Web/HTML/Global attributes/is

The is global attribute allows you to specify that a standard HTML element should behave like a defined custom built-in element (see Using custom elements for more details).

This attribute can only be used if the specified custom element name has been successfully defined in the current document, and extends the element type it is being applied to.

Examples

The following code is taken from our word-count-web-component example ([[../../../../../../../mdn.github.io/web-components-examples/word-count-web-component/index|see it live also]]).

// Create a class for the element
class WordCount extends HTMLParagraphElement {
  constructor() {
    // Always call super first in constructor
    super();

    // Constructor contents ommitted for brevity
    ...

  }
}

// Define the new element
customElements.define('word-count', WordCount, { extends: 'p' });

<p is="word-count"></p>

Specifications

Specification	Status	Comment
HTML Living StandardThe definition of 'is' in that specification.	Living Standard

Browser compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
is	Chrome Full support 67	Edge Full support 79	Firefox Full support 63 Full support 63 No support 59 — 63 Disabled' Disabled' From version 59 until version 63 (exclusive): this feature is behind the dom.webcomponents.customelements.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config. No support ? — 59 Disabled' Disabled' Until version 59 (exclusive): this feature is behind the dom.webcomponents.enabled preference (needs to be set to true) and the dom.webcomponents.customelements.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.	IE No support No	Opera Full support 55	Safari No support No	WebView Android Full support 67	Chrome Android Full support 67	Firefox Android Full support 63 Full support 63 No support 59 — 63 Disabled' Disabled' From version 59 until version 63 (exclusive): this feature is behind the dom.webcomponents.customelements.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config. No support ? — 59 Disabled' Disabled' Until version 59 (exclusive): this feature is behind the dom.webcomponents.enabled preference (needs to be set to true) and the dom.webcomponents.customelements.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.	Opera Android Full support 48	Safari iOS No support No	Samsung Internet Android Full support 9.0

Legend

Full support  

Full support

No support  

No support

User must explicitly enable this feature.'

User must explicitly enable this feature.

See also

• All global attributes.

is by Mozilla Contributors is licensed under CC-BY-SA 2.5.