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 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 Standard
The definition of 'AudioTrackList.length' in that specification.
Living Standard
HTML5
The definition of 'AudioTrackList.length' in that specification.
Recommendation

Browser compatibility

DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
lengthChrome Full support 45
Disabled
Full support 45
Disabled
Disabled From version 45: 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 10Opera Full support 32
Disabled
Full support 32
Disabled
Disabled From version 32: this feature is behind the enable-experimental-web-platform-features preference (needs to be set to enabled).
Safari Full support 6.1WebView Android Full support 45Chrome Android Full support 45
Disabled
Full support 45
Disabled
Disabled From version 45: 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 32
Disabled
Full support 32
Disabled
Disabled From version 32: this feature is behind the enable-experimental-web-platform-features preference (needs to be set to enabled).
Safari iOS Full support 7Samsung 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.