title: Return promise from a Backbone Model
body: <p>I have a model, which is fetched from the server. I would like to return a promise on creation, so that views that are using this model know, when to render.
  I could bind the promise to the window (or app), but a neater way would be to just return it, when the model is initialized (var promise = new app.User()).
  Is there a way to do this. And also: Is this a good way of handling async data?</p>
  
  <pre><code>app.User = Backbone.Model.extend({
      urlRoot: baseUrl+"/user",
  
      initialize: function(){
          this.promise = this.fetch();
          return this.promise; // Doesn't work ofc
      }
  
  });
  </code></pre>