New Twiddle

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
    test: Ember.computed('appName', function() {
    var _this = this;
    
    // throws an exception
 	  console.log('this.$', this.$());
    
    Ember.run('afterRender', function() {
      //undefined
      console.log('afterRender _this.$', _this.$()); 
    });
  })
});

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>
{{outlet}}

<br>
<br>

templates.components.my-component.hbs

{{yield}}
Test: {{test}}

twiddle.json

{
  "version": "0.9.3",
  "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"
  }
}