FWIW, it's generally considered a bad idea to depend on javascript for essential functions (unless you're coding for an intranet environment where you know / have control over what browser and options people will be using). Is there some reason the cookie needs to be changed via javascript? I can't think of one: if it's a matter of changing it based on form input, you should use a server-side script to handle that, both because a lot of people surf with javascript disabled, and because javascript has to be viewable by the client to work, which could open up security problems, as someone has already pointed out.

The shorter answer is that whatever cookie is there will, under normal circumstances, be readable by your script, whether it's created by perl, javascript, or altered by the client in a text editor. :-)

IOW, this seems like a "can I use X to do Y" question, and if X = javascript, the answer is a very qualified "yes, but you may not want to do Y in that way."

BCE
--Your punctuation skills are insufficient!