New Twiddle

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  classNames: ['class-0'],
  init() {
    this._super();
//    this.classNames = this.classNames.slice();
    this.classNames.pushObjects(['WOLOLO']);
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
	number: 1,
  classForMyThing: Em.computed('number', function() { return `class-${this.get('number')}`; }),
  
  actions: {
    incrementNumber() {
      this.incrementProperty('number');
	  }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
{{number}}
<br>
{{
	my-component
  classNames=classForMyThing
}}
<button {{action 'incrementNumber'}}>Increment</button>
<br>
<br>

templates.components.my-component.hbs

O_O

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.8.2",
    "ember-template-compiler": "2.8.2",
    "ember-testing": "2.8.2"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}