New Twiddle

application.controller.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName:'Ember Twiddle',
  images: [
    {'id': 0, 'name':'first', 'src': 'https://i.imgur.com/uQbAV8a.gif'},
    {'id': 1, 'name':'second', 'src': 'http://replygif.net/i/715.gif'},
    {'id': 2, 'name':'third', 'src': 'http://25.media.tumblr.com/tumblr_lovjrlNfbB1qaxm3co6_500.gif'} 
  ]
});

application.template.hbs

{{product-image images=images}}

helpers.equals-helper.js

import Ember from 'ember';

export function equalsHelper(params/*, hash*/) {
  return params[0] === params[1];
}

export default Ember.Helper.helper(equalsHelper);

product-image.component.js

import Ember from 'ember';

export default Ember.Component.extend({
  currentImage: 0,
  currentImageSrc: Ember.computed('currentImage', function() {
  	return this.images[this.currentImage].src;
  }),
  actions: {
  	setCurrentImage(id) {
    	this.set('currentImage', id);
    }
  }
});

product-image.template.hbs

<img class="product-image-current-image" src="{{currentImageSrc}}" />
{{#each images as |image index|}}
<img
	class="image {{if (equals-helper index currentImage) 'active'}}"
  src="{{image.src}}"
  {{action 'setCurrentImage' index}}
 />
{{/each}}

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

.image {
	height: 50px;
  width: 50px;
  border: 1px solid black;
  display: inline-block;
  margin: 10px;
}

.image.active {
	border: 2px solid red;
}

.product-image-current-image {
  display: block;
}

twiddle.json

{
  "version": "0.5.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.2.0/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.2.0/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.2.0/ember-template-compiler.js"
  }
}