Computed vs Observer

application.controller.js

import Ember from 'ember';

export default Ember.Controller.extend({
 
  vehicleType:"Car",
  
  numWheels: Ember.on('init',Ember.computed('vehicleType',function(){
		if(this.get('vehicleType') === 'Car'){
    	this.set('numWheels',4);
    }
    else{
    	this.set('numWheels',0);
    }
  })),
                      
  observerForNumWheels: Ember.on('init', Ember.observer('vehicleType',function(){
		this.set('numWheels', 8);
	}))
});

application.template.hbs

The type of vehicle is an {{vehicleType}} and it has {{numWheels}} wheels.

twiddle.json

{
  "version": "0.6.3",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.4.1",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.4.0/ember-data.js",
    "ember-template-compiler": "2.4.1"
  }
}