Is there a free Javascript compression tool which works?

If you are using such a tool, please let me know

[iProgram]

I want to compress my /js/*.js files and tried a lot of products on SERP. However, almost all of them do not work correctly. For example, some product will change

var a = 'http://www.example.com';

into

var a = 'http:

(remove comment for me?). Are you using a javascript compression tool, which can remove extra spaces from source code, and does not modify any characters within "..."?

[MisYu]

Google for 'JavaScript Obfuscator'. There are several of them.

[edited by: DrDoc at 8:04 am (utc) on Sep. 24, 2006]
[edit reason] removed URL reference [/edit]