helper import stuff

controllers.application.js

import Ember from 'ember';
import { myHelper } from '../helpers/my-helper';
import { classBasedHelper } from '../helpers/class-based-helper';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  appNameCaptial: Ember.computed('appName',function(){
    return myHelper([this.get('appName')]);
  }),
  appNameCaptial2: Ember.computed('appName',function(){
    return myHelper([this.get('appName')]);
  }),
});

helpers.class-based-helper.js

import Ember from 'ember';

export default Ember.Helper.extend({
  compute([value],...rest){
    return value.toUpperCase();
  }
});

helpers.my-helper.js

import Ember from 'ember';

export function myHelper([value],...rest) {  
  return value.toUpperCase();
}

export default Ember.Helper.helper(myHelper);

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
{{appNameCaptial}}
{{appNameCaptial2}}
<br>
{{outlet}}
<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"
  }
}