I want to execute a method when my $http.selectedSong (model value) changes , but I can't seem to let it work anny ideas how this comes? : 

```
app.controller('songController', ['$http', function($http) {

    $songs = this;
    $songs.tracks = [];

    $http({
            url: "http://api.q-music.be/1.2/tracks/plays?limit=20",
            dataType: "jsonp",
            jsonp: "callback"
        })
        .success(function(lastSongsList) {

            $http.$watch('selectedSong', function (newVal, oldVal) {
                 if (newVal !== oldVal) {
                    alert('hej');
                 }
            });
        });

}]);

```

My goal is to work with data i achieved from this html code : 

```
<select ng-model="selectedSong"  ng-init="selectedSong === songs.tracks[0].title" ng-options="song as song.title for song in songs.tracks"></select>

```

I want to see when the value I select in 'select' changes so i can work with this value to do methods etc ...