New Twiddle

components.expanding-thing.js

import Ember from 'ember';

export default Ember.Component.extend({
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  init() {
    this.isExpanded = this.get('conversation.isNew');
  },
  
  conversation: Ember.Object.create({
    isNew: true
  }),
  
  actions: {
    toggleIsNew() {
      this.toggleProperty('conversation.isNew');
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
<h2>Conversation isNew bound</h2>
{{expanding-thing isExpanded=conversation.isNew}}

<h2>Conversation isNew unbound</h2>
{{expanding-thing isExpanded=(unbound conversation.isNew)}}

<h2>Separate property</h2>
{{expanding-thing isExpanded=isExpanded}}

<button {{action "toggleIsNew"}}>Toggle conversation.isNew</button>
<br>
<br>

templates.components.expanding-thing.hbs

isExpanded: {{isExpanded}}

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"
  }
}