title: Difficulty adding multiple classes wit ng-class
body: <p>I'm trying to add two classes to this div using <code>ng-class</code>, but even though <code>checkForActive</code> is returning <code>true</code>, it's being ignored and only <code>class_{{$index}}</code> is getting added.</p>
  
  <p>If I remove <code>class_{{$index}}</code> altogether, <code>active</code> is added correctly.</p>
  
  <p>Is there an obvious mistake in my syntax here?</p>
  
  <pre><code>&lt;div "ng-class="{active: checkForActive, disabled: checkForDisable, class_{{$index}}} "&gt;&lt;/div&gt;
  </code></pre>