I have this event...

   <textarea id=chat> </textarea>

   <button type=button onclick=play_song();>talk</button>

... triggering the following function:

   var input = function() {

           var chat = document.getElementById(chat).value.split( );

           return chat && console.log(chat);

        }

then there's this function:

   function setIntersection(a, b) {



      var result = [];



      for (var i = 0; i < a.length; i++) {

         if (b.indexOf(a[i]) !== -1 && result.indexOf(a[i]) === -1) {

            result.push(a[i]);

         }

      }

    return result;

   }

a prototype function:

   Song.prototype.lyricsIntersect = function(input) {





      var bestSong = null;

      var bestCount = -Infinity;



      for (var i in songs) {

        var currentCount = setIntersection(songs[i].lyrics, input).length;



    if (currentCount > bestCount) {

        bestSong = songs[i];

        bestCount = currentCount;

    }

}



return bestSong && bestSong.name;

}

the code ends here:

   function play_song() {



    var id = Song.prototype.lyricsIntersect(input);

    var element = document.getElementById(id);

    element.play();

}

but console.log returns: Uncaught TypeError: b.indexOf is not a function

if I test var input = [one, two];, however, I get the intersection done on the code depending on input.

what am I missing?