https://stackoverflow.com/questions/47686110/ember-js-computed-property-to-return-model-id-array/47689391

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  //if you use ()=> instead function() : this reference will be surrounding module when you use arrow function.
  result:Ember.computed('model',function(){
    return `${this.get('appName')} ${this.get('model')}`;
  }),
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  model(){
    return 'test';
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
{{result}}
<br>
{{outlet}}
<br>
<br>

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"
  }
}