req.open('POST', 'index.php', true);
//...код
//вместо send()
send('option=com_cmok&task=hello&format=row&p roduct_name='+encodeURIComponent(product_name)+'&p roduct_sku='+encodeURIComponent(product_sku)+'&pro duct_s_desc='+encodeURIComponent(product_s_desc)+' &product_desc='+encodeURIComponent(product_desc)+' &product_publish='+product_publish+'&product_price ='+encodeURIComponent(product_price)+'&pid='+pid);