New Twiddle

controllers.application.js

import Ember from 'ember';
const {get,set} = Ember;

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  filteredItems: Ember.computed('[email protected]', 'filter', {
    get() {
      return get(this, 'model').filter(m => get(m, 'cat') === get(this, 'filter'));
    }
  }),
  actions: {
    filter(filter) {
      set(this, 'filter', filter);
    }
  }
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    return [{ cat: 'lorem', name: 'foo' },
            { cat: 'lorem', name: 'bar' },
            { cat: 'lorem', name: 'baz' },
            { cat: 'ipsum', name: 'bam' }];
  }
});

styles.app.css

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

.active {
  background: red;
}

templates.application.hbs

filters: (active: {{filter}})<br>

<div
	class="{{if (eq 'lorem' filter) 'active'}}"
	onclick={{action 'filter' 'lorem'}}
>
	click for Lorem
</div>

<div
	class="{{if (eq 'ipsum' filter) 'active'}}"
	onclick={{action 'filter' 'ipsum'}}
>
  click for Ipsum
</div>

<br>
items:
<br>
{{#each filteredItems as |item|}}
	<div>{{item.cat}}:{{item.name}}</div>
{{/each}}
<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",
    "ember-truth-helpers": "1.3.0"
  }
}