HTMLScriptElement: async property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

The async property of the HTMLScriptElement interface is a boolean value that controls how the script should be executed. For classic scripts, if the async property is set to true, the external script will be fetched in parallel to parsing and evaluated as soon as it is available. For module scripts, if the async property is set to true, the script and all their dependencies will be fetched in parallel to parsing and evaluated as soon as they are available.

It reflects the async attribute of the <script> element.

Value

A boolean.

Examples

html
<script id="el" src="/example.js" async></script>
js
const el = document.getElementById("el");
console.log(el.async); // Output: true

Specifications

Specification
HTML
# dom-script-async

Browser compatibility

desktop mobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
async
Chrome – Full support
Chrome 6 (Release date: 2010-09-02)
footnote Full support
Edge – Full support
Edge 12 (Release date: 2015-07-29)
footnote Full support
Firefox – Full support
Firefox 3.6 (Release date: 2010-01-21)
footnote Full support
Opera – Full support
Opera 15 (Release date: 2013-07-02)
footnote Full support
Safari – Full support
Safari 5.1 (Release date: 2011-07-20)
footnote Full support
Chrome Android – Full support
Chrome Android 18 (Release date: 2012-06-27)
footnote Full support
Firefox for Android – Full support
Firefox for Android 4 (Release date: 2011-03-29)
footnote Full support
Opera Android – Full support
Opera Android 14 (Release date: 2013-05-21)
footnote Full support
Safari on iOS – Full support
Safari on iOS 5 (Release date: 2011-10-12)
footnote Full support
Samsung Internet – Full support
Samsung Internet 1 (Release date: 2013-04-27)
footnote Full support
WebView Android – Full support
WebView Android 3 (Release date: 2011-02-22)
footnote Full support
WebView on iOS – Full support
WebView on iOS 5 (Release date: 2011-10-12)
footnote Full support

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support

See also