New Twiddle

application.controller.js

import Ember from 'ember';

export default Ember.Controller.extend({
  spinner: Ember.inject.service(),
  appName:'Ember Twiddle',
  actions: {
    loadSomething() {
      this.get('spinner').loadStart();
      Ember.run.later(() => {
        this.get('spinner').loadEnd();
      }, 3000);
    }
  }
});

application.template.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<button {{action "loadSomething"}}>Load something</button>
<br>
<br>
{{#if spinner.isLoading}}
Loading...
{{/if}}

spinner.service.js

import Ember from 'ember';

export default Ember.Service.extend({
  isLoading: false,
  loadStart() {
    this.set('isLoading', true);
  },
  loadEnd() {
    this.set('isLoading', false);
  }
});

twiddle.json

{
  "version": "0.4.17",
  "EmberENV": {
    "FEATURES": {}
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.2.0/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.2.0/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.2.0/ember-template-compiler.js"
  }
}