New Twiddle

application.controller.js

import Ember from 'ember';

var observer = Ember.observer;
var  computed = Ember.computed;

var Car = Ember.Object.extend({
  isOn: 'false',
  color: 'blue',
  isOnChanged: observer('isOn','color', function() {
    console.log("changed set to " + this.get('isOn'));
  }),
});


export default Ember.Controller.extend({
  appName:'Observer Example',
  lambo: Car.create(),
  status: computed('lambo.isOn', function() {
    return "The lambo is " + (this.get('lambo').get('isOn') ? 'on' : 'off')
  }),
  actions: {
    pressed: function() {
      this.get('lambo').toggleProperty('isOn');

    }
  }
});

application.template.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
{{status}}
<br>
<button {{action 'pressed'}}>Press me</button>
<br>
<br>

twiddle.json

{
  "version": "0.4.10",
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.13.9/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/1.13.11/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.13.9/ember-template-compiler.js"
  }
}