title: Class type check in TypeScript
body: <p>In ActionScript, it is possible to check the type at run-time using the <a href="http://help.adobe.com/en_US/ActionScript/3.0_ProgrammingAS3/WS5b3ccc516d4fbf351e63e3d118a9b90204-7f8a.html" rel="noreferrer">is operator</a>:</p>
  
  <pre><code>var mySprite:Sprite = new Sprite(); 
  trace(mySprite is Sprite); // true 
  trace(mySprite is DisplayObject);// true 
  trace(mySprite is IEventDispatcher); // true
  </code></pre>
  
  <p>Is it possible to detect if a variable (extends or) is a certain class or interface with TypeScript?</p>
  
  <p>I couldn't find anything about it in the language specs. It should be there when working with classes/interfaces.</p>