HTMLScriptElement: defer 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 defer property of the HTMLScriptElement interface is a boolean value that controls how the script should be executed. For classic scripts, if the defer property is set to true, the external script will be executed after the document has been parsed, but before firing DOMContentLoaded event. For module scripts, the defer property has no effect.

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

Value

A boolean.

Examples

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

Specifications

Specification
HTML
# dom-script-defer

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
defer
Chrome – Full support
Chrome 1 (Release date: 2008-12-11)
footnote Full support
Edge – Full support
Edge 12 (Release date: 2015-07-29)
footnote Full support
Firefox – Full support
Firefox 3.5 (Release date: 2009-06-30)
footnote Full support
Opera – Full support
Opera 12.1 (Release date: 2012-11-20)
footnote Full support
Safari – Full support
Safari 3 (Release date: 2007-10-26)
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 12.1 (Release date: 2012-10-09)
footnote Full support
Safari on iOS – Full support
Safari on iOS 1 (Release date: 2007-06-29)
footnote Full support
Samsung Internet – Full support
Samsung Internet 1 (Release date: 2013-04-27)
footnote Full support
WebView Android – Full support
WebView Android 4.4 (Release date: 2013-12-09)
footnote Full support
WebView on iOS – Full support
WebView on iOS 1 (Release date: 2007-06-29)
footnote Full support

Legend

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

Full support
Full support

See also