looping background music in all major browsers with only moderate pain

song.js

/*
works in:
* chrome
* firefox 3.5+
* safari (with quicktime installed)
* ie 6+

I ended up only needing an ogg and mp3 version
of the file I wanted to play. Any browser that
has m4a support also worked with mp3.

I tried serving the files with node-paperboy,
but it made looping in chrome not work. Serving
files from lighttpd instead worked for me.

The ogg wasn't playing in firefox until I set
the content type to 'audio/ogg' in paperboy.
lighttpd knew the right content type without
prompting.

sources:
* http://mir.aculo.us/2011/03/16/how-to-play-a-sound-in-a-web-browser-it-aint-easy/
* http://stackoverflow.com/questions/3273552/html-5-audio-looping
* https://developer.mozilla.org/en/HTML/Element/audio
*/

var Song = function (filename) {
  if (!("Audio" in window)) { return; }
  var song = this,
      elt = this.elt = new Audio();
  var canPlay = function (c) {
    return elt.canPlayType && elt.canPlayType(c).replace('no', '');
  };
  if (canPlay('audio/mpeg;')) {
    elt.src = filename + '.mp3';
  }
  else if (canPlay('audio/ogg; codecs="vorbis"')) {
    elt.src = filename + '.ogg';
  }
  else {
    elt.src = filename + '.mp3';
  }
  if (typeof(elt.loop) == 'boolean') {
    elt.loop = true;
  }
  else {
    elt.addEventListener('ended', function() {
      if (!song.playing) { return; }
      elt.currentTime = 0;
      elt.play();
    }, false);
  }
  document.body.appendChild(elt);
};

Song.prototype.start = function () {
  if ("Audio" in window) {
    this.playing = true;
    this.elt.play();
  }
  else {
    var elt = this.elt = document.createElement('bgsound');
    elt.src = this.filename + '.mp3';
    elt.loop = 9;
    elt.autostart = 'autostart';
    document.body.appendChild(elt);
  }
};

Song.prototype.stop = function () {
  if ("Audio" in window) {
    this.playing = false;
    this.elt.pause();
  }
  else {                                                                               
    this.elt.parentNode.removeChild(this.elt);
  }
};