HTML attribute reference
Elements in HTML haveattributes; these are additional values that configure the elements or adjust their behavior in various ways to meet the criteria the users want.
Attribute list
| Attribute Name | Elements | Description |
|---|---|---|
accept | <form>,<input> | List of types the server accepts, typically a file type. |
accept-charset | <form> | The character set, which if provided must be"UTF-8". |
accesskey | Global attribute | Keyboard shortcut to activate or add focus to the element. |
action | <form> | The URI of a program that processes the information submitted via the form. |
alignDeprecated | <caption>,<col>,<colgroup>,<hr>,<iframe>,<img>,<table>,<tbody>,<td>,<tfoot>,<th>,<thead>,<tr> | Specifies the horizontal alignment of the element. |
allow | <iframe> | Specifies a feature-policy for the iframe. |
alt | <area>,<img>,<input> | Alternative text in case an image can't be displayed. |
as | <link> | Specifies the type of content being loaded by the link. |
async | <script> | Executes the script asynchronously. |
autocapitalize | Global attribute | Sets whether input is automatically capitalized when entered by user |
autocomplete | <form>,<input>,<select>,<textarea> | Indicates whether controls in this form can by default have their values automatically completed by the browser. |
autoplay | <audio>,<video> | The audio or video should play as soon as possible. |
background | <body>,<table>,<td>,<th> | Specifies the URL of an image file. Note: Although browsers and email clients may still support this attribute, it is obsolete. Use CSS |
bgcolor | <body>,<col>,<colgroup>,<marquee>,<table>,<tbody>,<tfoot>,<td>,<th>,<tr> | Background color of the element. Note: This is a legacy attribute. Please use the CSS |
border | <img>,<object>,<table> | The border width. Note: This is a legacy attribute. Please use the CSS |
capture | <input> | From theMedia Capture specification, specifies a new file can be captured. |
charset | <meta> | Declares the character encoding of the page or script. |
checked | <input> | Indicates whether the element should be checked on page load. |
cite | <blockquote>,<del>,<ins>,<q> | Contains a URI which points to the source of the quote or change. |
class | Global attribute | Often used with CSS to style elements with common properties. |
color | <font>,<hr> | This attribute sets the text color using either a named color or a color specified in the hexadecimal #RRGGBB format. Note: This is a legacy attribute. Please use the CSS |
cols | <textarea> | Defines the number of columns in a textarea. |
colspan | <td>,<th> | The colspan attribute defines the number of columns a cell should span. |
content | <meta> | A value associated withhttp-equiv orname depending on the context. |
contenteditable | Global attribute | Indicates whether the element's content is editable. |
controls | <audio>,<video> | Indicates whether the browser should show playback controls to the user. |
coords | <area> | A set of values specifying the coordinates of the hot-spot region. |
crossorigin | <audio>,<img>,<link>,<script>,<video> | How the element handles cross-origin requests |
cspExperimental | <iframe> | Specifies the Content Security Policy that an embedded document must agree to enforce upon itself. |
data | <object> | Specifies the URL of the resource. |
data-* | Global attribute | Lets you attach custom attributes to an HTML element. |
datetime | <del>,<ins>,<time> | Indicates the date and time associated with the element. |
decoding | <img> | Indicates the preferred method to decode the image. |
default | <track> | Indicates that the track should be enabled unless the user's preferences indicate something different. |
defer | <script> | Indicates that the script should be executed after the page has been parsed. |
dir | Global attribute | Defines the text direction. Allowed values are ltr (Left-To-Right) or rtl (Right-To-Left) |
dirname | <input>,<textarea> | |
disabled | <button>,<fieldset>,<input>,<optgroup>,<option>,<select>,<textarea> | Indicates whether the user can interact with the element. |
download | <a>,<area> | Indicates that the hyperlink is to be used for downloading a resource. |
draggable | Global attribute | Defines whether the element can be dragged. |
enctype | <form> | Defines the content type of the form data when themethod is POST. |
enterkeyhint | <textarea>,contenteditable | Theenterkeyhint specifies what action label (or icon) to present for the enter key on virtual keyboards. The attribute can be used with form controls (such as the value oftextarea elements), or in elements in an editing host (e.g., usingcontenteditable attribute). |
elementtiming | <img>,<image> elements inside an<svg>, poster images of<video> elements, elements which have abackground-image, and elements containing text nodes, such as a<p> | Indicates that an element is flagged for tracking byPerformanceObserver objects using the"element" type. For more details, see thePerformanceElementTiming interface. |
for | <label>,<output> | Describes elements which belongs to this one. |
form | <button>,<fieldset>,<input>,<label>,<meter>,<object>,<output>,<progress>,<select>,<textarea> | Indicates the form that is the owner of the element. |
formaction | <input>,<button> | Indicates the action of the element, overriding the action defined in the<form>. |
formenctype | <button>,<input> | If the button/input is asubmit button (e.g.,type="submit"), this attribute sets the encoding type to use during form submission. If this attribute is specified, it overrides theenctype attribute of the button'sform owner. |
formmethod | <button>,<input> | If the button/input is asubmit button (e.g.,type="submit"), this attribute sets the submission method to use during form submission (GET,POST, etc.). If this attribute is specified, it overrides themethod attribute of the button'sform owner. |
formnovalidate | <button>,<input> | If the button/input is asubmit button (e.g.,type="submit"), this boolean attribute specifies that the form is not to be validated when it is submitted. If this attribute is specified, it overrides thenovalidate attribute of the button'sform owner. |
formtarget | <button>,<input> | If the button/input is asubmit button (e.g.,type="submit"), this attribute specifies the browsing context (for example, tab, window, or inline frame) in which to display the response that is received after submitting the form. If this attribute is specified, it overrides thetarget attribute of the button'sform owner. |
headers | <td>,<th> | IDs of the<th> elements which applies to this element. |
height | <canvas>,<embed>,<iframe>,<img>,<input>,<object>,<video> | Specifies the height of elements listed here. For all other elements, use the CSS |
hidden | Global attribute | Prevents rendering of given element, while keeping child elements, e.g. script elements, active. |
high | <meter> | Indicates the lower bound of the upper range. |
href | <a>,<area>,<base>,<link> | The URL of a linked resource. |
hreflang | <a>,<link> | Specifies the language of the linked resource. |
http-equiv | <meta> | Defines a pragma directive. |
id | Global attribute | Often used with CSS to style a specific element. The value of this attribute must be unique. |
integrity | <link>,<script> | Specifies aSubresource Integrity value that allows browsers to verify what they fetch. |
inputmode | <textarea>,contenteditable | Provides a hint as to the type of data that might be entered by the user while editing the element or its contents. The attribute can be used with form controls (such as the value oftextarea elements), or in elements in an editing host (e.g., usingcontenteditable attribute). |
ismap | <img> | Indicates that the image is part of a server-side image map. |
itemprop | Global attribute | |
kind | <track> | Specifies the kind of text track. |
label | <optgroup>,<option>,<track> | Specifies a user-readable title of the element. |
lang | Global attribute | Defines the language used in the element. |
languageDeprecated | <script> | Defines the script language used in the element. |
loading | <img>,<iframe> | Indicates if the element should be loaded lazily (loading="lazy") or loaded immediately (loading="eager"). |
list | <input> | Identifies a list of pre-defined options to suggest to the user. |
loop | <audio>,<marquee>,<video> | Indicates whether the media should start playing from the start when it's finished. |
low | <meter> | Indicates the upper bound of the lower range. |
max | <input>,<meter>,<progress> | Indicates the maximum value allowed. |
maxlength | <input>,<textarea> | Defines the maximum number of characters allowed in the element. |
minlength | <input>,<textarea> | Defines the minimum number of characters allowed in the element. |
media | <a>,<area>,<link>,<source>,<style> | Specifies a hint of the media for which the linked resource was designed. |
method | <form> | Defines whichHTTP method to use when submitting the form. Can beGET (default) orPOST. |
min | <input>,<meter> | Indicates the minimum value allowed. |
multiple | <input>,<select> | Indicates whether multiple values can be entered in an input of the typeemail orfile. |
muted | <audio>,<video> | Indicates whether the audio will be initially silenced on page load. |
name | <button>,<form>,<fieldset>,<iframe>,<input>,<object>,<output>,<select>,<textarea>,<map>,<meta>,<param> | Name of the element. For example used by the server to identify the fields in form submits. |
novalidate | <form> | This attribute indicates that the form shouldn't be validated when submitted. |
open | <details>,<dialog> | Indicates whether the contents are currently visible (in the case of a<details> element) or whether the dialog is active and can be interacted with (in the case of a<dialog> element). |
optimum | <meter> | Indicates the optimal numeric value. |
pattern | <input> | Defines a regular expression which the element's value will be validated against. |
ping | <a>,<area> | Theping attribute specifies a space-separated list of URLs to be notified if a user follows the hyperlink. |
placeholder | <input>,<textarea> | Provides a hint to the user of what can be entered in the field. |
playsinline | <video> | A Boolean attribute indicating that the video is to be played "inline"; that is, within the element's playback area. Note that the absence of this attribute does not imply that the video will always be played in fullscreen. |
poster | <video> | A URL indicating a poster frame to show until the user plays or seeks. |
preload | <audio>,<video> | Indicates whether the whole resource, parts of it or nothing should be preloaded. |
readonly | <input>,<textarea> | Indicates whether the element can be edited. |
referrerpolicy | <a>,<area>,<iframe>,<img>,<link>,<script> | Specifies which referrer is sent when fetching the resource. |
rel | <a>,<area>,<link> | Specifies the relationship of the target object to the link object. |
required | <input>,<select>,<textarea> | Indicates whether this element is required to fill out or not. |
reversed | <ol> | Indicates whether the list should be displayed in a descending order instead of an ascending order. |
role | Global attribute | Defines an explicit role for an element for use by assistive technologies. |
rows | <textarea> | Defines the number of rows in a text area. |
rowspan | <td>,<th> | Defines the number of rows a table cell should span over. |
sandbox | <iframe> | Stops a document loaded in an iframe from using certain features (such as submitting forms or opening new windows). |
scope | <th> | Defines the cells that the header test (defined in theth element) relates to. |
selected | <option> | Defines a value which will be selected on page load. |
shape | <a>,<area> | |
size | <input>,<select> | Defines the width of the element (in pixels). If the element'stype attribute istext orpassword then it's the number of characters. |
sizes | <link>,<img>,<source> | |
slot | Global attribute | Assigns a slot in a shadow DOM shadow tree to an element. |
span | <col>,<colgroup> | |
spellcheck | Global attribute | Indicates whether spell checking is allowed for the element. |
src | <audio>,<embed>,<iframe>,<img>,<input>,<script>,<source>,<track>,<video> | The URL of the embeddable content. |
srcdoc | <iframe> | |
srclang | <track> | |
srcset | <img>,<source> | One or more responsive image candidates. |
start | <ol> | Defines the first number if other than 1. |
step | <input> | |
style | Global attribute | Defines CSS styles which will override styles previously set. |
summaryDeprecated | <table> | |
tabindex | Global attribute | Overrides the browser's default tab order and follows the one specified instead. |
target | <a>,<area>,<base>,<form> | Specifies where to open the linked document (in the case of an<a> element) or where to display the response received (in the case of a<form> element) |
title | Global attribute | Text to be displayed in a tooltip when hovering over the element. |
translate | Global attribute | Specify whether an element's attribute values and the values of itsText node children are to be translated when the page is localized, or whether to leave them unchanged. |
type | <button>,<input>,<embed>,<object>,<ol>,<script>,<source>,<style>,<menu>,<link> | Defines the type of the element. |
usemap | <img>,<input>,<object> | |
value | <button>,<data>,<input>,<li>,<meter>,<option>,<progress>,<param> | Defines a default value which will be displayed in the element on page load. |
width | <canvas>,<embed>,<iframe>,<img>,<input>,<object>,<video> | For the elements listed here, this establishes the element's width. |
wrap | <textarea> | Indicates whether the text should be wrapped. |
Content versus IDL attributes
In HTML, most attributes have two faces: thecontent attribute and theIDL (Interface Definition Language) attribute.
The content attribute is the attribute as you set it from the content (the HTML code) and you can set it or get it viaelement.setAttribute() orelement.getAttribute(). The content attribute is always a string even when the expected value should be an integer. For example, to set an<input> element'smaxlength to 42 using the content attribute, you have to callsetAttribute("maxlength", "42") on that element.
The IDL attribute is also known as a JavaScript property. These are the attributes you can read or set using JavaScript properties likeelement.foo. The IDL attribute is always going to use (but might transform) the underlying content attribute to return a value when you get it and is going to save something in the content attribute when you set it. In other words, the IDL attributes, in essence, reflect the content attributes.
Most of the time, IDL attributes will return their values as they are really used. For example, the defaulttype for<input> elements is "text", so if you setinput.type="foobar", the<input> element will be of type text (in the appearance and the behavior) but the "type" content attribute's value will be "foobar". However, thetype IDL attribute will return the string "text".
IDL attributes are not always strings; for example,input.maxlength is a number (a signed long). When using IDL attributes, you read or set values of the desired type, soinput.maxlength is always going to return a number and when you setinput.maxlength, it wants a number. If you pass another type, it is automatically converted to a number as specified by the standard JavaScript rules for type conversion.
IDL attributes canreflect other types such as unsigned long, URLs, booleans, etc. Unfortunately, there are no clear rules and the way IDL attributes behave in conjunction with their corresponding content attributes depends on the attribute. Most of the time, it will followthe rules laid out in the specification, but sometimes it doesn't. HTML specifications try to make this as developer-friendly as possible, but for various reasons (mostly historical), some attributes behave oddly (select.size, for example) and you should read the specifications to understand how exactly they behave.
Boolean Attributes
Some content attributes (e.g.,required,readonly,disabled) are calledboolean attributes. If a boolean attribute is present, its value istrue, and if it's absent, its value isfalse.
HTML defines restrictions on the allowed values of boolean attributes: If the attribute is present, its value must either be the empty string (equivalently, the attribute may have an unassigned value), or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace. The following examples are valid ways to mark up a boolean attribute:
<div itemscope>This is valid HTML but invalid XML.</div><div itemscope=itemscope>This is also valid HTML but invalid XML.</div><div itemscope="">This is valid HTML and also valid XML.</div><div itemscope="itemscope"> This is also valid HTML and XML, but perhaps a bit verbose.</div>To be clear, the values"true" and"false" are not allowed on boolean attributes. To represent a false value, the attribute has to be omitted altogether. This restriction clears up some common misunderstandings: Withchecked="false" for example, the element'schecked attribute would be interpreted astrue because the attribute is present.
Event handler attributes
Warning:The use of event handler content attributes is discouraged. The mix of HTML and JavaScript often produces unmaintainable code, and the execution of event handler attributes may also be blocked by content security policies.
In addition to the attributes listed in the table above, globalevent handlers — such asonclick — can also be specified ascontent attributes on all elements.
All event handler attributes accept a string. The string will be used to synthesize aJavaScript function likefunction name(/*args*/) {body}, wherename is the attribute's name, andbody is the attribute's value. The handler receives the same parameters as its JavaScript event handler counterpart — most handlers receive only oneevent parameter, whileonerror receives five:event,source,lineno,colno,error. This means you can, in general, use theevent variable within the attribute.
<div>Click me!</div><!-- The synthesized handler has a name; you can reference itself --><div>Click me!</div>