noppid,
Can you tell me how to do that?

I'm not good with JS syntax.
BTW I did try pasting the call to the js function in the action= line and this is what I got, a 404 error with the following: The requested URL /decodeVIN(entry,'mainbut'); return false was not found on this server. So it tried to load a page, not execute that specific JS function which means I have something wrong in the syntax I guess??