.js code for form mail

Where can I find .js formmail submit code. I use a desktop email autoresponder client program. (not aweber etc.)

Here's what I'm trying to prevent: Currently I use formmail.pl script and you can simply view source code and see my redirect page. So I'm losing opt-ins with people skipping over the opt-in by viewing source.

what's the best way to avoid this? I noticed that with aWeber they give you the option of html code or .js code.

How can I use .js? Anyone know of any scripts.

Thanks

Anyone familiar with this?