Height toggle test, latest ember

components.child-component.js

import Ember from 'ember';

export default Ember.Component.extend({
   heightToggled: false,
  
  click() {
    this.toggleProperty('heightToggled'); 
  }
});

components.parent-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  items: Ember.A(['red', 'blue','green']),
  
  actions: {
    addItem() {
      this.get('items').pushObject('yellow');
    }
  }
});

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>
{{parent-component}}
<br>
<br>

templates.components.child-component.hbs

<li style="height: {{if heightToggled '100px' '50px'}}">{{item}}</li>

templates.components.parent-component.hbs

<button {{action 'click'}}>Toggle heights</button>
<button {{action 'addItem'}}>Add item</button>
{{#each items as |item|}}
	{{child-component item=item}}
{{/each}}

twiddle.json

{
  "version": "0.7.2",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.4.4",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.4.3/ember-data.js",
    "ember-template-compiler": "2.4.4"
  }
}