function f_is_stock(required_quantity,exist_stock) {
	if (required_quantity>exist_stock) {
		text='Our stock is only ' + exist_stock + ' for this item, please choose less quantity';

		alert(text);
		return false;
	}
	return true;
}




function verif_form_form_add_cart(exist_stock) {
    if (f_is_stock(document.form_add_cart.quantity.value,exist_stock)==false) { return false; };


}