Another thing to note is that you can't pass a URL this way.  Also, the URL you need isn't on `playlist[0]` but on `playlist[0].url`.  You probably want to do something like this:

```javascript
var audio = new Audio();
...
  play: function() {
    if(!audio.src) {
      audio.src = playlist[0].url;
    }
    audio.play();
  }
```