Is Instance Of

The "`as`" operator attempts to cast a reference, and returns null if it fails.

 function CheckComponent(Component foo)
 {
     var myCustomComponent = foo as MyCustomComponent;
     if (myCustomComponent != null)
     {
         //do some stuff with your custom component
     }
     else
     {
         //the cast failed
     }
 }

You are looking for the is operator. Use:

 SomeType obj = new SomeType();
 
 if ( obj is SomeType ) {
     //Do somet$$anonymous$$ng
 }

Use instanceof:

 class _paddle {
         }
 class _paddle2 {
         }
  
 function Start(){
     var player1Paddle = new _paddle2();
     if (player1Paddle instanceof _paddle){
         print("yes it is");
     }    
     else{
          print("no it is not");
     }
 }

http://wiki.unity3d.com/index.php/UnityScript_Keywords#instanceof