HTML file format: Attributes

The attribute index of the HTML Living Standard, in three tables: the attributes every element takes, those of particular elements, and the event handler attributes, followed by the enumerated values. Values are strings; the types and rules are given per attribute. Attribute syntax is on the syntax page.

Global attributes

These can be used on any HTML element (and class, id, style, tabindex and nonce on SVG and MathML elements too). Attributes starting data- are for scripts, those starting aria- are WAI-ARIA states and properties.

Attribute	Meaning	Value
`accesskey`	Keyboard shortcut to focus or activate	Unique space-separated single characters
`autocapitalize`	How typed text is capitalised	off, none, on, sentences, words, characters
`autocorrect`	Whether typed text is corrected	on, off, or empty
`autofocus`	Focus when the page loads	Boolean
`class`	Classes the element belongs to	Space-separated tokens
`contenteditable`	Whether the user can edit it	true, false, plaintext-only, or empty (true)
`dir`	Text direction	ltr, rtl, auto
`draggable`	Whether it can be dragged	true, false
`enterkeyhint`	What Enter does on a virtual keyboard	enter, done, go, next, previous, search, send
`headingoffset`	Offsets heading levels inside it	Integer 0 to 8
`headingreset`	Stops a heading offset passing through	Boolean
`hidden`	Not relevant yet	hidden, until-found, or empty
`id`	A unique identifier	Text with no white space
`inert`	Makes it unfocusable and ignored by assistive technology	Boolean
`inputmode`	Which virtual keyboard to show	none, text, tel, email, url, numeric, decimal, search
`is`	Creates a customised built-in element	A custom element name
`itemid`	Microdata: global identifier of the item	URL
`itemprop`	Microdata: property names	Space-separated tokens
`itemref`	Microdata: other elements belonging to the item	Space-separated IDs
`itemscope`	Microdata: starts an item	Boolean
`itemtype`	Microdata: item types	Space-separated absolute URLs
`lang`	The language of the content	BCP 47 language tag, or empty
`nonce`	Nonce for Content Security Policy	Text
`popover`	Makes it a popover	auto, manual, hint, or empty (auto)
`slot`	The shadow tree slot it goes into	Text
`spellcheck`	Whether spelling is checked	true, false, or empty
`style`	Inline CSS	CSS declarations
`tabindex`	Whether and in what order it takes focus	Integer
`title`	Advisory text, usually a tooltip	Text
`translate`	Whether it is translated	yes, no, or empty
`writingsuggestions`	Whether writing suggestions are offered	true, false, or empty

Attributes of particular elements

Attribute	Elements	Meaning	Value
`abbr`	th	Short label for the header cell	Text
`accept`	input	File types accepted	Comma-separated MIME types or extensions
`accept-charset`	form	Encodings for submission	UTF-8 (case-insensitive)
`action`	form	Where the form is sent	URL
`allow`	iframe	Permissions Policy for the frame	Serialised policy
`allowfullscreen`	iframe	Allow fullscreen	Boolean
`alpha`	input	Allow a colour’s alpha to be set	Boolean
`alt`	area, img, input	Replacement text	Text
`as`	link	What a preload is for	see values
`async`	script	Run as soon as it arrives	Boolean
`autocomplete`	form, input, select, textarea	Autofill setting or hint	on or off on a form; field names and tokens on a control
`autoplay`	audio, video	Start playing when it can	Boolean
`blocking`	link, script, style	What it blocks until loaded	render
`charset`	meta	The encoding	utf-8
`checked`	input	Starts checked	Boolean
`cite`	blockquote, del, ins, q	Source of the quotation or change	URL
`closedby`	dialog	How it can be closed	any, closerequest, none
`color`	link	Colour for a site icon	CSS colour
`colorspace`	input	Colour space of the value	limited-srgb, display-p3
`cols`	textarea	Width in characters	Positive integer
`colspan`	td, th	Columns the cell spans	Positive integer
`command`	button	Action to request of the target	show-modal, close, request-close, toggle-popover, show-popover, hide-popover, or a custom command starting with --
`commandfor`	button	The element to act on	ID
`content`	meta	The metadata value	Text
`controls`	audio, video, img	Show the user agent’s controls	Boolean
`coords`	area	Coordinates of the shape	List of numbers
`crossorigin`	audio, img, link, script, video	CORS mode for fetches	anonymous, use-credentials, or empty
`data`	object	Address of the resource	URL
`datetime`	del, ins, time	When it happened, or a machine-readable date	Date and time strings
`decoding`	img	How to decode	sync, async, auto
`default`	track	Use this track when nothing better fits	Boolean
`defer`	script	Run after parsing	Boolean
`dirname`	input, textarea	Form field for the text direction	Text
`disabled`	button, fieldset, input, link, optgroup, option, select, textarea	Disabled	Boolean
`download`	a, area	Download and name the file	Text
`enctype`	form	Encoding of the form data	application/x-www-form-urlencoded, multipart/form-data, text/plain
`fetchpriority`	img, link, script	Fetch priority	auto, high, low
`for`	label, output, template	The control labelled, source controls, or what to update	ID, IDs, or text
`form`	button, fieldset, input, object, output, select, textarea	Associates with a form	ID
`formaction`, `formenctype`, `formmethod`, `formnovalidate`, `formtarget`	button, input	Override the form’s submission settings	As their form attributes
`headers`	td, th	The header cells for this cell	Space-separated IDs
`height`, `width`	canvas, embed, iframe, img, input, object, source, video	Dimensions	Non-negative integer
`high`, `low`, `optimum`	meter	Ends of the high and low ranges, and the best value	Number
`href`	a, area, base, link	Address of the link, or base URL	URL
`hreflang`	a, link	Language of the linked resource	Language tag
`http-equiv`	meta	Pragma directive	see values
`imagesizes`, `imagesrcset`	link	Image details for a preload	Source sizes and candidates
`integrity`	link, script	Subresource Integrity hash	Text
`ismap`	img	Server-side image map	Boolean
`kind`	track	Kind of text track	subtitles, captions, descriptions, chapters, metadata
`label`	optgroup, option, track	Text shown to the user	Text
`list`	input	A datalist of suggestions	ID
`loading`	audio, iframe, img, video	When to load	lazy, eager
`loop`	audio, video	Play again when finished	Boolean
`max`, `min`	input, meter, progress	Limits of the value	Varies
`maxlength`, `minlength`	input, textarea	Length limits	Non-negative integer
`media`	link, meta, source, style	Which media it applies to	Media query list
`method`	form	How to send the form	get, post, dialog
`multiple`	input, select	Allow several values	Boolean
`muted`	audio, video	Start muted	Boolean
`name`	button, details, fieldset, form, iframe, input, map, meta, object, output, select, slot, textarea	Name, whose purpose depends on the element	Text
`nomodule`	script	Not run in browsers that support modules	Boolean
`novalidate`	form	Skip validation	Boolean
`open`	details, dialog	Starts open	Boolean
`pattern`	input	Regular expression the value must match	JavaScript pattern
`ping`	a, area	URLs to ping when followed	Space-separated URLs
`placeholder`	input, textarea	Hint when empty	Text
`playsinline`	video	Play within the page	Boolean
`popovertarget`, `popovertargetaction`	button, input	The popover to control and how	ID; toggle, show, hide
`poster`	video	Image before playback	URL
`preload`	audio, video	How much to buffer	none, metadata, auto, or empty
`readonly`	input, textarea	Read only	Boolean
`referrerpolicy`	a, area, iframe, img, link, script	What referrer to send	see values
`rel`	a, area, form, link	Relationship to the linked resource	see values
`required`	input, select, textarea	Must be filled in	Boolean
`reversed`	ol	Numbered in reverse	Boolean
`rows`	textarea	Height in lines	Positive integer
`rowspan`	td, th	Rows the cell spans	Non-negative integer
`sandbox`	iframe	Restrictions on the frame	see values
`scope`	th	The cells it heads	row, col, rowgroup, colgroup
`selected`	option	Starts selected	Boolean
`shadowrootmode`, `shadowrootslotassignment`, `shadowrootdelegatesfocus`, `shadowrootserializable`, `shadowrootclonable`, `shadowrootcustomelementregistry`	template	Declare and configure a shadow root	open, closed; named, manual; Booleans
`shape`	area	The shape	circle, default, poly, rect
`size`	input, select	Size of the control	Positive integer
`sizes`	img, link, source	Display sizes, or icon sizes on link	Source sizes; on link, sizes such as 32x32 or any
`span`	col, colgroup	How many columns	Positive integer
`src`	audio, embed, iframe, img, input, script, source, track, video	Address of the resource	URL
`srcdoc`	iframe	An inline document	HTML source
`srclang`	track	Language of the track	Language tag
`srcset`	img, source	Image candidates	Image candidate strings
`start`	ol	Number of the first item	Integer
`step`	input	Granularity of the value	Number, or any
`target`	a, area, base, form	Where to open or show the result	_blank, _self, _parent, _top, or a browsing context name
`type`	a, button, embed, input, link, object, ol, script, source	Depends on the element	see values
`usemap`	img	An image map to use	Hash-name reference
`value`	button, data, input, li, meter, option, progress	The element’s value	Varies
`wrap`	textarea	How lines wrap when submitted	soft, hard

Event handler attributes

Each runs its value as script when the event fires. On any element: onauxclick, onbeforeinput, onbeforematch, onbeforetoggle, onblur, oncancel, oncanplay, oncanplaythrough, onchange, onclick, onclose, oncommand, oncontextlost, oncontextmenu, oncontextrestored, oncopy, oncuechange, oncut, ondblclick, ondrag, ondragend, ondragenter, ondragleave, ondragover, ondragstart, ondrop, ondurationchange, onemptied, onended, onerror, onfocus, onformdata, oninput, oninvalid, onkeydown, onkeypress, onkeyup, onload, onloadeddata, onloadedmetadata, onloadstart, onmousedown, onmouseenter, onmouseleave, onmousemove, onmouseout, onmouseover, onmouseup, onpaste, onpause, onplay, onplaying, onprogress, onratechange, onreset, onresize, onscroll, onscrollend, onsecuritypolicyviolation, onseeked, onseeking, onselect, onslotchange, onstalled, onsubmit, onsuspend, ontimeupdate, ontoggle, onvolumechange, onwaiting, onwheel.

On body, for events of the Window: onafterprint, onbeforeprint, onbeforeunload, onhashchange, onlanguagechange, onmessage, onmessageerror, onoffline, ononline, onpagehide, onpagereveal, onpageshow, onpageswap, onpopstate, onrejectionhandled, onstorage, onunhandledrejection, onunload.

Enumerated values

`input` types

Value	Control
`text`	One line of text (the default)
`search`	A search field
`tel`	A telephone number
`url`	A web address
`email`	An email address
`password`	Masked text
`date`, `month`, `week`, `time`, `datetime-local`	Date and time controls
`number`	A number
`range`	A slider
`color`	A colour
`checkbox`, `radio`	A checkbox, a radio button
`file`	A file picker
`submit`, `image`, `reset`, `button`	Buttons
`hidden`	Not displayed

Link relations, the `rel` attribute

Value	Meaning
`alternate`	Another version of the document
`author`	Information about the author
`bookmark`	A permalink (a, area)
`canonical`	The preferred URL
`dns-prefetch`	Look up the host early
`expect`	Hold rendering until an element arrives
`external`	A site outside this one
`help`	Help for this page
`icon`	The page’s icon
`license`	The licence
`manifest`	The web app manifest
`me`	Another address of the page’s owner
`modulepreload`	Fetch a module early
`next`, `prev`	The next or previous document in a series
`nofollow`	Do not count this link for ranking
`noopener`, `noreferrer`, `opener`	Control what the new page can reach and what referrer is sent
`pingback`	The pingback server
`preconnect`, `prefetch`, `preload`, `prerender`	Resource hints: connect, fetch, load or render ahead of time
`privacy-policy`, `terms-of-service`	The privacy policy, the terms
`search`	A search interface
`stylesheet`	A CSS style sheet
`tag`	A tag for this page (a, area)

`meta` names and pragmas

Attribute and value	Meaning
`name="application-name"`	The web application’s name
`name="author"`	The author
`name="description"`	A summary of the page
`name="generator"`	The software that made the page
`name="keywords"`	Keywords
`name="referrer"`	The default referrer policy
`name="theme-color"`	A colour for the browser’s interface
`name="color-scheme"`	Colour schemes supported
`name="viewport"`	Layout hints for small screens (CSS Viewport)
`name="robots"`	Directions for search engines (registered extension)
`http-equiv="content-type"`	Declares the encoding
`http-equiv="default-style"`	The preferred style sheet set
`http-equiv="refresh"`	Reload or redirect after a delay
`http-equiv="x-ua-compatible"`	Old Internet Explorer compatibility; only IE=edge conforms
`http-equiv="content-security-policy"`	A Content Security Policy

Other keyword sets

Attribute	Values
`as` (link)	fetch, audio, document, embed, font, image, object, script, style, track, video, worker
`referrerpolicy`	no-referrer, no-referrer-when-downgrade, origin, origin-when-cross-origin, same-origin, strict-origin, strict-origin-when-cross-origin (the default), unsafe-url
`sandbox` (iframe)	allow-downloads, allow-forms, allow-modals, allow-orientation-lock, allow-pointer-lock, allow-popups, allow-popups-to-escape-sandbox, allow-presentation, allow-same-origin, allow-scripts, allow-top-navigation, allow-top-navigation-by-user-activation, allow-top-navigation-to-custom-protocols
`type` (button)	submit, reset, button
`type` (ol)	1, a, A, i, I
`type` (script)	module, importmap, speculationrules; absent or a JavaScript MIME type is a classic script; any other value is a data block

.HTML File Format – Attributes