Code for previewing ember loading templates

books.js

// routes/books.js
export default Ember.Route.extend({
  model: function() {
    var route = this;
    return new Ember.RSVP.Promise(function(resolve) {
      Ember.run.later(function() {
        var model = route.store.find('book');
        resolve(model);
      }, 3000); // 3 second delay
    });
  }
});