title: backbone js cannot return a value in events on
body: <p>guys, I'm new to backboneJs, and I tried to write a basic program to return a value in events.on like below, but it does not work.</p>
  
  <pre><code>$(function(){
      // object.on(event, callback, [context])Alias: bind 
      var object = {};
      _.extend(object, Backbone.Events);
  
      object.on('add',function(a,b){
          return a + b;
      });
  
      var sum = object.trigger('add',1,3);
      // not as I expected.
      alert(sum);
  });
  </code></pre>
  
  <p>I hope someone give me some ideals, thanks a lot.</p>