[thelist] © of JavaScript code

Hello Experts,
I have seen lots of JavaScript code for public use on many sites, e.g.
www.javascriptkit.com
This code vary from Search Engines to stunning types of dynamic effects. In most
cases, this code contains a copyright notice from the developer.
I want to know:
What is the importance of such copyright notice in  JS code when it is easily
readable for anybody with the knowledge of JS?
Are there any laws to protect the rights of JS code?

I have put a downloadable game on my site. It uses lots of (a bit) complex JS.
How can I protect the rights of that JS code which I developed with painstaking
hardworking?

Thank you,
Syed Zeeshan Haider.
http://syedzeeshanhaider.faithweb.com/