New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  isGTSUser: Ember.computed('user.userType', function() {
    return this.get('user.userType') === 'gts_user'
  }),
  
  actions: {
    changeUserType () {
			if (this.get('user.userType') === 'gts_user') {
        this.set('user.userType', 'non_gts_user')
      } else {
        this.set('user.userType', 'gts_user')
      }
    }
  }
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  setupController(controller, model){
   	controller.set('user', Ember.Object.create({
      'userType': 'gts_user'
    }));
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{user.userType}}
<br/>
<button {{action 'changeUserType'}}>Click</button>
<br/>
{{isGTSUser}}
<br/>
{{outlet}}
<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"
  }
}