Ember `mut` helper

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  input(e) {
    // The `mut` helper changes the `appName` value to what 
    // is provided as the `action` argument.
  	this.get('onNewValue')(e.target.value);
  }
});

controllers.application.js

import Ember from 'ember';

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

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
{{outlet}}

{{!-- 
  The `mut` helper changes the `appName` value to 
  what is provided as the `action` argument.
--}}
{{my-component 
	onNewValue=(action (mut appName))
}}

templates.components.my-component.hbs

<input type="text" placeholder='Enter your app name...'>

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"
  }
}