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.
Instance properties
This interface also inherits properties from its parent interface, EventTarget
.
length
Read only-
The number of tracks in the list.
Instance methods
This interface also inherits methods from its parent interface, EventTarget
.
getTrackById()
-
Returns the
AudioTrack
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 the addtrack
and removetrack
events, so that you can detect when tracks are added to or removed from the media element's stream. See the addtrack
and removetrack
events for details and examples.
Examples
Getting a media element's audio track list
To get a media element's AudioTrackList
, use its audioTracks
property.
js
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 the addtrack
and removetrack
events are set up.
js
audioTracks.onaddtrack = updateTrackCount;
audioTracks.onremovetrack = updateTrackCount;
function updateTrackCount(event) {
trackCount = audioTracks.length;
drawTrackCountIndicator(trackCount);
}
Specifications
Specification |
---|
HTML Standard # audiotracklist-and-videotracklist-objects |
Browser compatibility
BCD tables only load in the browser