New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  items: [{
  id: 0,
  name: 'Root',
  isExpanded: true,
  isSelected: false,
  isVisible: true,
  children: [
    {
      id: 1,
      name: 'First Child',
      isExpanded: true,
      isSelected: false,
      isVisible: true,
      children: []
    },
    {
      id: 2,
      name: 'Second Child',
      isExpanded: true,
      isSelected: false,
      isVisible: true,
      children: [
        {
          id: 3,
          name: 'First Grand Child',
          isExpanded: true,
          isSelected: true,
          isVisible: true,
          children: []
        }
      ]
    }
  ]
}]
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
{{x-tree model=items checkable=true}}
<br>
<br>

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",
    "ember-simple-tree": "0.5.1"
  }
}