New Twiddle

controllers.application.js

import Ember from 'ember';

const FooMixin = Ember.Mixin.create({
  foo() {
    alert('foo');
  }
});

const obj = Ember.Object.extend(FooMixin).create();

FooMixin.reopen({
  foo() {
    alert('reopened');
  }
});

export default Ember.Controller.extend(FooMixin, {
  fooOnInit: Ember.on('init', function() {
    obj.foo();
  }),
  appName: 'Ember Twiddle'
});

templates.application.hbs

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