var mediaSource = new MediaSource();

mediaSource.addEventListener('sourceopen', function (data) {

    console.log('media source opened', data);

});

console.log('script started');

​

setTimeout(function () {

    console.log('timeout callback executed');

    var audioElement = new Audio();

    audioElement.src = URL.createObjectURL(mediaSource);

    console.log('audio element attached to media source');

}, 5000);