W3cubDocs

/Web APIs

HTMLSourceElement: sizes property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨March 2017⁩.

The sizes property of the HTMLSourceElement interface is a string representing a list of one or more sizes, representing sizes between breakpoints, to which the resource applies.

It reflects the sizes attribute of the <source> element.

Value

A string.

Examples

<source
  id="el"
  src="mediumVideo.mov"
  type="video/quicktime"
  sizes="(50em <= width <= 60px) 50em,
         (30em <= width < 50em) 30em" />

const el = document.getElementById("el");
console.log(el.sizes); // Output: "(50em <= width <= 60px) 50em, (30em <= width < 50em) 30em"
el.sizes = "(50em <= width <= 60px) 100em, (30em <= width < 50em) 60em"; // Updates the sizes value

Specifications

Specification
HTML>
# dom-source-sizes>

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
sizes 38 13 38 25
10.1The sizes attribute is supported since Safari 9.1.
 38 38 25
10.3The sizes attribute is supported since Safari on iOS 9.1.
 3.0 38
10.3The sizes attribute is supported since WebView on iOS 9.1.

See also

© 2005–2025 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/HTMLSourceElement/sizes