Web/API/AudioTrackList

The AudioTrackList interface is used to represent a list of the audio tracks contained within a given HTML media element, with each track represented by a separate AudioTrack object in the list.

Retrieve an instance of this object with HTMLMediaElement.audioTracks. The individual tracks can be accessed using array syntax.

Properties

This interface also inherits properties from its parent interface, EventTarget.

length Read only: The number of tracks in the list.

Event handlers

onaddtrack: An event handler to be called when the addtrack event is fired, indicating that a new audio track has been added to the media element.
onchange: An event handler to be called when the change event occurs. This occurs when one or more tracks have been enabled or disabled by their enabled flag being changed.
onremovetrack: An event handler to call when the removetrack event is sent, indicating that an audio track has been removed from the media element.

Methods

This interface also inherits methods from its parent interface, EventTarget.

getTrackById(): Returns the AudioTrack found within the AudioTrackList whose id matches the specified string. If no match is found, null is returned.

Events

addtrack: Fired when a new audio track has been added to the media element. Also available via the onaddtrack property.
change: Fired when a track has been enabled or disabled. Also available via the onchange property.
removetrack: Fired when a new audio track has been removed from the media element. Also available via the onremovetrack property.

Usage notes

In addition to being able to obtain direct access to the audio tracks present on a media element, AudioTrackList lets you set event handlers on the addtrack and removetrack events, so that you can detect when tracks are added to or removed from the media element's stream. See onaddtrack and onremovetrack for details and examples.

Examples

Getting a media element's audio track list

To get a media element's AudioTrackList, use its audioTracks property.

var audioTracks = document.querySelector("video").audioTracks;

Monitoring track count changes

In this example, we have an app that displays information about the number of channels available. To keep it up to date, handlers for the addtrack and removetrack events are set up.

audioTracks.onaddtrack = updateTrackCount;
audioTracks.onremovetrack = updateTrackCount;

function updateTrackCount(event) {
  trackCount = audioTracks.length;
  drawTrackCountIndicator(trackCount);
}

Specifications

Specification	Status	Comment
HTML Living StandardThe definition of 'AudioTrackList' in that specification.	Living Standard
HTML5The definition of 'AudioTrackList' 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
`AudioTrackList`	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
`addtrack` event	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
`change` event	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
`getTrackById`	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
`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
`onaddtrack`	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
`onchange`	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
`onremovetrack`	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
`removetrack` event	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 by Mozilla Contributors is licensed under CC-BY-SA 2.5.