Wait until callback

Question

I've got an array with audio-files, to play all one by one. I'm using a javascript player, that will play the audio and provides a callback when finished.

for (i = 0; i < audioFiles.length; i++) {
    PlayAudio(audioFiles[i], function(){
        alert('complete file #' + i);
    });
}

But my problem now, how to do this one by one. The snippet above will start several audio-files and play them parallel. What is the best solution, to wait until a callback is fired?

Answer 1

There are many solutions. Waiting until the callback fires seems like a good solution.

function playAudioFile(index) {
  PlaidAudio(audioFiles[index], function () {
    var next = index + 1;
    if (next < audioFiles.length) {
      playAudioFile(index+1);
    }
  });
}

function playAudioFiles() {
  playAudioFile(0);
}

Side note:

If you're looking for a more generic way to run tasks serially, you should look at promises here, here, or here (though the last post is only for AngularJS).