https://stackoverflow.com/q/60049608/901944

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  timeZoneOptions: Object.freeze([
    { groupName: "Asia", options:["Kabul","Yerevan","Baku","Dhaka","Brunei","Bangkok","Shanghai","Urumqi","Taipei","Macau","Tbilisi","Dili","Kolkata","Jakarta"]},
    { groupName: "Australia", options: ["Darwin", "Eucla", "Perth", "Brisbane","Lindeman","Adelaide","Hobbart","Currie","Melbourne"]},
  ]),
  
  
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<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-paper": "v1.0.0-beta.26"
  }
}