This is very much like the image-protecting issue... it's just not possible. As stated by Vadivel, you logically can't encrypt code perfectly. If it has been encrypted, it must be packaged with a method to decrypt it (to be able to run it) so it really isn't possible to restrict access to client-side scripts you use online.
If there is sensitive information that you need to protect, I suggest going server-side.
-Snib - http://www.snibworks.com
Where will you be in 100 years?