New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  init() {
    this._super(...arguments);
    this.set('foo', [1,2,3]);
  },
  actions: {
    notifyParent() {
      console.log('notifyParent');
      this.notifyPropertyChange('foo')
    }
    notifyChild() {
      console.log('notifyChild');
      this.foo.notifyPropertyChange('[]')
    }
  }
});

templates.application.hbs

<h1>notifyPropertyChange test</h1>

<ul>
  {{#each foo as |item|}}
    <li>{{item}}</li>
  {{/each}}
</ul>

<button {{action "notifyParent"}}>notify parent</button>
<button {{action "notifyChild"}}>notify child</button>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}