Hello forum

i need help on Javascript programming, to add a function on a script i've downloaded and start using.....
The script is NopCart.js and it is a shopping cart script; the "temp" site is online here:
<url>http://www.ecommercebiella.com/ita/itacart.htm</url>

This script (by my opinion it is a good script, simple to install and using) has a few but basically features: adding some <form> tag in static HTML pages, it counts Items, IDs, Prices, Shippings, etc etc

Here's the problem i need help.
When you checkout (if you go to my site please try buying items, the email will come to me.... dont worry) the cart does not "clean" the cart content, so if you come back to the site (also try closing browser, nothing....) you find the Items you have previously inserted in the cart.

So i need to add a function able to clean the cart content when closing order.....

Anyone would like to try helping me?
This script is GNU licensed, so we may use it (once fixed) for any similar purpose anyone needs; also, i will release an italian translated version of the script...

Hope to hear from you soon.
Nicola