New Twiddle

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  
  foo: '',
  
  init() {
    this._super(...arguments);
    console.info(this.constructor, 'init', this.getProperties('foo', 'attrs.foo.value'));
  },
  
  didReceiveAttrs() {
    this._super(...arguments);
    console.info(this.constructor, 'didReceiveAttrs', this.getProperties('foo', 'attrs.foo.value'));
  },
  
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  
  myFoo: 'bar',
  
  actions: {
    mutateAttr() {
      this.set('myFoo', 'baz');
    }
  }
  
});

templates.application.hbs

{{my-component foo=myFoo}}

<button {{action 'mutateAttr'}}>Mutate attr</button>

twiddle.json

{
  "version": "0.7.2",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.4.4",
    "ember-template-compiler": "2.4.4"
  }
}