http://www.dynamicdrive.com/dynamicindex9/encrypter.htm
and
http://www.rlrouse.com/html-encryptor.html
does the exact same lame thing.
Using the escape method is the oldest way to hide your code. And it's the easietst to break since it requires only one command...
If you want to make it atleast challenging you should use atleast a script compressor or the "standard" way to encode files using the Microsoft Javascript encoder. It doesn't need to have the actual decoding algorithm in the script since the browser supports <script language="JavaScript.Encode"> scripts. But there's a small and fast decoder available for those who knows how to google...
Here's a link to a good script compressor, it's not meant to encode the script but it can be used that way.
http://entries.the5k.org/1007/index.html# (Go to Step 6 to see the compressor)
This one is a bit slow so I made my own version of it which prevents the "This script is taking too long to run, it might have crashed"-box from popping up when you compress big files.