EC: Sync Loading State

components.x-card.js

import Ember from 'ember';
import { task, timeout } from 'ember-concurrency';

export default Ember.Component.extend({
  classNames: ['x-card'],
  timeout: 500,
  
  task: task(function *() {
  	yield timeout(this.get('timeout'));
  }).on('didReceiveAttrs').restartable()
});

controllers.application.js

import Ember from 'ember';

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

styles.app.css

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

.x-card {
 margin: 20px;
 padding: 20px;
 border-radius: 3px;
 box-shadow: 0 0 1px 1px #ccc;
 float: left;
 min-width: 200px;
  min-height: 100px;
}

.x-card h4 {
 margin: 0; 
}

templates.application.hbs

{{x-card name='Card 1' timeout=500}}
{{x-card name='Card 2' timeout=1000}}
{{x-card name='Card 3' timeout=1500}}
{{x-card name='Card 4' timeout=2000}}
{{x-card name='Card 5' timeout=2500}}

templates.components.x-card.hbs

<h4>{{name}}</h4>

<br><br>
{{#if task.isRunning}}
	Loading...
{{else}}
	Done!
{{/if}}

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",
    "ember-concurrency": "latest"
  }
}