise, run these steps:
If the current node is not an element with the same tag name as that of the token, then this is a parse error.
Pop elements from the stack of open elements until an element with the same tag name as the token has been popped from the stack.
If the Document
is not set to
quirks mode, and the stack of open
elements has a
p
element in button scope, then act as if an
end tag with the tag name "p" had been seen.
Insert an HTML element for the token.
Set the frameset-ok flag to "not ok".
Switch the insertion mode to "in table".
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
Set the frameset-ok flag to "not ok".
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
If the token does not have an attribute with the name "type",
or if it does, but that attribute's value is not an ASCII
case-insensitive match for the string "hidden
", then: set the frameset-ok
flag to "not ok".
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
If the stack of open elements has a p
element in button
scope, then act as if an end tag with the tag name
"p" had been seen.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
Set the frameset-ok flag to "not ok".
Parse error. Change the token's tag name to "img" and reprocess it. (Don't ask.)
If the form
element
pointer is not null, then ignore the token.
Otherwise:
Acknowledge the token's self-closing flag, if it is set.
Act as if a start tag token with the tag name "form" had been seen.
If the token has an attribute called "action", set the
action
attribute on the
resulting form
element to the value of the
"action" attribute of the token.
Act as if a start tag token with the tag name "hr" had been seen.
Act as if a start tag token with the tag name "label" had been seen.
Act as if a stream of character tokens had been seen (see below for what they should say).
Act as if a start tag token with the tag name "input" had been
seen, with all the attributes from the "isindex" token except
"name", "action", and "prompt". Set the name
attribute of the resulting
input
element to the value "isindex
".
Act as if a stream of character tokens had been seen (see below for what they should say).
Act as if an end tag token with the tag name "label" had been seen.
Act as if a start tag token with the tag name "hr" had been seen.
Act as if an end tag token with the tag name "form" had been seen.
If the token has an attribute with the name "prompt", then the
first stream of characters must be the same string as given in
that attribute, and the second stream of characters must be
empty. Otherwise, the two streams of character tokens together
should, together with the input
element, express the
equivalent of "This is a searchable index. Enter search keywords:
(input field)" in the user's preferred language.
Run these steps:
Insert an HTML element for the token.
If the next token is a U+000A LINE FEED (LF) character
token, then ignore that token and move on to the next
one. (Newlines at the start of textarea
elements are
ignored as an authoring convenience.)
Switch the tokenizer to the RCDATA state.
Let the original insertion mode be the current insertion mode.
Set the frameset-ok flag to "not ok".
Switch the insertion mode to "text".
If the stack of open elements has a p
element in button
scope, then act as if an end tag with the tag name
"p" had been seen.
Reconstruct the active formatting elements, if any.
Set the frameset-ok flag to "not ok".
Follow the generic raw text element parsing algorithm.
Set the frameset-ok flag to "not ok".
Follow the generic raw text element parsing algorithm.
Follow the generic raw text element parsing algorithm.
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
Set the frameset-ok flag to "not ok".
If the insertion mode is one of "in table", "in caption", "in table body", "in row", or "in cell", then switch the insertion mode to "in select in table". Otherwise, switch the insertion mode to "in select".
If the current node is an option
element, then act as if an end tag with the tag name "option" had
been seen.
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
If the stack of open elements has a ruby
element in scope,
then generate implied end tags. If the current
node is not then a ruby
element, this is a
parse error; pop all the nodes from the current
node up to the node immediately before the bottommost
ruby
element on the stack of open
elements.
Insert an HTML element for the token.
Parse error. Act as if a start tag token with the tag name "br" had been seen. Ignore the end tag token.
Reconstruct the active formatting elements, if any.
Adjust MathML attributes for the token. (This fixes the case of MathML attributes that are not all lowercase.)
Adjust foreign attributes for the token. (This fixes the use of namespaced attributes, in particular XLink.)
Insert a foreign element for the token, in the MathML namespace.
If the token has its self-closing flag set, pop the current node off the stack of open elements and acknowledge the token's self-closing flag.
Reconstruct the active formatting elements, if any.
Adjust SVG attributes for the token. (This fixes the case of SVG attributes that are not all lowercase.)
Adjust foreign attributes for the token. (This fixes the use of namespaced attributes, in particular XLink in SVG.)
Insert a foreign element for the token, in the SVG namespace.
If the token has its self-closing flag set, pop the current node off the stack of open elements and acknowledge the token's self-closing flag.
Parse error. Ignore the token.
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
This element will be an ordinary element.
Run these steps:
Initialize node to be the current node (the bottommost node of the stack).
Loop: If node has the same tag name as the token, then:
Generate implied end tags, except for elements with the same tag name as the token.
If the tag name of the end tag token does not match the tag name of the current node, this is a parse error.
Pop all the nodes from the current node up to node, including node, then stop these steps.
Otherwise, if node is in the special category, then this is a parse error; ignore the token, and abort these steps.
Set node to the previous entry in the stack of open elements.
Return to the step labeled loop.
When the user agent is to apply the rules for the "text" insertion mode, the user agent must handle the token as follows:
Insert the token's character into the current node.
This can never be a U+0000 NULL character; the tokenizer converts those to U+FFFD REPLACEMENT CHARACTER characters.
If the current node is a script
element, mark the script
element as "already
started".
Pop the current node off the stack of open elements.
Switch the insertion mode to the original insertion mode and reprocess the current token.
Let script be the current node
(which will be a script
element).
Pop the current node off the stack of open elements.
Switch the insertion mode to the original insertion mode.
Let the old insertion point have the same value as the current insertion point. Let the insertion point be just before the next input character.
Increment the parser's script nesting level by one.
Prepare the script. This might cause some script to execute, which might cause new characters to be inserted into the tokenizer, and might cause the tokenizer to output more tokens, resulting in a reentrant invocation of the parser.
Decrement the parser's script nesting level by one. If the parser's script nesting level is zero, then set the parser pause flag to false.
Let the insertion point have the value of the old insertion point. (In other words, restore the insertion point to its previous value. This value might be the "undefined" value.)
At this stage, if there is a pending parsing-blocking script, then:
Set the parser pause flag to true, and abort the processing of any nested invocations of the tokenizer, yielding control back to the caller. (Tokenization will resume when the caller returns to the "outer" tree construction stage.)
The tree construction stage of this particular
parser is being called reentrantly,
say from a call to document.write()
.
Run these steps:
Let the script be the pending parsing-blocking script. There is no longer a pending parsing-blocking script.
Block the tokenizer for this instance of the HTML parser, such that the event loop will not run tasks that invoke the tokenizer.
If the parser's Document
has a style
sheet that is blocking scripts or the
script's "ready to be parser-executed" flag
is not set: spin the event loop until the parser's
Document
has no style sheet that is blocking
scripts and the script's
"ready to be parser-executed" flag is
set.
Unblock the tokenizer for this instance of the HTML parser, such that tasks that invoke the tokenizer can again be run.
Let the insertion point be just before the next input character.
Increment the parser's script nesting level by one (it should be zero before this step, so this sets it to one).
Execute the script.
Decrement the parser's script nesting level by one. If the parser's script nesting level is zero (which it always should be at this point), then set the parser pause flag to false.
Let the insertion point be undefined again.
If there is once again a pending parsing-blocking script, then repeat these steps from step 1.
Pop the current node off the stack of open elements.
Switch the insertion mode to the original insertion mode.
When the user agent is to apply the rules for the "in table" insertion mode, the user agent must handle the token as follows:
Let the pending table character tokens be an empty list of tokens.
Let the original insertion mode be the current insertion mode.
Switch the insertion mode to "in table text" and reprocess the token.
Append a Comment
node to the current
node with the data
attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Clear the stack back to a table context. (See below.)
Insert a marker at the end of the list of active formatting elements.
Insert an HTML element for the token, then switch the insertion mode to "in caption".
Clear the stack back to a table context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in column group".
Act as if a start tag token with the tag name "colgroup" had been seen, then reprocess the current token.
Clear the stack back to a table context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in table body".
Act as if a start tag token with the tag name "tbody" had been seen, then reprocess the current token.
Parse error. Act as if an end tag token with the tag name "table" had been seen, then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the fragment case.
If the stack of open elements does not have an element in table scope with the same tag name as the token, this is a parse error. Ignore the token. (fragment case)
Otherwise:
Pop elements from this stack until a table
element has been popped from the stack.
Parse error. Ignore the token.
Process the token using the rules for the "in head" insertion mode.
If the token does not have an attribute with the name "type",
or if it does, but that attribute's value is not an ASCII
case-insensitive match for the string "hidden
", then: act as described in the "anything
else" entry below.
Otherwise:
Insert an HTML element for the token.
Pop that input
element off the stack of
open elements.
If the form
element
pointer is not null, ignore the token.
Otherwise:
Insert an HTML element for the token, and set the
form
element pointer to
point to the element created.
Pop that form
element off the stack of
open elements.
If the current node is not the root
html
element, then this is a parse
error.
It can only be the current node in the fragment case.
Parse error. Process the token using the
rules for the "in
body" insertion mode, except that if the
current node is a table
,
tbody
, tfoot
, thead
, or
tr
element, then, whenever a node would be inserted
into the current node, it must instead be foster parented.
When the steps above require the UA to clear the stack
back to a table context, it means that the UA must, while
the current node is not a table
element or an html
element, pop elements from the
stack of open elements.
The current node being an
html
element after this process is a fragment
case.
When the user agent is to apply the rules for the "in table text" insertion mode, the user agent must handle the token as follows:
Parse error. Ignore the token.
Append the character token to the pending table character tokens list.
If any of the tokens in the pending table character tokens list are character tokens that are not one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF), U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE, then reprocess those character tokens using the rules given in the "anything else" entry in the in table" insertion mode.
Otherwise, insert the characters given by the pending table character tokens list into the current node.
Switch the insertion mode to the original insertion mode and reprocess the token.
When the user agent is to apply the rules for the "in caption" insertion mode, the user agent must handle the token as follows:
If the stack of open elements does not have an element in table scope with the same tag name as the token, this is a parse error. Ignore the token. (fragment case)
Otherwise:
Now, if the current node is not a
caption
element, then this is a parse
error.
Pop elements from this stack until a caption
element has been popped from the stack.
Clear the list of active formatting elements up to the last marker.
Switch the insertion mode to "in table".
Parse error. Act as if an end tag with the tag name "caption" had been seen, then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the fragment case.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
When the user agent is to apply the rules for the "in column group" insertion mode, the user agent must handle the token as follows:
Insert the character into the current node.
Append a Comment
node to the current
node with the data
attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
If the current node is the root
html
element, then this is a parse
error; ignore the token. (fragment
case)
Otherwise, pop the current node (which will be
a colgroup
element) from the stack of open
elements. Switch the insertion mode to
"in table".
Parse error. Ignore the token.
If the current node is the root html
element, then stop parsing. (fragment
case)
Otherwise, act as described in the "anything else" entry below.
Act as if an end tag with the tag name "colgroup" had been seen, and then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the fragment case.
When the user agent is to apply the rules for the "in table body" insertion mode, the user agent must handle the token as follows:
Clear the stack back to a table body context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in row".
Parse error. Act as if a start tag with the tag name "tr" had been seen, then reprocess the current token.
If the stack of open elements does not have an element in table scope with the same tag name as the token, this is a parse error. Ignore the token.
Otherwise:
Clear the stack back to a table body context. (See below.)
Pop the current node from the stack of open elements. Switch the insertion mode to "in table".
If the stack of open elements does not have a
tbody
, thead
, or tfoot
element in table scope, this is a parse
error. Ignore the token. (fragment
case)
Otherwise:
Clear the stack back to a table body context. (See below.)
Act as if an end tag with the same tag name as the current node ("tbody", "tfoot", or "thead") had been seen, then reprocess the current token.
Parse error. Ignore the token.
Process the token using the rules for the "in table" insertion mode.
When the steps above require the UA to clear the stack
back to a table body context, it means that the UA must,
while the current node is not a tbody
,
tfoot
, thead
, or html
element, pop elements from the stack of open
elements.
The current node being an
html
element after this process is a fragment
case.
When the user agent is to apply the rules for the "in row" insertion mode, the user agent must handle the token as follows:
Clear the stack back to a table row context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in cell".
Insert a marker at the end of the list of active formatting elements.
If the stack of open elements does not have an element in table scope with the same tag name as the token, this is a parse error. Ignore the token. (fragment case)
Otherwise:
Clear the stack back to a table row context. (See below.)
Pop the current node (which will be a
tr
element) from the stack of open
elements. Switch the insertion mode to
"in table
body".
Act as if an end tag with the tag name "tr" had been seen, then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the fragment case.
If the stack of open elements does not have an element in table scope with the same tag name as the token, this is a parse error. Ignore the token.
Otherwise, act as if an end tag with the tag name "tr" had been seen, then reprocess the current token.
Parse error. Ignore the token.
Process the token using the rules for the "in table" insertion mode.
When the steps above require the UA to clear the stack
back to a table row context, it means that the UA must,
while the current node is not a tr
element or an html
element, pop elements from the
stack of open elements.
The current node being an
html
element after this process is a fragment
case.
When the user agent is to apply the rules for the "in cell" insertion mode, the user agent must handle the token as follows:
If the stack of open elements does not have an element in table scope with the same tag name as that of the token, then this is a parse error and the token must be ignored.
Otherwise:
Now, if the current node is not an element with the same tag name as the token, then this is a parse error.
Pop elements from the stack of open elements stack until an element with the same tag name as the token has been popped from the stack.
Clear the list of active formatting elements up to the last marker.
Switch the insertion mode to "in row".
If the stack of open elements does
not have
a td
or th
element in table
scope, then this is a parse error; ignore
the token. (fragment case)
Otherwise, close the cell (see below) and reprocess the current token.
Parse error. Ignore the token.
If the stack of open elements does not have an element in table scope with the same tag name as that of the token (which can only happen for "tbody", "tfoot" and "thead", or in the fragment case), then this is a parse error and the token must be ignored.
Otherwise, close the cell (see below) and reprocess the current token.
Process the token using the rules for the "in body" insertion mode.
Where the steps above say to close the cell, they mean to run the following algorithm:
If the stack of open elements has a td
element in table scope, then act as if an end tag token
with the tag name "td" had been seen.
Otherwise, the stack of open elements will
have a
th
element in table scope; act as if an end
tag token with the tag name "th" had been seen.
The stack of open elements cannot have
both a td
and a th
element in table scope at the
same time, nor can it have neither when the close the
cell algorithm is invoked.
When the user agent is to apply the rules for the "in select" insertion mode, the user agent must handle the token as follows:
Parse error. Ignore the token.
Insert the token's character into the current node.
Append a Comment
node to the current
node with the data
attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
If the current node is an option
element, act as if an end tag with the tag name "option" had
been seen.
Insert an HTML element for the token.
If the current node is an option
element, act as if an end tag with the tag name "option" had
been seen.
If the current node is an
optgroup
element, act as if an end tag with the
tag name "optgroup" had been seen.
Insert an HTML element for the token.
First, if the current node is an
option
element, and the node immediately before
it in the stack of open elements is an
optgroup
element, then act as if an end tag with
the tag name "option" had been seen.
If the current node is an
optgroup
element, then pop that node from the
stack of open elements. Otherwise, this is a
parse error; ignore the token.
If the current node is an option
element, then pop that node from the stack of open
elements. Otherwise, this is a parse
error; ignore the token.
If the stack of open elements does not have an element in select scope with the same tag name as the token, this is a parse error. Ignore the token. (fragment case)
Otherwise:
Pop elements from the stack of open elements
until a select
element has been popped from the
stack.
Parse error. Act as if the token had been an end tag with the tag name "select" instead.
If the stack of open elements does not have a select
element in select scope, ignore the token. (fragment
case)
Otherwise, act as if an end tag with the tag name "select" had been seen, and reprocess the token.
Process the token using the rules for the "in head" insertion mode.
If the current node is not the root
html
element, then this is a parse
error.
It can only be the current node in the fragment case.
Parse error. Ignore the token.
When the user agent is to apply the rules for the "in select in table" insertion mode, the user agent must handle the token as follows:
Parse error. Act as if an end tag with the tag name "select" had been seen, and reprocess the token.
If the stack of open elements has an element in table scope with the same tag name as that of the token, then act as if an end tag with the tag name "select" had been seen, and reprocess the token. Otherwise, ignore the token.
Process the token using the rules for the "in select" insertion mode.
When the user agent is to apply the rules for the "after body" insertion mode, the user agent must handle the token as follows:
Process the token using the rules for the "in body" insertion mode.
Append a Comment
node to the first element in
the stack of open elements (the html
element), with the data
attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
If the parser was originally created as part of the HTML fragment parsing algorithm, this is a parse error; ignore the token. (fragment case)
Otherwise, switch the insertion mode to "after after body".
Parse error. Switch the insertion mode to "in body" and reprocess the token.
When the user agent is to apply the rules for the "in frameset" insertion mode, the user agent must handle the token as follows:
Insert the character into the current node.
Append a Comment
node to the current
node with the data
attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Insert an HTML element for the token.
If the current node is the root
html
element, then this is a parse
error; ignore the token. (fragment
case)
Otherwise, pop the current node from the stack of open elements.
If the parser was not originally created as part
of the HTML fragment parsing algorithm
(fragment case), and the current
node is no longer a frameset
element, then
switch the insertion mode to "after
frameset".
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Acknowledge the token's self-closing flag, if it is set.
Process the token using the rules for the "in head" insertion mode.
If the current node is not the root
html
element, then this is a parse
error.
It can only be the current node in the fragment case.
Parse error. Ignore the token.
When the user agent is to apply the rules for the "after frameset" insertion mode, the user agent must handle the token as follows:
Insert the character into the current node.
Append a Comment
node to the current
node with the data
attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Process the token using the rules for the "in body" insertion mode.
Switch the insertion mode to "after after frameset".
Process the token using the rules for the "in head" insertion mode.
Parse error. Ignore the token.
When the user agent is to apply the rules for the "after after body" insertion mode, the user agent must handle the token as follows:
Append a Comment
node to the Document
object with the data
attribute set to the
data given in the comment token.
Process the token using the rules for the "in body" insertion mode.
Parse error. Switch the insertion mode to "in body" and reprocess the token.
When the user agent is to apply the rules for the "after after frameset" insertion mode, the user agent must handle the token as follows:
Append a Comment
node to the Document
object with the data
attribute set to the
data given in the comment token.
Process the token using the rules for the "in body" insertion mode.
Process the token using the rules for the "in head" insertion mode.
Parse error. Ignore the token.
When the user agent is to apply the rules for parsing tokens in foreign content, the user agent must handle the token as follows:
Parse error. Insert a U+FFFD REPLACEMENT CHARACTER character into the current node.
Insert the token's character into the current node.
Insert the token's character into the current node.
Set the frameset-ok flag to "not ok".
Append a Comment
node to the current
node with the data
attribute set to
the data given in the comment token.
Parse error. Ignore the token.
Pop an element from the stack of open elements, and then keep popping more elements from the stack of open elements until the current node is a MathML text integration point, an HTML integration point, or an element in the HTML namespace.
Then, reprocess the token.
If the current node is an element in the MathML namespace, adjust MathML attributes for the token. (This fixes the case of MathML attributes that are not all lowercase.)
If the current node is an element in the SVG namespace, and the token's tag name is one of the ones in the first column of the following table, change the tag name to the name given in the corresponding cell in the second column. (This fixes the case of SVG elements that are not all lowercase.)
Tag name | Element name |
---|---|
altglyph | altGlyph
|
altglyphdef | altGlyphDef
|
altglyphitem | altGlyphItem
|
animatecolor | animateColor
|
animatemotion | animateMotion
|
animatetransform | animateTransform
|
clippath | clipPath
|
feblend | feBlend
|
fecolormatrix | feColorMatrix
|
fecomponenttransfer | feComponentTransfer
|
fecomposite | feComposite
|
feconvolvematrix | feConvolveMatrix
|
fediffuselighting | feDiffuseLighting
|
fedisplacementmap | feDisplacementMap
|
fedistantlight | feDistantLight
|
feflood | feFlood
|
fefunca | feFuncA
|
fefuncb | feFuncB
|
fefuncg | feFuncG
|
fefuncr | feFuncR
|
fegaussianblur | feGaussianBlur
|
feimage | feImage
|
femerge | feMerge
|
femergenode | feMergeNode
|
femorphology | feMorphology
|
feoffset | feOffset
|
fepointlight | fePointLight
|
fespecularlighting | feSpecularLighting
|
fespotlight | feSpotLight
|
fetile | feTile
|
feturbulence | feTurbulence
|
foreignobject | foreignObject
|
glyphref | glyphRef
|
lineargradient | linearGradient
|
radialgradient | radialGradient
|
textpath | textPath
|
If the current node is an element in the SVG namespace, adjust SVG attributes for the token. (This fixes the case of SVG attributes that are not all lowercase.)
Adjust foreign attributes for the token. (This fixes the use of namespaced attributes, in particular XLink in SVG.)
Insert a foreign element for the token, in the same namespace as the current node.
If the token has its self-closing flag set, pop the current node off the stack of open elements and acknowledge the token's self-closing flag.
script
element in the SVG namespacePop the current node off the stack of open elements.
Let the old insertion point have the same value as the current insertion point. Let the insertion point be just before the next input character.
Increment the parser's script nesting level by one. Set the parser pause flag to true.
Process
the script
element according to the SVG
rules, if the user agent supports SVG. [SVG]
Even if this causes new characters to be inserted into the tokenizer, the parser will not be executed reentrantly, since the parser pause flag is true.
Decrement the parser's script nesting level by one. If the parser's script nesting level is zero, then set the parser pause flag to false.
Let the insertion point have the value of the old insertion point. (In other words, restore the insertion point to its previous value. This value might be the "undefined" value.)
Run these steps:
Initialize node to be the current node (the bottommost node of the stack).
If node is not an element with the same tag name as the token, then this is a parse error.
Loop: If node's tag name, converted to ASCII lowercase, is the same as the tag name of the token, pop elements from the stack of open elements until node has been popped from the stack, and then jump to the last step of this list of steps.
Set node to the previous entry in the stack of open elements.
If node is not an element in the HTML namespace, return to the step labeled loop.
Otherwise, process the token according to the rules given in the section corresponding to the current insertion mode in HTML content.
Once the user agent stops parsing the document, the user agent must run the following steps:
Set the current document readiness to "interactive" and the insertion point to undefined.
Pop all the nodes off the stack of open elements.
If the list of scripts that will execute when the document has finished parsing is not empty, run these substeps:
Spin the event loop until the first
script
in the list of scripts that will
execute when the document has finished parsing has its
"ready to be parser-executed" flag set and
the parser's Document
has no style sheet that
is blocking scripts.
Execute the
first script
in the list of scripts that will
execute when the document has finished parsing.
Remove the first script
element from the
list of scripts that will execute when the document has
finished parsing (i.e. shift out the first entry in the
list).
If the list of scripts that will execute when the document has finished parsing is still not empty, repeat these substeps again from substep 1.
Queue a task to fire a simple
event that bubbles named DOMContentLoaded
at the
Document
.
Spin the event loop until the set of scripts that will execute as soon as possible and the list of scripts that will execute in order as soon as possible are empty.
Spin the event loop until there is nothing that
delays the load event in
the Document
.
Queue a task to set the current document readiness to "complete".
If the Document
is in a browsing
context, then queue a task to fire a
simple event named load
at
the Document
's Window
object, but with
its target
set to the
Document
object (and the currentTarget
set to the
Window
object).
If the Document
is in a browsing
context, then queue a task to fire a pageshow
event at the
Window
object of the Document
, but with
its target
set to the
Document
object (and the currentTarget
set to the
Window
object), using the
PageTransitionEvent
interface, with the persisted
attribute set to false. This event must not bubble, must not be
cancelable, and has no default action.
If the Document
has any pending
application cache download process tasks, then queue each such task in the order they were added to
the list of pending application cache download process
tasks, and then empty the list of pending application
cache download process tasks. The task source
for these tasks is the
networking task source.
The Document
is now ready for post-load
tasks.
Queue a task to mark the Document
as completely loaded.
When the user agent is to abort a parser, it must run the following steps:
Throw away any pending content in the input stream, and discard any future content that would have been added to it.
Pop all the nodes off the stack of open elements.
Except where otherwise specified, the task source for the tasks mentioned in this section is the DOM manipulation task source.
When an application uses an HTML parser in
conjunction with an XML pipeline, it is possible that the
constructed DOM is not compatible with the XML tool chain in certain
subtle ways. For example, an XML toolchain might not be able to
represent attributes with the name xmlns
,
since they conflict with the Namespaces in XML syntax. There is also
some data that the HTML parser generates that isn't
included in the DOM itself. This section specifies some rules for
handling these issues.
If the XML API being used doesn't support DOCTYPEs, the tool may drop DOCTYPEs altogether.
If the XML API doesn't support attributes in no namespace that
are named "xmlns
", attributes whose names
start with "xmlns:
", or attributes in the
XMLNS namespace, then the tool may drop such
attributes.
The tool may annotate the output with any namespace declarations required for proper operation.
If the XML API being used restricts the allowable characters in the local names of elements and attributes, then the tool may map all element and attribute local names that the API wouldn't support to a set of names that are allowed, by replacing any character that isn't supported with the uppercase letter U and the six digits of the character's Unicode code point when expressed in hexadecimal, using digits 0-9 and capital letters A-F as the symbols, in increasing numeric order.
For example, the element name foo<bar
, which can be output by the HTML
parser, though it is neither a legal HTML element name nor a
well-formed XML element name, would be converted into fooU00003Cbar
, which is a well-formed XML
element name (though it's still not legal in HTML by any means).
As another example, consider the attribute
xlink:href
. Used on a MathML element, it becomes, after
being adjusted, an
attribute with a prefix "xlink
" and a local
name "href
". However, used on an HTML element,
it becomes an attribute with no prefix and the local name "xlink:href
", which is not a valid NCName, and thus
might not be accepted by an XML API. It could thus get converted,
becoming "xlinkU00003Ahref
".
The resulting names from this conversion conveniently can't clash with any attribute generated by the HTML parser, since those are all either lowercase or those listed in the adjust foreign attributes algorithm's table.
If the XML API restricts comments from having two consecutive U+002D HYPHEN-MINUS characters (--), the tool may insert a single U+0020 SPACE character between any such offending characters.
If the XML API restricts comments from ending in a U+002D HYPHEN-MINUS character (-), the tool may insert a single U+0020 SPACE character at the end of such comments.
If the XML API restricts allowed characters in character data, attribute values, or comments, the tool may replace any U+000C FORM FEED (FF) character with a U+0020 SPACE character, and any other literal non-XML character with a U+FFFD REPLACEMENT CHARACTER.
If the tool has no way to convey out-of-band information, then the tool may drop the following information:
form
element ancestor (use of the
form
element pointer in the parser)The mutations allowed by this section apply
after the HTML parser's rules have been
applied. For example, a <a::>
start tag
will be closed by a </a::>
end tag, and
never by a </aU00003AU00003A>
end tag, even
if the user agent is using the rules above to then generate an
actual element in the DOM with the name aU00003AU00003A
for that start tag.
This section is non-normative.
This section examines some erroneous markup and discusses how the HTML parser handles these cases.
This section is non-normative.
The most-often discussed example of erroneous markup is as follows:
<p>1<b>2<i>3</b>4</i>5</p>
The parsing of this markup is straightforward up to the "3". At this point, the DOM looks like this:
Here, the stack of open elements has five elements
on it: html
, body
, p
,
b
, and i
. The list of active
formatting elements just has two: b
and
i
. The insertion mode is "in body".
Upon receiving the end tag token with the tag name "b", the "adoption agency algorithm" is
invoked. This is a simple case, in that the formatting
element is the b
element, and there is no
furthest block. Thus, the stack of open
elements ends up with just three elements: html
,
body
, and p
, while the list of
active formatting elements has just one: i
. The
DOM tree is unmodified at this point.
The next token is a character ("4"), triggers the reconstruction of
the active formatting elements, in this case just the
i
element. A new i
element is thus created
for the "4" text node. After the end tag token for the "i" is also
received, and the "5" text node is inserted, the DOM looks as
follows:
This section is non-normative.
A case similar to the previous one is the following:
<b>1<p>2</b>3</p>
Up to the "2" the parsing here is straightforward:
The interesting part is when the end tag token with the tag name "b" is parsed.
Before that token is seen, the stack of open
elements has four elements on it: html
,
body
, b
, and p
. The
list of active formatting elements just has the one:
b
. The insertion mode is "in body".
Upon receiving the end tag token with the tag name "b", the "adoption agency algorithm" is invoked, as
in the previous example. However, in this case, there is a
furthest block, namely the p
element. Thus,
this time the adoption agency algorithm isn't skipped over.
The common ancestor is the body
element. A conceptual "bookmark" marks the position of the
b
in the list of active formatting
elements, but since that list has only one element in it,
the bookmark won't have much effect.
As the algorithm progresses, node ends up set
to the formatting element (b
), and last
node ends up set to the furthest block
(p
).
The last node gets appended (moved) to the common ancestor, so that the DOM looks like:
A new b
element is created, and the children of the
p
element are moved to it:
b
#text
: 2Finally, the new b
element is appended to the
p
element, so that the DOM looks like:
The b
element is removed from the list of
active formatting elements and the stack of open
elements, so that when the "3" is parsed, it is appended to
the p
element:
This section is non-normative.
Error handling in tables is, for historical reasons, especially strange. For example, consider the following markup:
<table><b><tr><td>aaa</td></tr>bbb</table>ccc
The highlighted b
element start tag is not allowed
directly inside a table like that, and the parser handles this case
by placing the element before the table. (This is called foster parenting.) This can be seen by
examining the DOM tree as it stands just after the
table
element's start tag has been seen:
...and then immediately after the b
element start
tag has been seen:
At this point, the stack of open elements has on it
the elements html
, body
,
table
, and b
(in that order, despite the
resulting DOM tree); the list of active formatting
elements just has the b
element in it; and the
insertion mode is "in table".
The tr
start tag causes the b
element
to be popped off the stack and a tbody
start tag to be
implied; the tbody
and tr
elements are
then handled in a rather straight-forward manner, taking the parser
through the "in table
body" and "in
row" insertion modes, after which the DOM looks as
follows:
Here, the stack of open elements has on it the
elements html
, body
, table
,
tbody
, and tr
; the list of active
formatting elements still has the b
element in
it; and the insertion mode is "in row".
The td
element start tag token, after putting a
td
element on the tree, puts a marker on the list
of active formatting elements (it also switches to the "in cell" insertion
mode).
The marker means that when the "aaa" character tokens are seen,
no b
element is created to hold the resulting text
node:
The end tags are handled in a straight-forward manner; after
handling them, the stack of open elements has on it the
elements html
, body
, table
,
and tbody
; the list of active formatting
elements still has the b
element in it (the
marker having been removed by the "td" end tag token); and the
insertion mode is "in table body".
Thus it is that the "bbb" character tokens are found. These
trigger the "in table
text" insertion mode to be used (with the original
insertion mode set to "in table body"). The character tokens are collected,
and when the next token (the table
element end tag) is
seen, they are processed as a group. Since they are not all spaces,
they are handled as per the "anything else" rules in the "in table" insertion mode,
which defer to the "in
body" insertion mode but with foster parenting.
When the
active formatting elements are reconstructed, a
b
element is created and foster parented, and then the "bbb" text node is
appended to it:
The stack of open elements has on it the elements
html
, body
, table
,
tbody
, and the new b
(again, note that
this doesn't match the resulting tree!); the list of active
formatting elements has the new b
element in it;
and the insertion mode is still "in table body".
Had the character tokens been only space characters instead of "bbb", then those
space characters would just be
appended to the tbody
element.
Finally, the table
is closed by a "table" end
tag. This pops all the nodes from the stack of open
elements up to and including the table
element,
but it doesn't affect the list of active formatting
elements, so the "ccc" character tokens after the table
result in yet another b
element being created, this
time after the table:
This section is non-normative.
Consider the following markup, which for this example we will
assume is the document with URL http://example.com/inner
, being rendered as the
content of an iframe
in another document with the
URL http://example.com/outer
:
<div id=a> <script> var div = document.getElementById('a'); parent.document.body.appendChild(div); </script> <script> alert(document.URL); </script> </div> <script> alert(document.URL); </script>
Up to the first "script" end tag, before the script is parsed, the result is relatively straightforward:
After the script is parsed, though, the div
element
and its child script
element are gone:
They are, at this point, in the Document
of the
aforementioned outer browsing context. However, the
stack of open elements still contains the
div
element.
Thus, when the second script
element is parsed, it
is inserted into the outer Document
object.
This also means that the script's global object is
the outer browsing context's Window
object, not the Window
object inside the
iframe
.
This isn't a security problem since the script that
moves the div
into the outer Document
can
only do so because the two Document
object have the
same origin.
Thus, the first alert says "http://example.com/outer".
Once the div
element's end tag is parsed, the
div
element is popped off the stack, and so the next
script
element is in the inner Document
:
This second alert will say "http://example.com/inner".
This section is non-normative.
Elaborating on the example in the previous section, consider a
case where a script
element with a src
attribute is parsed, but while
the external script is being downloaded, the element is moved to
another document.
In this case, the script's global object is that
second document's browsing context's
Window
object, not the Window
object of
the document into which the element was parsed.
This section is non-normative.
The following markup shows how nested formatting elements (such
as b
) get collected and continue to be applied even as
the elements they are contained in are closed, but that excessive
duplicates are thrown away.
<!DOCTYPE html> <p><b class=x><b class=x><b><b class=x><b class=x><b>X <p>X <p><b><b class=x><b>X <p></b></b></b></b></b></b>X
The resulting DOM tree is as follows:
Note how the second p
element in the markup has no
explicit b
elements, but in the resulting DOM, up to
three of each kind of formatting element (in this case three
b
elements with the class attribute, and two unadorned
b
elements) get reconstructed before the element's
"X".
Also note how this means that in the final paragraph only six
b
end tags are needed to completely clear the list of
formatting elements, even though nine b
start tags have
been seen up to this point.
The following steps form the HTML fragment serialization
algorithm. The algorithm takes as input a DOM
Element
, Document
, or
DocumentFragment
referred to as the
node, and either returns a string or raises an exception.
This algorithm serializes the children of the node being serialized, not the node itself.
Let s be a string, and initialize it to the empty string.
For each child node of the node, in tree order, run the following steps:
Let current node be the child node being processed.
Append the appropriate string from the following list to s:
Element
If current node is an element in the HTML namespace, the MathML namespace, or the SVG namespace, then let tagname be current node's local name. Otherwise, let tagname be current node's qualified name.
Append a U+003C LESS-THAN SIGN character (<), followed by tagname.
For HTML elements created by the
HTML parser or Document.createElement()
, tagname will be lowercase.
For each attribute that the element has, append a U+0020 SPACE character, the attribute's serialized name as described below, a U+003D EQUALS SIGN character (=), a U+0022 QUOTATION MARK character ("), the attribute's value, escaped as described below in attribute mode, and a second U+0022 QUOTATION MARK character (").
An attribute's serialized name for the purposes of the previous paragraph must be determined as follows:
The attribute's serialized name is the attribute's local name.
For attributes on HTML elements
set by the HTML parser or by Element.setAttributeNode()
or Element.setAttribute()
, the local name will
be lowercase.
The attribute's serialized name is the string "xml:
" followed by the attribute's local
name.
xmlns
The attribute's serialized name is the string "xmlns
".
xmlns
The attribute's serialized name is the string "xmlns:
" followed by the attribute's local
name.
The attribute's serialized name is the string "xlink:
" followed by the attribute's local
name.
The attribute's serialized name is the attribute's qualified name.
While the exact order of attributes is UA-defined, and may depend on factors such as the order that the attributes were given in the original markup, the sort order must be stable, such that consecutive invocations of this algorithm serialize an element's attributes in the same order.
Append a U+003E GREATER-THAN SIGN character (>).
If current node is an
area
, base
, basefont
,
bgsound
, br
, col
,
command
, embed
, frame
,
hr
, img
, input
,
keygen
, link
, meta
,
param
, source
, track
or
wbr
element, then continue on to the next child
node at this point.
If current node is a pre
,
textarea
, or listing
element, append
a U+000A LINE FEED (LF) character.
Append the value of running the HTML fragment serialization algorithm on the current node element (thus recursing into this algorithm for that element), followed by a U+003C LESS-THAN SIGN character (<), a U+002F SOLIDUS character (/), tagname again, and finally a U+003E GREATER-THAN SIGN character (>).
Text
or CDATASection
nodeIf the parent of current node is a
style
, script
, xmp
,
iframe
, noembed
,
noframes
, or plaintext
element, or
if the parent of current node is
noscript
element and scripting is enabled for the
node, then append the value of current
node's data
IDL attribute
literally.
Otherwise, append the value of current
node's data
IDL attribute, escaped as described
below.
Comment
Append the literal string <!--
(U+003C
LESS-THAN SIGN, U+0021 EXCLAMATION MARK, U+002D HYPHEN-MINUS,
U+002D HYPHEN-MINUS), followed by the value of current node's data
IDL
attribute, followed by the literal string -->
(U+002D HYPHEN-MINUS, U+002D HYPHEN-MINUS, U+003E GREATER-THAN
SIGN).
ProcessingInstruction
Append the literal string <?
(U+003C
LESS-THAN SIGN, U+003F QUESTION MARK), followed by the value
of current node's target
IDL attribute, followed by a single
U+0020 SPACE character, followed by the value of current node's data
IDL
attribute, followed by a single U+003E GREATER-THAN SIGN
character (>).
DocumentType
Append the literal string <!DOCTYPE
(U+003C
LESS-THAN SIGN, U+0021 EXCLAMATION MARK, U+0044 LATIN CAPITAL
LETTER D, U+004F LATIN CAPITAL LETTER O, U+0043 LATIN CAPITAL
LETTER C, U+0054 LATIN CAPITAL LETTER T, U+0059 LATIN CAPITAL
LETTER Y, U+0050 LATIN CAPITAL LETTER P, U+0045 LATIN CAPITAL
LETTER E), followed by a space (U+0020 SPACE), followed by the
value of current node's name
IDL attribute, followed by the literal
string >
(U+003E GREATER-THAN SIGN).
Other node types (e.g. Attr
) cannot
occur as children of elements. If, despite this, they somehow do
occur, this algorithm must raise an
INVALID_STATE_ERR
exception.
The result of the algorithm is the string s.
Entity reference nodes are assumed to be expanded by the user agent, and are therefore not covered in the algorithm above.
It is possible that the output of this algorithm, if parsed with an HTML parser, will not return the original tree structure.
For instance, if a textarea
element to which a
Comment
node has been appended is serialized
and the output is then reparsed, the comment will end up being
displayed in the text field. Similarly, if, as a result of DOM
manipulation, an element contains a comment that contains the
literal string "-->
", then when the result
of serializing the element is parsed, the comment will be truncated
at that point and the rest of the comment will be interpreted as
markup. More examples would be making a script
element
contain a text node with the text string
"</script>
", or having a p
element
that contains a ul
element (as the ul
element's start tag would
imply the end tag for the p
).
This can enable cross-site scripting attacks. An example of this
would be a page that lets the user enter some font names that are
then inserted into a CSS style
block via the DOM and
which then uses the innerHTML
IDL attribute to get the HTML serialization of that
style
element: if the user enters
"</style><script>attack</script>
" as a font
name, innerHTML
will return
markup that, if parsed in a different context, would contain a
script
node, even though no script
node
existed in the original DOM.
Escaping a string (for the purposes of the algorithm above) consists of running the following steps:
Replace any occurrence of the "&
"
character by the string "&
".
Replace any occurrences of the U+00A0 NO-BREAK SPACE
character by the string "
".
If the algorithm was invoked in the attribute mode,
replace any occurrences of the ""
"
character by the string ""
".
If the algorithm was not invoked in the
attribute mode, replace any occurrences of the "<
" character by the string "<
", and any occurrences of the ">
" character by the string ">
".
The following steps form the HTML fragment parsing
algorithm. The algorithm optionally takes as input an
Element
node, referred to as the context element,
which gives the context for the parser, as well as input, a string to parse, and returns a list of zero
or more nodes.
Parts marked fragment case in algorithms in the parser section are parts that only occur if the parser was created for the purposes of this algorithm (and with a context element). The algorithms have been annotated with such markings for informational purposes only; such markings have no normative weight. If it is possible for a condition described as a fragment case to occur even when the parser wasn't created for the purposes of handling this algorithm, then that is an error in the specification.
Create a new Document
node, and mark it as being
an HTML document.
If there is a context element, and the
Document
of the context element is in
quirks mode, then let the Document
be in
quirks mode. Otherwise, if there is a context element, and the
Document
of the context element is in
limited-quirks mode, then let the
Document
be in limited-quirks mode.
Otherwise, leave the Document
in no-quirks
mode.
Create a new HTML parser, and associate it with
the just created Document
node.
If there is a context element, run these substeps:
Set the state of the HTML parser's tokenization stage as follows:
title
or textarea
elementstyle
, xmp
,
iframe
, noembed
, or
noframes
elementscript
elementnoscript
elementplaintext
elementFor performance reasons, an implementation that does not report errors and that uses the actual state machine described in this specification directly could use the PLAINTEXT state instead of the RAWTEXT and script data states where those are mentioned in the list above. Except for rules regarding parse errors, they are equivalent, since there is no appropriate end tag token in the fragment case, yet they involve far fewer state transitions.
Let root be a new html
element
with no attributes.
Append the element root to the
Document
node created above.
Set up the parser's stack of open elements so that it contains just the single element root.
Reset the parser's insertion mode appropriately.
The parser will reference the context element as part of that algorithm.
Set the parser's form
element
pointer to the nearest node to the context element that is
a form
element (going straight up the ancestor
chain, and including the element itself, if it is a
form
element), or, if there is no such
form
element, to null.
Place into the input stream for the HTML parser just created the input. The encoding confidence is irrelevant.
Start the parser and let it run until it has consumed all the characters just inserted into the input stream.
If there is a context element, return the child nodes of root, in tree order.
Otherwise, return the children of the Document
object, in tree order.
This algorithm is invoked without a context element in the case
of Document.innerHTML
.
This table lists the character reference names that are supported by HTML, and the code points to which they refer. It is referenced by the previous sections.
Name | Character(s) | Glyph |
---|---|---|
AElig; | U+000C6 | Æ |
AMP; | U+00026 | & |
Aacute; | U+000C1 | Á |
Abreve; | U+00102 | Ă |
Acirc; | U+000C2 | Â |
Acy; | U+00410 | А |
Afr; | U+1D504 | 𝔄 |
Agrave; | U+000C0 | À |
Alpha; | U+00391 | Α |
Amacr; | U+00100 | Ā |
And; | U+02A53 | ⩓ |
Aogon; | U+00104 | Ą |
Aopf; | U+1D538 | 𝔸 |
ApplyFunction; | U+02061 | |
Aring; | U+000C5 | Å |
Ascr; | U+1D49C | 𝒜 |
Assign; | U+02254 | ≔ |
Atilde; | U+000C3 | Ã |
Auml; | U+000C4 | Ä |
Backslash; | U+02216 | ∖ |
Barv; | U+02AE7 | ⫧ |
Barwed; | U+02306 | ⌆ |
Bcy; | U+00411 | Б |
Because; | U+02235 | ∵ |
Bernoullis; | U+0212C | ℬ |
Beta; | U+00392 | Β |
Bfr; | U+1D505 | 𝔅 |
Bopf; | U+1D539 | 𝔹 |
Breve; | U+002D8 | ˘ |
Bscr; | U+0212C | ℬ |
Bumpeq; | U+0224E | ≎ |
CHcy; | U+00427 | Ч |
COPY; | U+000A9 | © |
Cacute; | U+00106 | Ć |
Cap; | U+022D2 | ⋒ |
CapitalDifferentialD; | U+02145 | ⅅ |
Cayleys; | U+0212D | ℭ |
Ccaron; | U+0010C | Č |
Ccedil; | U+000C7 | Ç |
Ccirc; | U+00108 | Ĉ |
Cconint; | U+02230 | ∰ |
Cdot; | U+0010A | Ċ |
Cedilla; | U+000B8 | ¸ |
CenterDot; | U+000B7 | · |
Cfr; | U+0212D | ℭ |
Chi; | U+003A7 | Χ |
CircleDot; | U+02299 | ⊙ |
CircleMinus; | U+02296 | ⊖ |
CirclePlus; | U+02295 | ⊕ |
CircleTimes; | U+02297 | ⊗ |
ClockwiseContourIntegral; | U+02232 | ∲ |
CloseCurlyDoubleQuote; | U+0201D | ” |
CloseCurlyQuote; | U+02019 | ’ |
Colon; | U+02237 | ∷ |
Colone; | U+02A74 | ⩴ |
Congruent; | U+02261 | ≡ |
Conint; | U+0222F | ∯ |
ContourIntegral; | U+0222E | ∮ |
Copf; | U+02102 | ℂ |
Coproduct; | U+02210 | ∐ |
CounterClockwiseContourIntegral; | U+02233 | ∳ |
Cross; | U+02A2F | ⨯ |
Cscr; | U+1D49E | 𝒞 |
Cup; | U+022D3 | ⋓ |
CupCap; | U+0224D | ≍ |
DD; | U+02145 | ⅅ |
DDotrahd; | U+02911 | ⤑ |
DJcy; | U+00402 | Ђ |
DScy; | U+00405 | Ѕ |
DZcy; | U+0040F | Џ |
Dagger; | U+02021 | ‡ |
Darr; | U+021A1 | ↡ |
Dashv; | U+02AE4 | ⫤ |
Dcaron; | U+0010E | Ď |
Dcy; | U+00414 | Д |
Del; | U+02207 | ∇ |
Delta; | U+00394 | Δ |
Dfr; | U+1D507 | 𝔇 |
DiacriticalAcute; | U+000B4 | ´ |
DiacriticalDot; | U+002D9 | ˙ |
DiacriticalDoubleAcute; | U+002DD | ˝ |
DiacriticalGrave; | U+00060 | ` |
DiacriticalTilde; | U+002DC | ˜ |
Diamond; | U+022C4 | ⋄ |
DifferentialD; | U+02146 | ⅆ |
Dopf; | U+1D53B | 𝔻 |
Dot; | U+000A8 | ¨ |
DotDot; | U+020DC | ◌⃜ |
DotEqual; | U+02250 | ≐ |
DoubleContourIntegral; | U+0222F | ∯ |
DoubleDot; | U+000A8 | ¨ |
DoubleDownArrow; | U+021D3 | ⇓ |
DoubleLeftArrow; | U+021D0 | ⇐ |
DoubleLeftRightArrow; | U+021D4 | ⇔ |
DoubleLeftTee; | U+02AE4 | ⫤ |
DoubleLongLeftArrow; | U+027F8 | ⟸ |
DoubleLongLeftRightArrow; | U+027FA | ⟺ |
DoubleLongRightArrow; | U+027F9 | ⟹ |
DoubleRightArrow; | U+021D2 | ⇒ |
DoubleRightTee; | U+022A8 | ⊨ |
DoubleUpArrow; | U+021D1 | ⇑ |
DoubleUpDownArrow; | U+021D5 | ⇕ |
DoubleVerticalBar; | U+02225 | ∥ |
DownArrow; | U+02193 | ↓ |
DownArrowBar; | U+02913 | ⤓ |
DownArrowUpArrow; | U+021F5 | ⇵ |
DownBreve; | U+00311 | ◌̑ |
DownLeftRightVector; | U+02950 | ⥐ |
DownLeftTeeVector; | U+0295E | ⥞ |
DownLeftVector; | U+021BD | ↽ |
DownLeftVectorBar; | U+02956 | ⥖ |
DownRightTeeVector; | U+0295F | ⥟ |
DownRightVector; | U+021C1 | ⇁ |
DownRightVectorBar; | U+02957 | ⥗ |
DownTee; | U+022A4 | ⊤ |
DownTeeArrow; | U+021A7 | ↧ |
Downarrow; | U+021D3 | ⇓ |
Dscr; | U+1D49F | 𝒟 |
Dstrok; | U+00110 | Đ |
ENG; | U+0014A | Ŋ |
ETH; | U+000D0 | Ð |
Eacute; | U+000C9 | É |
Ecaron; | U+0011A | Ě |
Ecirc; | U+000CA | Ê |
Ecy; | U+0042D | Э |
Edot; | U+00116 | Ė |
Efr; | U+1D508 | 𝔈 |
Egrave; | U+000C8 | È |
Element; | U+02208 | ∈ |
Emacr; | U+00112 | Ē |
EmptySmallSquare; | U+025FB | ◻ |
EmptyVerySmallSquare; | U+025AB | ▫ |
Eogon; | U+00118 | Ę |
Eopf; | U+1D53C | 𝔼 |
Epsilon; | U+00395 | Ε |
Equal; | U+02A75 | ⩵ |
EqualTilde; | U+02242 | ≂ |
Equilibrium; | U+021CC | ⇌ |
Escr; | U+02130 | ℰ |
Esim; | U+02A73 | ⩳ |
Eta; | U+00397 | Η |
Euml; | U+000CB | Ë |
Exists; | U+02203 | ∃ |
ExponentialE; | U+02147 | ⅇ |
Fcy; | U+00424 | Ф |
Ffr; | U+1D509 | 𝔉 |
FilledSmallSquare; | U+025FC | ◼ |
FilledVerySmallSquare; | U+025AA | ▪ |
Fopf; | U+1D53D | 𝔽 |
ForAll; | U+02200 | ∀ |
Fouriertrf; | U+02131 | ℱ |
Fscr; | U+02131 | ℱ |
GJcy; | U+00403 | Ѓ |
GT; | U+0003E | > |
Gamma; | U+00393 | Γ |
Gammad; | U+003DC | Ϝ |
Gbreve; | U+0011E | Ğ |
Gcedil; | U+00122 | Ģ |
Gcirc; | U+0011C | Ĝ |
Gcy; | U+00413 | Г |
Gdot; | U+00120 | Ġ |
Gfr; | U+1D50A | 𝔊 |
Gg; | U+022D9 | ⋙ |
Gopf; | U+1D53E | 𝔾 |
GreaterEqual; | U+02265 | ≥ |
GreaterEqualLess; | U+022DB | ⋛ |
GreaterFullEqual; | U+02267 | ≧ |
GreaterGreater; | U+02AA2 | ⪢ |
GreaterLess; | U+02277 | ≷ |
GreaterSlantEqual; | U+02A7E | ⩾ |
GreaterTilde; | U+02273 | ≳ |
Gscr; | U+1D4A2 | 𝒢 |
Gt; | U+0226B | ≫ |
HARDcy; | U+0042A | Ъ |
Hacek; | U+002C7 | ˇ |
Hat; | U+0005E | ^ |
Hcirc; | U+00124 | Ĥ |
Hfr; | U+0210C | ℌ |
HilbertSpace; | U+0210B | ℋ |
Hopf; | U+0210D | ℍ |
HorizontalLine; | U+02500 | ─ |
Hscr; | U+0210B | ℋ |
Hstrok; | U+00126 | Ħ |
HumpDownHump; | U+0224E | ≎ |
HumpEqual; | U+0224F | ≏ |
IEcy; | U+00415 | Е |
IJlig; | U+00132 | IJ |
IOcy; | U+00401 | Ё |
Iacute; | U+000CD | Í |
Icirc; | U+000CE | Î |
Icy; | U+00418 | И |
Idot; | U+00130 | İ |
Ifr; | U+02111 | ℑ |
Igrave; | U+000CC | Ì |
Im; | U+02111 | ℑ |
Imacr; | U+0012A | Ī |
ImaginaryI; | U+02148 | ⅈ |
Implies; | U+021D2 | ⇒ |
Int; | U+0222C | ∬ |
Integral; | U+0222B | ∫ |
Intersection; | U+022C2 | ⋂ |
InvisibleComma; | U+02063 | |
InvisibleTimes; | U+02062 | |
Iogon; | U+0012E | Į |
Iopf; | U+1D540 | 𝕀 |
Iota; | U+00399 | Ι |
Iscr; | U+02110 | ℐ |
Itilde; | U+00128 | Ĩ |
Iukcy; | U+00406 | І |
Iuml; | U+000CF | Ï |
Jcirc; | U+00134 | Ĵ |
Jcy; | U+00419 | Й |
Jfr; | U+1D50D | 𝔍 |
Jopf; | U+1D541 | 𝕁 |
Jscr; | U+1D4A5 | 𝒥 |
Jsercy; | U+00408 | Ј |
Jukcy; | U+00404 | Є |
KHcy; | U+00425 | Х |
KJcy; | U+0040C | Ќ |
Kappa; | U+0039A | Κ |
Kcedil; | U+00136 | Ķ |
Kcy; | U+0041A | К |
Kfr; | U+1D50E | 𝔎 |
Kopf; | U+1D542 | 𝕂 |
Kscr; | U+1D4A6 | 𝒦 |
LJcy; | U+00409 | Љ |
LT; | U+0003C | < |
Lacute; | U+00139 | Ĺ |
Lambda; | U+0039B | Λ |
Lang; | U+027EA | ⟪ |
Laplacetrf; | U+02112 | ℒ |
Larr; | U+0219E | ↞ |
Lcaron; | U+0013D | Ľ |
Lcedil; | U+0013B | Ļ |
Lcy; | U+0041B | Л |
LeftAngleBracket; | U+027E8 | 〈 |
LeftArrow; | U+02190 | ← |
LeftArrowBar; | U+021E4 | ⇤ |
LeftArrowRightArrow; | U+021C6 | ⇆ |
LeftCeiling; | U+02308 | ⌈ |
LeftDoubleBracket; | U+027E6 | ⟦ |
LeftDownTeeVector; | U+02961 | ⥡ |
LeftDownVector; | U+021C3 | ⇃ |
LeftDownVectorBar; | U+02959 | ⥙ |
LeftFloor; | U+0230A | ⌊ |
LeftRightArrow; | U+02194 | ↔ |
LeftRightVector; | U+0294E | ⥎ |
LeftTee; | U+022A3 | ⊣ |
LeftTeeArrow; | U+021A4 | ↤ |
LeftTeeVector; | U+0295A | ⥚ |
LeftTriangle; | U+022B2 | ⊲ |
LeftTriangleBar; | U+029CF | ⧏ |
LeftTriangleEqual; | U+022B4 | ⊴ |
LeftUpDownVector; | U+02951 | ⥑ |
LeftUpTeeVector; | U+02960 | ⥠ |
LeftUpVector; | U+021BF | ↿ |
LeftUpVectorBar; | U+02958 | ⥘ |
LeftVector; | U+021BC | ↼ |
LeftVectorBar; | U+02952 | ⥒ |
Leftarrow; | U+021D0 | ⇐ |
Leftrightarrow; | U+021D4 | ⇔ |
LessEqualGreater; | U+022DA | ⋚ |
LessFullEqual; | U+02266 | ≦ |
LessGreater; | U+02276 | ≶ |
LessLess; | U+02AA1 | ⪡ |
LessSlantEqual; | U+02A7D | ⩽ |
LessTilde; | U+02272 | ≲ |
Lfr; | U+1D50F | 𝔏 |
Ll; | U+022D8 | ⋘ |
Lleftarrow; | U+021DA | ⇚ |
Lmidot; | U+0013F | Ŀ |
LongLeftArrow; | U+027F5 | ⟵ |
LongLeftRightArrow; | U+027F7 | ⟷ |
LongRightArrow; | U+027F6 | ⟶ |
Longleftarrow; | U+027F8 | ⟸ |
Longleftrightarrow; | U+027FA | ⟺ |
Longrightarrow; | U+027F9 | ⟹ |
Lopf; | U+1D543 | 𝕃 |
LowerLeftArrow; | U+02199 | ↙ |
LowerRightArrow; | U+02198 | ↘ |
Lscr; | U+02112 | ℒ |
Lsh; | U+021B0 | ↰ |
Lstrok; | U+00141 | Ł |
Lt; | U+0226A | ≪ |
Map; | U+02905 | ⤅ |
Mcy; | U+0041C | М |
MediumSpace; | U+0205F | |
Mellintrf; | U+02133 | ℳ |
Mfr; | U+1D510 | 𝔐 |
MinusPlus; | U+02213 | ∓ |
Mopf; | U+1D544 | 𝕄 |
Mscr; | U+02133 | ℳ |
Mu; | U+0039C | Μ |
NJcy; | U+0040A | Њ |
Nacute; | U+00143 | Ń |
Ncaron; | U+00147 | Ň |
Ncedil; | U+00145 | Ņ |
Ncy; | U+0041D | Н |
NegativeMediumSpace; | U+0200B | |
NegativeThickSpace; | U+0200B | |
NegativeThinSpace; | U+0200B | |
NegativeVeryThinSpace; | U+0200B | |
NestedGreaterGreater; | U+0226B | ≫ |
NestedLessLess; | U+0226A | ≪ |
NewLine; | U+0000A | ␊ |
Nfr; | U+1D511 | 𝔑 |
NoBreak; | U+02060 | |
NonBreakingSpace; | U+000A0 | |
Nopf; | U+02115 | ℕ |
Not; | U+02AEC | ⫬ |
NotCongruent; | U+02262 | ≢ |
NotCupCap; | U+0226D | ≭ |
NotDoubleVerticalBar; | U+02226 | ∦ |
NotElement; | U+02209 | ∉ |
NotEqual; | U+02260 | ≠ |
NotEqualTilde; | U+02242 U+00338 | ≂̸ |
NotExists; | U+02204 | ∄ |
NotGreater; | U+0226F | ≯ |
NotGreaterEqual; | U+02271 | ≱ |
NotGreaterFullEqual; | U+02267 U+00338 | ≧̸ |
NotGreaterGreater; | U+0226B U+00338 | ≫̸ |
NotGreaterLess; | U+02279 | ≹ |
NotGreaterSlantEqual; | U+02A7E U+00338 | ⩾̸ |
NotGreaterTilde; | U+02275 | ≵ |
NotHumpDownHump; | U+0224E U+00338 | ≎̸ |
NotHumpEqual; | U+0224F U+00338 | ≏̸ |
NotLeftTriangle; | U+022EA | ⋪ |
NotLeftTriangleBar; | U+029CF U+00338 | ⧏̸ |
NotLeftTriangleEqual; | U+022EC | ⋬ |
NotLess; | U+0226E | ≮ |
NotLessEqual; | U+02270 | ≰ |
NotLessGreater; | U+02278 | ≸ |
NotLessLess; | U+0226A U+00338 | ≪̸ |
NotLessSlantEqual; | U+02A7D U+00338 | ⩽̸ |
NotLessTilde; | U+02274 | ≴ |
NotNestedGreaterGreater; | U+02AA2 U+00338 | ⪢̸ |
NotNestedLessLess; | U+02AA1 U+00338 | ⪡̸ |
NotPrecedes; | U+02280 | ⊀ |
NotPrecedesEqual; | U+02AAF U+00338 | ⪯̸ |
NotPrecedesSlantEqual; | U+022E0 | ⋠ |
NotReverseElement; | U+0220C | ∌ |
NotRightTriangle; | U+022EB | ⋫ |
NotRightTriangleBar; | U+029D0 U+00338 | ⧐̸ |
NotRightTriangleEqual; | U+022ED | ⋭ |
NotSquareSubset; | U+0228F U+00338 | ⊏̸ |
NotSquareSubsetEqual; | U+022E2 | ⋢ |
NotSquareSuperset; | U+02290 U+00338 | ⊐̸ |
NotSquareSupersetEqual; | U+022E3 | ⋣ |
NotSubset; | U+02282 U+020D2 | ⊂⃒ |
NotSubsetEqual; | U+02288 | ⊈ |
NotSucceeds; | U+02281 | ⊁ |
NotSucceedsEqual; | U+02AB0 U+00338 | ⪰̸ |
NotSucceedsSlantEqual; | U+022E1 | ⋡ |
NotSucceedsTilde; | U+0227F U+00338 | ≿̸ |
NotSuperset; | U+02283 U+020D2 | ⊃⃒ |
NotSupersetEqual; | U+02289 | ⊉ |
NotTilde; | U+02241 | ≁ |
NotTildeEqual; | U+02244 | ≄ |
NotTildeFullEqual; | U+02247 | ≇ |
NotTildeTilde; | U+02249 | ≉ |
NotVerticalBar; | U+02224 | ∤ |
Nscr; | U+1D4A9 | 𝒩 |
Ntilde; | U+000D1 | Ñ |
Nu; | U+0039D | Ν |
OElig; | U+00152 | Œ |
Oacute; | U+000D3 | Ó |
Ocirc; | U+000D4 | Ô |
Ocy; | U+0041E | О |
Odblac; | U+00150 | Ő |
Ofr; | U+1D512 | 𝔒 |
Ograve; | U+000D2 | Ò |
Omacr; | U+0014C | Ō |
Omega; | U+003A9 | Ω |
Omicron; | U+0039F | Ο |
Oopf; | U+1D546 | 𝕆 |
OpenCurlyDoubleQuote; | U+0201C | “ |
OpenCurlyQuote; | U+02018 | ‘ |
Or; | U+02A54 | ⩔ |
Oscr; | U+1D4AA | 𝒪 |
Oslash; | U+000D8 | Ø |
Otilde; | U+000D5 | Õ |
Otimes; | U+02A37 | ⨷ |
Ouml; | U+000D6 | Ö |
OverBar; | U+0203E | ‾ |
OverBrace; | U+023DE | ⏞ |
OverBracket; | U+023B4 | ⎴ |
OverParenthesis; | U+023DC | ⏜ |
PartialD; | U+02202 | ∂ |
Pcy; | U+0041F | П |
Pfr; | U+1D513 | 𝔓 |
Phi; | U+003A6 | Φ |
Pi; | U+003A0 | Π |
PlusMinus; | U+000B1 | ± |
Poincareplane; | U+0210C | ℌ |
Popf; | U+02119 | ℙ |
Pr; | U+02ABB | ⪻ |
Precedes; | U+0227A | ≺ |
PrecedesEqual; | U+02AAF | ⪯ |
PrecedesSlantEqual; | U+0227C | ≼ |
PrecedesTilde; | U+0227E | ≾ |
Prime; | U+02033 | ″ |
Product; | U+0220F | ∏ |
Proportion; | U+02237 | ∷ |
Proportional; | U+0221D | ∝ |
Pscr; | U+1D4AB | 𝒫 |
Psi; | U+003A8 | Ψ |
QUOT; | U+00022 | " |
Qfr; | U+1D514 | 𝔔 |
Qopf; | U+0211A | ℚ |
Qscr; | U+1D4AC | 𝒬 |
RBarr; | U+02910 | ⤐ |
REG; | U+000AE | ® |
Racute; | U+00154 | Ŕ |
Rang; | U+027EB | ⟫ |
Rarr; | U+021A0 | ↠ |
Rarrtl; | U+02916 | ⤖ |
Rcaron; | U+00158 | Ř |
Rcedil; | U+00156 | Ŗ |
Rcy; | U+00420 | Р |
Re; | U+0211C | ℜ |
ReverseElement; | U+0220B | ∋ |
ReverseEquilibrium; | U+021CB | ⇋ |
ReverseUpEquilibrium; | U+0296F | ⥯ |
Rfr; | U+0211C | ℜ |
Rho; | U+003A1 | Ρ |
RightAngleBracket; | U+027E9 | 〉 |
RightArrow; | U+02192 | → |
RightArrowBar; | U+021E5 | ⇥ |
RightArrowLeftArrow; | U+021C4 | ⇄ |
RightCeiling; | U+02309 | ⌉ |
RightDoubleBracket; | U+027E7 | ⟧ |
RightDownTeeVector; | U+0295D | ⥝ |
RightDownVector; | U+021C2 | ⇂ |
RightDownVectorBar; | U+02955 | ⥕ |
RightFloor; | U+0230B | ⌋ |
RightTee; | U+022A2 | ⊢ |
RightTeeArrow; | U+021A6 | ↦ |
RightTeeVector; | U+0295B | ⥛ |
RightTriangle; | U+022B3 | ⊳ |
RightTriangleBar; | U+029D0 | ⧐ |
RightTriangleEqual; | U+022B5 | ⊵ |
RightUpDownVector; | U+0294F | ⥏ |
RightUpTeeVector; | U+0295C | ⥜ |
RightUpVector; | U+021BE | ↾ |
RightUpVectorBar; | U+02954 | ⥔ |
RightVector; | U+021C0 | ⇀ |
RightVectorBar; | U+02953 | ⥓ |
Rightarrow; | U+021D2 | ⇒ |
Ropf; | U+0211D | ℝ |
RoundImplies; | U+02970 | ⥰ |
Rrightarrow; | U+021DB | ⇛ |
Rscr; | U+0211B | ℛ |
Rsh; | U+021B1 | ↱ |
RuleDelayed; | U+029F4 | ⧴ |
SHCHcy; | U+00429 | Щ |
SHcy; | U+00428 | Ш |
SOFTcy; | U+0042C | Ь |
Sacute; | U+0015A | Ś |
Sc; | U+02ABC | ⪼ |
Scaron; | U+00160 | Š |
Scedil; | U+0015E | Ş |
Scirc; | U+0015C | Ŝ |
Scy; | U+00421 | С |
Sfr; | U+1D516 | 𝔖 |
ShortDownArrow; | U+02193 | ↓ |
ShortLeftArrow; | U+02190 | ← |
ShortRightArrow; | U+02192 | → |
ShortUpArrow; | U+02191 | ↑ |
Sigma; | U+003A3 | Σ |
SmallCircle; | U+02218 | ∘ |
Sopf; | U+1D54A | 𝕊 |
Sqrt; | U+0221A | √ |
Square; | U+025A1 | □ |
SquareIntersection; | U+02293 | ⊓ |
SquareSubset; | U+0228F | ⊏ |
SquareSubsetEqual; | U+02291 | ⊑ |
SquareSuperset; | U+02290 | ⊐ |
SquareSupersetEqual; | U+02292 | ⊒ |
SquareUnion; | U+02294 | ⊔ |
Sscr; | U+1D4AE | 𝒮 |
Star; | U+022C6 | ⋆ |
Sub; | U+022D0 | ⋐ |
Subset; | U+022D0 | ⋐ |
SubsetEqual; | U+02286 | ⊆ |
Succeeds; | U+0227B | ≻ |
SucceedsEqual; | U+02AB0 | ⪰ |
SucceedsSlantEqual; | U+0227D | ≽ |
SucceedsTilde; | U+0227F | ≿ |
SuchThat; | U+0220B | ∋ |
Sum; | U+02211 | ∑ |
Sup; | U+022D1 | ⋑ |
Superset; | U+02283 | ⊃ |
SupersetEqual; | U+02287 | ⊇ |
Supset; | U+022D1 | ⋑ |
THORN; | U+000DE | Þ |
TRADE; | U+02122 | ™ |
TSHcy; | U+0040B | Ћ |
TScy; | U+00426 | Ц |
Tab; | U+00009 | ␉ |
Tau; | U+003A4 | Τ |
Tcaron; | U+00164 | Ť |
Tcedil; | U+00162 | Ţ |
Tcy; | U+00422 | Т |
Tfr; | U+1D517 | 𝔗 |
Therefore; | U+02234 | ∴ |
Theta; | U+00398 | Θ |
ThickSpace; | U+0205F U+0200A | |
ThinSpace; | U+02009 | |
Tilde; | U+0223C | ∼ |
TildeEqual; | U+02243 | ≃ |
TildeFullEqual; | U+02245 | ≅ |
TildeTilde; | U+02248 | ≈ |
Topf; | U+1D54B | 𝕋 |
TripleDot; | U+020DB | ◌⃛ |
Tscr; | U+1D4AF | 𝒯 |
Tstrok; | U+00166 | Ŧ |
Uacute; | U+000DA | Ú |
Uarr; | U+0219F | ↟ |
Uarrocir; | U+02949 | ⥉ |
Ubrcy; | U+0040E | Ў |
Ubreve; | U+0016C | Ŭ |
Ucirc; | U+000DB | Û |
Ucy; | U+00423 | У |
Udblac; | U+00170 | Ű |
Ufr; | U+1D518 | 𝔘 |
Ugrave; | U+000D9 | Ù |
Umacr; | U+0016A | Ū |
UnderBar; | U+0005F | _ |
UnderBrace; | U+023DF | ⏟ |
UnderBracket; | U+023B5 | ⎵ |
UnderParenthesis; | U+023DD | ⏝ |
Union; | U+022C3 | ⋃ |
UnionPlus; | U+0228E | ⊎ |
Uogon; | U+00172 | Ų |
Uopf; | U+1D54C | 𝕌 |
UpArrow; | U+02191 | ↑ |
UpArrowBar; | U+02912 | ⤒ |
UpArrowDownArrow; | U+021C5 | ⇅ |
UpDownArrow; | U+02195 | ↕ |
UpEquilibrium; | U+0296E | ⥮ |
UpTee; | U+022A5 | ⊥ |
UpTeeArrow; | U+021A5 | ↥ |
Uparrow; | U+021D1 | ⇑ |
Updownarrow; | U+021D5 | ⇕ |
UpperLeftArrow; | U+02196 | ↖ |
UpperRightArrow; | U+02197 | ↗ |
Upsi; | U+003D2 | ϒ |
Upsilon; | U+003A5 | Υ |
Uring; | U+0016E | Ů |
Uscr; | U+1D4B0 | 𝒰 |
Utilde; | U+00168 | Ũ |
Uuml; | U+000DC | Ü |
VDash; | U+022AB | ⊫ |
Vbar; | U+02AEB | ⫫ |
Vcy; | U+00412 | В |
Vdash; | U+022A9 | ⊩ |
Vdashl; | U+02AE6 | ⫦ |
Vee; | U+022C1 | ⋁ |
Verbar; | U+02016 | ‖ |
Vert; | U+02016 | ‖ |
VerticalBar; | U+02223 | ∣ |
VerticalLine; | U+0007C | | |
VerticalSeparator; | U+02758 | ❘ |
VerticalTilde; | U+02240 | ≀ |
VeryThinSpace; | U+0200A | |
Vfr; | U+1D519 | 𝔙 |
Vopf; | U+1D54D | 𝕍 |
Vscr; | U+1D4B1 | 𝒱 |
Vvdash; | U+022AA | ⊪ |
Wcirc; | U+00174 | Ŵ |
Wedge; | U+022C0 | ⋀ |
Wfr; | U+1D51A | 𝔚 |
Wopf; | U+1D54E | 𝕎 |
Wscr; | U+1D4B2 | 𝒲 |
Xfr; | U+1D51B | 𝔛 |
Xi; | U+0039E | Ξ |
Xopf; | U+1D54F | 𝕏 |
Xscr; | U+1D4B3 | 𝒳 |
YAcy; | U+0042F | Я |
YIcy; | U+00407 | Ї |
YUcy; | U+0042E | Ю |
Yacute; | U+000DD | Ý |
Ycirc; | U+00176 | Ŷ |
Ycy; | U+0042B | Ы |
Yfr; | U+1D51C | 𝔜 |
Yopf; | U+1D550 | 𝕐 |
Yscr; | U+1D4B4 | 𝒴 |
Yuml; | U+00178 | Ÿ |
ZHcy; | U+00416 | Ж |
Zacute; | U+00179 | Ź |
Zcaron; | U+0017D | Ž |
Zcy; | U+00417 | З |
Zdot; | U+0017B | Ż |
ZeroWidthSpace; | U+0200B | |
Zeta; | U+00396 | Ζ |
Zfr; | U+02128 | ℨ |
Zopf; | U+02124 | ℤ |
Zscr; | U+1D4B5 | 𝒵 |
aacute; | U+000E1 | á |
abreve; | U+00103 | ă |
ac; | U+0223E | ∾ |
acE; | U+0223E U+00333 | ∾̳ |
acd; | U+0223F | ∿ |
acirc; | U+000E2 | â |
acute; | U+000B4 | ´ |
acy; | U+00430 | а |
aelig; | U+000E6 | æ |
af; | U+02061 | |
afr; | U+1D51E | 𝔞 |
agrave; | U+000E0 | à |
alefsym; | U+02135 | ℵ |
aleph; | U+02135 | ℵ |
alpha; | U+003B1 | α |
amacr; | U+00101 | ā |
amalg; | U+02A3F | ⨿ |
amp; | U+00026 | & |
and; | U+02227 | ∧ |
andand; | U+02A55 | ⩕ |
andd; | U+02A5C | ⩜ |
andslope; | U+02A58 | ⩘ |
andv; | U+02A5A | ⩚ |
ang; | U+02220 | ∠ |
ange; | U+029A4 | ⦤ |
angle; | U+02220 | ∠ |
angmsd; | U+02221 | ∡ |
angmsdaa; | U+029A8 | ⦨ |
angmsdab; | U+029A9 | ⦩ |
angmsdac; | U+029AA | ⦪ |
angmsdad; | U+029AB | ⦫ |
angmsdae; | U+029AC | ⦬ |
angmsdaf; | U+029AD | ⦭ |
angmsdag; | U+029AE | ⦮ |
angmsdah; | U+029AF | ⦯ |
angrt; | U+0221F | ∟ |
angrtvb; | U+022BE | ⊾ |
angrtvbd; | U+0299D | ⦝ |
angsph; | U+02222 | ∢ |
angst; | U+000C5 | Å |
angzarr; | U+0237C | ⍼ |
aogon; | U+00105 | ą |
aopf; | U+1D552 | 𝕒 |
ap; | U+02248 | ≈ |
apE; | U+02A70 | ⩰ |
apacir; | U+02A6F | ⩯ |
ape; | U+0224A | ≊ |
apid; | U+0224B | ≋ |
apos; | U+00027 | ' |
approx; | U+02248 | ≈ |
approxeq; | U+0224A | ≊ |
aring; | U+000E5 | å |
ascr; | U+1D4B6 | 𝒶 |
ast; | U+0002A | * |
asymp; | U+02248 | ≈ |
asympeq; | U+0224D | ≍ |
atilde; | U+000E3 | ã |
auml; | U+000E4 | ä |
awconint; | U+02233 | ∳ |
awint; | U+02A11 | ⨑ |
bNot; | U+02AED | ⫭ |
backcong; | U+0224C | ≌ |
backepsilon; | U+003F6 | ϶ |
backprime; | U+02035 | ‵ |
backsim; | U+0223D | ∽ |
backsimeq; | U+022CD | ⋍ |
barvee; | U+022BD | ⊽ |
barwed; | U+02305 | ⌅ |
barwedge; | U+02305 | ⌅ |
bbrk; | U+023B5 | ⎵ |
bbrktbrk; | U+023B6 | ⎶ |
bcong; | U+0224C | ≌ |
bcy; | U+00431 | б |
bdquo; | U+0201E | „ |
becaus; | U+02235 | ∵ |
because; | U+02235 | ∵ |
bemptyv; | U+029B0 | ⦰ |
bepsi; | U+003F6 | ϶ |
bernou; | U+0212C | ℬ |
beta; | U+003B2 | β |
beth; | U+02136 | ℶ |
between; | U+0226C | ≬ |
bfr; | U+1D51F | 𝔟 |
bigcap; | U+022C2 | ⋂ |
bigcirc; | U+025EF | ◯ |
bigcup; | U+022C3 | ⋃ |
bigodot; | U+02A00 | ⨀ |
bigoplus; | U+02A01 | ⨁ |
bigotimes; | U+02A02 | ⨂ |
bigsqcup; | U+02A06 | ⨆ |
bigstar; | U+02605 | ★ |
bigtriangledown; | U+025BD | ▽ |
bigtriangleup; | U+025B3 | △ |
biguplus; | U+02A04 | ⨄ |
bigvee; | U+022C1 | ⋁ |
bigwedge; | U+022C0 | ⋀ |
bkarow; | U+0290D | ⤍ |
blacklozenge; | U+029EB | ⧫ |
blacksquare; | U+025AA | ▪ |
blacktriangle; | U+025B4 | ▴ |
blacktriangledown; | U+025BE | ▾ |
blacktriangleleft; | U+025C2 | ◂ |
blacktriangleright; | U+025B8 | ▸ |
blank; | U+02423 | ␣ |
blk12; | U+02592 | ▒ |
blk14; | U+02591 | ░ |
blk34; | U+02593 | ▓ |
block; | U+02588 | █ |
bne; | U+0003D U+020E5 | =⃥ |
bnequiv; | U+02261 U+020E5 | ≡⃥ |
bnot; | U+02310 | ⌐ |
bopf; | U+1D553 | 𝕓 |
bot; | U+022A5 | ⊥ |
bottom; | U+022A5 | ⊥ |
bowtie; | U+022C8 | ⋈ |
boxDL; | U+02557 | ╗ |
boxDR; | U+02554 | ╔ |
boxDl; | U+02556 | ╖ |
boxDr; | U+02553 | ╓ |
boxH; | U+02550 | ═ |
boxHD; | U+02566 | ╦ |
boxHU; | U+02569 | ╩ |
boxHd; | U+02564 | ╤ |
boxHu; | U+02567 | ╧ |
boxUL; | U+0255D | ╝ |
boxUR; | U+0255A | ╚ |
boxUl; | U+0255C | ╜ |
boxUr; | U+02559 | ╙ |
boxV; | U+02551 | ║ |
boxVH; | U+0256C | ╬ |
boxVL; | U+02563 | ╣ |
boxVR; | U+02560 | ╠ |
boxVh; | U+0256B | ╫ |
boxVl; | U+02562 | ╢ |
boxVr; | U+0255F | ╟ |
boxbox; | U+029C9 | ⧉ |
boxdL; | U+02555 | ╕ |
boxdR; | U+02552 | ╒ |
boxdl; | U+02510 | ┐ |
boxdr; | U+0250C | ┌ |
boxh; | U+02500 | ─ |
boxhD; | U+02565 | ╥ |
boxhU; | U+02568 | ╨ |
boxhd; | U+0252C | ┬ |
boxhu; | U+02534 | ┴ |
boxminus; | U+0229F | ⊟ |
boxplus; | U+0229E | ⊞ |
boxtimes; | U+022A0 | ⊠ |
boxuL; | U+0255B | ╛ |
boxuR; | U+02558 | ╘ |
boxul; | U+02518 | ┘ |
boxur; | U+02514 | └ |
boxv; | U+02502 | │ |
boxvH; | U+0256A | ╪ |
boxvL; | U+02561 | ╡ |
boxvR; | U+0255E | ╞ |
boxvh; | U+0253C | ┼ |
boxvl; | U+02524 | ┤ |
boxvr; | U+0251C | ├ |
bprime; | U+02035 | ‵ |
breve; | U+002D8 | ˘ |
brvbar; | U+000A6 | ¦ |
bscr; | U+1D4B7 | 𝒷 |
bsemi; | U+0204F | ⁏ |
bsim; | U+0223D | ∽ |
bsime; | U+022CD | ⋍ |
bsol; | U+0005C | \ |
bsolb; | U+029C5 | ⧅ |
bsolhsub; | U+027C8 | ⟈ |
bull; | U+02022 | • |
bullet; | U+02022 | • |
bump; | U+0224E | ≎ |
bumpE; | U+02AAE | ⪮ |
bumpe; | U+0224F | ≏ |
bumpeq; | U+0224F | ≏ |
cacute; | U+00107 | ć |
cap; | U+02229 | ∩ |
capand; | U+02A44 | ⩄ |
capbrcup; | U+02A49 | ⩉ |
capcap; | U+02A4B | ⩋ |
capcup; | U+02A47 | ⩇ |
capdot; | U+02A40 | ⩀ |
caps; | U+02229 U+0FE00 | ∩︀ |
caret; | U+02041 | ⁁ |
caron; | U+002C7 | ˇ |
ccaps; | U+02A4D | ⩍ |
ccaron; | U+0010D | č |
ccedil; | U+000E7 | ç |
ccirc; | U+00109 | ĉ |
ccups; | U+02A4C | ⩌ |
ccupssm; | U+02A50 | ⩐ |
cdot; | U+0010B | ċ |
cedil; | U+000B8 | ¸ |
cemptyv; | U+029B2 | ⦲ |
cent; | U+000A2 | ¢ |
centerdot; | U+000B7 | · |
cfr; | U+1D520 | 𝔠 |
chcy; | U+00447 | ч |
check; | U+02713 | ✓ |
checkmark; | U+02713 | ✓ |
chi; | U+003C7 | χ |
cir; | U+025CB | ○ |
cirE; | U+029C3 | ⧃ |
circ; | U+002C6 | ˆ |
circeq; | U+02257 | ≗ |
circlearrowleft; | U+021BA | ↺ |
circlearrowright; | U+021BB | ↻ |
circledR; | U+000AE | ® |
circledS; | U+024C8 | Ⓢ |
circledast; | U+0229B | ⊛ |
circledcirc; | U+0229A | ⊚ |
circleddash; | U+0229D | ⊝ |
cire; | U+02257 | ≗ |
cirfnint; | U+02A10 | ⨐ |
cirmid; | U+02AEF | ⫯ |
cirscir; | U+029C2 | ⧂ |
clubs; | U+02663 | ♣ |
clubsuit; | U+02663 | ♣ |
colon; | U+0003A | : |
colone; | U+02254 | ≔ |
coloneq; | U+02254 | ≔ |
comma; | U+0002C | , |
commat; | U+00040 | @ |
comp; | U+02201 | ∁ |
compfn; | U+02218 | ∘ |
complement; | U+02201 | ∁ |
complexes; | U+02102 | ℂ |
cong; | U+02245 | ≅ |
congdot; | U+02A6D | ⩭ |
conint; | U+0222E | ∮ |
copf; | U+1D554 | 𝕔 |
coprod; | U+02210 | ∐ |
copy; | U+000A9 | © |
copysr; | U+02117 | ℗ |
crarr; | U+021B5 | ↵ |
cross; | U+02717 | ✗ |
cscr; | U+1D4B8 | 𝒸 |
csub; | U+02ACF | ⫏ |
csube; | U+02AD1 | ⫑ |
csup; | U+02AD0 | ⫐ |
csupe; | U+02AD2 | ⫒ |
ctdot; | U+022EF | ⋯ |
cudarrl; | U+02938 | ⤸ |
cudarrr; | U+02935 | ⤵ |
cuepr; | U+022DE | ⋞ |
cuesc; | U+022DF | ⋟ |
cularr; | U+021B6 | ↶ |
cularrp; | U+0293D | ⤽ |
cup; | U+0222A | ∪ |
cupbrcap; | U+02A48 | ⩈ |
cupcap; | U+02A46 | ⩆ |
cupcup; | U+02A4A | ⩊ |
cupdot; | U+0228D | ⊍ |
cupor; | U+02A45 | ⩅ |
cups; | U+0222A U+0FE00 | ∪︀ |
curarr; | U+021B7 | ↷ |
curarrm; | U+0293C | ⤼ |
curlyeqprec; | U+022DE | ⋞ |
curlyeqsucc; | U+022DF | ⋟ |
curlyvee; | U+022CE | ⋎ |
curlywedge; | U+022CF | ⋏ |
curren; | U+000A4 | ¤ |
curvearrowleft; | U+021B6 | ↶ |
curvearrowright; | U+021B7 | ↷ |
cuvee; | U+022CE | ⋎ |
cuwed; | U+022CF | ⋏ |
cwconint; | U+02232 | ∲ |
cwint; | U+02231 | ∱ |
cylcty; | U+0232D | ⌭ |
dArr; | U+021D3 | ⇓ |
dHar; | U+02965 | ⥥ |
dagger; | U+02020 | † |
daleth; | U+02138 | ℸ |
darr; | U+02193 | ↓ |
dash; | U+02010 | ‐ |
dashv; | U+022A3 | ⊣ |
dbkarow; | U+0290F | ⤏ |
dblac; | U+002DD | ˝ |
dcaron; | U+0010F | ď |
dcy; | U+00434 | д |
dd; | U+02146 | ⅆ |
ddagger; | U+02021 | ‡ |
ddarr; | U+021CA | ⇊ |
ddotseq; | U+02A77 | ⩷ |
deg; | U+000B0 | ° |
delta; | U+003B4 | δ |
demptyv; | U+029B1 | ⦱ |
dfisht; | U+0297F | ⥿ |
dfr; | U+1D521 | 𝔡 |
dharl; | U+021C3 | ⇃ |
dharr; | U+021C2 | ⇂ |
diam; | U+022C4 | ⋄ |
diamond; | U+022C4 | ⋄ |
diamondsuit; | U+02666 | ♦ |
diams; | U+02666 | ♦ |
die; | U+000A8 | ¨ |
digamma; | U+003DD | ϝ |
disin; | U+022F2 | ⋲ |
div; | U+000F7 | ÷ |
divide; | U+000F7 | ÷ |
divideontimes; | U+022C7 | ⋇ |
divonx; | U+022C7 | ⋇ |
djcy; | U+00452 | ђ |
dlcorn; | U+0231E | ⌞ |
dlcrop; | U+0230D | ⌍ |
dollar; | U+00024 | $ |
dopf; | U+1D555 | 𝕕 |
dot; | U+002D9 | ˙ |
doteq; | U+02250 | ≐ |
doteqdot; | U+02251 | ≑ |
dotminus; | U+02238 | ∸ |
dotplus; | U+02214 | ∔ |
dotsquare; | U+022A1 | ⊡ |
doublebarwedge; | U+02306 | ⌆ |
downarrow; | U+02193 | ↓ |
downdownarrows; | U+021CA | ⇊ |
downharpoonleft; | U+021C3 | ⇃ |
downharpoonright; | U+021C2 | ⇂ |
drbkarow; | U+02910 | ⤐ |
drcorn; | U+0231F | ⌟ |
drcrop; | U+0230C | ⌌ |
dscr; | U+1D4B9 | 𝒹 |
dscy; | U+00455 | ѕ |
dsol; | U+029F6 | ⧶ |
dstrok; | U+00111 | đ |
dtdot; | U+022F1 | ⋱ |
dtri; | U+025BF | ▿ |
dtrif; | U+025BE | ▾ |
duarr; | U+021F5 | ⇵ |
duhar; | U+0296F | ⥯ |
dwangle; | U+029A6 | ⦦ |
dzcy; | U+0045F | џ |
dzigrarr; | U+027FF | ⟿ |
eDDot; | U+02A77 | ⩷ |
eDot; | U+02251 | ≑ |
eacute; | U+000E9 | é |
easter; | U+02A6E | ⩮ |
ecaron; | U+0011B | ě |
ecir; | U+02256 | ≖ |
ecirc; | U+000EA | ê |
ecolon; | U+02255 | ≕ |
ecy; | U+0044D | э |
edot; | U+00117 | ė |
ee; | U+02147 | ⅇ |
efDot; | U+02252 | ≒ |
efr; | U+1D522 | 𝔢 |
eg; | U+02A9A | ⪚ |
egrave; | U+000E8 | è |
egs; | U+02A96 | ⪖ |
egsdot; | U+02A98 | ⪘ |
el; | U+02A99 | ⪙ |
elinters; | U+023E7 | ⏧ |
ell; | U+02113 | ℓ |
els; | U+02A95 | ⪕ |
elsdot; | U+02A97 | ⪗ |
emacr; | U+00113 | ē |
empty; | U+02205 | ∅ |
emptyset; | U+02205 | ∅ |
emptyv; | U+02205 | ∅ |
emsp; | U+02003 | |
emsp13; | U+02004 | |
emsp14; | U+02005 | |
eng; | U+0014B | ŋ |
ensp; | U+02002 | |
eogon; | U+00119 | ę |
eopf; | U+1D556 | 𝕖 |
epar; | U+022D5 | ⋕ |
eparsl; | U+029E3 | ⧣ |
eplus; | U+02A71 | ⩱ |
epsi; | U+003B5 | ε |
epsilon; | U+003B5 | ε |
epsiv; | U+003F5 | ϵ |
eqcirc; | U+02256 | ≖ |
eqcolon; | U+02255 | ≕ |
eqsim; | U+02242 | ≂ |
eqslantgtr; | U+02A96 | ⪖ |
eqslantless; | U+02A95 | ⪕ |
equals; | U+0003D | = |
equest; | U+0225F | ≟ |
equiv; | U+02261 | ≡ |
equivDD; | U+02A78 | ⩸ |
eqvparsl; | U+029E5 | ⧥ |
erDot; | U+02253 | ≓ |
erarr; | U+02971 | ⥱ |
escr; | U+0212F | ℯ |
esdot; | U+02250 | ≐ |
esim; | U+02242 | ≂ |
eta; | U+003B7 | η |
eth; | U+000F0 | ð |
euml; | U+000EB | ë |
euro; | U+020AC | € |
excl; | U+00021 | ! |
exist; | U+02203 | ∃ |
expectation; | U+02130 | ℰ |
exponentiale; | U+02147 | ⅇ |
fallingdotseq; | U+02252 | ≒ |
fcy; | U+00444 | ф |
female; | U+02640 | ♀ |
ffilig; | U+0FB03 | ffi |
fflig; | U+0FB00 | ff |
ffllig; | U+0FB04 | ffl |
ffr; | U+1D523 | 𝔣 |
filig; | U+0FB01 | fi |
fjlig; | U+00066 U+0006A | fj |
flat; | U+0266D | ♭ |
fllig; | U+0FB02 | fl |
fltns; | U+025B1 | ▱ |
fnof; | U+00192 | ƒ |
fopf; | U+1D557 | 𝕗 |
forall; | U+02200 | ∀ |
fork; | U+022D4 | ⋔ |
forkv; | U+02AD9 | ⫙ |
fpartint; | U+02A0D | ⨍ |
frac12; | U+000BD | ½ |
frac13; | U+02153 | ⅓ |
frac14; | U+000BC | ¼ |
frac15; | U+02155 | ⅕ |
frac16; | U+02159 | ⅙ |
frac18; | U+0215B | ⅛ |
frac23; | U+02154 | ⅔ |
frac25; | U+02156 | ⅖ |
frac34; | U+000BE | ¾ |
frac35; | U+02157 | ⅗ |
frac38; | U+0215C | ⅜ |
frac45; | U+02158 | ⅘ |
frac56; | U+0215A | ⅚ |
frac58; | U+0215D | ⅝ |
frac78; | U+0215E | ⅞ |
frasl; | U+02044 | ⁄ |
frown; | U+02322 | ⌢ |
fscr; | U+1D4BB | 𝒻 |
gE; | U+02267 | ≧ |
gEl; | U+02A8C | ⪌ |
gacute; | U+001F5 | ǵ |
gamma; | U+003B3 | γ |
gammad; | U+003DD | ϝ |
gap; | U+02A86 | ⪆ |
gbreve; | U+0011F | ğ |
gcirc; | U+0011D | ĝ |
gcy; | U+00433 | г |
gdot; | U+00121 | ġ |
ge; | U+02265 | ≥ |
gel; | U+022DB | ⋛ |
geq; | U+02265 | ≥ |
geqq; | U+02267 | ≧ |
geqslant; | U+02A7E | ⩾ |
ges; | U+02A7E | ⩾ |
gescc; | U+02AA9 | ⪩ |
gesdot; | U+02A80 | ⪀ |
gesdoto; | U+02A82 | ⪂ |
gesdotol; | U+02A84 | ⪄ |
gesl; | U+022DB U+0FE00 | ⋛︀ |
gesles; | U+02A94 | ⪔ |
gfr; | U+1D524 | 𝔤 |
gg; | U+0226B | ≫ |
ggg; | U+022D9 | ⋙ |
gimel; | U+02137 | ℷ |
gjcy; | U+00453 | ѓ |
gl; | U+02277 | ≷ |
glE; | U+02A92 | ⪒ |
gla; | U+02AA5 | ⪥ |
glj; | U+02AA4 | ⪤ |
gnE; | U+02269 | ≩ |
gnap; | U+02A8A | ⪊ |
gnapprox; | U+02A8A | ⪊ |
gne; | U+02A88 | ⪈ |
gneq; | U+02A88 | ⪈ |
gneqq; | U+02269 | ≩ |
gnsim; | U+022E7 | ⋧ |
gopf; | U+1D558 | 𝕘 |
grave; | U+00060 | ` |
gscr; | U+0210A | ℊ |
gsim; | U+02273 | ≳ |
gsime; | U+02A8E | ⪎ |
gsiml; | U+02A90 | ⪐ |
gt; | U+0003E | > |
gtcc; | U+02AA7 | ⪧ |
gtcir; | U+02A7A | ⩺ |
gtdot; | U+022D7 | ⋗ |
gtlPar; | U+02995 | ⦕ |
gtquest; | U+02A7C | ⩼ |
gtrapprox; | U+02A86 | ⪆ |
gtrarr; | U+02978 | ⥸ |
gtrdot; | U+022D7 | ⋗ |
gtreqless; | U+022DB | ⋛ |
gtreqqless; | U+02A8C | ⪌ |
gtrless; | U+02277 | ≷ |
gtrsim; | U+02273 | ≳ |
gvertneqq; | U+02269 U+0FE00 | ≩︀ |
gvnE; | U+02269 U+0FE00 | ≩︀ |
hArr; | U+021D4 | ⇔ |
hairsp; | U+0200A | |
half; | U+000BD | ½ |
hamilt; | U+0210B | ℋ |
hardcy; | U+0044A | ъ |
harr; | U+02194 | ↔ |
harrcir; | U+02948 | ⥈ |
harrw; | U+021AD | ↭ |
hbar; | U+0210F | ℏ |
hcirc; | U+00125 | ĥ |
hearts; | U+02665 | ♥ |
heartsuit; | U+02665 | ♥ |
hellip; | U+02026 | … |
hercon; | U+022B9 | ⊹ |
hfr; | U+1D525 | 𝔥 |
hksearow; | U+02925 | ⤥ |
hkswarow; | U+02926 | ⤦ |
hoarr; | U+021FF | ⇿ |
homtht; | U+0223B | ∻ |
hookleftarrow; | U+021A9 | ↩ |
hookrightarrow; | U+021AA | ↪ |
hopf; | U+1D559 | 𝕙 |
horbar; | U+02015 | ― |
hscr; | U+1D4BD | 𝒽 |
hslash; | U+0210F | ℏ |
hstrok; | U+00127 | ħ |
hybull; | U+02043 | ⁃ |
hyphen; | U+02010 | ‐ |
iacute; | U+000ED | í |
ic; | U+02063 | |
icirc; | U+000EE | î |
icy; | U+00438 | и |
iecy; | U+00435 | е |
iexcl; | U+000A1 | ¡ |
iff; | U+021D4 | ⇔ |
ifr; | U+1D526 | 𝔦 |
igrave; | U+000EC | ì |
ii; | U+02148 | ⅈ |
iiiint; | U+02A0C | ⨌ |
iiint; | U+0222D | ∭ |
iinfin; | U+029DC | ⧜ |
iiota; | U+02129 | ℩ |
ijlig; | U+00133 | ij |
imacr; | U+0012B | ī |
image; | U+02111 | ℑ |
imagline; | U+02110 | ℐ |
imagpart; | U+02111 | ℑ |
imath; | U+00131 | ı |
imof; | U+022B7 | ⊷ |
imped; | U+001B5 | Ƶ |
in; | U+02208 | ∈ |
incare; | U+02105 | ℅ |
infin; | U+0221E | ∞ |
infintie; | U+029DD | ⧝ |
inodot; | U+00131 | ı |
int; | U+0222B | ∫ |
intcal; | U+022BA | ⊺ |
integers; | U+02124 | ℤ |
intercal; | U+022BA | ⊺ |
intlarhk; | U+02A17 | ⨗ |
intprod; | U+02A3C | ⨼ |
iocy; | U+00451 | ё |
iogon; | U+0012F | į |
iopf; | U+1D55A | 𝕚 |
iota; | U+003B9 | ι |
iprod; | U+02A3C | ⨼ |
iquest; | U+000BF | ¿ |
iscr; | U+1D4BE | 𝒾 |
isin; | U+02208 | ∈ |
isinE; | U+022F9 | ⋹ |
isindot; | U+022F5 | ⋵ |
isins; | U+022F4 | ⋴ |
isinsv; | U+022F3 | ⋳ |
isinv; | U+02208 | ∈ |
it; | U+02062 | |
itilde; | U+00129 | ĩ |
iukcy; | U+00456 | і |
iuml; | U+000EF | ï |
jcirc; | U+00135 | ĵ |
jcy; | U+00439 | й |
jfr; | U+1D527 | 𝔧 |
jmath; | U+00237 | ȷ |
jopf; | U+1D55B | 𝕛 |
jscr; | U+1D4BF | 𝒿 |
jsercy; | U+00458 | ј |
jukcy; | U+00454 | є |
kappa; | U+003BA | κ |
kappav; | U+003F0 | ϰ |
kcedil; | U+00137 | ķ |
kcy; | U+0043A | к |
kfr; | U+1D528 | 𝔨 |
kgreen; | U+00138 | ĸ |
khcy; | U+00445 | х |
kjcy; | U+0045C | ќ |
kopf; | U+1D55C | 𝕜 |
kscr; | U+1D4C0 | 𝓀 |
lAarr; | U+021DA | ⇚ |
lArr; | U+021D0 | ⇐ |
lAtail; | U+0291B | ⤛ |
lBarr; | U+0290E | ⤎ |
lE; | U+02266 | ≦ |
lEg; | U+02A8B | ⪋ |
lHar; | U+02962 | ⥢ |
lacute; | U+0013A | ĺ |
laemptyv; | U+029B4 | ⦴ |
lagran; | U+02112 | ℒ |
lambda; | U+003BB | λ |
lang; | U+027E8 | 〈 |
langd; | U+02991 | ⦑ |
langle; | U+027E8 | 〈 |
lap; | U+02A85 | ⪅ |
laquo; | U+000AB | « |
larr; | U+02190 | ← |
larrb; | U+021E4 | ⇤ |
larrbfs; | U+0291F | ⤟ |
larrfs; | U+0291D | ⤝ |
larrhk; | U+021A9 | ↩ |
larrlp; | U+021AB | ↫ |
larrpl; | U+02939 | ⤹ |
larrsim; | U+02973 | ⥳ |
larrtl; | U+021A2 | ↢ |
lat; | U+02AAB | ⪫ |
latail; | U+02919 | ⤙ |
late; | U+02AAD | ⪭ |
lates; | U+02AAD U+0FE00 | ⪭︀ |
lbarr; | U+0290C | ⤌ |
lbbrk; | U+02772 | ❲ |
lbrace; | U+0007B | { |
lbrack; | U+0005B | [ |
lbrke; | U+0298B | ⦋ |
lbrksld; | U+0298F | ⦏ |
lbrkslu; | U+0298D | ⦍ |
lcaron; | U+0013E | ľ |
lcedil; | U+0013C | ļ |
lceil; | U+02308 | ⌈ |
lcub; | U+0007B | { |
lcy; | U+0043B | л |
ldca; | U+02936 | ⤶ |
ldquo; | U+0201C | “ |
ldquor; | U+0201E | „ |
ldrdhar; | U+02967 | ⥧ |
ldrushar; | U+0294B | ⥋ |
ldsh; | U+021B2 | ↲ |
le; | U+02264 | ≤ |
leftarrow; | U+02190 | ← |
leftarrowtail; | U+021A2 | ↢ |
leftharpoondown; | U+021BD | ↽ |
leftharpoonup; | U+021BC | ↼ |
leftleftarrows; | U+021C7 | ⇇ |
leftrightarrow; | U+02194 | ↔ |
leftrightarrows; | U+021C6 | ⇆ |
leftrightharpoons; | U+021CB | ⇋ |
leftrightsquigarrow; | U+021AD | ↭ |
leftthreetimes; | U+022CB | ⋋ |
leg; | U+022DA | ⋚ |
leq; | U+02264 | ≤ |
leqq; | U+02266 | ≦ |
leqslant; | U+02A7D | ⩽ |
les; | U+02A7D | ⩽ |
lescc; | U+02AA8 | ⪨ |
lesdot; | U+02A7F | ⩿ |
lesdoto; | U+02A81 | ⪁ |
lesdotor; | U+02A83 | ⪃ |
lesg; | U+022DA U+0FE00 | ⋚︀ |
lesges; | U+02A93 | ⪓ |
lessapprox; | U+02A85 | ⪅ |
lessdot; | U+022D6 | ⋖ |
lesseqgtr; | U+022DA | ⋚ |
lesseqqgtr; | U+02A8B | ⪋ |
lessgtr; | U+02276 | ≶ |
lesssim; | U+02272 | ≲ |
lfisht; | U+0297C | ⥼ |
lfloor; | U+0230A | ⌊ |
lfr; | U+1D529 | 𝔩 |
lg; | U+02276 | ≶ |
lgE; | U+02A91 | ⪑ |
lhard; | U+021BD | ↽ |
lharu; | U+021BC | ↼ |
lharul; | U+0296A | ⥪ |
lhblk; | U+02584 | ▄ |
ljcy; | U+00459 | љ |
ll; | U+0226A | ≪ |
llarr; | U+021C7 | ⇇ |
llcorner; | U+0231E | ⌞ |
llhard; | U+0296B | ⥫ |
lltri; | U+025FA | ◺ |
lmidot; | U+00140 | ŀ |
lmoust; | U+023B0 | ⎰ |
lmoustache; | U+023B0 | ⎰ |
lnE; | U+02268 | ≨ |
lnap; | U+02A89 | ⪉ |
lnapprox; | U+02A89 | ⪉ |
lne; | U+02A87 | ⪇ |
lneq; | U+02A87 | ⪇ |
lneqq; | U+02268 | ≨ |
lnsim; | U+022E6 | ⋦ |
loang; | U+027EC | ⟬ |
loarr; | U+021FD | ⇽ |
lobrk; | U+027E6 | ⟦ |
longleftarrow; | U+027F5 | ⟵ |
longleftrightarrow; | U+027F7 | ⟷ |
longmapsto; | U+027FC | ⟼ |
longrightarrow; | U+027F6 | ⟶ |
looparrowleft; | U+021AB | ↫ |
looparrowright; | U+021AC | ↬ |
lopar; | U+02985 | ⦅ |
lopf; | U+1D55D | 𝕝 |
loplus; | U+02A2D | ⨭ |
lotimes; | U+02A34 | ⨴ |
lowast; | U+02217 | ∗ |
lowbar; | U+0005F | _ |
loz; | U+025CA | ◊ |
lozenge; | U+025CA | ◊ |
lozf; | U+029EB | ⧫ |
lpar; | U+00028 | ( |
lparlt; | U+02993 | ⦓ |
lrarr; | U+021C6 | ⇆ |
lrcorner; | U+0231F | ⌟ |
lrhar; | U+021CB | ⇋ |
lrhard; | U+0296D | ⥭ |
lrm; | U+0200E | |
lrtri; | U+022BF | ⊿ |
lsaquo; | U+02039 | ‹ |
lscr; | U+1D4C1 | 𝓁 |
lsh; | U+021B0 | ↰ |
lsim; | U+02272 | ≲ |
lsime; | U+02A8D | ⪍ |
lsimg; | U+02A8F | ⪏ |
lsqb; | U+0005B | [ |
lsquo; | U+02018 | ‘ |
lsquor; | U+0201A | ‚ |
lstrok; | U+00142 | ł |
lt; | U+0003C | < |
ltcc; | U+02AA6 | ⪦ |
ltcir; | U+02A79 | ⩹ |
ltdot; | U+022D6 | ⋖ |
lthree; | U+022CB | ⋋ |
ltimes; | U+022C9 | ⋉ |
ltlarr; | U+02976 | ⥶ |
ltquest; | U+02A7B | ⩻ |
ltrPar; | U+02996 | ⦖ |
ltri; | U+025C3 | ◃ |
ltrie; | U+022B4 | ⊴ |
ltrif; | U+025C2 | ◂ |
lurdshar; | U+0294A | ⥊ |
luruhar; | U+02966 | ⥦ |
lvertneqq; | U+02268 U+0FE00 | ≨︀ |
lvnE; | U+02268 U+0FE00 | ≨︀ |
mDDot; | U+0223A | ∺ |
macr; | U+000AF | ¯ |
male; | U+02642 | ♂ |
malt; | U+02720 | ✠ |
maltese; | U+02720 | ✠ |
map; | U+021A6 | ↦ |
mapsto; | U+021A6 | ↦ |
mapstodown; | U+021A7 | ↧ |
mapstoleft; | U+021A4 | ↤ |
mapstoup; | U+021A5 | ↥ |
marker; | U+025AE | ▮ |
mcomma; | U+02A29 | ⨩ |
mcy; | U+0043C | м |
mdash; | U+02014 | — |
measuredangle; | U+02221 | ∡ |
mfr; | U+1D52A | 𝔪 |
mho; | U+02127 | ℧ |
micro; | U+000B5 | µ |
mid; | U+02223 | ∣ |
midast; | U+0002A | * |
midcir; | U+02AF0 | ⫰ |
middot; | U+000B7 | · |
minus; | U+02212 | − |
minusb; | U+0229F | ⊟ |
minusd; | U+02238 | ∸ |
minusdu; | U+02A2A | ⨪ |
mlcp; | U+02ADB | ⫛ |
mldr; | U+02026 | … |
mnplus; | U+02213 | ∓ |
models; | U+022A7 | ⊧ |
mopf; | U+1D55E | 𝕞 |
mp; | U+02213 | ∓ |
mscr; | U+1D4C2 | 𝓂 |
mstpos; | U+0223E | ∾ |
mu; | U+003BC | μ |
multimap; | U+022B8 | ⊸ |
mumap; | U+022B8 | ⊸ |
nGg; | U+022D9 U+00338 | ⋙̸ |
nGt; | U+0226B U+020D2 | ≫⃒ |
nGtv; | U+0226B U+00338 | ≫̸ |
nLeftarrow; | U+021CD | ⇍ |
nLeftrightarrow; | U+021CE | ⇎ |
nLl; | U+022D8 U+00338 | ⋘̸ |
nLt; | U+0226A U+020D2 | ≪⃒ |
nLtv; | U+0226A U+00338 | ≪̸ |
nRightarrow; | U+021CF | ⇏ |
nVDash; | U+022AF | ⊯ |
nVdash; | U+022AE | ⊮ |
nabla; | U+02207 | ∇ |
nacute; | U+00144 | ń |
nang; | U+02220 U+020D2 | ∠⃒ |
nap; | U+02249 | ≉ |
napE; | U+02A70 U+00338 | ⩰̸ |
napid; | U+0224B U+00338 | ≋̸ |
napos; | U+00149 | ʼn |
napprox; | U+02249 | ≉ |
natur; | U+0266E | ♮ |
natural; | U+0266E | ♮ |
naturals; | U+02115 | ℕ |
nbsp; | U+000A0 | |
nbump; | U+0224E U+00338 | ≎̸ |
nbumpe; | U+0224F U+00338 | ≏̸ |
ncap; | U+02A43 | ⩃ |
ncaron; | U+00148 | ň |
ncedil; | U+00146 | ņ |
ncong; | U+02247 | ≇ |
ncongdot; | U+02A6D U+00338 | ⩭̸ |
ncup; | U+02A42 | ⩂ |
ncy; | U+0043D | н |
ndash; | U+02013 | – |
ne; | U+02260 | ≠ |
neArr; | U+021D7 | ⇗ |
nearhk; | U+02924 | ⤤ |
nearr; | U+02197 | ↗ |
nearrow; | U+02197 | ↗ |
nedot; | U+02250 U+00338 | ≐̸ |
nequiv; | U+02262 | ≢ |
nesear; | U+02928 | ⤨ |
nesim; | U+02242 U+00338 | ≂̸ |
nexist; | U+02204 | ∄ |
nexists; | U+02204 | ∄ |
nfr; | U+1D52B | 𝔫 |
ngE; | U+02267 U+00338 | ≧̸ |
nge; | U+02271 | ≱ |
ngeq; | U+02271 | ≱ |
ngeqq; | U+02267 U+00338 | ≧̸ |
ngeqslant; | U+02A7E U+00338 | ⩾̸ |
nges; | U+02A7E U+00338 | ⩾̸ |
ngsim; | U+02275 | ≵ |
ngt; | U+0226F | ≯ |
ngtr; | U+0226F | ≯ |
nhArr; | U+021CE | ⇎ |
nharr; | U+021AE | ↮ |
nhpar; | U+02AF2 | ⫲ |
ni; | U+0220B | ∋ |
nis; | U+022FC | ⋼ |
nisd; | U+022FA | ⋺ |
niv; | U+0220B | ∋ |
njcy; | U+0045A | њ |
nlArr; | U+021CD | ⇍ |
nlE; | U+02266 U+00338 | ≦̸ |
nlarr; | U+0219A | ↚ |
nldr; | U+02025 | ‥ |
nle; | U+02270 | ≰ |
nleftarrow; | U+0219A | ↚ |
nleftrightarrow; | U+021AE | ↮ |
nleq; | U+02270 | ≰ |
nleqq; | U+02266 U+00338 | ≦̸ |
nleqslant; | U+02A7D U+00338 | ⩽̸ |
nles; | U+02A7D U+00338 | ⩽̸ |
nless; | U+0226E | ≮ |
nlsim; | U+02274 | ≴ |
nlt; | U+0226E | ≮ |
nltri; | U+022EA | ⋪ |
nltrie; | U+022EC | ⋬ |
nmid; | U+02224 | ∤ |
nopf; | U+1D55F | 𝕟 |
not; | U+000AC | ¬ |
notin; | U+02209 | ∉ |
notinE; | U+022F9 U+00338 | ⋹̸ |
notindot; | U+022F5 U+00338 | ⋵̸ |
notinva; | U+02209 | ∉ |
notinvb; | U+022F7 | ⋷ |
notinvc; | U+022F6 | ⋶ |
notni; | U+0220C | ∌ |
notniva; | U+0220C | ∌ |
notnivb; | U+022FE | ⋾ |
notnivc; | U+022FD | ⋽ |
npar; | U+02226 | ∦ |
nparallel; | U+02226 | ∦ |
nparsl; | U+02AFD U+020E5 | ⫽⃥ |
npart; | U+02202 U+00338 | ∂̸ |
npolint; | U+02A14 | ⨔ |
npr; | U+02280 | ⊀ |
nprcue; | U+022E0 | ⋠ |
npre; | U+02AAF U+00338 | ⪯̸ |
nprec; | U+02280 | ⊀ |
npreceq; | U+02AAF U+00338 | ⪯̸ |
nrArr; | U+021CF | ⇏ |
nrarr; | U+0219B | ↛ |
nrarrc; | U+02933 U+00338 | ⤳̸ |
nrarrw; | U+0219D U+00338 | ↝̸ |
nrightarrow; | U+0219B | ↛ |
nrtri; | U+022EB | ⋫ |
nrtrie; | U+022ED | ⋭ |
nsc; | U+02281 | ⊁ |
nsccue; | U+022E1 | ⋡ |
nsce; | U+02AB0 U+00338 | ⪰̸ |
nscr; | U+1D4C3 | 𝓃 |
nshortmid; | U+02224 | ∤ |
nshortparallel; | U+02226 | ∦ |
nsim; | U+02241 | ≁ |
nsime; | U+02244 | ≄ |
nsimeq; | U+02244 | ≄ |
nsmid; | U+02224 | ∤ |
nspar; | U+02226 | ∦ |
nsqsube; | U+022E2 | ⋢ |
nsqsupe; | U+022E3 | ⋣ |
nsub; | U+02284 | ⊄ |
nsubE; | U+02AC5 U+00338 | ⫅̸ |
nsube; | U+02288 | ⊈ |
nsubset; | U+02282 U+020D2 | ⊂⃒ |
nsubseteq; | U+02288 | ⊈ |
nsubseteqq; | U+02AC5 U+00338 | ⫅̸ |
nsucc; | U+02281 | ⊁ |
nsucceq; | U+02AB0 U+00338 | ⪰̸ |
nsup; | U+02285 | ⊅ |
nsupE; | U+02AC6 U+00338 | ⫆̸ |
nsupe; | U+02289 | ⊉ |
nsupset; | U+02283 U+020D2 | ⊃⃒ |
nsupseteq; | U+02289 | ⊉ |
nsupseteqq; | U+02AC6 U+00338 | ⫆̸ |
ntgl; | U+02279 | ≹ |
ntilde; | U+000F1 | ñ |
ntlg; | U+02278 | ≸ |
ntriangleleft; | U+022EA | ⋪ |
ntrianglelefteq; | U+022EC | ⋬ |
ntriangleright; | U+022EB | ⋫ |
ntrianglerighteq; | U+022ED | ⋭ |
nu; | U+003BD | ν |
num; | U+00023 | # |
numero; | U+02116 | № |
numsp; | U+02007 | |
nvDash; | U+022AD | ⊭ |
nvHarr; | U+02904 | ⤄ |
nvap; | U+0224D U+020D2 | ≍⃒ |
nvdash; | U+022AC | ⊬ |
nvge; | U+02265 U+020D2 | ≥⃒ |
nvgt; | U+0003E U+020D2 | >⃒ |
nvinfin; | U+029DE | ⧞ |
nvlArr; | U+02902 | ⤂ |
nvle; | U+02264 U+020D2 | ≤⃒ |
nvlt; | U+0003C U+020D2 | <⃒ |
nvltrie; | U+022B4 U+020D2 | ⊴⃒ |
nvrArr; | U+02903 | ⤃ |
nvrtrie; | U+022B5 U+020D2 | ⊵⃒ |
nvsim; | U+0223C U+020D2 | ∼⃒ |
nwArr; | U+021D6 | ⇖ |
nwarhk; | U+02923 | ⤣ |
nwarr; | U+02196 | ↖ |
nwarrow; | U+02196 | ↖ |
nwnear; | U+02927 | ⤧ |
oS; | U+024C8 | Ⓢ |
oacute; | U+000F3 | ó |
oast; | U+0229B | ⊛ |
ocir; | U+0229A | ⊚ |
ocirc; | U+000F4 | ô |
ocy; | U+0043E | о |
odash; | U+0229D | ⊝ |
odblac; | U+00151 | ő |
odiv; | U+02A38 | ⨸ |
odot; | U+02299 | ⊙ |
odsold; | U+029BC | ⦼ |
oelig; | U+00153 | œ |
ofcir; | U+029BF | ⦿ |
ofr; | U+1D52C | 𝔬 |
ogon; | U+002DB | ˛ |
ograve; | U+000F2 | ò |
ogt; | U+029C1 | ⧁ |
ohbar; | U+029B5 | ⦵ |
ohm; | U+003A9 | Ω |
oint; | U+0222E | ∮ |
olarr; | U+021BA | ↺ |
olcir; | U+029BE | ⦾ |
olcross; | U+029BB | ⦻ |
oline; | U+0203E | ‾ |
olt; | U+029C0 | ⧀ |
omacr; | U+0014D | ō |
omega; | U+003C9 | ω |
omicron; | U+003BF | ο |
omid; | U+029B6 | ⦶ |
ominus; | U+02296 | ⊖ |
oopf; | U+1D560 | 𝕠 |
opar; | U+029B7 | ⦷ |
operp; | U+029B9 | ⦹ |
oplus; | U+02295 | ⊕ |
or; | U+02228 | ∨ |
orarr; | U+021BB | ↻ |
ord; | U+02A5D | ⩝ |
order; | U+02134 | ℴ |
orderof; | U+02134 | ℴ |
ordf; | U+000AA | ª |
ordm; | U+000BA | º |
origof; | U+022B6 | ⊶ |
oror; | U+02A56 | ⩖ |
orslope; | U+02A57 | ⩗ |
orv; | U+02A5B | ⩛ |
oscr; | U+02134 | ℴ |
oslash; | U+000F8 | ø |
osol; | U+02298 | ⊘ |
otilde; | U+000F5 | õ |
otimes; | U+02297 | ⊗ |
otimesas; | U+02A36 | ⨶ |
ouml; | U+000F6 | ö |
ovbar; | U+0233D | ⌽ |
par; | U+02225 | ∥ |
para; | U+000B6 | ¶ |
parallel; | U+02225 | ∥ |
parsim; | U+02AF3 | ⫳ |
parsl; | U+02AFD | ⫽ |
part; | U+02202 | ∂ |
pcy; | U+0043F | п |
percnt; | U+00025 | % |
period; | U+0002E | . |
permil; | U+02030 | ‰ |
perp; | U+022A5 | ⊥ |
pertenk; | U+02031 | ‱ |
pfr; | U+1D52D | 𝔭 |
phi; | U+003C6 | φ |
phiv; | U+003D5 | ϕ |
phmmat; | U+02133 | ℳ |
phone; | U+0260E | ☎ |
pi; | U+003C0 | π |
pitchfork; | U+022D4 | ⋔ |
piv; | U+003D6 | ϖ |
planck; | U+0210F | ℏ |
planckh; | U+0210E | ℎ |
plankv; | U+0210F | ℏ |
plus; | U+0002B | + |
plusacir; | U+02A23 | ⨣ |
plusb; | U+0229E | ⊞ |
pluscir; | U+02A22 | ⨢ |
plusdo; | U+02214 | ∔ |
plusdu; | U+02A25 | ⨥ |
pluse; | U+02A72 | ⩲ |
plusmn; | U+000B1 | ± |
plussim; | U+02A26 | ⨦ |
plustwo; | U+02A27 | ⨧ |
pm; | U+000B1 | ± |
pointint; | U+02A15 | ⨕ |
popf; | U+1D561 | 𝕡 |
pound; | U+000A3 | £ |
pr; | U+0227A | ≺ |
prE; | U+02AB3 | ⪳ |
prap; | U+02AB7 | ⪷ |
prcue; | U+0227C | ≼ |
pre; | U+02AAF | ⪯ |
prec; | U+0227A | ≺ |
precapprox; | U+02AB7 | ⪷ |
preccurlyeq; | U+0227C | ≼ |
preceq; | U+02AAF | ⪯ |
precnapprox; | U+02AB9 | ⪹ |
precneqq; | U+02AB5 | ⪵ |
precnsim; | U+022E8 | ⋨ |
precsim; | U+0227E | ≾ |
prime; | U+02032 | ′ |
primes; | U+02119 | ℙ |
prnE; | U+02AB5 | ⪵ |
prnap; | U+02AB9 | ⪹ |
prnsim; | U+022E8 | ⋨ |
prod; | U+0220F | ∏ |
profalar; | U+0232E | ⌮ |
profline; | U+02312 | ⌒ |
profsurf; | U+02313 | ⌓ |
prop; | U+0221D | ∝ |
propto; | U+0221D | ∝ |
prsim; | U+0227E | ≾ |
prurel; | U+022B0 | ⊰ |
pscr; | U+1D4C5 | 𝓅 |
psi; | U+003C8 | ψ |
puncsp; | U+02008 | |
qfr; | U+1D52E | 𝔮 |
qint; | U+02A0C | ⨌ |
qopf; | U+1D562 | 𝕢 |
qprime; | U+02057 | ⁗ |
qscr; | U+1D4C6 | 𝓆 |
quaternions; | U+0210D | ℍ |
quatint; | U+02A16 | ⨖ |
quest; | U+0003F | ? |
questeq; | U+0225F | ≟ |
quot; | U+00022 | " |
rAarr; | U+021DB | ⇛ |
rArr; | U+021D2 | ⇒ |
rAtail; | U+0291C | ⤜ |
rBarr; | U+0290F | ⤏ |
rHar; | U+02964 | ⥤ |
race; | U+0223D U+00331 | ∽̱ |
racute; | U+00155 | ŕ |
radic; | U+0221A | √ |
raemptyv; | U+029B3 | ⦳ |
rang; | U+027E9 | 〉 |
rangd; | U+02992 | ⦒ |
range; | U+029A5 | ⦥ |
rangle; | U+027E9 | 〉 |
raquo; | U+000BB | » |
rarr; | U+02192 | → |
rarrap; | U+02975 | ⥵ |
rarrb; | U+021E5 | ⇥ |
rarrbfs; | U+02920 | ⤠ |
rarrc; | U+02933 | ⤳ |
rarrfs; | U+0291E | ⤞ |
rarrhk; | U+021AA | ↪ |
rarrlp; | U+021AC | ↬ |
rarrpl; | U+02945 | ⥅ |
rarrsim; | U+02974 | ⥴ |
rarrtl; | U+021A3 | ↣ |
rarrw; | U+0219D | ↝ |
ratail; | U+0291A | ⤚ |
ratio; | U+02236 | ∶ |
rationals; | U+0211A | ℚ |
rbarr; | U+0290D | ⤍ |
rbbrk; | U+02773 | ❳ |
rbrace; | U+0007D | } |
rbrack; | U+0005D | ] |
rbrke; | U+0298C | ⦌ |
rbrksld; | U+0298E | ⦎ |
rbrkslu; | U+02990 | ⦐ |
rcaron; | U+00159 | ř |
rcedil; | U+00157 | ŗ |
rceil; | U+02309 | ⌉ |
rcub; | U+0007D | } |
rcy; | U+00440 | р |
rdca; | U+02937 | ⤷ |
rdldhar; | U+02969 | ⥩ |
rdquo; | U+0201D | ” |
rdquor; | U+0201D | ” |
rdsh; | U+021B3 | ↳ |
real; | U+0211C | ℜ |
realine; | U+0211B | ℛ |
realpart; | U+0211C | ℜ |
reals; | U+0211D | ℝ |
rect; | U+025AD | ▭ |
reg; | U+000AE | ® |
rfisht; | U+0297D | ⥽ |
rfloor; | U+0230B | ⌋ |
rfr; | U+1D52F | 𝔯 |
rhard; | U+021C1 | ⇁ |
rharu; | U+021C0 | ⇀ |
rharul; | U+0296C | ⥬ |
rho; | U+003C1 | ρ |
rhov; | U+003F1 | ϱ |
rightarrow; | U+02192 | → |
rightarrowtail; | U+021A3 | ↣ |
rightharpoondown; | U+021C1 | ⇁ |
rightharpoonup; | U+021C0 | ⇀ |
rightleftarrows; | U+021C4 | ⇄ |
rightleftharpoons; | U+021CC | ⇌ |
rightrightarrows; | U+021C9 | ⇉ |
rightsquigarrow; | U+0219D | ↝ |
rightthreetimes; | U+022CC | ⋌ |
ring; | U+002DA | ˚ |
risingdotseq; | U+02253 | ≓ |
rlarr; | U+021C4 | ⇄ |
rlhar; | U+021CC | ⇌ |
rlm; | U+0200F | |
rmoust; | U+023B1 | ⎱ |
rmoustache; | U+023B1 | ⎱ |
rnmid; | U+02AEE | ⫮ |
roang; | U+027ED | ⟭ |
roarr; | U+021FE | ⇾ |
robrk; | U+027E7 | ⟧ |
ropar; | U+02986 | ⦆ |
ropf; | U+1D563 | 𝕣 |
roplus; | U+02A2E | ⨮ |
rotimes; | U+02A35 | ⨵ |
rpar; | U+00029 | ) |
rpargt; | U+02994 | ⦔ |
rppolint; | U+02A12 | ⨒ |
rrarr; | U+021C9 | ⇉ |
rsaquo; | U+0203A | › |
rscr; | U+1D4C7 | 𝓇 |
rsh; | U+021B1 | ↱ |
rsqb; | U+0005D | ] |
rsquo; | U+02019 | ’ |
rsquor; | U+02019 | ’ |
rthree; | U+022CC | ⋌ |
rtimes; | U+022CA | ⋊ |
rtri; | U+025B9 | ▹ |
rtrie; | U+022B5 | ⊵ |
rtrif; | U+025B8 | ▸ |
rtriltri; | U+029CE | ⧎ |
ruluhar; | U+02968 | ⥨ |
rx; | U+0211E | ℞ |
sacute; | U+0015B | ś |
sbquo; | U+0201A | ‚ |
sc; | U+0227B | ≻ |
scE; | U+02AB4 | ⪴ |
scap; | U+02AB8 | ⪸ |
scaron; | U+00161 | š |
sccue; | U+0227D | ≽ |
sce; | U+02AB0 | ⪰ |
scedil; | U+0015F | ş |
scirc; | U+0015D | ŝ |
scnE; | U+02AB6 | ⪶ |
scnap; | U+02ABA | ⪺ |
scnsim; | U+022E9 | ⋩ |
scpolint; | U+02A13 | ⨓ |
scsim; | U+0227F | ≿ |
scy; | U+00441 | с |
sdot; | U+022C5 | ⋅ |
sdotb; | U+022A1 | ⊡ |
sdote; | U+02A66 | ⩦ |
seArr; | U+021D8 | ⇘ |
searhk; | U+02925 | ⤥ |
searr; | U+02198 | ↘ |
searrow; | U+02198 | ↘ |
sect; | U+000A7 | § |
semi; | U+0003B | ; |
seswar; | U+02929 | ⤩ |
setminus; | U+02216 | ∖ |
setmn; | U+02216 | ∖ |
sext; | U+02736 | ✶ |
sfr; | U+1D530 | 𝔰 |
sfrown; | U+02322 | ⌢ |
sharp; | U+0266F | ♯ |
shchcy; | U+00449 | щ |
shcy; | U+00448 | ш |
shortmid; | U+02223 | ∣ |
shortparallel; | U+02225 | ∥ |
shy; | U+000AD | |
sigma; | U+003C3 | σ |
sigmaf; | U+003C2 | ς |
sigmav; | U+003C2 | ς |
sim; | U+0223C | ∼ |
simdot; | U+02A6A | ⩪ |
sime; | U+02243 | ≃ |
simeq; | U+02243 | ≃ |
simg; | U+02A9E | ⪞ |
simgE; | U+02AA0 | ⪠ |
siml; | U+02A9D | ⪝ |
simlE; | U+02A9F | ⪟ |
simne; | U+02246 | ≆ |
simplus; | U+02A24 | ⨤ |
simrarr; | U+02972 | ⥲ |
slarr; | U+02190 | ← |
smallsetminus; | U+02216 | ∖ |
smashp; | U+02A33 | ⨳ |
smeparsl; | U+029E4 | ⧤ |
smid; | U+02223 | ∣ |
smile; | U+02323 | ⌣ |
smt; | U+02AAA | ⪪ |
smte; | U+02AAC | ⪬ |
smtes; | U+02AAC U+0FE00 | ⪬︀ |
softcy; | U+0044C | ь |
sol; | U+0002F | / |
solb; | U+029C4 | ⧄ |
solbar; | U+0233F | ⌿ |
sopf; | U+1D564 | 𝕤 |
spades; | U+02660 | ♠ |
spadesuit; | U+02660 | ♠ |
spar; | U+02225 | ∥ |
sqcap; | U+02293 | ⊓ |
sqcaps; | U+02293 U+0FE00 | ⊓︀ |
sqcup; | U+02294 | ⊔ |
sqcups; | U+02294 U+0FE00 | ⊔︀ |
sqsub; | U+0228F | ⊏ |
sqsube; | U+02291 | ⊑ |
sqsubset; | U+0228F | ⊏ |
sqsubseteq; | U+02291 | ⊑ |
sqsup; | U+02290 | ⊐ |
sqsupe; | U+02292 | ⊒ |
sqsupset; | U+02290 | ⊐ |
sqsupseteq; | U+02292 | ⊒ |
squ; | U+025A1 | □ |
square; | U+025A1 | □ |
squarf; | U+025AA | ▪ |
squf; | U+025AA | ▪ |
srarr; | U+02192 | → |
sscr; | U+1D4C8 | 𝓈 |
ssetmn; | U+02216 | ∖ |
ssmile; | U+02323 | ⌣ |
sstarf; | U+022C6 | ⋆ |
star; | U+02606 | ☆ |
starf; | U+02605 | ★ |
straightepsilon; | U+003F5 | ϵ |
straightphi; | U+003D5 | ϕ |
strns; | U+000AF | ¯ |
sub; | U+02282 | ⊂ |
subE; | U+02AC5 | ⫅ |
subdot; | U+02ABD | ⪽ |
sube; | U+02286 | ⊆ |
subedot; | U+02AC3 | ⫃ |
submult; | U+02AC1 | ⫁ |
subnE; | U+02ACB | ⫋ |
subne; | U+0228A | ⊊ |
subplus; | U+02ABF | ⪿ |
subrarr; | U+02979 | ⥹ |
subset; | U+02282 | ⊂ |
subseteq; | U+02286 | ⊆ |
subseteqq; | U+02AC5 | ⫅ |
subsetneq; | U+0228A | ⊊ |
subsetneqq; | U+02ACB | ⫋ |
subsim; | U+02AC7 | ⫇ |
subsub; | U+02AD5 | ⫕ |
subsup; | U+02AD3 | ⫓ |
succ; | U+0227B | ≻ |
succapprox; | U+02AB8 | ⪸ |
succcurlyeq; | U+0227D | ≽ |
succeq; | U+02AB0 | ⪰ |
succnapprox; | U+02ABA | ⪺ |
succneqq; | U+02AB6 | ⪶ |
succnsim; | U+022E9 | ⋩ |
succsim; | U+0227F | ≿ |
sum; | U+02211 | ∑ |
sung; | U+0266A | ♪ |
sup; | U+02283 | ⊃ |
sup1; | U+000B9 | ¹ |
sup2; | U+000B2 | ² |
sup3; | U+000B3 | ³ |
supE; | U+02AC6 | ⫆ |
supdot; | U+02ABE | ⪾ |
supdsub; | U+02AD8 | ⫘ |
supe; | U+02287 | ⊇ |
supedot; | U+02AC4 | ⫄ |
suphsol; | U+027C9 | ⟉ |
suphsub; | U+02AD7 | ⫗ |
suplarr; | U+0297B | ⥻ |
supmult; | U+02AC2 | ⫂ |
supnE; | U+02ACC | ⫌ |
supne; | U+0228B | ⊋ |
supplus; | U+02AC0 | ⫀ |
supset; | U+02283 | ⊃ |
supseteq; | U+02287 | ⊇ |
supseteqq; | U+02AC6 | ⫆ |
supsetneq; | U+0228B | ⊋ |
supsetneqq; | U+02ACC | ⫌ |
supsim; | U+02AC8 | ⫈ |
supsub; | U+02AD4 | ⫔ |
supsup; | U+02AD6 | ⫖ |
swArr; | U+021D9 | ⇙ |
swarhk; | U+02926 | ⤦ |
swarr; | U+02199 | ↙ |
swarrow; | U+02199 | ↙ |
swnwar; | U+0292A | ⤪ |
szlig; | U+000DF | ß |
target; | U+02316 | ⌖ |
tau; | U+003C4 | τ |
tbrk; | U+023B4 | ⎴ |
tcaron; | U+00165 | ť |
tcedil; | U+00163 | ţ |
tcy; | U+00442 | т |
tdot; | U+020DB | ◌⃛ |
telrec; | U+02315 | ⌕ |
tfr; | U+1D531 | 𝔱 |
there4; | U+02234 | ∴ |
therefore; | U+02234 | ∴ |
theta; | U+003B8 | θ |
thetasym; | U+003D1 | ϑ |
thetav; | U+003D1 | ϑ |
thickapprox; | U+02248 | ≈ |
thicksim; | U+0223C | ∼ |
thinsp; | U+02009 | |
thkap; | U+02248 | ≈ |
thksim; | U+0223C | ∼ |
thorn; | U+000FE | þ |
tilde; | U+002DC | ˜ |
times; | U+000D7 | × |
timesb; | U+022A0 | ⊠ |
timesbar; | U+02A31 | ⨱ |
timesd; | U+02A30 | ⨰ |
tint; | U+0222D | ∭ |
toea; | U+02928 | ⤨ |
top; | U+022A4 | ⊤ |
topbot; | U+02336 | ⌶ |
topcir; | U+02AF1 | ⫱ |
topf; | U+1D565 | 𝕥 |
topfork; | U+02ADA | ⫚ |
tosa; | U+02929 | ⤩ |
tprime; | U+02034 | ‴ |
trade; | U+02122 | ™ |
triangle; | U+025B5 | ▵ |
triangledown; | U+025BF | ▿ |
triangleleft; | U+025C3 | ◃ |
trianglelefteq; | U+022B4 | ⊴ |
triangleq; | U+0225C | ≜ |
triangleright; | U+025B9 | ▹ |
trianglerighteq; | U+022B5 | ⊵ |
tridot; | U+025EC | ◬ |
trie; | U+0225C | ≜ |
triminus; | U+02A3A | ⨺ |
triplus; | U+02A39 | ⨹ |
trisb; | U+029CD | ⧍ |
tritime; | U+02A3B | ⨻ |
trpezium; | U+023E2 | ⏢ |
tscr; | U+1D4C9 | 𝓉 |
tscy; | U+00446 | ц |
tshcy; | U+0045B | ћ |
tstrok; | U+00167 | ŧ |
twixt; | U+0226C | ≬ |
twoheadleftarrow; | U+0219E | ↞ |
twoheadrightarrow; | U+021A0 | ↠ |
uArr; | U+021D1 | ⇑ |
uHar; | U+02963 | ⥣ |
uacute; | U+000FA | ú |
uarr; | U+02191 | ↑ |
ubrcy; | U+0045E | ў |
ubreve; | U+0016D | ŭ |
ucirc; | U+000FB | û |
ucy; | U+00443 | у |
udarr; | U+021C5 | ⇅ |
udblac; | U+00171 | ű |
udhar; | U+0296E | ⥮ |
ufisht; | U+0297E | ⥾ |
ufr; | U+1D532 | 𝔲 |
ugrave; | U+000F9 | ù |
uharl; | U+021BF | ↿ |
uharr; | U+021BE | ↾ |
uhblk; | U+02580 | ▀ |
ulcorn; | U+0231C | ⌜ |
ulcorner; | U+0231C | ⌜ |
ulcrop; | U+0230F | ⌏ |
ultri; | U+025F8 | ◸ |
umacr; | U+0016B | ū |
uml; | U+000A8 | ¨ |
uogon; | U+00173 | ų |
uopf; | U+1D566 | 𝕦 |
uparrow; | U+02191 | ↑ |
updownarrow; | U+02195 | ↕ |
upharpoonleft; | U+021BF | ↿ |
upharpoonright; | U+021BE | ↾ |
uplus; | U+0228E | ⊎ |
upsi; | U+003C5 | υ |
upsih; | U+003D2 | ϒ |
upsilon; | U+003C5 | υ |
upuparrows; | U+021C8 | ⇈ |
urcorn; | U+0231D | ⌝ |
urcorner; | U+0231D | ⌝ |
urcrop; | U+0230E | ⌎ |
uring; | U+0016F | ů |
urtri; | U+025F9 | ◹ |
uscr; | U+1D4CA | 𝓊 |
utdot; | U+022F0 | ⋰ |
utilde; | U+00169 | ũ |
utri; | U+025B5 | ▵ |
utrif; | U+025B4 | ▴ |
uuarr; | U+021C8 | ⇈ |
uuml; | U+000FC | ü |
uwangle; | U+029A7 | ⦧ |
vArr; | U+021D5 | ⇕ |
vBar; | U+02AE8 | ⫨ |
vBarv; | U+02AE9 | ⫩ |
vDash; | U+022A8 | ⊨ |
vangrt; | U+0299C | ⦜ |
varepsilon; | U+003F5 | ϵ |
varkappa; | U+003F0 | ϰ |
varnothing; | U+02205 | ∅ |
varphi; | U+003D5 | ϕ |
varpi; | U+003D6 | ϖ |
varpropto; | U+0221D | ∝ |
varr; | U+02195 | ↕ |
varrho; | U+003F1 | ϱ |
varsigma; | U+003C2 | ς |
varsubsetneq; | U+0228A U+0FE00 | ⊊︀ |
varsubsetneqq; | U+02ACB U+0FE00 | ⫋︀ |
varsupsetneq; | U+0228B U+0FE00 | ⊋︀ |
varsupsetneqq; | U+02ACC U+0FE00 | ⫌︀ |
vartheta; | U+003D1 | ϑ |
vartriangleleft; | U+022B2 | ⊲ |
vartriangleright; | U+022B3 | ⊳ |
vcy; | U+00432 | в |
vdash; | U+022A2 | ⊢ |
vee; | U+02228 | ∨ |
veebar; | U+022BB | ⊻ |
veeeq; | U+0225A | ≚ |
vellip; | U+022EE | ⋮ |
verbar; | U+0007C | | |
vert; | U+0007C | | |
vfr; | U+1D533 | 𝔳 |
vltri; | U+022B2 | ⊲ |
vnsub; | U+02282 U+020D2 | ⊂⃒ |
vnsup; | U+02283 U+020D2 | ⊃⃒ |
vopf; | U+1D567 | 𝕧 |
vprop; | U+0221D | ∝ |
vrtri; | U+022B3 | ⊳ |
vscr; | U+1D4CB | 𝓋 |
vsubnE; | U+02ACB U+0FE00 | ⫋︀ |
vsubne; | U+0228A U+0FE00 | ⊊︀ |
vsupnE; | U+02ACC U+0FE00 | ⫌︀ |
vsupne; | U+0228B U+0FE00 | ⊋︀ |
vzigzag; | U+0299A | ⦚ |
wcirc; | U+00175 | ŵ |
wedbar; | U+02A5F | ⩟ |
wedge; | U+02227 | ∧ |
wedgeq; | U+02259 | ≙ |
weierp; | U+02118 | ℘ |
wfr; | U+1D534 | 𝔴 |
wopf; | U+1D568 | 𝕨 |
wp; | U+02118 | ℘ |
wr; | U+02240 | ≀ |
wreath; | U+02240 | ≀ |
wscr; | U+1D4CC | 𝓌 |
xcap; | U+022C2 | ⋂ |
xcirc; | U+025EF | ◯ |
xcup; | U+022C3 | ⋃ |
xdtri; | U+025BD | ▽ |
xfr; | U+1D535 | 𝔵 |
xhArr; | U+027FA | ⟺ |
xharr; | U+027F7 | ⟷ |
xi; | U+003BE | ξ |
xlArr; | U+027F8 | ⟸ |
xlarr; | U+027F5 | ⟵ |
xmap; | U+027FC | ⟼ |
xnis; | U+022FB | ⋻ |
xodot; | U+02A00 | ⨀ |
xopf; | U+1D569 | 𝕩 |
xoplus; | U+02A01 | ⨁ |
xotime; | U+02A02 | ⨂ |
xrArr; | U+027F9 | ⟹ |
xrarr; | U+027F6 | ⟶ |
xscr; | U+1D4CD | 𝓍 |
xsqcup; | U+02A06 | ⨆ |
xuplus; | U+02A04 | ⨄ |
xutri; | U+025B3 | △ |
xvee; | U+022C1 | ⋁ |
xwedge; | U+022C0 | ⋀ |
yacute; | U+000FD | ý |
yacy; | U+0044F | я |
ycirc; | U+00177 | ŷ |
ycy; | U+0044B | ы |
yen; | U+000A5 | ¥ |
yfr; | U+1D536 | 𝔶 |
yicy; | U+00457 | ї |
yopf; | U+1D56A | 𝕪 |
yscr; | U+1D4CE | 𝓎 |
yucy; | U+0044E | ю |
yuml; | U+000FF | ÿ |
zacute; | U+0017A | ź |
zcaron; | U+0017E | ž |
zcy; | U+00437 | з |
zdot; | U+0017C | ż |
zeetrf; | U+02128 | ℨ |
zeta; | U+003B6 | ζ |
zfr; | U+1D537 | 𝔷 |
zhcy; | U+00436 | ж |
zigrarr; | U+021DD | ⇝ |
zopf; | U+1D56B | 𝕫 |
zscr; | U+1D4CF | 𝓏 |
zwj; | U+0200D | |
zwnj; | U+0200C | |
AElig | U+000C6 | Æ |
AMP | U+00026 | & |
Aacute | U+000C1 | Á |
Acirc | U+000C2 | Â |
Agrave | U+000C0 | À |
Aring | U+000C5 | Å |
Atilde | U+000C3 | Ã |
Auml | U+000C4 | Ä |
COPY | U+000A9 | © |
Ccedil | U+000C7 | Ç |
ETH | U+000D0 | Ð |
Eacute | U+000C9 | É |
Ecirc | U+000CA | Ê |
Egrave | U+000C8 | È |
Euml | U+000CB | Ë |
GT | U+0003E | > |
Iacute | U+000CD | Í |
Icirc | U+000CE | Î |
Igrave | U+000CC | Ì |
Iuml | U+000CF | Ï |
LT | U+0003C | < |
Ntilde | U+000D1 | Ñ |
Oacute | U+000D3 | Ó |
Ocirc | U+000D4 | Ô |
Ograve | U+000D2 | Ò |
Oslash | U+000D8 | Ø |
Otilde | U+000D5 | Õ |
Ouml | U+000D6 | Ö |
QUOT | U+00022 | " |
REG | U+000AE | ® |
THORN | U+000DE | Þ |
Uacute | U+000DA | Ú |
Ucirc | U+000DB | Û |
Ugrave | U+000D9 | Ù |
Uuml | U+000DC | Ü |
Yacute | U+000DD | Ý |
aacute | U+000E1 | á |
acirc | U+000E2 | â |
acute | U+000B4 | ´ |
aelig | U+000E6 | æ |
agrave | U+000E0 | à |
amp | U+00026 | & |
aring | U+000E5 | å |
atilde | U+000E3 | ã |
auml | U+000E4 | ä |
brvbar | U+000A6 | ¦ |
ccedil | U+000E7 | ç |
cedil | U+000B8 | ¸ |
cent | U+000A2 | ¢ |
copy | U+000A9 | © |
curren | U+000A4 | ¤ |
deg | U+000B0 | ° |
divide | U+000F7 | ÷ |
eacute | U+000E9 | é |
ecirc | U+000EA | ê |
egrave | U+000E8 | è |
eth | U+000F0 | ð |
euml | U+000EB | ë |
frac12 | U+000BD | ½ |
frac14 | U+000BC | ¼ |
frac34 | U+000BE | ¾ |
gt | U+0003E | > |
iacute | U+000ED | í |
icirc | U+000EE | î |
iexcl | U+000A1 | ¡ |
igrave | U+000EC | ì |
iquest | U+000BF | ¿ |
iuml | U+000EF | ï |
laquo | U+000AB | « |
lt | U+0003C | < |
macr | U+000AF | ¯ |
micro | U+000B5 | µ |
middot | U+000B7 | · |
nbsp | U+000A0 | |
not | U+000AC | ¬ |
ntilde | U+000F1 | ñ |
oacute | U+000F3 | ó |
ocirc | U+000F4 | ô |
ograve | U+000F2 | ò |
ordf | U+000AA | ª |
ordm | U+000BA | º |
oslash | U+000F8 | ø |
otilde | U+000F5 | õ |
ouml | U+000F6 | ö |
para | U+000B6 | ¶ |
plusmn | U+000B1 | ± |
pound | U+000A3 | £ |
quot | U+00022 | " |
raquo | U+000BB | » |
reg | U+000AE | ® |
sect | U+000A7 | § |
shy | U+000AD | |
sup1 | U+000B9 | ¹ |
sup2 | U+000B2 | ² |
sup3 | U+000B3 | ³ |
szlig | U+000DF | ß |
thorn | U+000FE | þ |
times | U+000D7 | × |
uacute | U+000FA | ú |
ucirc | U+000FB | û |
ugrave | U+000F9 | ù |
uml | U+000A8 | ¨ |
uuml | U+000FC | ü |
yacute | U+000FD | ý |
yen | U+000A5 | ¥ |
yuml | U+000FF | ÿ |
The glyphs displayed above are non-normative. Refer to the Unicode specifications for formal definitions of the characters listed above.
This section only describes the rules for XML
resources. Rules for text/html
resources are discussed
in the section above entitled "The HTML syntax".
The syntax for using HTML with XML, whether in XHTML documents or embedded in other XML documents, is defined in the XML and Namespaces in XML specifications. [XML] [XMLNS]
This specification does not define any syntax-level requirements beyond those defined for XML proper.
XML documents may contain a DOCTYPE
if desired, but
this is not required to conform to this specification. This
specification does not define a public or system identifier, nor
provide a format DTD.
According to the XML specification, XML processors
are not guaranteed to process the external DTD subset referenced in
the DOCTYPE. This means, for example, that using entity references
for characters in XHTML documents is unsafe if they are defined in
an external file (except for <
, >
, &
, "
and '
).
This section describes the relationship between XML and the DOM, with a particular emphasis on how this interacts with HTML.
An XML parser, for the purposes of this specification,
is a construct that follows the rules given in the XML specification
to map a string of bytes or characters into a Document
object.
An XML parser is either associated with a
Document
object when it is created, or creates one
implicitly.
This Document
must then be populated with DOM nodes
that represent the tree structure of the input passed to the parser,
as defined by the XML specification, the Namespaces in XML
specification, and the DOM Core specification. DOM mutation events
must not fire for the operations that the XML parser
performs on the Document
's tree, but the user agent
must act as if elements and attributes were individually appended
and set respectively so as to trigger rules in this specification
regarding what happens when an element is inserted into a document
or has its attributes set. [XML] [XMLNS] [DOMCORE]
[DOMEVENTS]
Between the time an element's start tag is parsed and the time either the element's end tag is parsed or the parser detects a well-formedness error, the user agent must act as if the element was in a stack of open elements.
This is used by the object
element to
avoid instantiating plugins before the param
element
children have been parsed.
This specification provides the following additional information that user agents should use when retrieving an external entity: the public identifiers given in the following list all correspond to the URL given by this link.
-//W3C//DTD XHTML 1.0 Transitional//EN
-//W3C//DTD XHTML 1.1//EN
-//W3C//DTD XHTML 1.0 Strict//EN
-//W3C//DTD XHTML 1.0 Frameset//EN
-//W3C//DTD XHTML Basic 1.0//EN
-//W3C//DTD XHTML 1.1 plus MathML 2.0//EN
-//W3C//DTD XHTML 1.1 plus MathML 2.0 plus SVG 1.1//EN
-//W3C//DTD MathML 2.0//EN
-//WAPFORUM//DTD XHTML Mobile 1.0//EN
Furthermore, user agents should attempt to retrieve the above external entity's content when one of the above public identifiers is used, and should not attempt to retrieve any other external entity's content.
This is not strictly a violation of the XML specification, but it does contradict the spirit of the XML specification's requirements. This is motivated by a desire for user agents to all handle entities in an interoperable fashion without requiring any network access for handling external subsets. [XML]
When an XML parser creates a
script
element, it must be marked as being
"parser-inserted" and its "force-async"
flag must be unset. If the parser was originally created for the
XML fragment parsing algorithm, then the element must
be marked as "already started" also. When the element's
end tag is parsed, the user agent must provide a stable
state, and then prepare
the script
element. If this causes there to be a
pending parsing-blocking script, then the user agent
must run the following steps:
Block this instance of the XML parser, such that the event loop will not run tasks that invoke it.
Spin the event loop until the parser's
Document
has no style sheet that is blocking
scripts and the pending parsing-blocking
script's "ready to be parser-executed" flag is
set.
Unblock this instance of the XML parser, such that tasks that invoke it can again be run.
There is no longer a pending parsing-blocking script.
Since the document.write()
API is not
available for XML documents, much of the complexity in
the HTML parser is not needed in the XML
parser.
Certain algorithms in this specification spoon-feed the parser characters one string at a time. In such cases, the XML parser must act as it would have if faced with a single string consisting of the concatenation of all those characters.
When an XML parser reaches the end of its input, it must stop parsing, following the same rules as the HTML parser. An XML parser can also be aborted, which must again by done in the same way as for an HTML parser.
For the purposes of conformance checkers, if a resource is determined to be in the XHTML syntax, then it is an XML document.
The XML fragment serialization algorithm for a
Document
or Element
node either returns a
fragment of XML that represents that node or raises an
exception.
For Document
s, the algorithm must return a string in
the form of a document
entity, if none of the error cases below apply.
For Element
s, the algorithm must return a string in
the form of an internal general parsed
entity, if none of the error cases below apply.
In both cases, the string returned must be XML
namespace-well-formed and must be an isomorphic serialization of all
of that node's child nodes, in tree order. User agents
may adjust prefixes and namespace declarations in the serialization
(and indeed might be forced to do so in some cases to obtain
namespace-well-formed XML). User agents may use a combination of
regular text, character references, and CDATA sections to represent
text nodes in the DOM (and indeed
might be forced to use representations that don't match the DOM's,
e.g. if a CDATASection
node contains the string "]]>
").
For Element
s, if any of the elements in the
serialization are in no namespace, the default namespace in scope
for those elements must be explicitly declared as the empty
string. (This doesn't
apply in the Document
case.) [XML] [XMLNS]
For the purposes of this section, an internal general parsed entity is considered XML namespace-well-formed if a document consisting of an element with no namespace declarations whose contents are the internal general parsed entity would itself be XML namespace-well-formed.
If any of the following error cases are found in the DOM subtree
being serialized, then the algorithm must raise an
INVALID_STATE_ERR
exception instead of returning a
string:
Document
node with no child element nodes.DocumentType
node that has an external subset
public identifier that contains characters that are not matched by
the XML PubidChar
production. [XML]DocumentType
node that has an external subset
system identifier that contains both a U+0022 QUOTATION MARK (")
and a U+0027 APOSTROPHE (') or that contains characters that are
not matched by the XML Char
production. [XML]Name
production. [XML]Attr
node with no namespace whose local name is
the lowercase string "xmlns
". [XMLNS]Element
node with two or more attributes with
the same local name and namespace.Attr
node, Text
node,
CDATASection
node, Comment
node, or
ProcessingInstruction
node whose data contains
characters that are not matched by the XML Char
production. [XML]Comment
node whose data contains two adjacent
U+002D HYPHEN-MINUS characters (-) or ends with such a
character.ProcessingInstruction
node whose target name is
an ASCII case-insensitive match for the string "xml
".ProcessingInstruction
node whose target name
contains a U+003A COLON (:).ProcessingInstruction
node whose data contains
the string "?>
".These are the only ways to make a DOM
unserializable. The DOM enforces all the other XML constraints; for
example, trying to append two elements to a Document
node will raise a HIERARCHY_REQUEST_ERR
exception.
The XML fragment parsing algorithm either returns a
Document
or raises a SYNTAX_ERR
exception.
Given a string input and an optional context
element context, the
algorithm is as follows:
Create a new XML parser.
If there is a context element, feed the parser just created the string corresponding to the start tag of that element, declaring all the namespace prefixes that are in scope on that element in the DOM, as well as declaring the default namespace (if any) that is in scope on that element in the DOM.
A namespace prefix is in scope if the DOM Core lookupNamespaceURI()
method on the element would
return a non-null value for that prefix.
The default namespace is the namespace for which the DOM Core
isDefaultNamespace()
method on the element
would return true.
If there is a context element, no DOCTYPE
is passed to the parser, and therefore no
external subset is referenced, and therefore no entities will be
recognized.
Feed the parser just created the string input.
If there is a context element, feed the parser just created the string corresponding to the end tag of that element.
If there is an XML well-formedness or XML namespace
well-formedness error, then raise a SYNTAX_ERR
exception and abort these steps.
If there is a context element, then
return the child nodes of the root element of the resulting
Document
, in tree order.
Otherwise, return the children of the Document
object, in tree order.
User agents are not required to present HTML documents in any particular way. However, this section provides a set of suggestions for rendering HTML documents that, if followed, are likely to lead to a user experience that closely resembles the experience intended by the documents' authors. So as to avoid confusion regarding the normativity of this section, RFC2119 terms have not been used. Instead, the term "expected" is used to indicate behavior that will lead to this experience. For the purposes of conformance for user agents designated as supporting the suggested default rendering, the term "expected" in this section has the same conformance implications as the RFC2119-defined term "must".
In general, user agents are expected to support CSS, and many of the suggestions in this section are expressed in CSS terms. User agents that use other presentation mechanisms can derive their expected behavior by translating from the CSS rules given in this section.
In the absence of style-layer rules to the contrary (e.g. author style sheets), user agents are expected to render an element so that it conveys to the user the meaning that the element represents, as described by this specification.
The suggestions in this section generally assume a visual output medium with a resolution of 96dpi or greater, but HTML is intended to apply to multiple media (it is a media-independent language). User agent implementors are encouraged to adapt the suggestions in this section to their target media.
An element is being rendered if it is in a
Document
, either its parent node is itself
being rendered or it is the Document
node,
and it is not explicitly excluded from the rendering using either:
Just being off-screen does not mean the element is
not being rendered. The presence of the hidden
attribute normally means the
element is not being rendered, though this might be
overridden by the style sheets.
The CSS rules given in these subsections are, except where otherwise specified, expected to be used as part of the user-agent level style sheet defaults for all documents that contain HTML elements.
Some rules are intended for the author-level zero-specificity presentational hints part of the CSS cascade; these are explicitly called out as presentational hints.
Some of the rules regarding left and right margins are given here as appropriate for elements whose 'direction' property is 'ltr', and are expected to be flipped around on elements whose 'direction' property is 'rtl'. These are marked "LTR-specific".
Similarly, for the purpose of the rules marked "case-insensitive", user agents are expected to use ASCII case-insensitive matching of attribute values rather than case-sensitive matching, even for attributes in XHTML documents.
These markings only affect the handling of attribute values, not attribute names or element names.
When the text below says that an attribute attribute on an element element maps to the pixel length property (or properties) properties, it means that if element has an attribute attribute set, and parsing that attribute's value using the rules for parsing non-negative integers doesn't generate an error, then the user agent is expected to use the parsed value as a pixel length for a presentational hint for properties.
When the text below says that an attribute attribute on an element element maps to the dimension property (or properties) properties, it means that if element has an attribute attribute set, and parsing that attribute's value using the rules for parsing dimension values doesn't generate an error, then the user agent is expected to use the parsed dimension as the value for a presentational hint for properties, with the value given as a pixel length if the dimension was an integer, and with the value given as a percentage if the dimension was a percentage.
@namespace url(http://www.w3.org/1999/xhtml); [hidden], area, base, basefont, command, datalist, head, input[type=hidden], link, menu[type=context], meta, noembed, noframes, param, rp, script, source, style, track, title { /* case-insensitive */ display: none; } address, article, aside, blockquote, body, center, dd, dir, div, dl, dt, figure, figcaption, footer, form, h1, h2, h3, h4, h5, h6, header, hgroup, hr, html, legend, listing, menu, nav, ol, p, plaintext, pre, section, summary, ul, xmp { display: block; unicode-bidi: isolate; } table { display: table; unicode-bidi: isolate; } caption { display: table-caption; unicode-bidi: isolate; } colgroup, colgroup[hidden] { display: table-column-group; unicode-bidi: isolate; } col, col[hidden] { display: table-column; unicode-bidi: isolate; } thead, thead[hidden] { display: table-header-group; unicode-bidi: isolate; } tbody, tbody[hidden] { display: table-row-group; unicode-bidi: isolate; } tfoot, tfoot[hidden] { display: table-footer-group; unicode-bidi: isolate; } tr, tr[hidden] { display: table-row; unicode-bidi: isolate; } td, th, td[hidden], th[hidden] { display: table-cell; unicode-bidi: isolate; } colgroup[hidden], col[hidden], thead[hidden], tbody[hidden], tfoot[hidden], tr[hidden], td[hidden], th[hidden] { visibility: collapse; } li { display: list-item; unicode-bidi: isolate; } ruby { display: ruby; } rt { display: ruby-text; }
For the purposes of the CSS table model, the col
element is expected to be treated as if it was present as many times
as its span
attribute specifies.
For the purposes of the CSS table model, the
colgroup
element, if it contains no col
element, is expected to be treated as if it had as many such
children as its span
attribute specifies.
For the purposes of the CSS table model, the colspan
and rowspan
attributes on
td
and th
elements are expected to provide the
special knowledge regarding cells spanning rows and
columns.
For the purposes of the CSS ruby model, runs of children of
ruby
elements that are not rt
or
rp
elements are expected to be wrapped in anonymous
boxes whose 'display' property has the value 'ruby-base'. [CSSRUBY]
User agents that do not support correct ruby rendering are
expected to render parentheses around the text of rt
elements in the absence of rp
elements.
The user agent is expected to hide noscript
elements
for whom scripting is enabled,
irrespective of CSS rules.
In HTML documents, the user agent is expected to
hide form
elements that are children of
table
, thead
, tbody
,
tfoot
, or tr
elements, irrespective of CSS
rules.
@namespace url(http://www.w3.org/1999/xhtml); blockquote, dir, dl, figure, listing, menu, ol, p, plaintext, pre, ul, xmp { margin-top: 1em; margin-bottom: 1em; } dir dir, dir dl, dir menu, dir ol, dir ul, dl dir, dl dl, dl menu, dl ol, dl ul, menu dir, menu dl, menu menu, menu ol, menu ul, ol dir, ol dl, ol menu, ol ol, ol ul, ul dir, ul dl, ul menu, ul ol, ul ul { margin-top: 0; margin-bottom: 0; } h1 { margin-top: 0.67em; margin-bottom: 0.67em; } h2 { margin-top: 0.83em; margin-bottom: 0.83em; } h3 { margin-top: 1.00em; margin-bottom: 1.00em; } h4 { margin-top: 1.33em; margin-bottom: 1.33em; } h5 { margin-top: 1.67em; margin-bottom: 1.67em; } h6 { margin-top: 2.33em; margin-bottom: 2.33em; } dd { margin-left: 40px; } /* LTR-specific: use 'margin-right' for rtl elements */ dir, menu, ol, ul { padding-left: 40px; } /* LTR-specific: use 'padding-right' for rtl elements */ blockquote, figure { margin-left: 40px; margin-right: 40px; } table { border-spacing: 2px; border-collapse: separate; } td, th { padding: 1px; }
The article
, aside
, nav
,
and section
elements are expected to affect the margins
of h1
elements, based on the nesting depth. If x is a selector that matches elements that are either
article
, aside
, nav
, or
section
elements, then the following rules capture what
is expected:
@namespace url(http://www.w3.org/1999/xhtml); x h1 { margin-top: 0.83em; margin-bottom: 0.83em; } x x h1 { margin-top: 1.00em; margin-bottom: 1.00em; } x x x h1 { margin-top: 1.33em; margin-bottom: 1.33em; } x x x x h1 { margin-top: 1.67em; margin-bottom: 1.67em; } x x x x x h1 { margin-top: 2.33em; margin-bottom: 2.33em; }
For each property in the table below, given a body
element, the first attribute that exists maps to the pixel
length property on the body
element. If none of
the attributes for a property are found, or if the value of the
attribute that was found cannot be parsed successfully, then a
default value of 8px is expected to be used for that property
instead.
Property | Source |
---|---|
'margin-top' | body element's marginheight attribute
|
The body element's container frame element's marginheight attribute
| |
body element's topmargin attribute
| |
'margin-right' | body element's marginwidth attribute
|
The body element's container frame element's marginwidth attribute
| |
body element's rightmargin attribute
| |
'margin-bottom' | body element's marginheight attribute
|
The body element's container frame element's marginheight attribute
| |
body element's bottommargin attribute
| |
'margin-left' | body element's marginwidth attribute
|
The body element's container frame element's marginwidth attribute
| |
body element's leftmargin attribute
|
If the body
element's Document
's
browsing context is a nested browsing
context, and the browsing context container of
that nested browsing context is a frame
or
iframe
element, then the container frame
element of the body
element is that
frame
or iframe
element. Otherwise, there
is no container frame element.
The above requirements imply that a page can
change the margins of another page (including one from another
origin) using, for example, an
iframe
. This is potentially a security risk, as it
might in some cases allow an attack to contrive a situation in which
a page is rendered not as the author intended, possibly for the
purposes of phishing or otherwise misleading the user.
If the Document
has a root element, and
the Document
's browsing context is a
nested browsing context, and the browsing context
container of that nested browsing context is a
frame
or iframe
element, and that element
has a scrolling
attribute, then the user agent is expected to compare the value of
the attribute in an ASCII case-insensitive manner to
the values in the first column of the following table, and if one of
them matches, then the user agent is expected to treat that
attribute as a presentational
hint for the aforementioned root element's 'overflow'
property, setting it to the value given in the corresponding cell on
the same row in the second column:
Attribute value | 'overflow' value |
---|---|
on
| 'scroll' |
scroll
| 'scroll' |
yes
| 'scroll' |
off
| 'hidden' |
noscroll
| 'hidden' |
no
| 'hidden' |
auto
| 'auto' |
The table
element's cellspacing
attribute
maps to the pixel length property 'border-spacing' on the
element.
The table
element's cellpadding
attribute maps to the pixel length
properties 'padding-top', 'padding-right', 'padding-bottom',
and 'padding-left' of any td
and th
elements that have corresponding cells in the table corresponding to the
table
element.
The table
element's hspace
attribute maps to the dimension properties
'margin-left' and 'margin-right' on the table
element.
The table
element's vspace
attribute maps to the dimension properties
'margin-top' and 'margin-bottom' on the table
element.
The table
element's height
attribute maps to the
dimension property 'height' on the table
element.
The table
element's width
attribute maps to the
dimension property 'width' on the table
element.
The col
element's width
attribute maps to the
dimension property 'width' on the col
element.
The tr
element's height
attribute maps to the
dimension property 'height' on the tr
element.
The td
and th
elements' height
attributes map to the dimension property 'height'
on the element.
The td
and th
elements' width
attributes map to the dimension property 'width'
on the element.
In quirks mode, the following rules are also expected to apply:
@namespace url(http://www.w3.org/1999/xhtml); form { margin-bottom: 1em; }
When a Document
is in quirks mode,
margins on HTML elements at the top or bottom of
body
, td
, or th
elements are
expected to be collapsed to zero.
@namespace url(http://www.w3.org/1999/xhtml); thead, tbody, tfoot, table > tr { vertical-align: middle; } tr, td, th { vertical-align: inherit; } sub { vertical-align: sub; } sup { vertical-align: super; }
The following rules are also expected to apply, as presentational hints:
@namespace url(http://www.w3.org/1999/xhtml); table[align=left] { float: left; } /* case-insensitive */ table[align=right] { float: right; } /* case-insensitive */ table[align=center], table[align=abscenter], table[align=absmiddle], table[align=middle] { /* case-insensitive */ margin-left: auto; margin-right: auto; } thead[align=absmiddle], tbody[align=absmiddle], tfoot[align=absmiddle], tr[align=absmiddle], td[align=absmiddle], th[align=absmiddle] { /* case-insensitive */ text-align: center; } caption[align=bottom] { caption-side: bottom; } /* case-insensitive */ p[align=left], h1[align=left], h2[align=left], h3[align=left], h4[align=left], h5[align=left], h6[align=left] { /* case-insensitive */ text-align: left; } p[align=right], h1[align=right], h2[align=right], h3[align=right], h4[align=right], h5[align=right], h6[align=right] { /* case-insensitive */ text-align: right; } p[align=center], h1[align=center], h2[align=center], h3[align=center], h4[align=center], h5[align=center], h6[align=center] { /* case-insensitive */ text-align: center; } p[align=justify], h1[align=justify], h2[align=justify], h3[align=justify], h4[align=justify], h5[align=justify], h6[align=justify] { /* case-insensitive */ text-align: justify; } thead[valign=top], tbody[valign=top], tfoot[valign=top], tr[valign=top], td[valign=top], th[valign=top] { /* case-insensitive */ vertical-align: top; } thead[valign=middle], tbody[valign=middle], tfoot[valign=middle], tr[valign=middle], td[valign=middle], th[valign=middle] { /* case-insensitive */ vertical-align: middle; } thead[valign=bottom], tbody[valign=bottom], tfoot[valign=bottom], tr[valign=bottom], td[valign=bottom], th[valign=bottom] { /* case-insensitive */ vertical-align: bottom; } thead[valign=baseline], tbody[valign=baseline], tfoot[valign=baseline], tr[valign=baseline], td[valign=baseline], th[valign=baseline] { /* case-insensitive */ vertical-align: baseline; }
The center
element, the caption
element
unless specified otherwise below, and the div
,
thead
, tbody
, tfoot
,
tr
, td
, and th
elements when
they have an align
attribute
whose value is an ASCII case-insensitive match for
either the string "center
" or the string
"middle
", are expected to center text within
themselves, as if they had their 'text-align' property set to
'center' in a presentational
hint, and to align descendants to the
center.
The div
, caption
, thead
,
tbody
, tfoot
, tr
,
td
, and th
elements, when they have an
align
attribute whose value is an
ASCII case-insensitive match for the string "left
", are expected to left-align text within
themselves, as if they had their 'text-align' property set to 'left'
in a presentational hint,
and to align descendants to the left.
The div
, caption
, thead
,
tbody
, tfoot
, tr
,
td
, and th
elements, when they have an
align
attribute whose value is an
ASCII case-insensitive match for the string "right
", are expected to right-align text within
themselves, as if they had their 'text-align' property set to
'right' in a presentational
hint, and to align descendants to the right.
The div
, caption
, thead
,
tbody
, tfoot
, tr
,
td
, and th
elements, when they have an
align
attribute whose value is an
ASCII case-insensitive match for the string "justify
", are expected to full-justify text within
themselves, as if they had their 'text-align' property set to
'justify' in a presentational
hint, and to align descendants to the left.
When a user agent is to align descendants of a node,
the user agent is expected to align only those descendants that have
both their 'margin-left' and 'margin-right' properties computing to
a value other than 'auto', that are over-constrained and that have
one of those two margins with a used value forced to a greater
value, and that do not themselves have an applicable align
attribute. When multiple elements
are to align a particular
descendant, the most deeply nested such element is expected to
override the others.
User agents are expected to have a rule in their user agent
stylesheet that matches th
elements that have a parent
node whose computed value for the 'text-align' property is its
initial value, whose declaration block consists of just a single
declaration that sets the 'text-align' property to the value
'center'.
@namespace url(http://www.w3.org/1999/xhtml); address, cite, dfn, em, i, var { font-style: italic; } b, strong, th { font-weight: bold; } code, kbd, listing, plaintext, pre, samp, tt, xmp { font-family: monospace; } h1 { font-size: 2.00em; font-weight: bold; } h2 { font-size: 1.50em; font-weight: bold; } h3 { font-size: 1.17em; font-weight: bold; } h4 { font-size: 1.00em; font-weight: bold; } h5 { font-size: 0.83em; font-weight: bold; } h6 { font-size: 0.67em; font-weight: bold; } big { font-size: larger; } small, sub, sup { font-size: smaller; } sub, sup { line-height: normal; } :link { color: blue; } :visited { color: purple; } mark { background: yellow; color: black; } table, td, th { border-color: gray; } thead, tbody, tfoot, tr { border-color: inherit; } table[rules=none], table[rules=groups], table[rules=rows], table[rules=cols], table[rules=all], table[frame=void], table[frame=above], table[frame=below], table[frame=hsides], table[frame=lhs], table[frame=rhs], table[frame=vsides], table[frame=box], table[frame=border], table[rules=none] > tr > td, table[rules=none] > tr > th, table[rules=groups] > tr > td, table[rules=groups] > tr > th, table[rules=rows] > tr > td, table[rules=rows] > tr > th, table[rules=cols] > tr > td, table[rules=cols] > tr > th, table[rules=all] > tr > td, table[rules=all] > tr > th, table[rules=none] > thead > tr > td, table[rules=none] > thead > tr > th, table[rules=groups] > thead > tr > td, table[rules=groups] > thead > tr > th, table[rules=rows] > thead > tr > td, table[rules=rows] > thead > tr > th, table[rules=cols] > thead > tr > td, table[rules=cols] > thead > tr > th, table[rules=all] > thead > tr > td, table[rules=all] > thead > tr > th, table[rules=none] > tbody > tr > td, table[rules=none] > tbody > tr > th, table[rules=groups] > tbody > tr > td, table[rules=groups] > tbody > tr > th, table[rules=rows] > tbody > tr > td, table[rules=rows] > tbody > tr > th, table[rules=cols] > tbody > tr > td, table[rules=cols] > tbody > tr > th, table[rules=all] > tbody > tr > td, table[rules=all] > tbody > tr > th, table[rules=none] > tfoot > tr > td, table[rules=none] > tfoot > tr > th, table[rules=groups] > tfoot > tr > td, table[rules=groups] > tfoot > tr > th, table[rules=rows] > tfoot > tr > td, table[rules=rows] > tfoot > tr > th, table[rules=cols] > tfoot > tr > td, table[rules=cols] > tfoot > tr > th, table[rules=all] > tfoot > tr > td, table[rules=all] > tfoot > tr > th { /* case-insensitive */ border-color: black; }
The initial value for the 'color' property is expected to be black. The initial value for the 'background-color' property is expected to be 'transparent'. The canvas' background is expected to be white.
The article
, aside
, nav
,
and section
elements are expected to affect the font
size of h1
elements, based on the nesting depth. If
x is a selector that matches elements that are
either article
, aside
, nav
,
or section
elements, then the following rules capture
what is expected:
@namespace url(http://www.w3.org/1999/xhtml); x h1 { font-size: 1.50em; } x x h1 { font-size: 1.17em; } x x x h1 { font-size: 1.00em; } x x x x h1 { font-size: 0.83em; } x x x x x h1 { font-size: 0.67em; }
When a body
, table
, thead
,
tbody
, tfoot
, tr
,
td
, or th
element has a background
attribute set to a
non-empty value, the new value is expected to be resolved relative to the element, and
if this is successful, the user agent is expected to treat the
attribute as a presentational
hint setting the element's 'background-image' property to the
resulting absolute URL.
When a body
, table
, thead
,
tbody
, tfoot
, tr
,
td
, or th
element has a bgcolor
attribute set, the new value is expected to
be parsed using the rules for parsing a legacy color
value, and if that does not return an error, the user agent
is expected to treat the attribute as a presentational hint setting the element's
'background-color' property to the resulting color.
When a body
element has a text
attribute, its value is expected
to be parsed using the rules for parsing a legacy color
value, and if that does not return an error, the user
agent is expected to treat the attribute as a presentational hint setting the
element's 'color' property to the resulting color.
When a body
element has a link
attribute, its value is expected
to be parsed using the rules for parsing a legacy color
value, and if that does not return an error, the user agent
is expected to treat the attribute as a presentational hint setting the 'color' property of
any element in the Document
matching the ':link'
pseudo-class to the resulting color.
When a body
element has a vlink
attribute, its value is
expected to be parsed using the rules for parsing a legacy
color value, and if that does not return an error, the user
agent is expected to treat the attribute as a presentational hint setting the
'color' property of any element in the Document
matching the ':visited' pseudo-class to the resulting color.
When a body
element has a alink
attribute, its value is
expected to be parsed using the rules for parsing a legacy
color value, and if that does not return an error, the user
agent is expected to treat the attribute as a presentational hint setting the
'color' property of any element in the Document
matching the ':active' pseudo-class and either the ':link'
pseudo-class or the ':visited' pseudo-class to the resulting
color.
When a table
element has a bordercolor
attribute, its
value is expected to be parsed using the rules for parsing a
legacy color value, and if that does not return an error, the
user agent is expected to treat the attribute as a presentational hint setting the
element's 'border-top-color', 'border-right-color',
'border-bottom-color', and 'border-right-color' properties to the
resulting color.
When a font
element has a color
attribute, its value is
expected to be parsed using the rules for parsing a legacy
color value, and if that does not return an error, the user
agent is expected to treat the attribute as a presentational hint setting the
element's 'color' property to the resulting color.
When a font
element has a face
attribute, the user agent is
expected to treat the attribute as a presentational hint setting the element's
'font-family' property to the attribute's value.
When a font
element has a size
attribute, the user agent is
expected to use the following steps to treat the attribute as a
presentational hint
setting the element's 'font-size' property:
Let input be the attribute's value.
Let position be a pointer into input, initially pointing at the start of the string.
If position is past the end of input, there is no presentational hint. Abort these steps.
If the character at position is a U+002B PLUS SIGN character (+), then let mode be relative-plus, and advance position to the next character. Otherwise, if the character at position is a U+002D HYPHEN-MINUS character (-), then let mode be relative-minus, and advance position to the next character. Otherwise, let mode be absolute.
Collect a sequence of characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9), and let the resulting sequence be digits.
If digits is the empty string, there is no presentational hint. Abort these steps.
Interpret digits as a base-ten integer. Let value be the resulting number.
If mode is relative-plus, then increment value by 3. If mode is relative-minus, then let value be the result of subtracting value from 3.
If value is greater than 7, let it be 7.
If value is less than 1, let it be 1.
Set 'font-size' to the keyword corresponding to the value of value according to the following table:
value | 'font-size' keyword | Notes |
---|---|---|
1 | xx-small | |
2 | small | |
3 | medium | |
4 | large | |
5 | x-large | |
6 | xx-large | |
7 | xxx-large | see below |
The 'xxx-large' value is a non-CSS value used here to indicate a font size one "step" larger than 'xx-large'.
@namespace url(http://www.w3.org/1999/xhtml); :link, :visited, ins, u { text-decoration: underline; } abbr[title], acronym[title] { text-decoration: dotted underline; } del, s, strike { text-decoration: line-through; } blink { text-decoration: blink; } :focus { outline: auto; } q:before { content: open-quote; } q:after { content: close-quote; } br { content: '\A'; white-space: pre; } nobr { white-space: nowrap; } listing, plaintext, pre, xmp { white-space: pre; } textarea { white-space: pre-wrap; } ol { list-style-type: decimal; } dir, menu, ul { list-style-type: disc; } dir dl, dir menu, dir ul, menu dl, menu menu, menu ul, ol dl, ol menu, ol ul, ul dl, ul menu, ul ul { list-style-type: circle; } dir dir dl, dir dir menu, dir dir ul, dir menu dl, dir menu menu, dir menu ul, dir ol dl, dir ol menu, dir ol ul, dir ul dl, dir ul menu, dir ul ul, menu dir dl, menu dir menu, menu dir ul, menu menu dl, menu menu menu, menu menu ul, menu ol dl, menu ol menu, menu ol ul, menu ul dl, menu ul menu, menu ul ul, ol dir dl, ol dir menu, ol dir ul, ol menu dl, ol menu menu, ol menu ul, ol ol dl, ol ol menu, ol ol ul, ol ul dl, ol ul menu, ol ul ul, ul dir dl, ul dir menu, ul dir ul, ul menu dl, ul menu menu, ul menu ul, ul ol dl, ul ol menu, ul ol ul, ul ul dl, ul ul menu, ul ul ul { list-style-type: square; } table { border-style: outset; } td, th { border-style: inset; } :ltr { direction: ltr; } :rtl { direction: rtl; } [dir] { unicode-bidi: embed; } bdi, output, [dir=auto] { unicode-bidi: isolate; } /* case-insensitive */ bdo, bdo[dir] { unicode-bidi: bidi-override; } bdo[dir=auto] { unicode-bidi: bidi-override isolate; } /* case-insensitive */ textarea[dir=auto], pre[dir=auto] { unicode-bidi: plaintext; } /* case-insensitive */
Rules setting the 'quotes' property appropriately for the locales and languages understood by the user are expected to be present.
User agents are expected to
support the 'clear' property on inline elements (in order to render
br
elements with clear
attributes) in the manner
described in the non-normative note to this effect in CSS2.1.
The following rules are also expected to apply, as presentational hints:
@namespace url(http://www.w3.org/1999/xhtml); td[nowrap], th[nowrap] { white-space: nowrap; } pre[wrap] { white-space: pre-wrap; } br[clear=left] { clear: left; } /* case-insensitive */ br[clear=right] { clear: right; } /* case-insensitive */ br[clear=all], br[clear=both] { clear: both; } /* case-insensitive */ ol[type=1], li[type=1] { list-style-type: decimal; } ol[type=a], li[type=a] { list-style-type: lower-alpha; } ol[type=A], li[type=A] { list-style-type: upper-alpha; } ol[type=i], li[type=i] { list-style-type: lower-roman; } ol[type=I], li[type=I] { list-style-type: upper-roman; } ul[type=disc], li[type=disc] { list-style-type: disc; } /* case-insensitive */ ul[type=circle], li[type=circle] { list-style-type: circle; } /* case-insensitive */ ul[type=square], li[type=square] { list-style-type: square; } /* case-insensitive */ table[rules=none], table[rules=groups], table[rules=rows], table[rules=cols], table[rules=all] { border-style: none; border-collapse: collapse; } table[frame=void] { border-style: hidden hidden hidden hidden; } table[frame=above] { border-style: solid hidden hidden hidden; } table[frame=below] { border-style: hidden hidden solid hidden; } table[frame=hsides] { border-style: solid hidden solid hidden; } table[frame=lhs] { border-style: hidden hidden hidden solid; } table[frame=rhs] { border-style: hidden solid hidden hidden; } table[frame=vsides] { border-style: hidden solid hidden solid; } table[frame=box], table[frame=border] { border-style: solid solid solid solid; } table[rules=none] > tr > td, table[rules=none] > tr > th, table[rules=none] > thead > tr > td, table[rules=none] > thead > tr > th, table[rules=none] > tbody > tr > td, table[rules=none] > tbody > tr > th, table[rules=none] > tfoot > tr > td, table[rules=none] > tfoot > tr > th, table[rules=groups] > tr > td, table[rules=groups] > tr > th, table[rules=groups] > thead > tr > td, table[rules=groups] > thead > tr > th, table[rules=groups] > tbody > tr > td, table[rules=groups] > tbody > tr > th, table[rules=groups] > tfoot > tr > td, table[rules=groups] > tfoot > tr > th, table[rules=rows] > tr > td, table[rules=rows] > tr > th, table[rules=rows] > thead > tr > td, table[rules=rows] > thead > tr > th, table[rules=rows] > tbody > tr > td, table[rules=rows] > tbody > tr > th, table[rules=rows] > tfoot > tr > td, table[rules=rows] > tfoot > tr > th { border-style: none; } table[rules=groups] > colgroup, table[rules=groups] > thead, table[rules=groups] > tbody, table[rules=groups] > tfoot { border-style: solid; } table[rules=rows] > tr, table[rules=rows] > thead > tr, table[rules=rows] > tbody > tr, table[rules=rows] > tfoot > tr { border-style: solid; } table[rules=cols] > tr > td, table[rules=cols] > tr > th, table[rules=cols] > thead > tr > td, table[rules=cols] > thead > tr > th, table[rules=cols] > tbody > tr > td, table[rules=cols] > tbody > tr > th, table[rules=cols] > tfoot > tr > td, table[rules=cols] > tfoot > tr > th { border-style: none solid none solid; } table[rules=all] > tr > td, table[rules=all] > tr > th, table[rules=all] > thead > tr > td, table[rules=all] > thead > tr > th, table[rules=all] > tbody > tr > td, table[rules=all] > tbody > tr > th, table[rules=all] > tfoot > tr > td, table[rules=all] > tfoot > tr > th { border-style: solid; } table[border] > tr > td, table[border] > tr > th, table[border] > thead > tr > td, table[border] > thead > tr > th, table[border] > tbody > tr > td, table[border] > tbody > tr > th, table[border] > tfoot > tr > td, table[border] > tfoot > tr > th { border-width: 1px; }
When rendering li
elements, user agents are expected
to use the ordinal value of the li
element
to render the counter in the list item marker.
The table
element's border
attribute maps to the pixel length
properties 'border-top-width', 'border-right-width',
'border-bottom-width', 'border-left-width' on the element. If the
attribute is present but parsing the attribute's value using the
rules for parsing non-negative integers generates an
error, a default value of 1px is expected to be used for that
property instead.
The wbr
element is expected to override the
'white-space' property and always provide a line-breaking
opportunity.
The following rules are also expected to be in play, resetting certain properties to block inheritance by default.
@namespace url(http://www.w3.org/1999/xhtml); table, input, select, option, optgroup, button, textarea, keygen { text-indent: initial; }
In quirks mode, the following rules are also expected to apply:
@namespace url(http://www.w3.org/1999/xhtml); table { font-weight: initial; font-style: initial; font-variant: initial; font-size: initial; line-height: initial; white-space: initial; text-align: initial; } input { box-sizing: border-box; }
hr
element@namespace url(http://www.w3.org/1999/xhtml); hr { color: gray; border-style: inset; border-width: 1px; margin: 0.5em auto; }
The following rules are also expected to apply, as presentational hints:
@namespace url(http://www.w3.org/1999/xhtml); hr[align=left] { margin-left: 0; margin-right: auto; } /* case-insensitive */ hr[align=right] { margin-left: auto; margin-right: 0; } /* case-insensitive */ hr[align=center] { margin-left: auto; margin-right: auto; } /* case-insensitive */ hr[color], hr[noshade] { border-style: solid; }
If an hr
element has either a color
attribute or a noshade
attribute, and furthermore
also has a size
attribute, and
parsing that attribute's value using the rules for parsing
non-negative integers doesn't generate an error, then the
user agent is expected to use the parsed value divided by two as a
pixel length for presentational hints for the properties
'border-top-width', 'border-right-width', 'border-bottom-width', and
'border-left-width' on the element.
Otherwise, if an hr
element has neither a color
attribute nor a noshade
attribute, but does have a
size
attribute, and parsing that
attribute's value using the rules for parsing non-negative
integers doesn't generate an error, then: if the parsed value
is one, then the user agent is expected to use the attribute as a
presentational hint
setting the element's 'border-bottom-width' to 0; otherwise, if the
parsed value is greater than one, then the user agent is expected to
use the parsed value minus two as a pixel length for
presentational hints for the 'height' property on the
element.
The width
attribute on an
hr
element maps to the dimension property
'width' on the element.
When an hr
element has a color
attribute, its value is expected
to be parsed using the rules for parsing a legacy color
value, and if that does not return an error, the user agent
is expected to treat the attribute as a presentational hint setting the element's 'color'
property to the resulting color.
fieldset
element@namespace url(http://www.w3.org/1999/xhtml); fieldset { margin-left: 2px; margin-right: 2px; border: groove 2px ThreeDFace; padding: 0.35em 0.625em 0.75em; }
The fieldset
element is expected to establish a new
block formatting context.
If the fieldset
element has a child that matches the
conditions in the list below, then the first such child is the
fieldset
element's rendered legend:
legend
element.A fieldset
element's rendered legend,
if any, is expected to be rendered over the top border edge of the
fieldset
element as a 'block' box (overriding any
explicit 'display' value). In the absence of an explicit width, the
box should shrink-wrap. If the legend
element in
question has an align
attribute, and its value is an ASCII case-insensitive
match for one of the strings in the first column of the following
table, then the legend
is expected to be rendered
horizontally aligned over the border edge in the position given in
the corresponding cell on the same row in the second column. If the
attribute is absent or has a value that doesn't match any of the
cases in the table, then the position is expected to be on the right
if the 'direction' property on this element has a computed value of
'rtl', and on the left otherwise.
Attribute value | Alignment position |
---|---|
left
| On the left |
right
| On the right |
center
| In the middle |
The embed
, iframe
, and
video
elements are expected to be treated as replaced
elements.
A canvas
element that represents
embedded content is expected to be treated as a
replaced element. Other canvas
elements are expected to
be treated as ordinary elements in the rendering model.
An object
element that represents an
image, plugin, or nested browsing context is expected
to be treated as a replaced element. Other object
elements are expected to be treated as ordinary elements in the
rendering model.
An applet
element that represents a
plugin is expected to be treated as a replaced
element. Other applet
elements are expected to be
treated as ordinary elements in the rendering model.
The audio
element, when it is exposing a user interface, is
expected to be treated as a replaced element about one line high, as
wide as is necessary to expose the user agent's user interface
features. When an audio
element is not exposing a user
interface, the user agent is expected to hide it,
irrespective of CSS rules.
Whether a video
element is exposing a user interface is not
expected to affect the size of the rendering; controls are expected
to be overlaid with the page content without causing any layout
changes, and are expected to disappear when the user does not need
them.
When a video
element represents a poster frame or
frame of video, the poster frame or frame of video is expected to be
rendered at the largest size that maintains the aspect ratio of that
poster frame or frame of video without being taller or wider than
the video
element itself, and is expected to be
centered in the video
element.
Any subtitles or captions are expected to be overlayed directly
on top of their video
element, as defined by the
relevant rendering rules; for WebVTT, those are the
WebVTT cue text rendering rules defined below.
When the user agent starts exposing a user interface for a
video
element, the user agent should run the rules
for updating the text track rendering of each of the text tracks in the video
element's list of text tracks that are showing or showing by default (e.g., for text tracks based on
WebVTT, the rules for updating the display of
WebVTT text tracks).
Resizing video
and canvas
elements does not interrupt video playback or clear the canvas.
The following CSS rules are expected to apply:
@namespace url(http://www.w3.org/1999/xhtml);
iframe:not([seamless]) { border: 2px inset; }
video { object-fit: contain; }
This section is intended to be moved to its own CSS module once an editor is found to run with it.
The rules for updating the display of WebVTT text
tracks render the text
tracks of a media element (specifically, a
video
element), or of another playback mechanism, by
applying the steps below. All the text
tracks that use these rules for a given media
element, or other playback mechanism, are rendered together,
to avoid overlapping subtitles from multiple tracks.
The output of the steps below is a set of CSS boxes that covers the rendering area of the media element or other playback mechanism, which user agents are expected to render in a manner suiting the user.
The rules are as follows:
If the media element is an audio
element, or is another playback mechanism with no rendering area,
abort these steps. There is nothing to render.
Let video be the media element or other playback mechanism.
Let output be an empty list of absolutely positioned CSS block boxes.
If the user agent is exposing a user interface for video, add to output one or more completely transparent positioned CSS block boxes that cover the same region as the user interface.
If the last time these rules were run, the user agent was not exposing a user interface for video, but now it is, let reset be true. Otherwise, let reset be false.
Let tracks be the subset of video's list of text tracks that have as their rules for updating the text track rendering these rules for updating the display of WebVTT text tracks, and whose text track mode is showing or showing by default.
Let cues be an empty list of text track cues.
For each track track in tracks, append to cues all the cues from track's list of cues that have their text track cue active flag set.
If reset is false, then, for each text track cue cue in cues: if cue's text track cue display state has a set of CSS boxes, then add those boxes to output, and remove cue from cues.
For each text track cue cue in cues that has not yet had corresponding CSS boxes added to output, in text track cue order, run the following substeps:
Let nodes be the list of WebVTT Node Objects obtained by applying the WebVTT cue text parsing rules to the cue's text track cue text.
Apply the Unicode Bidirectional Algorithm's Paragraph Level steps to nodes using the following constraints, to determine the paragraph embedding level of the cue: [BIDI]
If the paragraph embedding level determined in the previous step is even (the paragraph direction is left-to-right), let direction be 'ltr', otherwise, let it be 'rtl'.
If the text track cue writing direction is horizontal, then let block-flow be 'tb'. Otherwise, if the text track cue writing direction is vertical growing left, then let block-flow be 'lr'. Otherwise, the text track cue writing direction is vertical growing right; let block-flow be 'rl'.
Determine the value of maximum size for cue as per the appropriate rules from the following list:
Let maximum size be the text track cue text position subtracted from 100.
Let maximum size be the text track cue text position.
Let maximum size be the text track cue text position multiplied by two.
Let maximum size be the result of subtracting text track cue text position from 100 and then multiplying the result by two.
If the text track cue size is less than maximum size, then let size be text track cue size. Otherwise, let size be maximum size.
If the text track cue writing direction is horizontal, then let width be 'size vw' and height be 'auto'. Otherwise, let width be 'auto' and height be 'size vh'. (These are CSS values used by the next section to set CSS properties for the rendering; 'vw' and 'vh' are CSS units.) [CSSVALUES]
Determine the value of x-position or y-position for cue as per the appropriate rules from the following list:
Let x-position be the text track cue text position.
Let x-position be the text track cue text position subtracted from 100.
Let y-position be the text track cue text position.
Let y-position be the text track cue text position subtracted from 100.
Let x-position be the text track cue text position minus half of size.
Let x-position-reverse be the text track cue text position minus half of size.
Let x-position be x-position-reverse subtracted from 100.
Let y-position be the text track cue text position minus half of size.
Determine the value of whichever of x-position or y-position is not yet calculated for cue as per the appropriate rules from the following list:
Let y-position be zero.
Let y-position be the text track cue line position.
Let x-position be zero.
Let x-position be the text track cue line position.
Let left be 'x-position vw' and top be 'y-position vh'. (These again are CSS values used by the next section to set CSS properties for the rendering; 'vw' and 'vh' are CSS units.) [CSSVALUES]
Apply the terms of the CSS specifications to nodes within the following constraints, thus obtaining a set of CSS boxes positioned relative to an initial containing block: [CSS]
The document tree is the tree of WebVTT Node Objects rooted at nodes.
For the purposes of processing by the CSS specification, WebVTT Internal Node Objects are equivalent to elements with the same contents.
Let boxes be the boxes generated as descendants of the initial containing block, along with their positions.
If there are no line boxes in boxes, skip the remainder of these substeps for cue. The cue is ignored.
Adjust the positions of boxes according to the appropriate steps from the following list:
Many of the steps in this algorithm vary according to the text track cue writing direction. Steps labeled "Horizontal" must be followed only when the text track cue writing direction is horizontal, steps labeled "Vertical" must be followed when the text track cue writing direction is either vertical growing left or vertical growing right, steps labeled "Vertical Growing Left" must be followed only when the text track cue writing direction is vertical growing left, and steps labeled "Vertical Growing Right" must be followed only when the text track cue writing direction is vertical growing right.
Horizontal: Let step be the height of the first line box in boxes.
Vertical: Let step be the width of the first line box in boxes.
If step is zero, then jump to the step labeled done positioning below.
Let line position be the text track cue line position.
Vertical Growing Left: Add one to line position then negate it.
Let position be the result of multiplying step and line position.
Vertical Growing Left: Decrease position by the width of the bounding box of the boxes in boxes, then increase position by step.
Horizontal: If line position is less than zero then increase position by the height of the video's rendering area, and negate step (so its value is now minus the height of the first line box in boxes).
Vertical: If line position is less than zero then increase position by the width of the video's rendering area, and negate step.
Horizontal: Move all the boxes in boxes down by the distance given by position.
Vertical: Move all the boxes in boxes right by the distance given by position.
Default: Remember the position of all the boxes in boxes as their default position.
Let switched be false.
Step loop: If none of the boxes in boxes would overlap any of the boxes in output, and all the boxes in output are within the video's rendering area, then jump to the step labeled done positioning below.
Horizontal: If step is negative and the top of the first line box in boxes is now above the top of the video's rendering area, or if step is positive and the bottom of the first line box in boxes is now below the bottom of the video's rendering area, jump to the step labeled switch direction.
Vertical: If step is negative and the left edge of the first line box in boxes is now to the left of the left edge of the video's rendering area, or if step is positive and the right edge of the first line box in boxes is now to the right of the right edge of the video's rendering area, jump to the step labeled switch direction.
Horizontal: Move all the boxes in boxes down by the distance given by step. (If step is negative, then this will actually result in an upwards movement of the boxes in absolute terms.)
Vertical: Move all the boxes in boxes right by the distance given by step. (If step is negative, then this will actually result in a leftwards movement of the boxes in absolute terms.)
Jump back to the step labeled step loop.
Switch direction: Move all the boxes in boxes back to their default position as determined in the step above labeled default.
If switched is true, jump to the step labeled done positioning below.
Negate step.
Set switched to true.
Jump back to the step labeled step loop.
Set up x and y as follows:
Let x be a percentage given by the text track cue text position, and let y be a percentage given by the text track cue line position.
Let x be a percentage given by the text track cue text position subtracted from 100, and let y be a percentage given by the text track cue line position.
Let x be a percentage given by the text track cue line position subtracted from 100, and let y be a percentage given by the text track cue text position.
Let x be a percentage given by the text track cue line position, and let y be a percentage given by the text track cue text position.
Position the boxes in boxes such that the point x% along the width of the bounding box of the boxes in boxes is x% of the way across the width of the video's rendering area, and the point y% along the height of the bounding box of the boxes in boxes is y% of the way across the height of the video's rendering area, while maintaining the relative positions of the boxes in boxes to each other.
If none of the boxes in boxes would overlap any of the boxes in output, and all the boxes in output are within the video's rendering area, then jump to the step labeled done positioning below.
If there is a position to which the boxes in boxes can be moved while maintaining the relative positions of the boxes in boxes to each other such that none of the boxes in boxes would overlap any of the boxes in output, and all the boxes in output would be within the video's rendering area, then move the boxes in boxes to the closest such position to their current position, and then jump to the step labeled done positioning below. If there are multiple such positions that are equidistant from their current position, use the highest one amongst them; if there are several at that height, then use the leftmost one amongst them.
Otherwise, jump to the step labeled done positioning below. (The boxes will unfortunately overlap.)
Done positioning: If there are any line boxes in the (possibly now repositioned) boxes that do not completely fit inside video's rendering area, remove those offending line boxes from boxes.
Let cue's text track cue display state have the CSS boxes in boxes.
Add the CSS boxes in boxes to output.
Return output.
When following the rules for updating the display of WebVTT text tracks, user agents must set properties of WebVTT Node Objects as defined in this section. [CSS]
On the (root) List of WebVTT Node Objects, the 'position' property must be set to 'absolute', the 'direction' property must be set to direction, the 'block-flow' property must be set to block-flow, the 'top' property must be set to top, the 'left' property must be set to left, the 'width' property must be set to width, and the 'height' property must be set to height, where direction, block-flow, top, left, width, and height are the values with those names determined by the rules for updating the display of WebVTT text tracks for the text track cue from whose text the List of WebVTT Node Objects was constructed.
The 'font' shorthand property on the (root) List of WebVTT Node Objects must be set to '0.1vh sans-serif'. [CSSRUBY] [CSSVALUES]
The 'color' property on the (root) List of WebVTT Node Objects must be set to 'rgba(255,255,255,0)'. [CSSCOLOR]
The 'background' shorthand property on the WebVTT cue background box must be set to 'rgba(0,0,0,0.8)'. [CSSCOLOR]
A text outline or stroke may also be set on the (root) List of WebVTT Node Objects, if supported.
The 'font-style' property on WebVTT Italic Objects must be set to 'italic'.
The 'font-weight' property on WebVTT Bold Objects must be set to 'bold'.
The 'text-decoration' property on WebVTT Underline Objects must be set to 'underline'.
The 'display' property on WebVTT Ruby Objects must be set to 'ruby'. [CSSRUBY]
The 'display' property on WebVTT Ruby Text Objects must be set to 'ruby-text'. [CSSRUBY]
If there are style sheets that apply to the media element or other playback mechanism, then they must be interpreted as defined in the next section.
All other non-inherited properties must be set to their initial values; inherited properties on the root List of WebVTT Node Objects must inherit their values from the media element for which the text track cue is being rendered, if any. If there is no media element (i.e. if the text track is being rendered for another media playback mechanism), then inherited properties on the root List of WebVTT Node Objects must take their initial values.
When a user agent is rendering one or more text track cues according to the WebVTT cue text rendering rules, WebVTT Node Objects in the list of WebVTT Node Objects used in the rendering can be matched by certain pseudo-selectors as defined below. These selectors can begin or stop matching individual WebVTT Node Objects while a cue is being rendered, even in between applications of the WebVTT cue text rendering rules (which are only run when the set of active cues changes). User agents that support the pseudo-element described below must dynamically update renderings accordingly.
Pseudo-elements apply to elements that are matched by selectors. For the purpose of this section, that element is the matched element. The pseudo-elements defined in the following sections affect the styling of parts of text track cues that are being rendered for the matched element.
If the matched element is not a
video
element, the pseudo-elements defined below won't
have any effect according to this specification.
A CSS user agent that implements the text tracks model must implement the '::cue' and '::cue(selector)' pseudo-elements, and the ':past' and ':future' pseudo-classes.
The '::cue' pseudo-element (with no argument) matches any List of WebVTT Node Objects constructed for the matched element, with the exception that the properties corresponding to the 'background' shorthand must be applied to the WebVTT cue background box rather than the List of WebVTT Node Objects.
The following properties apply to the '::cue' pseudo-element with no argument; other properties set on the pseudo-element must be ignored:
The '::cue(selector)' pseudo-element with an argument must have an argument that consists of a group of selectors. It matches any WebVTT Internal Node Object constructed for the matched element that also matches the given group of selectors, with the nodes being treated as follows:
The document tree against which the selectors are matched is the tree of WebVTT Node Objects rooted at the list of WebVTT Node Objects for the cue.
WebVTT Internal Node Objects are elements in the tree.
For the purposes of element type selectors, the names of WebVTT Internal Node Objects are as given by the following table, where objects having the concrete class given in a cell in the first column have the name given by the second column of the same row:
Concrete class | Name |
---|---|
WebVTT Class Objects | c
|
WebVTT Italic Objects | i
|
WebVTT Bold Objects | b
|
WebVTT Underline Objects | u
|
WebVTT Ruby Objects | ruby
|
WebVTT Ruby Text Objects | rt
|
WebVTT Voice Objects | v
|
Other elements (specifically, Lists of WebVTT Node Objects) | No explicit name. |
For the purposes of element type and universal selectors, WebVTT Internal Node Objects are considered as being in the namespace expressed as the empty string.
For the purposes of attribute selector matching, WebVTT Internal Node
Objects have no attributes, except for WebVTT Voice Objects, which
have a single attribute named "voice
"
whose value is the value of the WebVTT Voice
Object.
For the purposes of class selector matching, WebVTT Internal Node Objects have the classes described as the WebVTT Node Object's applicable classes.
The following properties apply to the '::cue()' pseudo-element with an argument:
The following properties apply to the '::cue()' pseudo-element with an argument when the selector does not contain the ':past' and ':future' pseudo-classes:
Properties that do not apply must be ignored.
As a special exception, the properties corresponding to the 'background' shorthand, when they would have been applied to the List of WebVTT Node Objects, must instead be applied to the WebVTT cue background box.
The ':past' and ':future' pseudo-classes only match WebVTT Node Objects.
The ':past' pseudo-class only matches WebVTT Node Objects that are in the past.
A WebVTT Node Object c is in the past if, in a pre-order, depth-first traversal of the text track cue's List of WebVTT Node Objects, there exists a WebVTT Timestamp Object whose value is less than the current playback position of the media element that is the matched element, entirely after the WebVTT Node Object c.
The ':future' pseudo-class only matches WebVTT Node Objects that are in the future.
A WebVTT Node Object c is in the future if, in a pre-order, depth-first traversal of the text track cue's List of WebVTT Node Objects, there exists a WebVTT Timestamp Object whose value is greater than the current playback position of the media element that is the matched element, entirely before the WebVTT Node Object c.
When an img
element or an input
element
when its type
attribute is in
the Image Button state
represents an image, it is expected to be treated as a
replaced element.
When an img
element or an input
element
when its type
attribute is in
the Image Button state
does not represent an image, but the
element already has intrinsic dimensions (e.g. from the
dimension attributes or CSS rules), and either the user
agent has reason to believe that the image will become available
and be rendered in due course or the Document
is in
quirks mode, the element is expected to be treated as a
replaced element whose content is the text that the element
represents, if any, optionally alongside an icon indicating that the
image is being obtained. For input
elements, the text
is expected to appear button-like to indicate that the element is a
button.
When an img
element represents some
text and the user agent does not expect this to change, the element
is expected to be treated as an inline element whose content is the
text, optionally with an icon indicating that an image is
missing.
When an img
element represents nothing
and the user agent does not expect this to change, the element is
expected to not be rendered at all.
When an img
element might be a key part of the
content, but neither the image nor any kind of alternative text is
available, and the user agent does not expect this to change, the
element is expected to be treated as an inline element whose content
is an icon indicating that an image is missing.
When an input
element whose type
attribute is in the Image Button state does not
represent an image and the user
agent does not expect this to change, the element is expected to be
treated as a replaced element consisting of a button whose content
is the element's alternative text. The intrinsic dimensions of the
button are expected to be about one line in height and whatever
width is necessary to render the text on one line.
The icons mentioned above are expected to be relatively small so as not to disrupt most text but be easily clickable. In a visual environment, for instance, icons could be 16 pixels by 16 pixels square, or 1em by 1em if the images are scalable. In an audio environment, the icon could be a short bleep. The icons are intended to indicate to the user that they can be used to get to whatever options the UA provides for images, and, where appropriate, are expected to provide access to the context menu that would have come up if the user interacted with the actual image.
All animated images with the same absolute URL and the same image data are expected to be rendered synchronized to the same timeline as a group, with the timeline starting at the time of the most recent addition to the group.
In other words, the animation loop of an animated image is restarted each time another image with the same absolute URL and image data begins to animate, e.g. after being inserted into the document.
The following CSS rules are expected to apply when the
Document
is in quirks mode:
@namespace url(http://www.w3.org/1999/xhtml); img[align=left] { margin-right: 3px; } /* case-insensitive */ img[align=right] { margin-left: 3px; } /* case-insensitive */
The following CSS rules are expected to apply as presentational hints:
@namespace url(http://www.w3.org/1999/xhtml); iframe[frameborder=0], iframe[frameborder=no] { border: none; } /* case-insensitive */ applet[align=left], embed[align=left], iframe[align=left], img[align=left], input[type=image][align=left], object[align=left] { /* case-insensitive */ float: left; } applet[align=right], embed[align=right], iframe[align=right], img[align=right], input[type=image][align=right], object[align=right] { /* case-insensitive */ float: right; } applet[align=top], embed[align=top], iframe[align=top], img[align=top], input[type=image][align=top], object[align=top] { /* case-insensitive */ vertical-align: top; } applet[align=baseline], embed[align=baseline], iframe[align=baseline], img[align=baseline], input[type=image][align=baseline], object[align=baseline] { /* case-insensitive */ vertical-align: baseline; } applet[align=texttop], embed[align=texttop], iframe[align=texttop], img[align=texttop], input[type=image][align=texttop], object[align=texttop] { /* case-insensitive */ vertical-align: text-top; } applet[align=absmiddle], embed[align=absmiddle], iframe[align=absmiddle], img[align=absmiddle], input[type=image][align=absmiddle], object[align=absmiddle], applet[align=abscenter], embed[align=abscenter], iframe[align=abscenter], img[align=abscenter], input[type=image][align=abscenter], object[align=abscenter] { /* case-insensitive */ vertical-align: middle; } applet[align=bottom], embed[align=bottom], iframe[align=bottom], img[align=bottom], input[type=image][align=bottom], object[align=bottom] { /* case-insensitive */ vertical-align: bottom; }
When an applet
, embed
,
iframe
, img
, or object
element, or an input
element whose type
attribute is in the Image Button state, has an
align
attribute whose value is
an ASCII case-insensitive match for the string "center
" or the string "middle
", the user agent is expected to act as if the
element's 'vertical-align' property was set to a value that aligns
the vertical middle of the element with the parent element's
baseline.
The hspace
attribute of
applet
, embed
, iframe
,
img
, or object
elements, and
input
elements with a type
attribute in the Image Button state, maps to the dimension
properties 'margin-left' and 'margin-right' on the
element.
The vspace
attribute of
applet
, embed
, iframe
,
img
, or object
elements, and
input
elements with a type
attribute in the Image Button state, maps to the dimension
properties 'margin-top' and 'margin-bottom' on the
element.
When an img
element, object
element, or
input
element with a type
attribute in the Image Button state is contained
within a hyperlink and has a border
attribute whose value, when
parsed using the rules for parsing non-negative
integers, is found to be a number greater than zero, the user
agent is expected to use the parsed value for eight
presentational hints: four setting the parsed value as
a pixel length for the element's 'border-top-width',
'border-right-width', 'border-bottom-width', and 'border-left-width'
properties, and four setting the element's 'border-top-style',
'border-right-style', 'border-bottom-style', and 'border-left-style'
properties to the value 'solid'.
The width
and height
attributes on
applet
, embed
, iframe
,
img
, object
or video
elements, and input
elements with a type
attribute in the Image Button state, map to the dimension
properties 'width' and 'height' on the element
respectively.
Shapes on an image map are expected to act, for the
purpose of the CSS cascade, as elements independent of the original
area
element that happen to match the same style rules
but inherit from the img
or object
element.
For the purposes of the rendering, only the 'cursor' property is expected to have any effect on the shape.
Thus, for example, if an area
element has a style
attribute that
sets the 'cursor' property to 'help', then when the user designates
that shape, the cursor would change to a Help cursor.
Similarly, if an area
element had a
CSS rule that set its 'cursor' property to 'inherit' (or if no rule
setting the 'cursor' property matched the element at all), the
shape's cursor would be inherited from the img
or
object
element of the image map, not from
the parent of the area
element.
When a menu
element's type
attribute is in the toolbar state, the element is
expected to be treated as a replaced element with a height about two
lines high and a width derived from the contents of the element.
The element is expected to have, by default, the appearance of a toolbar on the user agent's platform. It is expected to contain the menu that is built from the element.
A number of elements have their rendering defined in terms of the 'binding' property. [BECSS]
The CSS snippets below set the 'binding' property to a
user-agent-defined value, represented below by keywords like button
. The rules then described for
these bindings are only expected to apply if the element's 'binding'
property has not been overridden (e.g. by the author) to have
another value.
Exactly how the bindings are implemented is not specified by this specification. User agents are encouraged to make their bindings set the 'appearance' CSS property appropriately to achieve platform-native appearances for widgets, and are expected to implement any relevant animations, etc, that are appropriate for the platform. [CSSUI]
button
element@namespace url(http://www.w3.org/1999/xhtml); button { binding: button; }
When the button binding applies to a
button
element, the element is expected to render as an
'inline-block' box rendered as a button whose contents are the
contents of the element.
details
element@namespace url(http://www.w3.org/1999/xhtml); details { binding: details; }
When the details binding applies to a
details
element, the element is expected to render as a
'block' box with its 'padding-left' property set to '40px' for
left-to-right elements (LTR-specific) and with its
'padding-right' property set to '40px' for right-to-left
elements. The element's shadow tree is expected to take the
element's first child summary
element, if any, and
place it in a first 'block' box container, and then take the
element's remaining descendants, if any, and place them in a second
'block' box container.
The first container is expected to contain at least one line box,
and that line box is expected to contain a disclosure widget
(typically a triangle), horizontally positioned within the left
padding of the details
element. That widget is expected
to allow the user to request that the details be shown or
hidden.
The second container is expected to have its 'overflow' property
set to 'hidden'. When the details
element does not have
an open
attribute, this
second container is expected to be removed from the rendering.
input
element as a text entry widget@namespace url(http://www.w3.org/1999/xhtml); input { binding: input-textfield; } input[type=password] { binding: input-password; } /* case-insensitive */ /* later rules override this for other values of type="" */
When the input-textfield binding applies to an
input
element whose type
attribute is in the Text, Search, Telephone, URL, or E-mail state, the element is
expected to render as an 'inline-block' box rendered as a text
field.
When the input-password binding applies, to an
input
element whose type
attribute is in the Password state, the element
is expected to render as an 'inline-block' box rendered as a text
field whose contents are obscured.
If an input
element whose type
attribute is in one of the above
states has a size
attribute,
and parsing that attribute's value using the rules for parsing
non-negative integers doesn't generate an error, then the
user agent is expected to use the attribute as a presentational hint for the
'width' property on the element, with the value obtained from
applying the converting a character width to pixels
algorithm to the value of the attribute.
If an input
element whose type
attribute is in one of the above
states does not have a size
attribute, then the user agent
is expected to act as if it had a user-agent-level style sheet rule
setting the 'width' property on the element to the value obtained
from applying the converting a character width to
pixels algorithm to the number 20.
The converting a character width to pixels algorithm returns (size-1)×avg + max, where size is the character width to convert, avg is the average character width of the primary font for the element for which the algorithm is being run, in pixels, and max is the maximum character width of that same font, also in pixels. (The element's 'letter-spacing' property does not affect the result.)
input
element as domain-specific widgets@namespace url(http://www.w3.org/1999/xhtml); input[type=datetime] { binding: input-datetime; } /* case-insensitive */ input[type=date] { binding: input-date; } /* case-insensitive */ input[type=month] { binding: input-month; } /* case-insensitive */ input[type=week] { binding: input-week; } /* case-insensitive */ input[type=time] { binding: input-time; } /* case-insensitive */ input[type=datetime-local] { binding: input-datetime-local; } /* case-insensitive */ input[type=number] { binding: input-number; } /* case-insensitive */
When the input-datetime binding applies to an
input
element whose type
attribute is in the Date and Time state, the
element is expected to render as an 'inline-block' box depicting a
Date and Time control.
When the input-date binding applies to an
input
element whose type
attribute is in the Date state, the element is
expected to render as an 'inline-block' box depicting a Date
control.
When the input-month binding applies to an
input
element whose type
attribute is in the Month state, the element is
expected to render as an 'inline-block' box depicting a Month
control.
When the input-week binding applies to an
input
element whose type
attribute is in the Week state, the element is
expected to render as an 'inline-block' box depicting a Week
control.
When the input-time binding applies to an
input
element whose type
attribute is in the Time state, the element is
expected to render as an 'inline-block' box depicting a Time
control.
When the input-datetime-local binding applies to an
input
element whose type
attribute is in the Local Date and Time
state, the element is expected to render as an 'inline-block' box
depicting a Local Date and Time control.
When the input-number binding applies to an
input
element whose type
attribute is in the Number state, the element is
expected to render as an 'inline-block' box depicting a Number
control.
These controls are all expected to be about one line high, and about as wide as necessary to show the widest possible value.
input
element as a range control@namespace url(http://www.w3.org/1999/xhtml); input[type=range] { binding: input-range; } /* case-insensitive */
When the input-range binding applies to an
input
element whose type
attribute is in the Range state, the element is
expected to render as an 'inline-block' box depicting a slider
control.
When the control is wider than it is tall (or square), the control is expected to be a horizontal slider, with the lowest value on the right if the 'direction' property on this element has a computed value of 'rtl', and on the left otherwise. When the control is taller than it is wide, it is expected to be a vertical slider, with the lowest value on the bottom.
Predefined suggested values (provided by the list
attribute) are expected to be
shown as tick marks on the slider, which the slider can snap to.
input
element as a color well@namespace url(http://www.w3.org/1999/xhtml); input[type=color] { binding: input-color; } /* case-insensitive */
When the input-color binding applies to an
input
element whose type
attribute is in the Color state, the element is
expected to render as an 'inline-block' box depicting a color well,
which, when activated, provides the user with a color picker (e.g. a
color wheel or color palette) from which the color can be
changed.
Predefined suggested values (provided by the list
attribute) are expected to be
shown in the color picker interface, not on the color well
itself.
input
element as a checkbox and radio button widgets@namespace url(http://www.w3.org/1999/xhtml); input[type=checkbox] { binding: input-checkbox; } /* case-insensitive */ input[type=radio] { binding: input-radio; } /* case-insensitive */
When the input-checkbox binding applies to an
input
element whose type
attribute is in the Checkbox state, the element
is expected to render as an 'inline-block' box containing a single
checkbox control, with no label.
When the input-radio binding applies to an
input
element whose type
attribute is in the Radio Button state, the element
is expected to render as an 'inline-block' box containing a single
radio button control, with no label.
input
element as a file upload control@namespace url(http://www.w3.org/1999/xhtml); input[type=file] { binding: input-file; } /* case-insensitive */
When the input-file binding applies to an
input
element whose type
attribute is in the File Upload state, the element
is expected to render as an 'inline-block' box containing a span of
text giving the filename(s) of the selected files, if
any, followed by a button that, when activated, provides the user
with a file picker from which the selection can be changed.
input
element as a button@namespace url(http://www.w3.org/1999/xhtml); input[type=submit], input[type=reset], input[type=button] { /* case-insensitive */ binding: input-button; }
When the input-button binding applies to an
input
element whose type
attribute is in the Submit Button, Reset Button, or Button state, the element is
expected to render as an 'inline-block' box rendered as a button,
about one line high, containing the contents of the element's value
attribute, if any, or text
derived from the element's type
attribute in a user-agent-defined (and probably locale-specific)
fashion, if not.
marquee
element@namespace url(http://www.w3.org/1999/xhtml); marquee { binding: marquee; }
When the marquee binding applies to a
marquee
element, while the element is turned on, the element is expected
to render in an animated fashion according to its attributes as
follows:
behavior
attribute is in the
scroll stateSlide the contents of the element in the direction described by
the direction
attribute as defined below, such that it begins off the start side
of the marquee
, and ends flush with the inner end
side.
For example, if the direction
attribute is left (the default),
then the contents would start such that their left edge are off
the side of the right edge of the marquee
's content
area, and the contents would then slide up to the point where the
left edge of the contents are flush with the left inner edge of
the marquee
's content area.
Once the animation has ended, the user agent is expected to increment the marquee current loop index. If the element is still turned on after this, then the user agent is expected to restart the animation.
behavior
attribute is in the
slide stateSlide the contents of the element in the direction described by
the direction
attribute as defined below, such that it begins off the start side
of the marquee
, and ends off the end side of the
marquee
.
For example, if the direction
attribute is left (the default),
then the contents would start such that their left edge are off
the side of the right edge of the marquee
's content
area, and the contents would then slide up to the point where the
right edge of the contents are flush with the left inner
edge of the marquee
's content area.
Once the animation has ended, the user agent is expected to increment the marquee current loop index. If the element is still turned on after this, then the user agent is expected to restart the animation.
behavior
attribute is in the
alternate
stateWhen the marquee current loop index is even (or
zero), slide the contents of the element in the direction
described by the direction
attribute as
defined below, such that it begins flush with the start side of
the marquee
, and ends flush with the end side of the
marquee
.
When the marquee current loop index is odd, slide
the contents of the element in the opposite direction than that
described by the direction
attribute as
defined below, such that it begins flush with the end side of the
marquee
, and ends flush with the start side of the
marquee
.
For example, if the direction
attribute is left (the default),
then the contents would with their right edge flush with the right
inner edge of the marquee
's content area, and the
contents would then slide up to the point where the left
edge of the contents are flush with the left inner edge of the
marquee
's content area.
Once the animation has ended, the user agent is expected to increment the marquee current loop index. If the element is still turned on after this, then the user agent is expected to continue the animation.
The direction
attribute has the meanings described in the following table:
direction attribute state
| Direction of animation | Start edge | End edge | Opposite direction |
---|---|---|---|---|
left | ← Right to left | Right | Left | → Left to Right |
right | → Left to Right | Left | Right | ← Right to left |
up | ↑ Up (Bottom to Top) | Bottom | Top | ↓ Down (Top to Bottom) |
down | ↓ Down (Top to Bottom) | Top | Bottom | ↑ Up (Bottom to Top) |
In any case, the animation should proceed such that there is a delay given by the marquee scroll interval between each frame, and such that the content moves at most the distance given by the marquee scroll distance with each frame.
When a marquee
element has a bgcolor
attribute set, the value
is expected to be parsed using the rules for parsing a legacy
color value, and if that does not return an error, the user
agent is expected to treat the attribute as a presentational hint setting the
element's 'background-color' property to the resulting color.
The width
and height
attributes on a
marquee
element map to the dimension properties 'width' and
'height' on the element respectively.
The intrinsic height of a marquee
element with its
direction
attribute in
the up or down states is 200 CSS
pixels.
The vspace
attribute of
a marquee
element maps to the dimension properties 'margin-top' and
'margin-bottom' on the element. The hspace
attribute of a
marquee
element maps to the dimension properties 'margin-left' and
'margin-right' on the element.
The 'overflow' property on the marquee
element is
expected to be ignored; overflow is expected to always be
hidden.
meter
element@namespace url(http://www.w3.org/1999/xhtml); meter { binding: meter; }
When the meter binding applies to a
meter
element, the element is expected to render as an
'inline-block' box with a 'height' of '1em' and a 'width' of '5em',
a 'vertical-align' of '-0.2em', and with its contents depicting a
gauge.
When the element is wider than it is tall (or square), the depiction is expected to be of a horizontal gauge, with the minimum value on the right if the 'direction' property on this element has a computed value of 'rtl', and on the left otherwise. When the element is taller than it is wide, it is expected to depict a vertical gauge, with the minimum value on the bottom.
User agents are expected to use a presentation consistent with platform conventions for gauges, if any.
Requirements for what must be depicted in the gauge
are included in the definition of the meter
element.
progress
element@namespace url(http://www.w3.org/1999/xhtml); progress { binding: progress; }
When the progress binding applies to a
progress
element, the element is expected to render as
an 'inline-block' box with a 'height' of '1em' and a 'width' of
'10em', and a 'vertical-align' of '-0.2em'.
When the element is wider than it is tall, the element is expected to be depicted as a horizontal progress bar, with the start on the right and the end on the left if the 'direction' property on this element has a computed value of 'rtl', and with the start on the left and the end on the right otherwise. When the element is taller than it is wide, it is expected to depicted as a vertical progress bar, with the lowest value on the bottom. When the element is square, it is expected to be depicted as a direction-independent progress widget (e.g. a circular progress ring).
User agents are expected to use a presentation consistent with platform conventions for progress bars. In particular, user agents are expected to use different presentations for determinate and indeterminate progress bars. User agents are also expected to vary the presentation based on the dimensions of the element.
For example, on some platforms for showing indeterminate progress there is an asynchronous progress indicator with square dimensions, which could be used when the element is square, and an indeterminate progress bar, which could be used when the element is wide.
Requirements for how to determine if the progress
bar is determinate or indeterminate, and what progress a determinate
progress bar is to show, are included in the definition of the
progress
element.
select
element@namespace url(http://www.w3.org/1999/xhtml); select { binding: select; }
When the select binding applies to a
select
element whose multiple
attribute is present,
the element is expected to render as a multi-select list box.
When the select binding applies to a
select
element whose multiple
attribute is absent,
and the element's display
size is greater than 1, the element is expected to render as
a single-select list box.
When the element renders as a list box, it is expected to render
as an 'inline-block' box whose 'height' is the height necessary to
contain as many rows for items as given by the element's display size, or four rows if the
attribute is absent, and whose 'width' is the width of the
select
's labels plus the width of a
scrollbar.
When the select binding applies to a
select
element whose multiple
attribute is absent,
and the element's display
size is 1, the element is expected to render as a one-line
drop down box whose width is the width of the
select
's labels.
In either case (list box or drop-down box), the element's items
are expected to be the element's list of options, with the
element's optgroup
element children providing headers
for groups of options where applicable.
An optgroup
element is expected to be rendered by
displaying the element's label
attribute.
An option
element is expected to be rendered by
displaying the element's label
, indented under its
optgroup
element if it has one.
The width of the select
's labels is the
wider of the width necessary to render the widest
optgroup
, and the width necessary to render the widest
option
element in the element's list of options (including
its indent, if any).
If a select
element contains a placeholder
label option, the user agent is expected to render that
option
in a manner that conveys that it is a label,
rather than a valid option of the control. This can include
preventing the placeholder label option from being
explicitly selected by the user. When the placeholder label
option's selectedness is true, the
control is expected to be displayed in a fashion that indicates that
no valid option is currently selected.
User agents are expected to render the labels in a
select
in such a manner that any alignment remains
consistent whether the label is being displayed as part of the page
or in a menu control.
textarea
element@namespace url(http://www.w3.org/1999/xhtml); textarea { binding: textarea; white-space: pre-wrap; }
When the textarea binding applies to a
textarea
element, the element is expected to render as
an 'inline-block' box rendered as a multiline text field.
If the element has a cols
attribute, and parsing that attribute's value using the rules
for parsing non-negative integers doesn't generate an error,
then the user agent is expected to use the attribute as a presentational hint for the
'width' property on the element, with the value being the
textarea effective width (as defined below). Otherwise,
the user agent is expected to act as if it had a user-agent-level
style sheet rule setting the 'width' property on the element to the
textarea effective width.
The textarea effective width of a
textarea
element is size×avg + sbw, where size is the
element's character
width, avg is the average character width
of the primary font of the element, in CSS pixels, and sbw is the width of a scroll bar, in CSS pixels. (The
element's 'letter-spacing' property does not affect the result.)
If the element has a rows
attribute, and parsing that attribute's value using the rules
for parsing non-negative integers doesn't generate an error,
then the user agent is expected to use the attribute as a presentational hint for the
'height' property on the element, with the value being the
textarea effective height (as defined
below). Otherwise, the user agent is expected to act as if it had a
user-agent-level style sheet rule setting the 'height' property on
the element to the textarea effective height.
The textarea effective height of a
textarea
element is the height in CSS pixels of the
number of lines specified the element's character height, plus the
height of a scrollbar in CSS pixels.
User agents are expected to apply the 'white-space' CSS property
to textarea
elements. For historical reasons, if the
element has a wrap
attribute
whose value is an ASCII case-insensitive match for the
string "off
", then the
user agent is expected to treat the attribute as a presentational hint setting the
element's 'white-space' property to 'pre'.
keygen
element@namespace url(http://www.w3.org/1999/xhtml); keygen { binding: keygen; }
When the keygen binding applies to a
keygen
element, the element is expected to render as an
'inline-block' box containing a user interface to configure the key
pair to be generated.
time
element@namespace url(http://www.w3.org/1999/xhtml); time[datetime] { binding: time; }
When the time binding applies to a
time
element, the element is expected to render as if
it contained text conveying the date (if known), time (if known), and time-zone offset (if known)
represented by the element, in the fashion most convenient for the
user.
When an html
element's second child element is a
frameset
element, the user agent is expected to render
the frameset
element as described below across the
surface of the viewport, instead of applying the usual CSS rendering
rules.
When rendering a frameset
on a surface, the user
agent is expected to use the following layout algorithm:
The cols and rows variables are lists of zero or more pairs consisting of a number and a unit, the unit being one of percentage, relative, and absolute.
Use the rules for parsing a list of dimensions to
parse the value of the element's cols
attribute, if there is
one. Let cols be the result, or an empty list
if there is no such attribute.
Use the rules for parsing a list of dimensions to
parse the value of the element's rows
attribute, if there is
one. Let rows be the result, or an empty list
if there is no such attribute.
For any of the entries in cols or rows that have the number zero and the unit relative, change the entry's number to one.
If cols has no entries, then add a single entry consisting of the value 1 and the unit relative to cols.
If rows has no entries, then add a single entry consisting of the value 1 and the unit relative to rows.
Invoke the algorithm defined below to convert a list of
dimensions to a list of pixel values using cols as the input list, and the width of the
surface that the frameset
is being rendered into, in
CSS pixels, as the input dimension. Let sized
cols be the resulting list.
Invoke the algorithm defined below to convert a list of
dimensions to a list of pixel values using rows as the input list, and the height of the
surface that the frameset
is being rendered into, in
CSS pixels, as the input dimension. Let sized
rows be the resulting list.
Split the surface into a grid of w×h rectangles, where w is the number of entries in sized cols and h is the number of entries in sized rows.
Size the columns so that each column in the grid is as many CSS pixels wide as the corresponding entry in the sized cols list.
Size the rows so that each row in the grid is as many CSS pixels high as the corresponding entry in the sized rows list.
Let children be the list of
frame
and frameset
elements that are
children of the frameset
element for which the
algorithm was invoked.
For each row of the grid of rectangles created in the previous step, from top to bottom, run these substeps:
For each rectangle in the row, from left to right, run these substeps:
If there are any elements left in children, take the first element in the list, and assign it to the rectangle.
If this is a frameset
element, then recurse
the entire frameset
layout algorithm for that
frameset
element, with the rectangle as the
surface.
Otherwise, it is a frame
element; create a
nested browsing context sized to fit the
rectangle.
If there are any elements left in children, remove the first element from children.
If the frameset
element has a border,
draw an outer set of borders around the rectangles, using the
element's frame border color.
For each rectangle, if there is an element assigned to that rectangle, and that element has a border, draw an inner set of borders around that rectangle, using the element's frame border color.
For each (visible) border that does not abut a rectangle that
is assigned a frame
element with a noresize
attribute (including
rectangles in further nested frameset
elements), the
user agent is expected to allow the user to move the border,
resizing the rectangles within, keeping the proportions of any
nested frameset
grids.
A frameset
or frame
element has
a border if the following algorithm returns true:
If the element has a frameborder
attribute
whose value is not the empty string and whose first character is
either a U+0031 DIGIT ONE (1) character, a U+0079 LATIN SMALL
LETTER Y character (y), or a U+0059 LATIN CAPITAL LETTER Y
character (Y), then return true.
Otherwise, if the element has a frameborder
attribute,
return false.
Otherwise, if the element has a parent element that is a
frameset
element, then return true if that
element has a border, and false if it does
not.
Otherwise, return true.
The frame border color of a frameset
or
frame
element is the color obtained from the
following algorithm:
If the element has a bordercolor
attribute, and
applying the rules for parsing a legacy color value
to that attribute's value does not result in an error, then
return the color so obtained.
Otherwise, if the element has a parent element that is a
frameset
element, then the frame border
color of that element.
Otherwise, return gray.
The algorithm to convert a list of dimensions to a list of pixel values consists of the following steps:
Let input list be the list of numbers and units passed to the algorithm.
Let output list be a list of numbers the same length as input list, all zero.
Entries in output list correspond to the entries in input list that have the same position.
Let input dimension be the size passed to the algorithm.
Let count percentage be the number of entries in input list whose unit is percentage.
Let total percentage be the sum of all the numbers in input list whose unit is percentage.
Let count relative be the number of entries in input list whose unit is relative.
Let total relative be the sum of all the numbers in input list whose unit is relative.
Let count absolute be the number of entries in input list whose unit is absolute.
Let total absolute be the sum of all the numbers in input list whose unit is absolute.
Let remaining space be the value of input dimension.
If total absolute is greater than remaining space, then for each entry in input list whose unit is absolute, set the corresponding value in output list to the number of the entry in input list multiplied by remaining space and divided by total absolute. Then, set remaining space to zero.
Otherwise, for each entry in input list whose unit is absolute, set the corresponding value in output list to the number of the entry in input list. Then, decrement remaining space by total absolute.
If total percentage multiplied by the input dimension and divided by 100 is greater than remaining space, then for each entry in input list whose unit is percentage, set the corresponding value in output list to the number of the entry in input list multiplied by remaining space and divided by total percentage. Then, set remaining space to zero.
Otherwise, for each entry in input list whose unit is percentage, set the corresponding value in output list to the number of the entry in input list multiplied by the input dimension and divided by 100. Then, decrement remaining space by total percentage multiplied by the input dimension and divided by 100.
For each entry in input list whose unit is relative, set the corresponding value in output list to the number of the entry in input list multiplied by remaining space and divided by total relative.
Return output list.
User agents working with integer values for frame widths (as opposed to user agents that can lay frames out with subpixel accuracy) are expected to distribute the remainder first to the last entry whose unit is relative, then equally (not proportionally) to each entry whose unit is percentage, then equally (not proportionally) to each entry whose unit is absolute, and finally, failing all else, to the last entry.
User agents are expected to allow the user to control aspects of hyperlink activation and form submission, such as which browsing context is to be used for the subsequent navigation.
User agents are expected to allow users to discover the destination of hyperlinks and of forms before triggering their navigation.
User agents are expected to allow users to
navigate browsing contexts to the resources indicated by the cite
attributes on q
,
blockquote
,
ins
, and del
elements.
User agents are expected to surface hyperlinks created by link
elements in their user interface.
While link
elements that create hyperlinks will match the ':link' or
':visited' pseudo-classes, will react to clicks if visible, and so
forth, this does not extend to any browser interface constructs that
expose those same links. Activating a link through the browser's
interface, rather than in the page itself, does not trigger click
events and the like.
title
attributeGiven an element (e.g. the element designated by the mouse
cursor), if the element, or one of its ancestors, has a title
attribute, and the nearest such
attribute has a value that is not the empty string, it is expected
that the user agent will expose the contents of that attribute as a
tooltip.
U+000A LINE FEED (LF) characters are expected to cause line breaks in the tooltip, U+0009 CHARACTER TABULATION (tab) characters are expected to render as a non-zero horizontal shift that lines up the next glpyh with the next tab stop, with tab stops occurring at points that are multiples of 8 times the width of a U+0020 SPACE character.
User agents are encouraged to make it possible to view tooltips without the use of a pointing device, since not all users are able to use pointing devices.
For example, a visual user agent could make elements with a
title
attribute focusable, and
could make any focused element with a title
attribute show its tooltip under
the element while the element has focus. This would allow a user to
tab around the document to find all the advisory text.
As another example, a screen reader could provide an audio cue when reading an element with a tooltip, with an associated key to read the last tooltip for which a cue was played.
The current text editing caret (the one at the caret position in a focused editing host) is expected to act like an inline replaced element with the vertical dimensions of the caret and with zero width for the purposes of the CSS rendering model.
This means that even an empty block can have the caret inside it, and that when the caret is in such an element, it prevents margins from collapsing through the element.
User agents are expected to honor the Unicode semantics of text that is exposed in user interfaces, for example supporting the bidirectional algorithm in text shown in dialogs, title bars, pop-up menus, and tooltips. Text from elements (either attribute values or the contents of elements) is expected to be rendered in a manner that honors the directionality of the element from which the text was obtained.
Consider the following markup, which has Hebrew text asking for a programming language, the languages being text for which a left-to-right direction is important given the punctuation in some of their names:
<p dir="rtl" lang="he">
<label>
בחר שפת תכנות:
<select>
<option dir="ltr">C++</option>
<option dir="ltr">C#</option>
<option dir="ltr">FreePascal</option>
<option dir="ltr">F#</option>
</select>
</label>
</p>
If the select
element was rendered as a drop down
box, a correct rendering would ensure that the punctuation was the
same both in the drop down, and in the box showing the current
selection.
A string provided by a script (e.g. the argument to window.alert()
) is expected to be treated
as an independent set of one or more bidirectional algorithm
paragraphs when displayed, as defined by the bidirectional
algorithm, including, for instance, supporting the
paragraph-breaking behaviour of U+000A LINE FEED (LF) characters.
For the purposes of determining the paragraph level of such text in
the bidirectional algorithm, this specification does not
provide a higher-level override of rules P2 and P3. [BIDI]
When necessary, authors can enforce a particular direction for a given paragraph by starting it with the Unicode U+200E LEFT-TO-RIGHT MARK or U+200F RIGHT-TO-LEFT MARK characters.
Thus, the following script:
alert('\u05DC\u05DE\u05D3 HTML \u05D4\u05D9\u05D5\u05DD!')
...would always result in a message reading "למד LMTH היום!" (not "דמל HTML םויה!"), regardless of the language of the user agent interface or the direction of the page or any of its elements.
For a more complex example, consider the following script:
/* Warning: this script does not handle right-to-left scripts correctly */ var s; if (s = prompt('What is your name?')) { alert(s + '! Ok, Fred, ' + s + ', and Wilma will get the car.'); }
When the user enters "Kitty", the user agent would alert "Kitty! Ok, Fred, Kitty, and Wilma will get the car.". However, if the user enters "لا أفهم", then the bidirectional algorithm will determine that the direction of the paragraph is right-to-left, and so the output will be the following unintended mess: "لا أفهم! derF ,kO, لا أفهم, rac eht teg lliw amliW dna."
To force an alert that starts with user-provided text (or other text of unknown directionality) to render left-to-right, the string can be prefixed with a U+200E LEFT-TO-RIGHT MARK character:
var s; if (s = prompt('What is your name?')) { alert('\u200E' + s + '! Ok, Fred, ' + s + ', and Wilma will get the car.'); }
User agents are expected to allow the user to request the
opportunity to obtain a physical form (or a
representation of a physical form) of a Document
. For
example, selecting the option to print a page or convert it to PDF
format.
When the user actually obtains a physical form (or a representation of a
physical form) of a Document
, the user agent is
expected to create a new rendering of the Document
for
the print media.
Features listed in this section will trigger warnings in conformance checkers.
Authors should not specify a border
attribute on an
img
element. If the attribute is present, its value
must be the string "0
". CSS should be used
instead.
Authors should not specify a language
attribute on a
script
element. If the attribute is present, its value
must be an ASCII case-insensitive match for the string
"JavaScript
" and either the type
attribute must be omitted or
its value must be an ASCII case-insensitive match for
the string "text/javascript
". The attribute
should be entirely omitted instead (with the value "JavaScript
", it has no effect), or replaced with use
of the type
attribute.
Authors should not specify the name
attribute on a
elements. If the attribute is present, its value must not be the
empty string and must neither be equal to the value of any of the
IDs in the element's home
subtree other than the element's own ID, if any, nor be equal to the value of
any of the other name
attributes on
a
elements in the element's home
subtree. If this attribute is present and the element has an
ID, then the attribute's value must
be equal to the element's ID. In
earlier versions of the language, this attribute was intended as a
way to specify possible targets for fragment identifiers in URLs. The id
attribute should be used instead.
In the HTML syntax, specifying a DOCTYPE that is an obsolete permitted DOCTYPE will also trigger a warning.
To ease the transition from HTML4 Transitional documents to the language defined in this specification, and to discourage certain features that are only allowed in very few circumstances, conformance checkers are required to warn the user when the following features are used in a document. These are generally old obsolete features that have no effect, and are allowed only to distinguish between likely mistakes (regular conformance errors) and mere vestigial markup or unusual and discouraged practices (these warnings).
The following features must be categorized as described above:
The presence of an obsolete permitted DOCTYPE in an HTML document.
The presence of a border
attribute on an
img
element if its value is the string "0
".
The presence of a language
attribute on a
script
element if its value is an ASCII
case-insensitive match for the string "JavaScript
" and if there is no type
attribute or there is and its
value is an ASCII case-insensitive match for the
string "text/javascript
".
The presence of a name
attribute on an a
element, if its value is not the
empty string.
Conformance checkers must distinguish between pages that have no conformance errors and have none of these obsolete features, and pages that have no conformance errors but do have some of these obsolete features.
For example, a validator could report some pages as "Valid HTML" and others as "Valid HTML with warnings".
Elements in the following list are entirely obsolete, and must not be used by authors:
applet
acronym
Use abbr
instead.
bgsound
Use audio
instead.
dir
Use ul
instead.
frame
frameset
noframes
Either use iframe
and CSS instead, or use server-side includes to generate complete pages with the various invariant parts merged in.
isindex
Use an explicit form
and text field combination instead.
listing
nextid
Use GUIDs instead.
noembed
plaintext
Use the "text/plain
" MIME type instead.
rb
Providing the ruby base directly inside the ruby
element is sufficient; the rb
element is unnecessary. Omit it altogether.
strike
Use del
instead if the element is marking an edit, otherwise use s
instead.
xmp
Use code
instead, and escape "<
" and "&
" characters as "<
" and "&
" respectively.
basefont
big
blink
center
font
marquee
multicol
nobr
spacer
tt
Use appropriate elements and/or CSS instead.
Where the tt
element would have been used for
marking up keyboard input, consider the kbd
element;
for variables, consider the var
element; for computer
code, consider the code
element; and for computer
output, consider the samp
element.
Similarly, if the big
element is being used to
denote a heading, consider using the h1
element; if
it is being used for marking up important passages, consider the
strong
element; and if it is being used for
highlighting text for reference purposes, consider the
mark
element.
See also the text-level semantics usage summary for more suggestions with examples.
The following attributes are obsolete (though the elements are still part of the language), and must not be used by authors:
charset
on a
elementscharset
on link
elementsUse an HTTP Content-Type header on the linked resource instead.
coords
on a
elementsshape
on a
elementsmethods
on a
elementsmethods
on link
elementsUse the HTTP OPTIONS feature instead.
name
on a
elements (except as noted in the previous section)name
on embed
elementsname
on img
elementsname
on option
elementsUse the id
attribute instead.
rev
on a
elementsrev
on link
elementsUse the rel
attribute instead, with an opposite term. (For example, instead of
rev="made"
, use rel="author"
.)
urn
on a
elementsurn
on link
elementsSpecify the preferred persistent identifier using the href
attribute instead.
nohref
on area
elementsOmitting the href
attribute is sufficient; the nohref
attribute is
unnecessary. Omit it altogether.
profile
on head
elementsWhen used for declaring which meta
terms are
used in the document, unnecessary; omit it altogether, and register the names.
When used for triggering specific user agent behaviors: use
a link
element instead.
version
on html
elementsUnnecessary. Omit it altogether.
usemap
on input
elementslongdesc
on iframe
elementslongdesc
on img
elementsUse a regular a
element to link to the
description, or (in the case of images) use an image
map to provide a link from the image to the image's
description.
lowsrc
on img
elementsUse a progressive JPEG image (given in the src
attribute),
instead of using two separate images.
target
on link
elementsUnnecessary. Omit it altogether.
scheme
on meta
elementsUse only one scheme per field, or make the scheme declaration part of the value.
archive
on object
elementsclassid
on object
elementscode
on object
elementscodebase
on object
elementscodetype
on object
elementsUse the data
and type
attributes to invoke plugins. To set parameters with these names
in particular, the param
element can be used.
declare
on object
elementsRepeat the object
element completely each time the resource is to be reused.
standby
on object
elementsOptimize the linked resource so that it loads quickly or, at least, incrementally.
type
on param
elementsvaluetype
on param
elementsUse the name
and value
attributes without declaring
value types.
language
on script
elements (except as noted in the previous section)Use the type
attribute
instead.
event
on script
elementsfor
on script
elementsUse DOM Events mechanisms to register event listeners. [DOMEVENTS]
datapagesize
on table
elementsUnnecessary. Omit it altogether.
summary
on table
elementsUse one of the techniques for describing
tables given in the table
section
instead.
abbr
on td
and th
elementsUse text that begins in an unambiguous and terse manner, and include any more elaborate text after that. The title
attribute can also be useful in including more detailed text, so that the cell's contents can be made terse.
axis
on td
and th
elementsdatasrc
on a
, applet
, button
, div
, frame
, iframe
, img
, input
, label
, legend
, marquee
, object
, option
, select
, span
, table
, and textarea
elementsdatafld
on a
, applet
, button
, div
, fieldset
, frame
, iframe
, img
, input
, label
, legend
, marquee
, object
, param
, select
, span
, and textarea
elementsdataformatas
on button
, div
, input
, label
, legend
, marquee
, object
, option
, select
, span
, and table
elementsUse script and a mechanism such as XMLHttpRequest
to populate the page dynamically. [XHR]
alink
on body
elementsbgcolor
on body
elementslink
on body
elementsmarginbottom
on body
elementsmarginheight
on body
elementsmarginleft
on body
elementsmarginright
on body
elementsmargintop
on body
elementsmarginwidth
on body
elementstext
on body
elementsvlink
on body
elementsclear
on br
elementsalign
on caption
elementsalign
on col
elementschar
on col
elementscharoff
on col
elementsvalign
on col
elementswidth
on col
elementsalign
on div
elementscompact
on dl
elementsalign
on embed
elementshspace
on embed
elementsvspace
on embed
elementsalign
on hr
elementscolor
on hr
elementsnoshade
on hr
elementssize
on hr
elementswidth
on hr
elementsalign
on h1
—h6
elementsalign
on iframe
elementsallowtransparency
on iframe
elementsframeborder
on iframe
elementshspace
on iframe
elementsmarginheight
on iframe
elementsmarginwidth
on iframe
elementsscrolling
on iframe
elementsvspace
on iframe
elementsalign
on input
elementshspace
on input
elementsvspace
on input
elementsalign
on img
elementsborder
on img
elements (except as noted in the previous section)hspace
on img
elementsvspace
on img
elementsalign
on legend
elementstype
on li
elementscompact
on menu
elementsalign
on object
elementsborder
on object
elementshspace
on object
elementsvspace
on object
elementscompact
on ol
elementsalign
on p
elementswidth
on pre
elementsalign
on table
elementsbgcolor
on table
elementscellpadding
on table
elementscellspacing
on table
elementsframe
on table
elementsrules
on table
elementswidth
on table
elementsalign
on tbody
, thead
, and tfoot
elementschar
on tbody
, thead
, and tfoot
elementscharoff
on tbody
, thead
, and tfoot
elementsvalign
on tbody
, thead
, and tfoot
elementsalign
on td
and th
elementsbgcolor
on td
and th
elementschar
on td
and th
elementscharoff
on td
and th
elementsheight
on td
and th
elementsnowrap
on td
and th
elementsvalign
on td
and th
elementswidth
on td
and th
elementsalign
on tr
elementsbgcolor
on tr
elementschar
on tr
elementscharoff
on tr
elementsvalign
on tr
elementscompact
on ul
elementstype
on ul
elementsbackground
on body
, table
, thead
, tbody
, tfoot
, tr
, td
, and th
elementsUse CSS instead.
The border
attribute on
the table
element can be used to provide basic fallback
styling for the purpose of making tables legible in browsing
environments where CSS support is limited or absent, such as
text-based browsers, WYSIWYG editors, and in situations where CSS
support is disabled or the style sheet is lost. Only the empty
string and the value "1
" may be used as border
values for this purpose.
Other values are considered obsolete. To regulate the thickness of
such borders, authors should instead use CSS.
applet
elementThe applet
element is a Java-specific variant of the
embed
element. The applet
element is now
obsoleted so that all extension frameworks (Java, .NET, Flash, etc)
are handled in a consistent manner.
When the element is still in the
stack of open elements of an HTML parser
or XML parser, and when the element is not in a
Document
, and when the element's document is not
fully active, and when the element's
Document
's browsing context had its
sandboxed plugins browsing context flag when that
Document
was created, and when the element's
Document
was parsed from a resource whose sniffed type as determined
during navigation is
text/html-sandboxed
, and when the element has an
ancestor media element, and when the element has an
ancestor object
element that is not showing
its fallback content, and when no Java Language runtime
plugin is available, and when one is available
but it is disabled, the element represents its
contents.
Otherwise, the user agent should instantiate a Java Language
runtime plugin, and should pass the names and values of
all the attributes on the element, in the order they were added to
the element, with the attributes added by the parser being ordered
in source order, and then a parameter named "PARAM" whose value is
null, and then all the names and values of parameters given by
param
elements that are children of the
applet
element, in tree order, to the
plugin used. If the plugin supports a
scriptable interface, the HTMLAppletElement
object
representing the element should expose that interface. The
applet
element represents the
plugin.
The applet
element is unaffected by the
CSS 'display' property. The Java Language runtime is instantiated
even if the element is hidden with a 'display:none' CSS style.
The applet
element must implement the
HTMLAppletElement
interface.
interface HTMLAppletElement : HTMLElement { attribute DOMString align; attribute DOMString alt; attribute DOMString archive; attribute DOMString code; attribute DOMString codeBase; attribute DOMString height; attribute unsigned long hspace; attribute DOMString name; attribute DOMString _object; // the underscore is not part of the identifier attribute unsigned long vspace; attribute DOMString width; };
The align
, alt
, archive
, code
, height
, hspace
, name
, object
, vspace
, and width
IDL attributes
must reflect the respective content attributes of the
same name. For the purposes of reflection, the applet
element's object
content
attribute is defined as containing a URL.
The codeBase
IDL attribute must reflect the codebase
content attribute,
which for the purposes of reflection is defined as containing a
URL.
marquee
elementThe marquee
element is a presentational element that
animates content. CSS transitions and animations are a more
appropriate mechanism.
The task source for tasks mentioned in this section is the DOM manipulation task source.
The marquee
element must implement the
HTMLMarqueeElement
interface.
interface HTMLMarqueeElement : HTMLElement { attribute DOMString behavior; attribute DOMString bgColor; attribute DOMString direction; attribute DOMString height; attribute unsigned long hspace; attribute long loop; attribute unsigned long scrollAmount; attribute unsigned long scrollDelay; attribute boolean trueSpeed; attribute unsigned long vspace; attribute DOMString width; attribute Function onbounce; attribute Function onfinish; attribute Function onstart; void start(); void stop(); };
A marquee
element can be turned on or turned off. When it is created, it
is turned on.
When the start()
method is
called, the marquee
element must be turned on.
When the stop()
method is called, the marquee
element must be turned off.
When a marquee
element is created, the user agent
must queue a task to fire a simple event
named start
at the element.
The behavior
content
attribute on marquee
elements is an enumerated
attribute with the following keywords (all
non-conforming):
Keyword | State |
---|---|
scroll
| scroll |
slide
| slide |
alternate
| alternate |
The missing value default is the scroll state.
The direction
content
attribute on marquee
elements is an enumerated
attribute with the following keywords (all
non-conforming):
Keyword | State |
---|---|
left
| left |
right
| right |
up
| up |
down
| down |
The missing value default is the left state.
The truespeed
content
attribute on marquee
elements is a boolean
attribute.
A marquee
element has a marquee scroll
interval, which is obtained as follows:
If the element has a scrolldelay
attribute, and
parsing its value using the rules for parsing non-negative
integers does not return an error, then let delay be the parsed value. Otherwise, let delay be 85.
If the element does not have a truespeed
attribute, and the
delay value is less than 60, then let delay be 60 instead.
The marquee scroll interval is delay, interpreted in milliseconds.
A marquee
element has a marquee scroll
distance, which, if the element has a scrollamount
attribute, and
parsing its value using the rules for parsing non-negative
integers does not return an error, is the parsed value
interpreted in CSS pixels, and otherwise is 6 CSS pixels.
A marquee
element has a marquee loop
count, which, if the element has a loop
attribute, and parsing its
value using the rules for parsing integers does not
return an error or a number less than 1, is the parsed value, and
otherwise is −1.
The loop
IDL
attribute, on getting, must return the element's marquee loop
count; and on setting, if the new value is different than the
element's marquee loop count and either greater than
zero or equal to −1, must set the element's loop
content attribute (adding it
if necessary) to the valid integer that represents the
new value. (Other values are ignored.)
A marquee
element also has a marquee current
loop index, which is zero when the element is created.
The rendering layer will occasionally increment the marquee current loop index, which must cause the following steps to be run:
If the marquee loop count is −1, then abort these steps.
Increment the marquee current loop index by one.
If the marquee current loop index is now equal to
or greater than the element's marquee loop count,
turn off the
marquee
element and queue a task to
fire a simple event named finish
at the marquee
element.
Otherwise, if the behavior
attribute is in the
alternate
state, then queue a task to fire a simple
event named bounce
at
the marquee
element.
Otherwise, queue a task to fire a simple
event named start
at the
marquee
element.
The following are the event handlers (and their
corresponding event handler
event types) that must be supported, as content and IDL
attributes, by marquee
elements:
Event handler | Event handler event type |
---|---|
onbounce | bounce
|
onfinish | finish
|
onstart | start
|
The behavior
, direction
, height
, hspace
, vspace
, and width
IDL attributes
must reflect the respective content attributes of the
same name.
The bgColor
IDL attribute must reflect the bgcolor
content attribute.
The scrollAmount
IDL attribute must reflect the scrollamount
content
attribute. The default value is 6.
The scrollDelay
IDL
attribute must reflect the scrolldelay
content
attribute. The default value is 85.
The trueSpeed
IDL
attribute must reflect the truespeed
content
attribute.
The frameset
element acts as the
body element in documents that use frames.
The frameset
element must implement the
HTMLFrameSetElement
interface.
interface HTMLFrameSetElement : HTMLElement { attribute DOMString cols; attribute DOMString rows; attribute Function onafterprint; attribute Function onbeforeprint; attribute Function onbeforeunload; attribute Function onblur; attribute Function onerror; attribute Function onfocus; attribute Function onhashchange; attribute Function onload; attribute Function onmessage; attribute Function onoffline; attribute Function ononline; attribute Function onpagehide; attribute Function onpageshow; attribute Function onpopstate; attribute Function onredo; attribute Function onresize; attribute Function onscroll; attribute Function onstorage; attribute Function onundo; attribute Function onunload; };
The cols
and
rows
IDL
attributes of the frameset
element must
reflect the respective content attributes of the same
name.
The frameset
element must support the following
event handler content attributes exposing the
event handlers of the Window
object:
onafterprint
onbeforeprint
onbeforeunload
onblur
onerror
onfocus
onhashchange
onload
onmessage
onoffline
ononline
onpagehide
onpageshow
onpopstate
onredo
onresize
onscroll
onstorage
onundo
onunload
The DOM interface also exposes event handler IDL
attributes that mirror those on the Window
element.
The onblur
, onerror
, onfocus
, onload
, and onscroll
event handler
IDL attributes of the Window
object, exposed on
the frameset
element, shadow the generic event
handler IDL attributes with the same names normally supported
by HTML elements.
The frame
element defines a nested
browsing context similar to the iframe
element,
but rendered within a frameset
element.
When the browsing context is created, if a src
attribute is present, the user
agent must resolve the value of
that attribute, relative to the element, and if that is successful,
must then navigate the element's
browsing context to the resulting absolute URL, with
replacement enabled, and with the frame
element's document's browsing context as the
source browsing context.
Whenever the src
attribute is
set, the user agent must resolve
the value of that attribute, relative to the element, and if that is
successful, the nested browsing context must be navigated to the resulting
absolute URL, with the frame
element's
document's browsing context as the source
browsing context.
When the browsing context is created, if a name
attribute is present, the
browsing context name must be set to the value of this
attribute; otherwise, the browsing context name must be
set to the empty string.
Whenever the name
attribute
is set, the nested browsing context's name must be changed to the new
value. If the attribute is removed, the browsing context
name must be set to the empty string.
When content loads in a frame
, after any load
events are fired within the content
itself, the user agent must queue a task to fire
a simple event named load
at
the frame
element. When content fails to load (e.g. due
to a network error), then the user agent must queue a
task to fire a simple event named error
at the element instead.
The task source for the tasks above is the DOM manipulation task source.
When there is an active parser in the
frame
, and when anything in the frame
is
delaying the load event of
the frame
's browsing context's
active document, the frame
must
delay the load event of its document.
The frame
element must implement the
HTMLFrameElement
interface.
interface HTMLFrameElement : HTMLElement { attribute DOMString frameBorder; attribute DOMString longDesc; attribute DOMString marginHeight; attribute DOMString marginWidth; attribute DOMString name; attribute boolean noResize; attribute DOMString scrolling; attribute DOMString src; readonly attribute Document contentDocument; readonly attribute WindowProxy contentWindow; };
The name
, scrolling
, and src
IDL attributes of the
frame
element must reflect the respective
content attributes of the same name.
The frameBorder
IDL
attribute of the frame
element must
reflect the element's frameborder
content
attribute.
The longDesc
IDL attribute of the frame
element must
reflect the element's longdesc
content attribute, which
for the purposes of reflection is defined as containing a
URL.
The marginHeight
IDL
attribute of the frame
element must
reflect the element's marginheight
content
attribute.
The marginWidth
IDL
attribute of the frame
element must
reflect the element's marginwidth
content
attribute.
The noResize
IDL attribute of the frame
element must
reflect the element's noresize
content attribute.
The contentDocument
IDL attribute of the frame
element must return the
Document
object of the active document of
the frame
element's nested browsing
context.
The contentWindow
IDL attribute must return the WindowProxy
object of the
frame
element's nested browsing
context.
User agents must treat acronym
elements in a manner
equivalent to abbr
elements in terms of semantics and
for purposes of rendering.
[Supplemental] interface HTMLAnchorElement { attribute DOMString coords; attribute DOMString charset; attribute DOMString name; attribute DOMString rev; attribute DOMString shape; };
The coords
, charset
, name
, rev
, and shape
IDL attributes of the
a
element must reflect the respective
content attributes of the same name.
[Supplemental] interface HTMLAreaElement { attribute boolean noHref; };
The noHref
IDL
attribute of the area
element must reflect
the element's nohref
content
attribute.
The basefont
element must implement the
HTMLBaseFontElement
interface.
interface HTMLBaseFontElement : HTMLElement { attribute DOMString color; attribute DOMString face; attribute long size; };
The color
,
face
, and size
IDL attributes of
the basefont
element must reflect the
respective content attributes of the same name.
[Supplemental] interface HTMLBodyElement { attribute DOMString text; attribute DOMString bgColor; attribute DOMString background; attribute DOMString link; attribute DOMString vLink; attribute DOMString aLink; };
The text
IDL
attribute of the body
element must reflect
the element's text
content
attribute.
The bgColor
IDL
attribute of the body
element must reflect
the element's bgcolor
content
attribute.
The background
IDL
attribute of the body
element must reflect
the element's background
content attribute. (The background
content is not
defined to contain a URL, despite rules regarding its
handling in the rendering section above.)
The link
IDL
attribute of the body
element must reflect
the element's link
content
attribute.
The aLink
IDL
attribute of the body
element must reflect
the element's alink
content
attribute.
The vLink
IDL
attribute of the body
element must reflect
the element's vlink
content
attribute.
[Supplemental] interface HTMLBRElement { attribute DOMString clear; };
The clear
IDL
attribute of the br
element must reflect
the content attribute of the same name.
[Supplemental] interface HTMLTableCaptionElement { attribute DOMString align; };
The align
IDL
attribute of the caption
element must
reflect the content attribute of the same name.
[Supplemental] interface HTMLTableColElement { attribute DOMString align; attribute DOMString ch; attribute DOMString chOff; attribute DOMString vAlign; attribute DOMString width; };
The align
and width
IDL attributes of
the col
element must reflect the
respective content attributes of the same name.
The ch
IDL attribute
of the col
element must reflect the
element's char
content
attribute.
The chOff
IDL
attribute of the col
element must reflect
the element's charoff
content
attribute.
The vAlign
IDL
attribute of the col
element must reflect
the element's valign
content
attribute.
User agents must treat dir
elements in a manner
equivalent to ul
elements in terms of semantics and for
purposes of rendering.
The dir
element must implement the
HTMLDirectoryElement
interface.
interface HTMLDirectoryElement : HTMLElement { attribute boolean compact; };
The compact
IDL
attribute of the dir
element must reflect
the content attribute of the same name.
[Supplemental] interface HTMLDivElement { attribute DOMString align; };
The align
IDL
attribute of the div
element must reflect
the content attribute of the same name.
[Supplemental] interface HTMLDListElement { attribute boolean compact; };
The compact
IDL
attribute of the dl
element must reflect
the content attribute of the same name.
[Supplemental] interface HTMLEmbedElement { attribute DOMString align; attribute DOMString name; };
The name
and align
IDL attributes of
the embed
element must reflect the
respective content attributes of the same name.
The font
element must implement the
HTMLFontElement
interface.
interface HTMLFontElement : HTMLElement { attribute DOMString color; attribute DOMString face; attribute DOMString size; };
The color
,
face
, and size
IDL attributes of
the font
element must reflect the
respective content attributes of the same name.
[Supplemental] interface HTMLHeadingElement { attribute DOMString align; };
The align
IDL
attribute of the h1
–h6
elements must
reflect the content attribute of the same name.
The profile
IDL attribute on
head
elements (with the HTMLHeadElement
interface) is intentionally omitted. Unless so required by another applicable
specification, implementations would therefore not support
this attribute. (It is mentioned here as it was defined in a
previous version of the DOM specifications.)
[Supplemental] interface HTMLHRElement { attribute DOMString align; attribute DOMString color; attribute boolean noShade; attribute DOMString size; attribute DOMString width; };
The align
, color
, size
, and width
IDL attributes of the
hr
element must reflect the respective
content attributes of the same name.
The noShade
IDL
attribute of the hr
element must reflect
the element's noshade
content attribute.
[Supplemental] interface HTMLHtmlElement { attribute DOMString version; };
The version
IDL
attribute of the html
element must reflect
the content attribute of the same name.
[Supplemental] interface HTMLIFrameElement { attribute DOMString align; attribute DOMString frameBorder; attribute DOMString longDesc; attribute DOMString marginHeight; attribute DOMString marginWidth; attribute DOMString scrolling; };
The align
and
scrolling
IDL
attributes of the iframe
element must
reflect the respective content attributes of the same
name.
The frameBorder
IDL
attribute of the iframe
element must
reflect the element's frameborder
content
attribute.
The longDesc
IDL attribute of the iframe
element must
reflect the element's longdesc
content attribute,
which for the purposes of reflection is defined as containing a
URL.
The marginHeight
IDL
attribute of the iframe
element must
reflect the element's marginheight
content
attribute.
The marginWidth
IDL
attribute of the iframe
element must
reflect the element's marginwidth
content
attribute.
[Supplemental] interface HTMLImageElement { attribute DOMString name; attribute DOMString align; attribute DOMString border; attribute unsigned long hspace; attribute DOMString longDesc; attribute unsigned long vspace; };
The name
, align
, border
, hspace
, and vspace
IDL attributes of
the img
element must reflect the
respective content attributes of the same name.
The longDesc
IDL
attribute of the img
element must reflect
the element's longdesc
content attribute, which for the purposes of reflection is defined
as containing a URL.
[Supplemental] interface HTMLInputElement { attribute DOMString align; attribute DOMString useMap; };
The align
IDL
attribute of the input
element must reflect
the content attribute of the same name.
The useMap
IDL
attribute of the input
element must
reflect the element's usemap
content attribute.
[Supplemental] interface HTMLLegendElement { attribute DOMString align; };
The align
IDL
attribute of the legend
element must reflect
the content attribute of the same name.
[Supplemental] interface HTMLLIElement { attribute DOMString type; };
The type
IDL
attribute of the li
element must reflect
the content attribute of the same name.
[Supplemental] interface HTMLLinkElement { attribute DOMString charset; attribute DOMString rev; attribute DOMString target; };
The charset
,
rev
, and target
IDL attributes of
the link
element must reflect the
respective content attributes of the same name.
User agents must treat listing
elements in a manner
equivalent to pre
elements in terms of semantics and
for purposes of rendering.
[Supplemental] interface HTMLMenuElement { attribute boolean compact; };
The compact
IDL
attribute of the menu
element must reflect
the content attribute of the same name.
[Supplemental] interface HTMLMetaElement { attribute DOMString scheme; };
User agents may treat the scheme
content attribute on the
meta
element as an extension of the element's name
content attribute when processing
a meta
element with a name
attribute whose value is one that
the user agent recognizes as supporting the scheme
attribute.
User agents are encouraged to ignore the scheme
attribute and instead process
the value given to the metadata name as if it had been specified for
each expected value of the scheme
attribute.
For example, if the user agent acts on meta
elements with name
attributes
having the value "eGMS.subject.keyword", and knows that the scheme
attribute is used with this
metadata name, then it could take the scheme
attribute into account,
acting as if it was an extension of the name
attribute. Thus the following
two meta
elements could be treated as two elements
giving values for two different metadata names, one consisting of a
combination of "eGMS.subject.keyword" and "LGCL", and the other
consisting of a combination of "eGMS.subject.keyword" and
"ORLY":
<!-- this markup is invalid --> <meta name="eGMS.subject.keyword" scheme="LGCL" content="Abandoned vehicles"> <meta name="eGMS.subject.keyword" scheme="ORLY" content="Mah car: kthxbye">
The recommended processing of this markup, however, would be equivalent to the following:
<meta name="eGMS.subject.keyword" content="Abandoned vehicles"> <meta name="eGMS.subject.keyword" content="Mah car: kthxbye">
The scheme
IDL
attribute of the meta
element must reflect
the content attribute of the same name.
[Supplemental] interface HTMLObjectElement { attribute DOMString align; attribute DOMString archive; attribute DOMString border; attribute DOMString code; attribute DOMString codeBase; attribute DOMString codeType; attribute boolean declare; attribute unsigned long hspace; attribute DOMString standby; attribute unsigned long vspace; };
The align
, archive
, border
, code
, declare
, hspace
, standby
, and vspace
IDL attributes
of the object
element must reflect the
respective content attributes of the same name.
The codeBase
IDL attribute of the object
element must
reflect the element's codebase
content attribute,
which for the purposes of reflection is defined as containing a
URL.
The codeType
IDL
attribute of the object
element must reflect
the element's codetype
content
attribute.
[Supplemental] interface HTMLOListElement { attribute boolean compact; };
The compact
IDL
attribute of the ol
element must reflect
the content attribute of the same name.
[Supplemental] interface HTMLParagraphElement { attribute DOMString align; };
The align
IDL
attribute of the p
element must reflect
the content attribute of the same name.
[Supplemental] interface HTMLParamElement { attribute DOMString type; attribute DOMString valueType; };
The type
IDL
attribute of the param
element must
reflect the content attribute of the same name.
The valueType
IDL attribute of the param
element must
reflect the element's valuetype
content attribute.
User agents must treat plaintext
elements in a
manner equivalent to pre
elements in terms of semantics
and for purposes of rendering. (The parser has special behavior for
this element, though.)
[Supplemental] interface HTMLPreElement { attribute unsigned long width; };
The width
IDL
attribute of the pre
element must reflect
the content attribute of the same name.
[Supplemental] interface HTMLScriptElement { attribute DOMString event; attribute DOMString htmlFor; };
The event
and
htmlFor
IDL
attributes of the script
element must return the empty
string on getting, and do nothing on setting.
[Supplemental] interface HTMLTableElement { attribute DOMString align; attribute DOMString bgColor; attribute DOMString cellPadding; attribute DOMString cellSpacing; attribute DOMString frame; attribute DOMString rules; attribute DOMString summary; attribute DOMString width; };
The align
, frame
, summary
, rules
, and width
, IDL attributes of
the table
element must reflect the
respective content attributes of the same name.
The bgColor
IDL
attribute of the table
element must reflect
the element's bgcolor
content
attribute.
The cellPadding
IDL
attribute of the table
element must reflect
the element's cellpadding
content
attribute.
The cellSpacing
IDL
attribute of the table
element must reflect
the element's cellspacing
content
attribute.
[Supplemental] interface HTMLTableSectionElement { attribute DOMString align; attribute DOMString ch; attribute DOMString chOff; attribute DOMString vAlign; };
The align
IDL
attribute of the tbody
, thead
, and
tfoot
elements must reflect the content
attribute of the same name.
The ch
IDL attribute
of the tbody
, thead
, and
tfoot
elements must reflect the elements'
char
content attributes.
The chOff
IDL
attribute of the tbody
, thead
, and
tfoot
elements must reflect the elements'
charoff
content attributes.
The vAlign
IDL
attribute of the tbody
, thead
, and
tfoot
element must reflect the elements'
valign
content
attributes.
[Supplemental] interface HTMLTableCellElement { attribute DOMString abbr; attribute DOMString align; attribute DOMString axis; attribute DOMString bgColor; attribute DOMString ch; attribute DOMString chOff; attribute DOMString height; attribute boolean noWrap; attribute DOMString vAlign; attribute DOMString width; };
The abbr
, align
, axis
, height
, and width
IDL attributes of
the td
and th
elements must
reflect the respective content attributes of the same
name.
The bgColor
IDL
attribute of the td
and th
elements must
reflect the elements' bgcolor
content attributes.
The ch
IDL
attribute of the td
and th
elements must
reflect the elements' char
content attributes.
The chOff
IDL
attribute of the td
and th
elements must
reflect the elements' charoff
content attributes.
The noWrap
IDL
attribute of the td
and th
elements must
reflect the elements' nowrap
content attributes.
The vAlign
IDL
attribute of the td
and th
element must
reflect the elements' valign
content attributes.
[Supplemental] interface HTMLTableRowElement { attribute DOMString align; attribute DOMString bgColor; attribute DOMString ch; attribute DOMString chOff; attribute DOMString vAlign; };
The align
IDL
attribute of the tr
element must reflect
the content attribute of the same name.
The bgColor
IDL
attribute of the tr
element must reflect
the element's bgcolor
content
attribute.
The ch
IDL attribute of
the tr
element must reflect the element's
char
content attribute.
The chOff
IDL
attribute of the tr
element must reflect
the element's charoff
content
attribute.
The vAlign
IDL
attribute of the tr
element must reflect
the element's valign
content
attribute.
[Supplemental] interface HTMLUListElement { attribute boolean compact; attribute DOMString type; };
The compact
and
type
IDL attributes of
the ul
element must reflect the respective
content attributes of the same name.
User agents must treat xmp
elements in a manner
equivalent to pre
elements in terms of semantics and
for purposes of rendering. (The parser has special behavior for this
element though.)
The bgsound
, isindex
,
multicol
, nextid
, rb
, and
spacer
elements must use the
HTMLUnknownElement
interface.
[Supplemental] interface HTMLDocument { attribute DOMString fgColor; attribute DOMString bgColor; attribute DOMString linkColor; attribute DOMString vlinkColor; attribute DOMString alinkColor; readonly attribute HTMLCollection anchors; readonly attribute HTMLCollection applets; void clear(); readonly attribute HTMLAllCollection all; };
The attributes of the Document
object listed in the
first column of the following table must reflect the
content attribute on the body element with the name
given in the corresponding cell in the second column on the same
row, if the body element is a body
element
(as opposed to a frameset
element). When there is no
body element or if it is a
frameset
element, the attributes must instead return
the empty string on getting and do nothing on setting.
IDL attribute | Content attribute |
---|---|
fgColor
| text
|
bgColor
| bgcolor
|
linkColor
| link
|
vlinkColor
| vlink
|
alinkColor
| alink
|
The anchors
attribute must return an HTMLCollection
rooted at the
Document
node, whose filter matches only a
elements with name
attributes.
The applets
attribute must return an HTMLCollection
rooted at the
Document
node, whose filter matches only
applet
elements.
The clear()
method must do nothing.
The all
attribute must return an HTMLAllCollection
rooted at the
Document
node, whose filter matches all elements.
The object returned for all
has several unusual behaviors:
The user agent must act as if the ToBoolean() operator in
JavaScript converts the object returned for all
to the false value.
The user agent must act as if, for the purposes of the ==
and !=
operators in
JavaScript, the object returned for all
is equal to the undefined
value.
The user agent must act such that the typeof
operator in JavaScript returns the string
undefined
when applied to the object returned
for all
.
These requirements are a willful
violation of the JavaScript specification current at the time
of writing (ECMAScript edition 3). The JavaScript specification
requires that the ToBoolean() operator convert all objects to the
true value, and does not have provisions for objects acting as if
they were undefined
for the purposes of
certain operators. This violation is motivated by a desire for
compatibility with two classes of legacy content: one that uses the
presence of document.all
as a
way to detect legacy user agents, and one that only supports those
legacy user agents and uses the document.all
object without testing
for its presence first. [ECMA262]
text/html
This registration is for community review and will be submitted to the IESG for review, approval, and registration with IANA.
charset
The charset
parameter may be provided
to definitively specify the document's character
encoding, overriding any character encoding declarations in the
document. The parameter's value must be the name of the
character encoding used to serialize the file, must be a valid
character encoding name, and must be an ASCII
case-insensitive match for the preferred MIME
name for that encoding. [IANACHARSET]
Entire novels have been written about the security considerations that apply to HTML documents. Many are listed in this document, to which the reader is referred for more details. Some general concerns bear mentioning here, however:
HTML is scripted language, and has a large number of APIs (some of which are described in this document). Script can expose the user to potential risks of information leakage, credential leakage, cross-site scripting attacks, cross-site request forgeries, and a host of other problems. While the designs in this specification are intended to be safe if implemented correctly, a full implementation is a massive undertaking and, as with any software, user agents are likely to have security bugs.
Even without scripting, there are specific features in HTML
which, for historical reasons, are required for broad
compatibility with legacy content but that expose the user to
unfortunate security problems. In particular, the img
element can be used in conjunction with some other features as a
way to effect a port scan from the user's location on the
Internet. This can expose local network topologies that the
attacker would otherwise not be able to determine.
HTML relies on a compartmentalization scheme sometimes known as the same-origin policy. An origin in most cases consists of all the pages served from the same host, on the same port, using the same protocol.
It is critical, therefore, to ensure that any untrusted content that forms part of a site be hosted on a different origin than any sensitive content on that site. Untrusted content can easily spoof any other page on the same origin, read data from that origin, cause scripts in that origin to execute, submit forms to and from that origin even if they are protected from cross-site request forgery attacks by unique tokens, and make use of any third-party resources exposed to or rights granted to that origin.
html
" and "htm
"
are commonly, but certainly not exclusively, used as the
extension for HTML documents.TEXT
Fragment identifiers used with text/html
resources
refer to the indicated part of the document.
text/html-sandboxed
This registration is for community review and will be submitted to the IESG for review, approval, and registration with IANA.
text/html
text/html
The purpose of the text/html-sandboxed
MIME type
is to provide a way for content providers to indicate that they
want the file to be interpreted in a manner that does not give the
file's contents access to the rest of the site. This is achieved
by assigning the Document
objects generated from
resources labeled as text/html-sandboxed
unique
origins.
To avoid having legacy user agents treating resources labeled
as text/html-sandboxed
as regular
text/html
files, authors should avoid using the .html
or .htm
extensions for
resources labeled as text/html-sandboxed
.
Furthermore, since the text/html-sandboxed
MIME
type impacts the origin security model, authors should be careful
to prevent tampering with the MIME type labeling mechanism itself
when documents are labeled as text/html-sandboxed
. If
an attacker can cause a file to be served as
text/html
instead of
text/html-sandboxed
, then the sandboxing will not
take effect and a cross-site scripting attack will become
possible.
Beyond this, the type is identical to text/html
,
and the same considerations apply.
text/html
text/html-sandboxed
type asserts that the
resource is an HTML document
using the HTML syntax.
text/html
text/html-sandboxed
are
heuristically indistinguishable from those labeled as
text/html
.sandboxed
"TEXT
Fragment identifiers used with text/html-sandboxed
resources refer to the indicated part of the
document.
application/xhtml+xml
This registration is for community review and will be submitted to the IESG for review, approval, and registration with IANA.
application/xml
[RFC3023]application/xml
[RFC3023]application/xml
[RFC3023]application/xml
[RFC3023]application/xml
[RFC3023]application/xhtml+xml
type asserts that the resource is an XML document that likely has
a root element from the HTML namespace. As such, the
relevant specifications are the XML specification, the Namespaces
in XML specification, and this specification. [XML] [XMLNS]
application/xml
[RFC3023]application/xml
[RFC3023]xhtml
" and "xht
"
are sometimes used as extensions for XML resources that have a
root element from the HTML namespace.TEXT
Fragment identifiers used with application/xhtml+xml
resources have the same semantics as with any XML MIME
type. [RFC3023]
text/cache-manifest
This registration is for community review and will be submitted to the IESG for review, approval, and registration with IANA.
Cache manifests themselves pose no immediate risk unless sensitive information is included within the manifest. Implementations, however, are required to follow specific rules when populating a cache based on a cache manifest, to ensure that certain origin-based restrictions are honored. Failure to correctly implement these rules can result in information leakage, cross-site scripting attacks, and the like.
CACHE
MANIFEST
", followed by either a U+0020 SPACE character, a
U+0009 CHARACTER TABULATION (tab) character, a U+000A LINE FEED
(LF) character, or a U+000D CARRIAGE RETURN (CR) character.appcache
"Fragment identifiers have no meaning with
text/cache-manifest
resources.
The following sections only cover conforming elements and features.
This section is non-normative.
An asterisk (*) in a cell indicates that the actual rules are more complicated than indicated in the table above.
† Categories in the "Parents" column refer to parents that
list the given categories in their content model, not to elements
that themselves are in those categories. For example, the
a
element's "Parents" column says "phrasing", so any
element whose content model contains the "phrasing" category could
be a parent of an a
element. Since the "flow" category
includes all the "phrasing" elements, that means the
address
element could be a parent to an a
element.
This section is non-normative.
This section is non-normative.
Attribute | Element(s) | Description | Value |
---|---|---|---|
accept
| input
| Hint for expected file type in file upload controls | Set of comma-separated tokens* consisting of valid MIME types with no parameters or audio/* , video/* , or image/*
|
accept-charset
| form
| Character encodings to use for form submission | Ordered set of unique space-separated tokens, ASCII case-insensitive, consisting of preferred MIME names of ASCII-compatible character encodings* |
accesskey
| HTML elements | Keyboard shortcut to activate or focus element | Ordered set of unique space-separated tokens, case-sensitive, consisting of one Unicode code point in length |
action
| form
| URL to use for form submission | Valid URL potentially surrounded by spaces |
alt
| area ;
img ;
input
| Replacement text for use when images are not available | Text* |
async
| script
| Execute script asynchronously | Boolean attribute |
autocomplete
| form ;
input
| Prevent the user agent from providing autocompletions for the form control(s) | "on "; "off "
|
autofocus
| button ;
input ;
keygen ;
select ;
textarea
| Automatically focus the form control when the page is loaded | Boolean attribute |
autoplay
| audio ;
video
| Hint that the media resource can be started automatically when the page is loaded | Boolean attribute |
border
| border
| Explicit indication that the table element is not being used for layout purposes
| The empty string, or "1 "
|
challenge
| keygen
| String to package with the generated and signed public key | Text |
charset
| meta
| Character encoding declaration | Preferred MIME name of an encoding* |
charset
| script
| Character encoding of the external script resource | Preferred MIME name of an encoding* |
checked
| command ;
input
| Whether the command or control is checked | Boolean attribute |
cite
| blockquote ;
del ;
ins ;
q
| Link to the source of the quotation or more information about the edit | Valid URL potentially surrounded by spaces |
class
| HTML elements | Classes to which the element belongs | Set of space-separated tokens |
cols
| textarea
| Maximum number of characters per line | Valid non-negative integer greater than zero |
colspan
| td ;
th
| Number of columns that the cell is to span | Valid non-negative integer greater than zero |
content
| meta
| Value of the element | Text* |
contenteditable
| HTML elements | Whether the element is editable | "true "; "false "
|
contextmenu
| HTML elements | The element's context menu | ID* |
controls
| audio ;
video
| Show user agent controls | Boolean attribute |
coords
| area
| Coordinates for the shape to be created in an image map | Valid list of integers* |
data
| object
| Address of the resource | Valid non-empty URL potentially surrounded by spaces |
datetime
| del ;
ins
| Date and (optionally) time of the change | Valid date string with optional time |
datetime
| time
| Value of the element | Valid date or time string* |
default
| track
| Enable the track if no other text track is more suitable. | Boolean attribute |
defer
| script
| Defer script execution | Boolean attribute |
dir
| HTML elements | The text directionality of the element | "ltr "; "rtl "
|
dirname
| input ;
textarea
| Name of form field to use for sending the element's directionality in form submission | Text* |
disabled
| button ;
command ;
fieldset ;
input ;
keygen ;
optgroup ;
option ;
select ;
textarea
| Whether the form control is disabled | Boolean attribute |
draggable
| HTML elements | Whether the element is draggable | "true "; "false "
|
dropzone
| HTML elements | Accepted item types for drag-and-drop | Unordered set of unique space-separated tokens, ASCII case-insensitive, consisting of accepted types and drag feedback* |
enctype
| form
| Form data set encoding type to use for form submission | "application/x-www-form-urlencoded "; "multipart/form-data "; "text/plain "
|
for
| label
| Associate the label with form control | ID* |
for
| output
| Specifies controls from which the output was calculated | Unordered set of unique space-separated tokens, case-sensitive, consisting of IDs* |
form
| button ;
fieldset ;
input ;
keygen ;
label ;
meter ;
object ;
output ;
progress ;
select ;
textarea
| Associates the control with a form element
| ID* |
formaction
| button ;
input
| URL to use for form submission | Valid URL potentially surrounded by spaces |
formenctype
| button ;
input
| Form data set encoding type to use for form submission | "application/x-www-form-urlencoded "; "multipart/form-data "; "text/plain "
|
formmethod
| button ;
input
| HTTP method to use for form submission | "GET "; "POST "
|
formnovalidate
| button ;
input
| Bypass form control validation for form submission | Boolean attribute |
formtarget
| button ;
input
| Browsing context for form submission | Valid browsing context name or keyword |
headers
| td ;
th
| The header cells for this cell | Unordered set of unique space-separated tokens, case-sensitive, consisting of IDs* |
height
| canvas ;
embed ;
iframe ;
img ;
input ;
object ;
video
| Vertical dimension | Valid non-negative integer |
hidden
| HTML elements | Whether the element is relevant | Boolean attribute |
high
| meter
| Low limit of high range | Valid floating point number* |
href
| a ;
area
| Address of the hyperlink | Valid URL potentially surrounded by spaces |
href
| link
| Address of the hyperlink | Valid non-empty URL potentially surrounded by spaces |
href
| base
| Document base URL | Valid URL potentially surrounded by spaces |
hreflang
| a ;
area ;
link
| Language of the linked resource | Valid BCP 47 language tag |
http-equiv
| meta
| Pragma directive | Text* |
icon
| command
| Icon for the command | Valid non-empty URL potentially surrounded by spaces |
id
| HTML elements | The element's ID | Text* |
ismap
| img
| Whether the image is a server-side image map | Boolean attribute |
keytype
| keygen
| The type of cryptographic key to generate | Text* |
kind
| track
| The type of text track | "subtitles ";
"captions ";
"descriptions ";
"chapters ";
"metadata "
|
label
| command ;
menu ;
optgroup ;
option ;
track
| User-visible label | Text |
lang
| HTML elements | Language of the element | Valid BCP 47 language tag or the empty string |
list
| input
| List of autocomplete options | ID* |
loop
| audio ;
video
| Whether to loop the media resource | Boolean attribute |
low
| meter
| High limit of low range | Valid floating point number* |
manifest
| html
| Application cache manifest | Valid non-empty URL potentially surrounded by spaces |
max
| input
| Maximum value | varies* |
max
| meter ;
progress
| Upper bound of range | Valid floating point number* |
maxlength
| input ;
textarea
| Maximum length of value | Valid non-negative integer |
media
| a ;
area ;
link ;
source ;
style
| Applicable media | Valid media query |
mediagroup
| audio ;
video
| Groups media elements together with an implicit MediaController
| Text |
method
| form
| HTTP method to use for form submission | "GET "; "POST "
|
min
| input
| Minimum value | varies* |
min
| meter
| Lower bound of range | Valid floating point number* |
multiple
| input ;
select
| Whether to allow multiple values | Boolean attribute |
name
| button ;
fieldset ;
input ;
keygen ;
output ;
select ;
textarea
| Name of form control to use for form submission and in the form.elements API
| Text* |
name
| form
| Name of form to use in the document.forms API
| Text* |
name
| iframe ;
object
| Name of nested browsing context | Valid browsing context name or keyword |
name
| map
| Name of image map to reference from the usemap attribute
| Text* |
name
| meta
| Metadata name | Text* |
name
| param
| Name of parameter | Text |
novalidate
| form
| Bypass form control validation for form submission | Boolean attribute |
open
| details
| Whether the details are visible | Boolean attribute |
optimum
| meter
| Optimum value in gauge | Valid floating point number* |
pattern
| input
| Pattern to be matched by the form control's value | Regular expression matching the JavaScript Pattern production |
placeholder
| input ;
textarea
| User-visible label to be placed within the form control | Text* |
poster
| video
| Poster frame to show prior to video playback | Valid non-empty URL potentially surrounded by spaces |
preload
| audio ;
video
| Hints how much buffering the media resource will likely need | "none ";
"metadata ";
"auto "
|
pubdate
| time
| Whether the element's value represents a publication time for the nearest article or body
| Boolean attribute |
radiogroup
| command
| Name of group of commands to treat as a radio button group | Text |
readonly
| input ;
textarea
| Whether to allow the value to be edited by the user | Boolean attribute |
rel
| a ;
area ;
link
| Relationship between the document containing the hyperlink and the destination resource | Set of space-separated tokens* |
required
| input ;
select ;
textarea
| Whether the control is required for form submission | Boolean attribute |
reversed
| ol
| Number the list backwards | Boolean attribute |
rows
| textarea
| Number of lines to show | Valid non-negative integer greater than zero |
rowspan
| td ;
th
| Number of rows that the cell is to span | Valid non-negative integer |
sandbox
| iframe
| Security rules for nested content | Unordered set of unique space-separated tokens, ASCII case-insensitive, consisting of
"allow-same-origin ",
"allow-forms ", and
"allow-scripts "
|
spellcheck
| HTML elements | Whether the element is to have its spelling and grammar checked | "true "; "false "
|
scope
| th
| Specifies which cells the header cell applies to | "row ";
"col ";
"rowgroup ";
"colgroup "
|
scoped
| style
| Whether the styles apply to the entire document or just the parent subtree | Boolean attribute |
seamless
| iframe
| Whether to apply the document's styles to the nested content | Boolean attribute |
selected
| option
| Whether the option is selected by default | Boolean attribute |
shape
| area
| The kind of shape to be created in an image map | "circle ";
"default ";
"poly ";
"rect "
|
size
| input ;
select
| Size of the control | Valid non-negative integer greater than zero |
sizes
| link
| Sizes of the icons (for rel ="icon ")
| Unordered set of unique space-separated tokens, ASCII case-insensitive, consisting of sizes* |
span
| col ;
colgroup
| Number of columns spanned by the element | Valid non-negative integer greater than zero |
src
| audio ;
embed ;
iframe ;
img ;
input ;
script ;
source ;
track ;
video
| Address of the resource | Valid non-empty URL potentially surrounded by spaces |
srcdoc
| iframe
| A document to render in the iframe
| The source of an iframe srcdoc document*
|
srclang
| track
| Language of the text track | Valid BCP 47 language tag |
start
| ol
| Ordinal value of the first item | Valid integer |
step
| input
| Granularity to be matched by the form control's value | Valid floating point number greater than zero, or "any "
|
style
| HTML elements | Presentational and formatting instructions | CSS declarations* |
tabindex
| HTML elements | Whether the element is focusable, and the relative order of the element for the purposes of sequential focus navigation | Valid integer |
target
| a ;
area
| Browsing context for hyperlink navigation | Valid browsing context name or keyword |
target
| base
| Default browsing context for hyperlink navigation and form submission | Valid browsing context name or keyword |
target
| form
| Browsing context for form submission | Valid browsing context name or keyword |
title
| HTML elements | Advisory information for the element | Text |
title
| abbr ;
dfn
| Full term or expansion of abbreviation | Text |
title
| command
| Hint describing the command | Text |
title
| link
| Title of the link | Text |
title
| link ;
style
| Alternative style sheet set name | Text |
type
| a ;
area ;
link
| Hint for the type of the referenced resource | Valid MIME type |
type
| button
| Type of button | "submit ";
"reset ";
"button "
|
type
| button ;
input
| Type of form control | input type keyword
|
type
| command
| Type of command | "command ";
"checkbox ";
"radio "
|
type
| embed ;
object ;
script ;
source ;
style
| Type of embedded resource | Valid MIME type |
type
| menu
| Type of menu | "context "; "toolbar "
|
usemap
| img ;
object
| Name of image map to use | Valid hash-name reference* |
value
| button ;
option
| Value to be used for form submission | Text |
value
| input
| Value of the form control | varies* |
value
| li
| Ordinal value of the list item | Valid integer |
value
| meter ;
progress
| Current value of the element | Valid floating point number |
value
| param
| Value of parameter | Text |
width
| canvas ;
embed ;
iframe ;
img ;
input ;
object ;
video
| Horizontal dimension | Valid non-negative integer |
wrap
| textarea
| How the value of the form control is to be wrapped for form submission | "soft ";
"hard "
|
An asterisk (*) in a cell indicates that the actual rules are more complicated than indicated in the table above.
This section is non-normative.
This section is non-normative.
Event | Interface | Description |
---|---|---|
DOMContentLoaded
| Event
| Fired at the Document once it and its scripts have loaded, without waiting for other subresources
|
abort
| Event
| Fired at the Window when the download was aborted by the user
|
afterprint
| Event
| Fired at the Window after printing
|
beforeprint
| Event
| Fired at the Window before printing
|
beforeunload
| BeforeUnloadEvent
| Fired at the Window when the page is about to be unloaded, in case the page would like to show a warning prompt
|
blur
| Event
| Fired at nodes losing focus |
change
| Event
| Fired at controls when the user commits a value change |
click
| Event
| Fired at an element before its activation behavior is run |
contextmenu
| Event
| Fired at elements when the user requests their context menu |
error
| Event
| Fired at elements when network and script errors occur |
focus
| Event
| Fired at nodes gaining focus |
hashchange
| HashChangeEvent
| Fired at the Window when the fragment identifier part of the document's current address changes
|
input
| Event
| Fired at controls when the user changes the value |
invalid
| Event
| Fired at controls during form validation if they do not satisfy their constraints |
load
| Event
| Fired at the Window when the document has finished loading; fired at an element containing a resource (e.g. img , embed ) when its resource has finished loading
|
message
| MessageEvent
| Fired at an object when the object receives a message |
offline
| Event
| Fired at the Window when the network connections fails
|
online
| Event
| Fired at the Window when the network connections returns
|
pagehide
| PageTransitionEvent
| Fired at the Window when the page's entry in the session history stops being the current entry
|
pageshow
| PageTransitionEvent
| Fired at the Window when the page's entry in the session history becomes the current entry
|
popstate
| PopStateEvent
| Fired at the Window when the user navigates the session history
|
readystatechange
| Event
| Fired at the Document when it finishes parsing and again when all its subresources have finished loading
|
reset
| Event
| Fired at a form element when it is reset
|
show
| Event
| Fired at a menu element when it is shown as a context menu
|
submit
| Event
| Fired at a form element when it is submitted
|
unload
| Event
| Fired at the Window object when the page is going away
|
See also media element events, application cache events, and drag-and-drop events.
All references are normative unless marked "Non-normative".
XMLHttpRequest
,
A. van Kesteren. W3C.Thanks to Tim Berners-Lee for inventing HTML, without which none of this would exist.
Thanks to Aankhen, Aaron Boodman, Aaron Leventhal, Adam Barth, Adam de Boor, Adam Hepton, Adam Roben, Addison Phillips, Adele Peterson, Adrian Bateman, Adrian Sutton, Agustín Fernández, Ajai Tirumali, Akatsuki Kitamura, Alan Plum, Alastair Campbell, Alejandro G. Castro, Alex Bishop, Alex Nicolaou, Alex Rousskov, Alexander J. Vincent, Alexey Feldgendler, Алексей Проскуряков (Alexey Proskuryakov), Alexis Deveria, Allan Clements, Amos Jeffries, Anders Carlsson, Andreas, Andreas Kling, Andrei Popescu, André E. Veltstra, Andrew Barfield, Andrew Clover, Andrew Gove, Andrew Grieve, Andrew Oakley, Andrew Sidwell, Andrew Smith, Andrew W. Hagen, Andrey V. Lukyanov, Andy Heydon, Andy Palay, Anne van Kesteren, Anthony Boyd, Anthony Bryan, Anthony Hickson, Anthony Ricaud, Antti Koivisto, Arne Thomassen, Aron Spohr, Arphen Lin, Aryeh Gregor, Asbjørn Ulsberg, Ashley Sheridan, Atsushi Takayama, Aurelien Levy, Ave Wrigley, Ben Boyle, Ben Godfrey, Ben Lerner, Ben Leslie, Ben Meadowcroft, Ben Millard, Benjamin Carl Wiley Sittler, Benjamin Hawkes-Lewis, Bert Bos, Bijan Parsia, Bil Corry, Bill Mason, Bill McCoy, Billy Wong, Bjartur Thorlacius, Björn Höhrmann, Blake Frantz, Boris Zbarsky, Brad Fults, Brad Neuberg, Brad Spencer, Brady Eidson, Brendan Eich, Brenton Simpson, Brett Wilson, Brett Zamir, Brian Campbell, Brian Korver, Brian Kuhn, Brian Ryner, Brian Smith, Brian Wilson, Bryan Sullivan, Bruce D'Arcus, Bruce Lawson, Bruce Miller, C. Williams, Cameron McCormack, Cao Yipeng, Carlos Gabriel Cardona, Carlos Perelló Marín, Chao Cai, 윤석찬 (Channy Yun), Charl van Niekerk, Charles Iliya Krempeaux, Charles McCathieNevile, Chris Apers, Chris Cressman, Chris Evans, Chris Morris, Chris Pearce, Christian Biesinger, Christian Johansen, Christian Schmidt, Christopher Aillon, Chriswa, Clark Buehler, Cole Robison, Colin Fine, Collin Jackson, Corprew Reed, Craig Cockburn, Csaba Gabor, Csaba Marton, Cynthia Shelly, Dan Yoder, Daniel Barclay, Daniel Bratell, Daniel Brooks, Daniel Brumbaugh Keeney, Daniel Cheng, Daniel Davis, Daniel Glazman, Daniel Peng, Daniel Schattenkirchner, Daniel Spång, Daniel Steinberg, Danny Sullivan, Darin Adler, Darin Fisher, Darxus, Dave Camp, Dave Hodder, Dave Lampton, Dave Singer, Dave Townsend, David Baron, David Bloom, David Bruant, David Carlisle, David E. Cleary, David Egan Evans, David Flanagan, David Gerard, David Håsäther, David Hyatt, David I. Lehn, David John Burrowes, David Matja, David Remahl, David Smith, David Woolley, DeWitt Clinton, Dean Edridge, Dean Edwards, Debi Orton, Derek Featherstone, Devdatta, Dimitri Glazkov, Dimitry Golubovsky, Dirk Pranke, Divya Manian, Dmitry Titov, dolphinling, Dominique Hazaël-Massieux, Don Brutzman, Doron Rosenberg, Doug Kramer, Doug Simpkinson, Drew Wilson, Edmund Lai, Eduard Pascual, Eduardo Vela, Edward O'Connor, Edward Welbourne, Edward Z. Yang, Eira Monstad, Eitan Adler, Eliot Graff, Elizabeth Castro, Elliott Sprehn, Elliotte Harold, Eric Carlson, Eric Law, Eric Rescorla, Eric Semling, Erik Arvidsson, Erik Rose, Evan Martin, Evan Prodromou, Evert, fantasai, Felix Sasaki, Francesco Schwarz, Francis Brosnan Blazquez, Franck 'Shift' Quélain, Frank Barchard, 鵜飼文敏 (Fumitoshi Ukai), Futomi Hatano, Gavin Carothers, Gareth Rees, Garrett Smith, Geoffrey Garen, Geoffrey Sneddon, George Lund, Gianmarco Armellin, Giovanni Campagna, Glenn Adams, Glenn Maynard, Graham Klyne, Greg Botten, Greg Houston, Greg Wilkins, Gregg Tavares, Gregory J. Rosmaita, Grey, Guilherme Johansson Tramontina, Gytis Jakutonis, Håkon Wium Lie, Hallvord Reiar Michaelsen Steen, Hans S. Tømmerhalt, Hans Stimer, Harald Alvestrand, Henri Sivonen, Henrik Lied, Henry Mason, Hugh Winkler, Ian Bicking, Ian Davis, Ignacio Javier, Ivan Enderlin, Ivo Emanuel Gonçalves, J. King, Jacques Distler, James Craig, James Graham, James Justin Harrell, James M Snell, James Perrett, James Robinson, Jamie Lokier, Jan-Klaas Kollhof, Jason Kersey, Jason Lustig, Jason White, Jasper Bryant-Greene, Jatinder Mann, Jed Hartman, Jeff Balogh, Jeff Cutsinger, Jeff Schiller, Jeff Walden, Jeffrey Zeldman, 胡慧鋒 (Jennifer Braithwaite), Jens Bannmann, Jens Fendler, Jens Lindström, Jens Meiert, Jeremy Keith, Jeremy Orlow, Jeroen van der Meer, Jian Li, Jim Jewett, Jim Ley, Jim Meehan, Jjgod Jiang, João Eiras, Joe Clark, Joe Gregorio, Joel Spolsky, Johan Herland, John Boyer, John Bussjaeger, John Carpenter, John Fallows, John Foliot, John Harding, John Keiser, John Snyders, John-Mark Bell, Johnny Stenback, Jon Ferraiolo, Jon Gibbins, Jon Perlow, Jonas Sicking, Jonathan Cook, Jonathan Rees, Jonathan Worent, Jonny Axelsson, Jorgen Horstink, Jorunn Danielsen Newth, Joseph Kesselman, Joseph Pecoraro, Josh Aas, Josh Levenberg, Joshua Bell, Joshua Randall, Jukka K. Korpela, Jules Clément-Ripoche, Julian Reschke, Jürgen Jeka, Justin Lebar, Justin Schuh, Justin Sinclair, Kai Hendry, Kartikaya Gupta, Kathy Walton, Kelly Norton, Kevin Benson, Kornél Pál, Kornel Lesinski, Kris Northfield, Kristof Zelechovski, Krzysztof Maczyński, 黒澤剛志 (Kurosawa Takeshi), Kyle Hofmann, Kyle Huey, Léonard Bouchet, Lachlan Hunt, Larry Masinter, Larry Page, Lars Gunther, Lars Solberg, Laura Carlson, Laura Granka, Laura L. Carlson, Laura Wisewell, Laurens Holst, Lee Kowalkowski, Leif Halvard Silli, Lenny Domnitser, Leons Petrazickis, Lobotom Dysmon, Logan, Loune, Luke Kenneth Casson Leighton, Maciej Stachowiak, Magnus Kristiansen, Maik Merten, Malcolm Rowe, Mark Birbeck, Mark Miller, Mark Nottingham, Mark Pilgrim, Mark Rowe, Mark Schenk, Mark Wilton-Jones, Martijn Wargers, Martin Atkins, Martin Dürst, Martin Honnen, Martin Janecke, Martin Kutschker, Martin Nilsson, Martin Thomson, Masataka Yakura, Mathieu Henri, Matias Larsson, Matt Schmidt, Matt Wright, Matthew Gregan, Matthew Mastracci, Matthew Raymond, Matthew Thomas, Mattias Waldau, Max Romantschuk, Menno van Slooten, Micah Dubinko, Michael 'Ratt' Iannarelli, Michael A. Nachbaur, Michael A. Puls II, Michael Carter, Michael Daskalov, Michael Enright, Michael Gratton, Michael Nordman, Michael Powers, Michael Rakowski, Michael(tm) Smith, Michal Zalewski, Michel Fortin, Michelangelo De Simone, Michiel van der Blonk, Mihai Şucan, Mihai Parparita, Mike Brown, Mike Dierken, Mike Dixon, Mike Schinkel, Mike Shaver, Mikko Rantalainen, Mohamed Zergaoui, Mounir Lamouri, Ms2ger, NARUSE Yui, Neil Deakin, Neil Rashbrook, Neil Soiffer, Nicholas Shanks, Nicholas Stimpson, Nicholas Zakas, Nickolay Ponomarev, Nicolas Gallagher, Noah Mendelsohn, Noah Slater, NoozNooz42, Ojan Vafai, Olaf Hoffmann, Olav Junker Kjær, Oldřich Vetešník, Oli Studholme, Oliver Hunt, Oliver Rigby, Olivier Gendrin, Olli Pettay, oSand, Patrick H. Lauke, Patrik Persson, Paul Norman, Per-Erik Brodin, Perry Smith, Peter Beverloo, Peter Karlsson, Peter Kasting, Peter Stark, Peter-Paul Koch, Phil Pickering, Philip Jägenstedt, Philip Taylor, Philip TAYLOR, Prateek Rungta, Pravir Gupta, Rachid Finge, Rajas Moonka, Ralf Stoltze, Ralph Giles, Raphael Champeimont, Remco, Remy Sharp, Rene Saarsoo, Rene Stach, Ric Hardacre, Rich Doughty, Richard Ishida, Rigo Wenning, Rikkert Koppes, Rimantas Liubertas, Riona Macnamara, Rob Ennals, Rob Jellinghaus, Robert Blaut, Robert Collins, Robert O'Callahan, Robert Sayre, Robin Berjon, Rodger Combs, Roland Steiner, Roman Ivanov, Roy Fielding, Ruud Steltenpool, Ryan King, Ryosuke Niwa, S. Mike Dierken, Salvatore Loreto, Sam Dutton, Sam Kuper, Sam Ruby, Sam Weinig, Sander van Lambalgen, Sarven Capadisli, Scott González, Scott Hess, Sean Fraser, Sean Hayes, Sean Hogan, Sean Knapp, Sebastian Markbåge, Sebastian Schnitzenbaumer, Seth Call, Shanti Rao, Shaun Inman, Shiki Okasaka, Sierk Bornemann, Sigbjørn Vik, Silvia Pfeiffer, Simon Montagu, Simon Pieters, Simon Spiegel, skeww, Stanton McCandlish, Stefan Håkansson, Stefan Haustein, Stefan Santesson, Stefan Weiss, Steffen Meschkat, Stephen Ma, Steve Faulkner, Steve Runyon, Steven Bennett, Steven Garrity, Steven Tate, Stewart Brodie, Stuart Ballard, Stuart Parmenter, Subramanian Peruvemba, Sunava Dutta, Susan Borgrink, Susan Lesch, Sylvain Pasche, T. J. Crowder, Tab Atkins, Tantek Çelik, 田村健人 (TAMURA Kent), Ted Mielczarek, Terrence Wood, Thomas Broyer, Thomas Koetter, Thomas O'Connor, Tim Altman, Tim Johansson, Toby Inkster, Todd Moody, Tom Baker, Tom Pike, Tommy Thorsen, Travis Leithead, Tyler Close, Vladimir Katardjiev, Vladimir Vukićević, voracity, Wakaba, Wayne Carr, Wayne Pollock, Wellington Fernando de Macedo, Weston Ruter, Will Levine, William Swanson, Wladimir Palant, Wojciech Mach, Wolfram Kriesing, Yang Chen, Ye-Kui Wang, Yehuda Katz, Yi-An Huang, Yngve Nysaeter Pettersen, Yuzo Fujishima, Zhenbin Xu, Zoltan Herczeg, and Øistein E. Andersen, for their useful comments, both large and small, that have led to changes to this specification over the years.
Thanks also to everyone who has ever posted about HTML to their blogs, public mailing lists, or forums, including all the contributors to the various W3C HTML WG lists and the various WHATWG lists.
Special thanks to Richard Williamson for creating the first
implementation of canvas
in Safari, from which the
canvas feature was designed.
Special thanks also to the Microsoft employees who first
implemented the event-based drag-and-drop mechanism, contenteditable
, and other
features first widely deployed by the Windows Internet Explorer
browser.
Thanks to the SubRip community, including in particular Zuggy and ai4spam, for their work on the SubRip software program whose SRT file format was used as the basis for the WebVTT text track file format.
Special thanks and $10,000 to David Hyatt who came up with a broken implementation of the adoption agency algorithm that the editor had to reverse engineer and fix before using it in the parsing section.
Thanks to the many sources that provided inspiration for the examples used in the specification.
Thanks also to the Microsoft blogging community for some ideas, to the attendees of the W3C Workshop on Web Applications and Compound Documents for inspiration, to the #mrt crew, the #mrt.no crew, and the #whatwg crew, and to Pillar and Hedral for their ideas and support.