Creating an "exit" page?

I'm working on a client's site on which they'd like a user to go to a "Thank you for visiting, you are now leaving our site" page when that user clicks on an external link and then forwarding them along to the external link's page they'd clicked on.

I've researched this a bit and found a way to do it in ASP but I'm wondering if there's some way to code it in Javascript or plain HTML? (The site is very basic– plain .shtml with no bells and whistles, so the solution needs to be simple as well.) I've used redirect pages before but this is a bit trickier as I need one forwarding page for all the external links (about 50 total) so I'd rather not manually make 50 redirect pages... I've also found a Javascript code to pop up a YES/NO window for leaving to an external link, but that won't work either- we don't want the user to have to choose yes or no, we just want the exit page to come up and then forward them along to the external link.

It doesn't necessarily have to be a full page, either. I could also have a popup that says "you're leaving our site" when you click a specific external link. User clicks okay, then they continue on to the external link. (So it's a little different in that it's not presenting a YES/NO option.)

Thanks,
m19

 

javascript.. look up WINDOW.LOCATION