The AudioTrack property enabled specifies whether or not the described audio track is currently enabled for use. If the track is disabled by setting enabled to false, the track is muted and does not produce audio.

The enabled property is a Boolean whose value is true if the track is enabled; enabled tracks produce audio while the media is playing. Setting enabled to false effectively mutes the audio track, preventing it from contributing to the media's audio performance.

This example switches between the main and commentary audio tracks of a media element.

function swapCommentaryMain() {
  const videoElem = document.getElementById("main-video");
  let audioTrackMain;
  let audioTrackCommentary;

  videoElem.audioTracks.forEach((track) => {
    if (track.kind === "main") {
      audioTrackMain = track;
    } else if (track.kind === "commentary") {
      audioTrackCommentary = track;
    }
  });

  if (audioTrackMain && audioTrackCommentary) {
    const commentaryEnabled = audioTrackCommentary.enabled;
    audioTrackCommentary.enabled = audioTrackMain.enabled;
    audioTrackMain.enabled = commentaryEnabled;
  }
}

The swapCommentaryMain() function above finds within the audio tracks of the <video> element "main-video" the audio tracks whose kind values are "main" and "commentary". These represent the primary audio track and the commentary track.

The element's audio tracks are then scanned through using the JavaScript forEach() method (although the audioTracks property of a media element isn't actually a JavaScript array, it can be accessed like one for the most part).

The scan looks for the tracks whose kind values are "main" and "commentary" and remembers those AudioTrack objects. Once those have been found, the values of the two tracks' enabled properties are exchanged, which results in swapping which of the two tracks is currently active.