New Twiddle

controllers.application.js

import Ember from 'ember';

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

simple-menu-container.component.js

import Ember from 'ember';

export default Ember.Component.extend({
  
  expandMenu: false
});

simple-menu-container.template.hbs

<h1>Simple menu container - PARENT</h1>
<p>expandMenu property is here in component.js</p>
==================================================
{{yield}}

simple-menu.component.js

import Ember from 'ember';

export default Ember.Component.extend({
  
  expandMenu: Ember.computed.alias('parentView.expandMenu'),	
  
  // Remove this observer and everything will load again
  toggle: Ember.observer('expandMenu', () => {
  	console.log(this.get('expandMenu'))
  }),
  // Or this construct too -> Old way
  //toggle2: function(){
	//	console.log(this.get('expandMenu'))
	//}.observes('expandMenu')
});

simple-menu.template.hbs

<h3>Simple menu compomponent is here - CHILD</h3>
<p>computed aliases are here pointing to parentView</p>
==================================================
{{yield}}

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
{{#simple-menu-container}}
	<pre>Rendering inside of simple-menu-container</pre>
	{{#simple-menu}}
		<pre>content of simple menu compoennt block</pre>
	{{/simple-menu}}
{{/simple-menu-container}}
<br>
<br>

twiddle.json

{
  "version": "0.10.5",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": true,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.8.1",
    "ember-data": "2.8.0",
    "ember-template-compiler": "2.8.1",
    "ember-testing": "2.8.0"
  },
  "addons": {}
}