Computed Properties

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  bar: "bar",
  baz: "baz",
  foo: Ember.computed('bar', 'baz', {
    get (key) {
      return `${this.get('bar')} ${this.get('baz')}`;
    },
    set (key, value) {
      let [bar, baz] = value.split(/\s+/);
      this.set('bar', bar);
      this.set('baz', baz);
      return value;
    }
  }),
  actions: {
    changeBar() {
      if (this.get('bar') !== 'qux') {
        	this.set('bar', 'qux')
      }
      else {
          this.set('bar', 'bar')
      }            	
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<button {{action "changeBar"}} type="button">Set bar to qux</button>
<br>
<br>
<h2>Foo value: {{foo}}</h2>
{{outlet}}
<br>
<br>

twiddle.json

{
  "version": "0.10.5",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.8.0",
    "ember-data": "2.8.0",
    "ember-template-compiler": "2.8.0",
    "ember-testing": "2.8.0"
  },
  "addons": {}
}