AudioTrackList: length property

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

The read-only AudioTrackList property length returns the number of entries in the AudioTrackList, each of which is an AudioTrack representing one audio track in the media element. A value of 0 indicates that there are no audio tracks in the media.

Value

A number indicating how many audio tracks are included in the AudioTrackList. Each track can be accessed by treating the AudioTrackList as an array of objects of type AudioTrack.

Examples

This snippet gets the number of audio tracks in the first <video> element found in the DOM by querySelector().

js
const videoElem = document.querySelector("video");
let numAudioTracks = 0;

if (videoElem.audioTracks) {
  numAudioTracks = videoElem.audioTracks.length;
}

Note that this sample checks to be sure HTMLMediaElement.audioTracks is defined, to avoid failing on browsers without support for AudioTrack.

Specifications

Specification
HTML
# dom-audiotracklist-length-dev

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
length

Legend

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Full support
Full support
No support
No support
User must explicitly enable this feature.
Has more compatibility info.