I know basic things about Array class, but i got stuck often on things like what happen with index that stored game object that got destroyed.
edit:
the slot that the game object got destroyed returns null.
still i appreciate a good tutorial about Array class :P
thanks in advance.
The properties of a destroyed object become null cause they lose the reference and are cleaned on the next call of garbage collector.
I hope these are of some use for you:
http://www.unifycommunity.com/wiki/index.php?title=JavascriptMultiDimArrays
http://answers.unity3d.com/questions/7929/geting-the-closest-object-from-a-array
also for in depth knowledge of js I recommend the book Head First Javascript, it have a lot of content and an easy to catch language, you can find it cheap on amazon.com :]