HTML is the core language of the World Wide Web. The W3C publishes HTML5, which is the fifth major revision of HTML. The WHATWG publishes HTML, which is a rough superset of HTML5. "HTML5 differences from HTML4" describes the differences of these documents from HTML4, and calls out cases where HTML is different from HTML5. This document may not provide accurate information as the specifications are still actively in development. When in doubt, always check the specifications themselves. [HTML5] [HTML]
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 latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
This is the 25 October 2012 W3C Working Draft produced by the HTML Working Group, part of the HTML Activity. The Working Group intends to publish this document as a Working Group Note to accompany the HTML5 specification. The appropriate forum for comments is W3C Bugzilla. (firstname.lastname@example.org, a mailing list with a public archive, is no longer used for tracking comments.)
Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
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.
HTML has been in continuous evolution since it was introduced to the Internet in the early 1990s. Some features were introduced in specifications; others were introduced in software releases. In some respects, implementations and author practices have converged with each other and with specifications and standards, but in other ways, they have diverged.
The HTML5 draft reflects an effort, started in 2004, to study contemporary HTML implementations and deployed content. The draft:
HTML5 is still a draft. The contents of HTML5, as well as the contents of this document which depend on HTML5, are still being discussed on the HTML Working Group and WHATWG mailing lists. The open issues are linked from the HTML5 draft.
HTML5 is defined in a way that it is backwards compatible with the way user agents handle deployed content. To keep the authoring language relatively simple for authors, several elements and attributes are not included, as outlined in the other sections of this document, such as presentational elements that are better dealt with using CSS.
User agents, however, will always have to support these older
elements and attributes and this is why the HTML5 specification clearly
separates requirements for authors and user agents. For instance, this
means that authors cannot use the
isindex or the
plaintext element, but user agents are required to support
them in a way that is compatible with how these elements need to behave
for compatibility with deployed content.
Since HTML5 has separate conformance requirements for authors and user agents there is no longer a need for marking features "deprecated".
The HTML5 specification will not be considered finished before there are at least two complete implementations of the specification. A test suite will be used to measure completeness of the implementations. This approach differs from previous versions of HTML, where the final specification would typically be approved by a committee before being actually implemented. The goal of this change is to ensure that the specification is implementable, and usable by authors once it is finished.
HTML5 defines an HTML syntax that is
compatible with HTML4 and XHTML1 documents published on the
Web, but is not compatible with the more esoteric SGML features of
HTML4, such as
as these are not supported by most user agents. Documents using the HTML
syntax are served with the
HTML5 also defines detailed parsing rules (including "error
handling") for this syntax which are largely compatible with HTML4-era
implementations. User agents must use these rules for resources that
text/html media type. Here is an example document
that conforms to the HTML syntax:
<!doctype html> <html> <head> <meta charset="UTF-8"> <title>Example document</title> </head> <body> <p>Example paragraph</p> </body> </html>
The other syntax that can be used for HTML5 is XML. This syntax
is compatible with XHTML1 documents and implementations. Documents
using this syntax need to be served with an XML media type and elements
need to be put in the
namespace following the rules set forth by the XML specifications.
Below is an example document that conforms to the XML syntax of
HTML5. Note that XML documents must be served with an XML media type
<?xml version="1.0" encoding="UTF-8"?> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Example document</title> </head> <body> <p>Example paragraph</p> </body> </html>
For the HTML syntax, authors are required to declare the character encoding. There are three ways to do that:
Content-Typeheader for instance.
metaelement with a
charsetattribute that specifies the encoding within the first 1024 bytes of the document. For instance,
<meta charset="UTF-8">could be used to specify the UTF-8 encoding. This replaces the need for
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">although that syntax is still allowed.
For the XML syntax, authors have to use the rules as set forth in the XML specifications to set the character encoding.
The HTML syntax of HTML5 requires a doctype to be specified to ensure that the browser renders the page in standards mode. The doctype has no other purpose. [DOCTYPE]
The doctype declaration for the HTML syntax is
<!DOCTYPE html> and is
case-insensitive. Doctypes from earlier versions of
HTML were longer because the HTML language was SGML-based and therefore
required a reference to a DTD. With HTML5 this is no longer the case and
the doctype is only needed to enable standards mode for documents
written using the HTML syntax. Browsers already do this for
To support legacy markup generators that cannot generate the preferred
short doctype, the doctype
<!DOCTYPE html SYSTEM
"about:legacy-compat"> is allowed in the HTML syntax.
The strict doctypes for HTML 4.0, HTML 4.01, XHTML 1.0 as well as XHTML 1.1 are also allowed (but are discouraged) in the HTML syntax.
In the XML syntax, any doctype declaration may be used, or it may be omitted altogether. Documents with an XML media type are always handled in standards mode.
The HTML syntax of HTML5 allows for MathML and SVG elements to
be used inside a document. An
tag causes the HTML parser to switch to a special insertion mode which puts
elements and attributes in the appropriate namespaces, does case fixups for
elements and attributes that have mixed case, and supports the empty-element
syntax as in XML. The syntax is still case-insensitive and attributes allow
the same syntax as for HTML elements. Namespace declarations may be omitted.
CDATA sections are supported in this insertion mode.
Some MathML and SVG elements cause the parser to switch back to "HTML
foreignObject, so you can
use HTML elements or a new
For instance, a very simple document using some of the minimal syntax features could look like:
<!doctype html> <title>SVG in text/html</title> <p> A green circle: <svg> <circle r="50" cx="50" cy="50" fill="green"/> </svg> </p>
There are a few other changes in the HTML syntax worthy of mentioning:
⟩ named character
references now expand to U+27E8 and U+27E9 instead of U+2329 and U+232A,
Many new named character references have been added, including all from MathML.
Void elements (known as "EMPTY" in HTML4) are allowed to have a trailing slash.
The ampersand (
&) may be left unescaped in some more
cases compared to HTML4.
Attributes have to be separated by at least one whitespace character.
Attributes with an empty value may be written as just the attribute name omitting the equals sign and the value, even if it's not a boolean attribute. (HTML4 actually allowed using only the attribute value and omitting the attribute name, for enumerated attributes, but this was not supported in browsers.)
Attributes omitting quotes for the value are allowed to use a larger set of characters compared to HTML4.
optgroup end tag is now optional.
colgroup start tag is now optional and is inferred by
the HTML parser.
This section is split up in several subsections to more clearly illustrate the various differences there are between HTML4 and HTML5.
The following elements have been introduced for better structure:
represents an independent piece of content of a document, such as a
blog entry or newspaper article.
represents a piece of content that is only slightly related to the
rest of the page.
represents the header of a section.
represents a group of introductory or navigational aids.
represents a footer for a section and can contain information about
the author, copyright information, etc.
represents a section of the document intended for navigation.
represents a piece of self-contained flow content, typically
referenced as a single unit from the main flow of the document.
<figure> <video src="example.webm" controls></video> <figcaption>Example</figcaption> </figure>
figcaption can be used as caption (it is optional).
Then there are several other new elements:
audio for multimedia content. Both
provide an API so application authors can script their own user
interface, but there is also a way to trigger a user interface
provided by the user agent.
elements are used together with these elements if there are multiple
streams available of different types.
embed is used for plugin
mark represents a run of
text in one document marked or highlighted for reference purposes, due
to its relevance in another context.
progress represents a
completion of a task, such as downloading or when performing a series
of expensive operations.
meter represents a
measurement, such as disk usage.
time represents a date
WHATWG HTML has
allows content to be annotated with a machine-readable value.
WHATWG HTML has
dialog for showing a dialog.
bdi represents a span of
text that is to be isolated from its surroundings for the purposes of
bidirectional text formatting.
wbr represents a line break
canvas is used for rendering
dynamic bitmap graphics on the fly, such as graphs or games.
represents a command the user can invoke.
<input list="browsers"> <datalist id="browsers"> <option value="Safari"> <option value="Internet Explorer"> <option value="Opera"> <option value="Firefox"> </datalist>
represents control for key pair generation.
represents some type of output, such as from a calculation done
type attribute now has the
following new values:
The idea of these new types is that the user agent can provide the user interface, such as a calendar date picker or integration with the user's address book, and submit a defined format to the server. It gives the user a better experience as his input is checked before sending it to the server meaning there is less time to wait for feedback.
Several attributes have been introduced to various elements that were already part of HTML4:
autofocus attribute can be specified on the
input (except when the
type attribute is
button elements. It provides a declarative way to focus a
form control during page load. Using this feature should enhance the
user experience compared to focusing the element with script as the user can turn it off if the user does not like
it, for instance.
<input type=email placeholder="email@example.com">
form attribute for
fieldset elements allows for
controls to be associated with a form. These elements can now be
placed anywhere on a page, not just as descendants of the
form element, and still be associated with a
<table> <tr> <th>Key <th>Value <th>Action <tr> <td><form id=1><input name=1-key></form> <td><input form=1 name=1-value> <td><button form=1 name=1-action value=save>✓</button> <button form=1 name=1-action value=delete>✗</button> ... </table>
required attribute applies to
input (except when the
type attribute is
image or some button type such as
textarea. It indicates that the user
has to fill in a value in order to submit the form. For
select, the first
option element has to be a placeholder with an empty value.
<label>Color: <select name=color required> <option value="">Choose one <option>Red <option>Green <option>Blue </select></label>
fieldset element now allows the
disabled attribute which disables all descendant controls (excluding those that are descendants of the
when specified, and the
name attribute which can be used for script access.
input element has several new attributes to
step. As mentioned before it also has a new
list attribute which can be used together with the
datalist element. It also now has the
height attributes to specify the dimensions of the image when using
button elements have
formtarget as new attributes. If present, they override
target attributes on the
menu element has two new attributes:
allow the element to transform into a menu as found in typical user
interfaces as well as providing for context menus in conjunction with the
link element has a new attribute called
sizes. It can be used in conjunction with the
icon relationship (set through the
attribute; can be used for e.g. favicons) to indicate the size of the
referenced icon. Thus allowing for icons of distinct dimensions.
img element has a new attribute called
crossorigin to use CORS in the fetch and if it is successful, allows the image data to be read with the
canvas API. In WHATWG HTML, there is also a new attribute called
srcset to support multiple images for different resolutions and different images for different viewport sizes.
Several attributes from HTML4 now apply to all elements. These
are called global attributes:
title. Additionally, XHTML 1.0
xml:space on some elements, which is now allowed
on all elements in XHTML documents.
There are also several new global attributes:
contenteditable attribute indicates that
the element is an editable area. The user can change the contents of the
element and manipulate the markup.
contextmenu attribute can be used to point
to a context menu provided by the author.
data-* collection of author-defined
attributes. Authors can define any attribute they want as long as they
prefix it with
data- to avoid clashes with future versions of
HTML. These are intended to be used to store custom data to be consumed by
the Web page or application itself. They are not intended for
data to be consumed by other parties (e.g. user agents).
attribute indicates that an element is not yet, or is no longer, relevant.
spellcheck attribute allows for hinting
whether content can be checked for spelling or not.
translate attribute gives a hint to
translators whether the content should be translated.
HTML5 also makes all event handler attributes from HTML4, which take the
onevent, global attributes and adds
several new event handler attributes for new events it defines. For
event handler attribute for the
play event which is used by the API for the
media elements (
These elements have slightly modified meanings in HTML5 to better reflect how they are used on the Web or to make them more useful:
b element now 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.
cite element now solely
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). Specifically the example in HTML4
where it is used to mark up the name of a person is no longer considered
dl element now represents an
association list of name-value groups, and is no longer said to be
appropriate for dialogue.
hr element now represents a
paragraph-level thematic break.
i element now 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.
label element the
browser should no longer move focus from the label to the control unless
such behavior is standard for the underlying platform user
menu element is redefined to
be useful for toolbars and context menus.
s element now represents
contents that are no longer accurate or no longer relevant.
script element can now be
used for scripts or for custom data blocks.
small element now represents
side comments such as small print.
strong element now
represents importance rather than strong emphasis.
u element now 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
Several attributes have changed in various ways.
accesskey global attribute now allows multiple
characters to be specified, which the user agent can choose from.
attribute now allows the value
object are no longer allowed to contain
percentages. They are also not allowed to be used to stretch the image to
a different aspect ratio than its intrinsic aspect ratio.
attribute is now allowed to have any value, as long as it is unique, is
not the empty string, and does not contain space characters.
attribute takes the empty string in addition to a valid language
identifier, just like
xml:lang does in XML.
The event handler attributes (e.g.
global attribute now always uses CSS as the styling language.
global attribute now allows negative values which indicate that the
element can receive focus but cannot be tabbed to.
The following attributes are allowed but authors are discouraged from using them and instead strongly encouraged to use an alternative solution:
language attribute on
script. It is required to have the value
conflict with the
type attribute. Authors can simply omit it as
it has no useful function.
The elements in this section are not to be used by authors. User
agents will still have to support them and various sections in
HTML5 define how. E.g. the obsolete
is handled by the parser section.
The following elements are not in HTML5 because their effect is purely presentational and their function is better handled by CSS:
The following elements are not in HTML5 because using them damages usability and accessibility:
The following elements are not included because they have not been used often, created confusion, or their function can be handled by other elements:
acronymis not included because it has created a lot of confusion. Authors are to use
applethas been obsoleted in favor of
isindexusage can be replaced by usage of form controls.
dirhas been obsoleted in favor of
noscript element is only conforming in the
HTML syntax. It is not allowed in the XML syntax. This is because in order to not only hide visually but also prevent the content to run scripts, apply style sheets, have submittable form controls, load resources, and so forth, the HTML parser parses the content of the
noscript element as plain text. The same is not possible with an XML parser.
Some attributes from HTML4 are no longer allowed in HTML5. The specification defines how user agents should process them in legacy documents, but authors must not use them and they will not validate.
HTML5 has advice on what you can use instead.
In addition, HTML5 has none of the presentational attributes that were in HTML4 as their functions are better handled by CSS:
Content model is what defines how elements may be nested — what is allowed as children (or descendants) of a certain element.
At a high level, HTML4 had two major categories of elements, "inline"
img, text), and "block-level" (e.g.
table). Some elements did not fit in
Some elements allowed "inline" elements (e.g.
p), some allowed "block-level" elements (e.g.
body), some allowed both (e.g.
div), while other elements did not allow either
category but only allowed other specific elements (e.g.
or did now allow any children at all (e.g.
Notice the difference between an element itself being in a
certain category, and having a content model of a certain category. For
p element is itself a
"block-level" element, but has a content model of "inline".
To make it more confusing, HTML4 had different content model rules in its
Strict, Transitional and Frameset flavors. For instance, in Strict, the
body element allowed only "block-level"
elements, but in Transitional, it allowed both "inline" and "block-level".
To make things more confusing still, CSS uses the terms "block-level element" and "inline-level element" for its visual formatting model, which is related to CSS's 'display' property and has nothing to do with HTML's content model rules.
HTML5 does not use the terms "block-level" or "inline" as part of its content model rules, to reduce confusion with CSS. However, it has more categories than HTML4, and an element can be part of none of them, one of them, or several of them.
div, text. This is roughly like HTML4's "block-level" and "inline" together.
img, text. This is roughly like HTML4's "inline". Elements that are phrasing content are also flow content.
label. Interactive content is not allowed to be nested.
As broad changes from HTML4, HTML5 no longer has any element that only
accepts what HTML4 called "block-level" elements; e.g. the
body element now allows flow content. This is
thus closer to HTML4 Transitional than HTML4 Strict.
Further changes include:
noscript element was a
"block-level" element in HTML4, but is phrasing content in HTML5.
Table elements have to conform to the table model (e.g. two cells are not allowed to overlap).
a element now has a transparent content model (except it does not
allow interactive content descendants), meaning that it has the same
content model as its parent. This means that the
a element can now contain e.g.
div elements, if its parent allows flow
map element also has a
transparent content model. The
element is considered phrasing content if there is a
map element ancestor, which means that they
do not need to be direct children of
HTML5 has introduced many new APIs and have extended, changed or obsoleted some existing APIs.
HTML5 introduces a number of APIs that help in creating Web applications. These can be used together with the new elements introduced for applications:
An API for form constraint validation (e.g. the
An API that enables offline Web applications, with an application cache.
Editing API in combination with a new global
Drag & drop API in combination with a
An API that exposes the components of the document's URL and allows
scripts to navigate, redirect and reload (the
An API that exposes the session history and allows scripts to
update the document's URL without actually navigating, so that
applications don't need to abuse the fragment component for "Ajax-style"
An API for printing the document (
Window object has been defined.
WHATWG HTML has further APIs that are not in HTML5 but are separate specifications at the W3C:
An API for microdata.
An API for bidirectional client-server communication (
An API for server-to-client data push (
The following features from DOM Level 2 HTML are changed in various ways:
document.title now collapses whitespace on
document.domain is made settable, which
can change the document's effective script origin.
document.open() now either clears the
document (if invoked with two or less arguments), or acts like
window.open() (if invoked with
three or four arguments). In the former case, throws an exception in XML.
document.writeln() throw an exception in
XML. The latter two now support variadic arguments; they can add text to
the document's input stream while it is still being parsed, or can imply a
document.open() or be ignored altogether in
now returns all HTML elements with a
name attribute matching
DOM Level 2 HTML had an
HTMLDocument interface that
Document and provided HTML-specific members on
documents. HTML5 has moved these members to the
Document interface, and extended it in a number
of ways. Since all documents use the
Document interface, the
HTML-specific members are now available on all documents, so they are usable
in e.g. SVG documents as well. It also has several new members:
commands, and a
generic name getter, to access various parts of the DOM tree. WHATWG HTML
getItems() for microdata and
cssElementMap to accompany the CSS
Existing scripts that modified the prototype of
should continue to work because
window.HTMLDocument now returns
Document interface object.
HTMLElement interface has also gained several extensions
dataset is a
convenience feature for handling the
data-* attributes, which are exposed as
camel-cased properties. For instance,
= 'test' sets the
data-foo-bar content attribute on
isContentEditable returns true if the
element is editable.
All event handler IDL attributes.
Some interfaces in DOM Level 2 HTML have been extended.
HTMLFormElement now has a named
getter and an indexed getter.
HTMLSelectElement now has a
namedItem() methods, a setter creator,
labels IDL attributes,
and members for the form constrain validation API:
HTMLInputElement now has the
stepDown(), the form
constraint validation API members,
labels, members for the text field selection
HTMLAnchorElement now has the
text, the URL
decomposition IDL attributes:
HTMLAreaElement also have the
relList IDL attribute.
HTMLAreaElement also has the URL
decomposition IDL attributes.
In addition, most new content attributes also have corresponding IDL
attributes on the elements' interfaces, e.g. the
sizes IDL attribute on
HTMLLinkElement which reflects the
sizes content attribute.
Some APIs are now either removed altogether, or marked as obsolete.
All IDL attributes that reflect a content attribute that is itself
obsolete, are now also obsolete. For instance, the
bgColor IDL attribute on
HTMLBodyElement which reflects the
The following interfaces are marked obsolete since the elements are
HTMLIsIndexElement interface is removed altogether since
the HTML parser expands an
isindex tag into other elements.
The following members of the
HTMLDocument interface (which
have now moved to
Document) are now
The changelogs in this section indicate what has been changed between publications of the HTML5 drafts, as well as changes in WHATWG HTML that do not affect HTML5. Rationale for changes can be found in the firstname.lastname@example.org and whatwg@whatwg. org mailing list archives, and the WHATWG Weekly series of blog posts. More fundamental rationale is being collected on the WHATWG Rationale wiki page. Many editorial and minor technical changes are not included in these changelogs. Implementors are strongly encouraged to follow the development of the main specification on a frequent basis so they become aware of all changes that affect them early on.
The changes in the changelogs are in rough chronological order.
rubywas changed with regards to nested
scripttags in the HTML syntax now execute.
find()API has been dropped.
inBandMetadataTrackDispatchTypeIDL attribute was added to
TextTrackCue()constructor now has fewer arguments.
acceptattribute now supports file extensions as well as MIME types.
initialTimeIDL attribute on media elements has been dropped.
startOffsetTimeIDL attribute on media elements has been renamed to
Further changes to WHATWG HTML that do not affect HTML5:
addElement()was dropped from the Drag and Drop API.
iframeelements with the
:disabledpseudo-classes now apply to
inputelements in the Hidden state.
magnetschemes are now in the
tableelements now have 'box-sizing:border-box' by default.
alttext can now use a specific attribute on
imgthat makes validators ignore the missing
inputmodeattribute has been added to
autocompleteattribute has been extended to support prefilling specific things.
ArrayBufferViewas well as
tableis non-conforming again.
connectevent now also exposes the source port in the
setRangeText()method has been added to
srcsetattribute has been added to
inertglobal attribute and the
currentTransformIDL attribute, several IDL attributes for font metrics,
removeHitRegion()method, support for dashed lines, have been added to the canvas 2d context.
directionwere renamed to
commandelement now has a
translateglobal attribute was added.
prompt()methods are now allowed to do nothing during
scriptelement now supports
window.onerrornow supports a fourth argument for column position.
window.openerIDL attribute can now return null in some cases.
clearInterval()methods were made synonymous.
@globalat-rule was introduced, for use together with
styleelements with the
objectelements now have a legacy caller.
window.onerror's return value was changed to match reality.
setTimeout()API is now allowed to be throttled in background tabs.
:invalidpseudo-classes now apply to
canvasnow honors the origin-clean flag.
activeElementIDL attribute now points to the relevant browsing context container (e.g.
iframe) when a child document has focus.
atob()method now ignores whitespace.
dropzoneattribute was changed to use "
string:" and "
file:" instead of "
s:" and "
cueAsSourceIDL attribute on
TextTrackCuegot renamed to
window.onerrorAPI is now invoked with dummy arguments for cross-origin scripts.
textLengthIDL attributes have their newlines normalized to LF.
qelement now has language-specific quotes rendered by default.
dataelement was introduced.
timeelement was redesigned to make it match how people wanted to use it. Its
pubdateattribute was dropped.
location.resolveURL()method was removed.
trackelement now sniffs instead of obeying the MIME type.
load()method on documents created by
createDocument()is now defined on the
window.HTMLDocumentnow just returns
TextTrackinterfaces were merged and
TextTrackCuewas made more mutable.
selectedOptionIDL attribute on
readyStateIDL attribute moved from
text/html-sandboxedMIME type was dropped.
footer, sectioning content or heading content descendants.
addtrackevent on the relevant track list objects.
currentTimeon media elements before the media has loaded now defers the seek instead of throwing.
iframes if they honor the
MediaControllers now get paused when they end.
init*Event()methods were removed.
suspendevent when the resource is loaded.
UndoManagerand related features moved to UndoManager and DOM Transaction.
registerContentHandler()now has a blacklist of MIME types.
registerProtocolHandler()now has a whitelist of protocols, but also supports any protocol that starts with "
text/htmlresources now don't need to point to an element with a matching ID.
audioelements are now allowed to have zero
sizeattributes are allowed (but give warnings in validators) on
shortcut icon" is now allowed.
EventTargetnow inherit from it instead of using "implements".
setInterval()API now clamps to 4ms instead of 10ms.
selectelement and its
optionscollection now have a setter.
rel=helpon links now show a help cursor by default.
window.print()before the document is loaded defers the print until it is loaded.
createHTMLDocument(), HTML-specific overrides to some DOM Core features (like
createElement()), some definitions, the
idIDL attribute and ID handling moved to DOM4.
replaceState()methods now change the history entry to GET.
window.postMessagenow supports transferring some objects instead of cloning them, and supports transferring
placeholderattribute is now allowed on
objectelement gained a new attribute
typemustmatch, to make it safer for authors to embed untrusted resources where they expect a certain content type.
formattribute was removed from
text/plain) that are guaranteed to never be supported as scripting types for
scriptwere specified, so authors can safely use them for custom data blocks.
about:blankdocuments created from
window.open()now get a
window.statuswas specified to exist but do nothing.
DataTransferItemswas renamed to
crossoriginattribute has been added to
audioto use CORS.
externalIDL attribute has been added on
windowand has the members
Further changes to WHATWG HTML that do not affect HTML5:
arcTo()methods and the new
Pathobjects. SVG path data can be added to a
https+aes:URL schemes were added to allow sensitive resources to be held on untrusted servers.
itempropattribute is used on an element where microdata gets its value from an attribute (like
aelements), that attribute is now required.
PeerConnectionwas moved to WebRTC.
itemtypeattribute now allows multiple types.
CanvasPixelArraywas dropped in favor of
linkelement is no longer allowed to have both
aelement got a new
downloadattribute. This attribute is not included in HTML5.
window.find()method was added.
strokeText()methods now do not collapse whitespace.
EventSourcenow supports CORS.
EventSourcewas made stricter in its MIME type checking.
object, CSS, etc, has been dropped.
toBlob()method has been added to
drawFocusRing()method on the
canvas2d context has been split into two methods,
PropertyNodeListhas been replaced with a
selectevent has been specified.
selectDirectionIDL attribute has been added to
:disabledpseudo-classes now match
fieldset, and the
:indeterminatepseudo-class can now match
getKind()method has been added to
MediaControllerAPI and the
mediagroupattribute have been added to synchronize playback of media elements.
TrackListwas renamed to
tableis now conforming.
uelement is now conforming.
tableis now non-conforming.
videowas changed to a boolean
Content-Languagemeta pragma is now non-conforming.
replaceStatefeatures have been changed based on implementation feedback in Firefox, and
history.statehas been introduced.
tracksIDL attribute on media elements has been renamed to
formchangeevents, and the
dispatchFormChange()methods have been dropped.
firstand related synonyms have been dropped.
videoelement's letterboxing rules are now specified in terms of CSS 'object-fit'.
onerrorevent handler on
windowis now invoked for compile-time script errors as well as runtime errors.
scriptelements now have
true, which can be set to
falseto make the scripts execute in insertion order.
btoa()methods have been specified.
formactionattributes are no longer allowed to have the empty string as value.
dropzoneattribute was added.
bdielement was added to aid with user-generated content that may have bidi implications.
dirattribute gained a new "
dirnameattribute was added to
inputelements. When specified the directionality as specified by the user will be submitted to the server as well.
trackelement and associated TextTrack API were added for video text tracks.
typeattribute on the
olelement is now allowed.
getSelection() API moved to a separate
DOM Range draft.
UndoManager has been removed from the W3C copy of
HTML5 for now as it is not ready yet.
hiddenattribute now works for table-related elements.
getContext()method is now defined to be able to handle multiple contexts better.
startTimeIDL attribute was renamed to
prefetchlink relationship can now be used on
delno longer requires a time to be specified.
formelement is no longer supported.
selement is no longer deprecated.
videoelement has a new
Per usual, lots of other minor fixes have been made as well.
pingattribute has been removed from the W3C version of HTML5.
titleelement is optional for
srcdocdocuments and other scenarios where a title is already available. As is the case with email.
keywordsis now a standard metadata name for the
allow-top-navigationvalue has been added for the
sandboxattribute on the
iframeelement. It allows the embedded content to navigate its parent when specified.
wbrelement has been added.
alternatekeyword for the
relattribute of the
linkelement can now be used to point to feeds again, even if the feed is not an alternative for the document.
In addition lots of minor changes, clarifications, and fixes have been made to the document.
dialogelement has been removed. A section with advice on how to mark up conversations has effectively replaced it.
document.headhas been introduced to provide convenient access to the
headelement from script.
feedhas been removed.
alternatewith specific media types is to be used instead.
createHTMLDocument()has been introduced as API to allow easy creation of HTML documents.
progresselements no longer have "magic" processing of their contents because it could not be made to work internationally.
progresselements, as well as the
outputelement, can now be labeled using the
text/html-sandboxed, was introduced to allow hosting of potentially hostile content without it causing harm.
srcdocattribute for the
iframeelement was introduced to allow embedding of potentially hostile content inline. It is expected to be used together with the
figureelement now uses a new element
legendbecause people want to use HTML5 long before it reaches W3C Recommendation.
detailselement now uses a new element
summaryfor exactly the same reason.
autobufferattribute on media elements was renamed to
A whole lot of other smaller issues have also been resolved. The above list summarizes what is thought to be of primary interest to authors.
In addition to all of the above, Microdata, the 2D context API for
canvas, and Web Messaging (
have been split into their own drafts at the W3C (the WHATWG still
publishes a version of HTML5 that includes them):
Specific microdata vocabularies are gone altogether in the W3C draft of HTML5 and are not published as a separate draft. The WHATWG draft of HTML5 still includes them.
timeelement is empty user agents have to render the time in a locale-specific manner.
loadevent is dispatched at
Window, but now has
Documentas its target.
pushState()now affects the
onredoare now on
startTimemember that indicates where the current resource starts.
headerhas been renamed to
hgroupand a new
headerelement has been introduced.
createImageData()now also takes
createPattern()can now take a
videoelement as argument too.
footerelement is no longer allowed in
headeris not allowed in
accesskeyis now properly defined.
articlenow take a
textLengthhas been added as member of the
rpelement now takes phrasing content rather than a single character.
location.reload()is now defined.
hashchangeevent now fires asynchronously.
spellcheckIDL attribute now maps to a
hasFeature()support has been reduced to a minimum.
Audio()constructor sets the
tdelement is no longer allowed in
DataTransferobject now have a
bbhave been removed due to their design not being agreed upon.
On top of this list quite a few minor clarifications, typos, issues specific to implementors, and other small problems have been resolved.
In addition, the following parts of HTML5 have been taken out and will likely be further developed at the IETF:
spellcheckhas been added.
thisin the global object returns a
WindowProxyobject rather than the
valueIDL attribute for
inputelements in the File Upload state is now defined.
designModewas changed to be more in line with legacy implementations.
drawImage()method of the 2D drawing API can now take a
videoelement as well.
document.domainis now IPv6-compatible.
videoelement gained an
autobufferboolean attribute that serves as a hint.
metaelement with a
charsetattribute in XML documents if the value of that attribute matches the encoding of the document. (Note that it does not specify the value, it is just a talisman.)
bufferingThrottledmembers of media elements have been removed.
postMessage()API now takes an array of
MessagePortobjects rather than just one.
add()method on the
selectelement and the
optionsmember of the
selectelement is now optional.
buttonelements have been renamed to
localStorage) at the same time. The
getStorageUpdates()method to allow it to be explicitly released.
placeholderattribute has been added to the
keygenelement for key pair generation.
datagridelement was revised to make the API more asynchronous and allow for unloaded parts of the grid.
In addition, several parts of HTML5 have been taken out and will be further developed by the Web Applications Working Group as standalone specifications:
ImageDataobjects has been changed from an array to a
canvaselement and its API.
canvashave been made in response to implementation and author feedback. E.g. clarifying what happens when NaN and Infinity are passed and fixing the definitions of
innerHTMLin XML was slightly changed to improve round-tripping.
toDataURL()method on the
canvaselement now supports setting a quality level when the media type argument is
posterattribute of the
videoelement now affects its intrinsic dimensions.
typeattribute of the
linkelement has been clarified.
linkwhen the expected type is an image.
hrefattribute of the
baseelement does not depend on
xmlnsattribute with the value
http://www.w3.org/1999/xhtmlis now allowed on all HTML elements.
data-*attributes and custom attributes on the
embedelement now have to match the XML
Nameproduction and cannot contain a colon.
volumeon media elements is now 1.0 rather than 0.5.
event-sourcewas renamed to
eventsourcebecause no other HTML element uses a hyphen.
bbhas been added. It represents a user agent command that the user can invoke.
addCueRange()method on media elements has been modified to take an identifier which is exposed in the callbacks.
parentattribute of the
Windowobject is now defined.
embedelement is defined to do extension sniffing for compatibility with servers that deliver Flash as
text/plain. (This is marked as an issue in the specification to figure out if there is a better way to make this work.)
embedcan now be used without its
getElementsByClassName()is defined to be ASCII case-insensitive in quirks mode for consistency with CSS.
localNameno longer returns the node name in uppercase.
data-*attributes are defined to be always lowercase.
openerattribute of the
Windowobject is not to be present when the page was opened from a link with
topattribute of the
Windowobject is now defined.
aelement now allows nested flow content, but not nested interactive content.
headerelement means to document summaries and table of contents.
autosubmitattribute has been removed from the
insertAdjacentHTML()has been added.
xml:langis now allowed in HTML when
langis also specified and they have the same value. In XML
langis allowed if
xml:langis also specified and they have the same value.
frameElementattribute of the
Windowobject is now defined.
altattribute is omitted a
titleattribute, an enclosing
figureelement with a
legendelement descendant, or an enclosing section with an associated heading must be present.
irrelevantattribute has been renamed to
definitionURLattribute of MathML is now properly supported. Previously it would have ended up being all lowercase during parsing.
load()method on media elements has been redefined as asynchronous. It also tries out files in turn now rather than just looking at the
typeattribute of the
canPlayType()has been added to the media elements.
bufferedBytesattributes have been removed from the media elements.
Locationobject gained a
qelement has changed again. Punctuation is to be provided by the user agent again.
beforeunloadevents are now defined.
headersattribute pointing to a
thelement, but authors are required to only let them point to
metaelement has a
charsetattribute it must occur within the first 512 bytes.
StorageEventobject now has a
Windowobjects is now defined.
Windowobject gained the
toolbarattributes giving information about the user interface.
document.domainnow relies on the Public Suffix List. [PSL]
Web Forms 2.0, previously a standalone specification, has been fully integrated into HTML5 since last publication. The following changes were made to the forms chapter:
datalistelements through the
dataattribute has been removed.
dispatchFormChange()methods have been removed from the
inputmodeattribute has been removed.
inputelement in the File Upload state no longer supports the
inputelements in the File Upload state is no longer authoritative.
textareahave been removed.
submit()method now just submits, it no longer ensures the form controls are valid.
inputelement in the Range state now defaults to the middle, rather than the minimum value.
sizeattribute on the
inputelement is now conforming (rather than deprecated).
objectelements now partake in form submission.
typeattribute of the
inputelement gained the values
inputelement gained a
multipleattribute which allows for either multiple e-mails or multiple files to be uploaded depending on the value of the
formelements now have a
novalidateattribute to indicate that the form fields should not be required to have valid values upon submission.
labelelement contains an
inputit may still have a
forattribute as long as it points to the
inputelement it contains.
inputelement now has an
inputelement gained a
pingattribute have changed.
<meta http-equiv=content-type>is now a conforming way to set the character encoding.
canvaselement has been cleaned up. Text support has been added.
globalStorageis now restricted to the same-origin policy and renamed to
localStorage. Related event dispatching has been clarified.
postMessage()API changed. Only the origin of the message is exposed, no longer the URL. It also requires a second argument that indicates the origin of the target document.
dataTransferobject now has a
typesattribute indicating the type of data being transferred.
melement is now called
figureelement no longer requires a caption.
olelement has a new
queryCommandEnabled()and related methods.
headersattribute has been added for
tableelement has a new
data-nameand can access these through the DOM using
dataset[name]on the element in question.
qelement has changed to require punctuation inside rather than having the browser render it.
targetattribute can now have the value
showModalDialogAPI has been added.
document.domainAPI has been defined.
sourceelement now has a new
pixelratioattribute useful for videos that have some kind encoding error.
bufferingThrottledIDL attributes have been added to the
beginevent has been renamed to
loadstartfor consistency with the Progress Events specification.
charsetattribute has been added to
iframeelement has gained the
seamlessattributes which provide sandboxing functionality.
rpelements have been added to support ruby annotation.
showNotification()method has been added to show notification messages to the user.
afterprintevents has been added.
The editors would like to thank Ben Millard, Bruce Lawson, Cameron McCormack, Charles McCathieNevile, Dan Connolly, David Håsäther, Dennis German, Frank Ellermann, Frank Palinkas, Futomi Hatano, Gordon P. Hemsley, Henri Sivonen, James Graham, Jens Meiert, Jeremy Keith, Jürgen Jeka, Krijn Hoetmer, Leif Halvard Silli, Maciej Stachowiak, Mallory van Achterberg, Marcos Caceres, Mark Pilgrim, Martijn Wargers, Martin Leese, Martyn Haigh, Masataka Yakura, Michael Smith, Mike Taylor, Ms2ger, Olivier Gendrin, Øistein E. Andersen, Philip Jägenstedt, Philip Taylor, Randy Peterman, Toby Inkster, and Yngve Spjeld Landro for their contributions to this document as well as to all the people who have contributed to HTML over the years for improving the Web!