I just spent over an hour on this and the guy didn't even show us how to actually add the song files!!!!!!!!!!!!!

function Song(title, artist, duration, path) { // added the path parameter
  this.title = title;
  this.artist = artist;
  this.duration = duration;
  this.isPlaying = false;
  this.mp3 = new Audio(path);  // created the mp3 property which is an HTMLAudioElement
}

Song.prototype.play = function() {
  this.mp3.play();  // added this to actually play the audio
  this.isPlaying = true;
};

Song.prototype.stop = function() {
  this.mp3.pause(); // HTMLAudioElement doesn't have a stop() method,
  this.mp3.currentTime = 0; // so we pause and reset the time instead.
  this.isPlaying = false;
};

// the rest of this file can stay the same

var playlist = new Playlist();

// just adding the path parameter we defined in our object - you'll need to upload the files.
// I put them in an audio folder, but you don't have to. You'd just leave off the audio/ if not.
var hereComesTheSun = new Song("Here Comes the Sun", "The Beatles", "2:54", "audio/hereComesTheSun.mp3");
var walkingOnSunshine = new Song("Walking on Sunshine", "Katrina and the Waves", "3:43", "audio/walkingOnSunshine.mp3");

// the rest of the code in this file can remain unchanged