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

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

Instance properties

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

lengthRead only

The number of tracks in the list.

Instance methods

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

getTrackById()

Returns theAudioTrack found within theAudioTrackList whoseid 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.

change

Fired when a track has been enabled or disabled.

removetrack

Fired when a new audio track has been removed from the media element.

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 theaddtrack andremovetrack events, so that you can detect when tracks are added to or removed from the media element's stream. See theaddtrack andremovetrack events for details and examples.

Examples

Getting a media element's audio track list

To get a media element'sAudioTrackList, use itsaudioTracks property.

const 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 theaddtrack andremovetrack events are set up.

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

Specifications

Browser compatibility