New Twiddle

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  tagName: 'span',
  foo: null,
  actions: {
    increment() { this.incrementProperty('foo'); }
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  foo: 0
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
Application foo: {{foo}}<br/>
{{my-component foo=foo}}<br/>
readonly {{my-component foo=(readonly foo)}}<br/>
unbound {{my-component foo=(unbound foo)}}<br/>

<br>
<br>

templates.components.my-component.hbs

Component foo: {{foo}} <button {{action 'increment'}}>+</button>

twiddle.json

{
  "version": "0.10.6",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.9.0",
    "ember-data": "2.9.0",
    "ember-template-compiler": "2.9.0",
    "ember-testing": "2.9.0"
  },
  "addons": {}
}