Client-side security code

Hi

What sort of security code (if any) can I add to forms to at least help stop people sending nasties to their associated cgi files via the textboxes and textareas on these forms?

Define "nasties".

You might be able to set up something simple with JavaScript, but this is easily circumvented; to really set up a decent security system, or input screening, you'll have to do it server-side.

For a basic JavaScript protection script you might want to browse resources like JavaScript Kit (http://javascriptkit.com/), Dynamic Drive (http://www.dynamicdrive.com/) or Hotscripts (http://www.hotscripts.com/JavaScript/index.html).