helper test

application.controller.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName:'Ember Twiddle',
  model: Ember.computed(function() {
  	return [{
    	id: 1
  	},{
    	id: 2
  	}];
  })
});

application.template.hbs

<h1>Welcome to {{appName}}</h1>
{{#each model as |thing|}}
 	{{foo-bar id=(getId thing.id)}}
{{/each}}
<br>
<br>
{{outlet}}
<br>
<br>

foo-bar.component.js

import Ember from 'ember';

export default Ember.Component.extend({
});

foo-bar.template.hbs

{{id}}

helpers.get-id.js

import Ember from 'ember';

export function getId(params/*, hash*/) {
  return 'Foo-Bar ' + params;
}

export default Ember.Helper.helper(getId);

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"
  }
}