function popupWindow(url) {
  window.open(url,'popupWindow','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,resizable=yes,copyhistory=no,width=600,height=600,screenX=150,screenY=150,top=150,left=150')
}

function decrement(index) {
 if(document.forms["cart_box"].elements["cart_quantity[]"][index].value >1) {
   document.forms["cart_box"].elements["cart_quantity[]"][index].value--;
   document.cart_box.submit();
 }
}

function increment(index) {
   document.forms["cart_box"].elements["cart_quantity[]"][index].value++;
   document.cart_box.submit();
}

function mark(pid) {
   document.forms["remove_product"].elements["cart_delete[]"][0].value=pid;
   document.forms["remove_product"].elements["products_id[]"][0].value=pid;
   document.remove_product.submit();
}

var sURL = document.URL.toString();
if (sURL.indexOf("?") > 0){
 urlsplitter = '';
} else {
 urlsplitter = '?';
}
document.write('<form ');
document.write(' name="remove_product" ');
document.write(' action="' + document.URL + urlsplitter + '&action=update_product"');
document.write(' method="post">');
//one element is not an array so add 2 of each!
document.write('<input type="hidden" name="products_id[]">');
document.write('<input type="hidden" name="cart_delete[]">');
document.write('<input type="hidden" name="products_id[]">');
document.write('<input type="hidden" name="cart_delete[]">');
document.write('</form>');

document.write('<form ');
document.write(' name="cart_box" ');
document.write(' action="' + document.URL + urlsplitter + '&action=update_product"');
document.write(' method="post">');