Add items to cart through script

[Community Alums]

I am trying to have a script add additional items to a cart when a user clicks "proceed to checkout" automatically.   I have tried to write a client script, but get the alert the glide system cant be used.   Any ideas how I could add a catalog item to a cart automatically through a script when someone proceeds to a checkout?

This is what I currently have which is not working:

function onSubmit() {
var existingCart = new GlideRecord('sc_cart');
existingCart.addQuery('user', gs.getUserID());
existingCart.query();
if(existingCart.next()){
       var cart = new Cart(); // using "new Cart()" object without parameters
       cart.getCart(existingCart.sys_id);   // here is where you grab the existing cart. this is not the "getCart()" function from the wiki
       var item = cart.addItem('e212a942c0a80165008313c59764eea1');
}
}

[Deepak Ingale1]

Hi Josh,

We can not use server side API directly in client script,

in order to do that, we need to write down client callable script include

http://wiki.servicenow.com/index.php?title=GlideAjax#Overview

[Community Alums]

Deepak - is there an easier way of achieving what I am trying to do?

[Community Alums]

pradeepksharma any ideas?