New Twiddle

components.x-foo.js

import Ember from 'ember';

export default Ember.Component.extend({
  hasBlock: false
});

controllers.application.js

import Ember from 'ember';

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

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>
{{#x-foo}}
	foo
{{/x-foo}}
{{x-foo}}

templates.components.x-foo.hbs

{{#if hasBlock}}
	<h2>in block</h2>
	{{yield}}
{{else}}
	hey!
{{/if}}

twiddle.json

{
  "version": "0.13.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.7.3",
    "ember-template-compiler": "2.7.3",
    "ember-testing": "2.7.3"
  },
  "addons": {
    "ember-data": "2.16.3"
  }
}