ugh-loading

application.controller.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName:'Ember Twiddle'
});

application.js

import Ember from 'ember';

export default Ember.Route.extend({
  actions: {
    loading() {
      Ember.Logger.info("loading hook of Application Route");
    }
  }
});

application.template.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

loading.hbs

<p>Hey, I'm loading</p>

loading.js

import Ember from 'ember';

export default Ember.Route.extend({
  actions: {
    willTransition() {
      Ember.Logger.info("willTransition of loading route");
    },
  
    didTransition() {
      Ember.Logger.info("didTransition of loading route");
    }
  }
});

twiddle.json

{
  "version": "0.4.11",
  "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"
  }
}