New Twiddle

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  twoDArray: [[0, 0, 0], [0, 0, 0]],
  actions: {
		changeArray() {
  		this.set('twoDArray', [[1, 1, 1], [0, 0, 0]])
      // this.notifyPropertyChange('twoDArray')
	  },
  },
  arrayObserverA: Ember.observer('twoDArray', function() {
			alert('change observed A')
	}),
  didRender() {
     // register observers
   	this.get('arrayObserverA')
    this.get('arrayObserverB')
  },
  arrayCP: Ember.computed('twoDArray.[]', function() {
   	return "CP fired"
  }),
  anotherArrayCP: Ember.computed('twoDArray', function() {
   	return "CP fired"
  }),
});

controllers.application.js

import Ember from 'ember';

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

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{my-component}}
<br>
<br>

templates.components.my-component.hbs

<button {{action "changeArray"}}>should trigger alert</button>
<br>
<br>
Array CP: {{arrayCP}}

<br>
<br>

AnotherArray CP: {{anotherArrayCP}}

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": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}