New Twiddle

components.child-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  didReceiveAttrs(...args) {
    this.set('lastReceiveAttrsArgs', JSON.stringify(args, null, 2));
  }
});

components.parent-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  foo: 0,
  bar: 0,
  actions: {
    changeFoo() {
      this.incrementProperty('foo');
    },
    changeBar() {
      this.incrementProperty('bar');
    }
  }
});

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>
{{parent-component}}
{{outlet}}
<br>
<br>

templates.components.child-component.hbs

Foo: {{attrs.foo}}<br />
Bar: {{attrs.bar}}<br /><br />
Last args to <code>didReceiveAttrs</code>: 
<pre>{{lastReceiveAttrsArgs}}</pre>

templates.components.parent-component.hbs

<button {{action "changeFoo"}}>Change Foo</button>
<button {{action "changeBar"}}>Change Foo</button>
{{child-component foo=foo bar=bar}}

twiddle.json

{
  "version": "0.10.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.6.0",
    "ember-data": "2.6.1",
    "ember-template-compiler": "2.6.0"
  },
  "addons": {}
}