Web/API/AudioTrackList/length

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.

Syntax

var trackCount = AudioTrackList.length;

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.

Example

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

var videoElem = document.querySelector("video");
var 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	Status	Comment
HTML Living StandardThe definition of 'AudioTrackList.length' in that specification.	Living Standard
HTML5The definition of 'AudioTrackList.length' in that specification.	Recommendation

Browser compatibility

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
`length`	Chrome Full support 37 Disabled' Full support 37 Disabled' Disabled' From version 37: this feature is behind the `enable-experimental-web-platform-features` preference (needs to be set to `enabled`). To change preferences in Chrome, visit chrome://flags.	Edge Full support 79 Disabled' Full support 79 Disabled' Disabled' From version 79: this feature is behind the `enable-experimental-web-platform-features` preference (needs to be set to `enabled`). No support 12 — 79	Firefox Full support 33 Disabled' Full support 33 Disabled' Disabled' From version 33: this feature is behind the `media.track.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE Full support 10	Opera Full support 24 Disabled' Full support 24 Disabled' Disabled' From version 24: this feature is behind the `enable-experimental-web-platform-features` preference (needs to be set to `enabled`).	Safari Full support 6.1	WebView Android No support No	Chrome Android Full support 37 Disabled' Full support 37 Disabled' Disabled' From version 37: this feature is behind the `enable-experimental-web-platform-features` preference (needs to be set to `enabled`). To change preferences in Chrome, visit chrome://flags.	Firefox Android Full support 33 Disabled' Full support 33 Disabled' Disabled' From version 33: this feature is behind the `media.track.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	Opera Android Full support 24 Disabled' Full support 24 Disabled' Disabled' From version 24: this feature is behind the `enable-experimental-web-platform-features` preference (needs to be set to `enabled`).	Safari iOS Full support 7	Samsung Internet Android No support No

Legend

Full support: Full support
No support: No support
User must explicitly enable this feature.': User must explicitly enable this feature.

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