How can I encrypt JavaScript code so that it's not decryptable?

Question

I have some JavaScript code I need to encrypt, but I want to be sure no one can decrypt it.

What tools can I use to do this?

-- Edit --

Answer 1

What you're looking for is obfuscation, not encryption. There are tools such as JSMin and the YUI Compressor that will make your code very unreadable, to the point where no one would want to try to make sense of it. However, there is no way to make it so that someone can't copy and paste it onto their own website and run it there. I wouldn't worry about it, honestly, because you'd be wasting your time trying to protect something that can't be protected. Try putting all your "important" logic on the server-side, if possible, because that's the only foolproof way to do it. If the browser can access it, so can anyone else.