New Twiddle

controllers.application.js

import Ember from 'ember';
let called = 0;
export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  changingProp: 5,
  notChangingCp: Ember.computed('changingProp', function() {
  let prop = this.get('changingProp');
  // Simulate calc that doesn't end up changing.
  return 10;
}),
  expensiveCp: Ember.computed('notChangingCp', function() {
    called++;
    return `Expensive CP has been called: ${called} times.`;
  }),
  actions: {
    inc() {
      this.incrementProperty('changingProp')
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
<p>
changingProp: {{changingProp}}
<button onclick={{action 'inc'}}>Inc</button>
</p>
<p>
notChangingCp: {{notChangingCp}}
</p>
<p>
expensiveCp: {{expensiveCp}}
</p>
<br>
<br>

twiddle.json

{
  "version": "0.10.5",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.8.0",
    "ember-data": "2.8.0",
    "ember-template-compiler": "2.8.0",
    "ember-testing": "2.8.0"
  },
  "addons": {}
}