New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle1',
  a: 3,
  b: 4,
  c: 5,
  d: Ember.computed('a','b','c', function(){
		return this.get('a') + this.get('b') + this.get('c');
	}),
  firstname: 'Tom',
  lastname: 'Dale',
  fullname: Ember.computed('firstname','lastname', {
  	get() {
    	return this.get('lastname') + ' ' + this.get('firstname');
    },
    set(propertyName, val) {
      if (!val) {
      	val = '';
      }
    	this.set('lastname',val.split(' ')[0]);
      this.set('firstname', val.split(' ').pop());
      return val;
    }
  })
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
{{input value=a placeholder="a"}}
{{input value=b placeholder="b"}}
{{input value=c placeholder="c"}}
<br>
<b>a+b+c = {{d}}</b><br>
{{outlet}}
<br>
{{input value=firstname placeholder="firstname"}}
{{input value=lastname placeholder="lastname"}}

{{input value=fullname placeholder="fullname"}}
<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"
  }
}