function add_sw(product_step_buy,feld1)
{
var quant = parseInt(document.getElementById(feld1).value) + parseInt(product_step_buy);
document.getElementById(feld1).value = quant;
feld1 = 'customer_' + feld1;
document.getElementById(feld1).value = quant;
document.forms["cart_quantity"].submit();
}
function subtr_sw(product_min_buy,product_step_buy,feld1)
{
var quant = parseInt(document.getElementById(feld1).value) - parseInt(product_step_buy);
if(quant < 0)
{quant=0;}

var loeschen = true;

if(quant == 0)
{loeschen = confirm ("Soll das Produkt aus dem Warenkorb entfernt werden?");}

if(loeschen == true)
{
document.getElementById(feld1).value = quant;
feld1 = 'customer_' + feld1;
document.getElementById(feld1).value = quant;
document.forms["cart_quantity"].submit();
}
}