New Twiddle

application.controller.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  notificationText: '',
  notificationTextLimit: 140,
  notificationTextOverLimit: Ember.computed('notificationText', 'notificationTextLimit', {
    get() {
      return this.get('notificationText.length') > this.get('notificationTextLimit');
    }
  })
});

application.template.hbs

<div class="label {{if notificationTextOverLimit 'red-text'}}">Notification Text:</div>
{{textarea value=notificationText}}
<div class="count {{if notificationTextOverLimit 'red-text'}}">
{{notificationText.length}} / {{notificationTextLimit}}
</div>

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

.red-text {
  color: red;
}

twiddle.json

{
  "version": "0.6.5",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.4.0/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember-template-compiler.js"
  }
}