http://stackoverflow.com/questions/43512614/change-event-for-textarea-in-ember

components.my-textarea.js

import Ember from 'ember';

export default Ember.TextArea.extend({
  change(){    
    this.sendAction('onTextFiledChange');
    return true;
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  actions:{
    onTextFiledChange(){
      console.log('onTextFiledChange');
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<textarea value={{appName}} onchange={{action 'onTextFiledChange'}} />
{{textarea value=appName focus-out='onTextFiledChange' }}
{{my-textarea value=appName onTextFiledChange='onTextFiledChange'}}
<br>
{{outlet}}
<br>
<br>

templates.components.my-textarea.hbs

{{yield}}

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"
  }
}