function back() {
	history.go(-1);
}

function update() {
	document.update_form.submit();
}

function reset() {
	document.reset_form.submit();
}

function remove(code) {
	var id = 'product_'+code;
	document.getElementById(id).value = '0';
	update();
}

function checkout() {
	update();
	window.location = "checkout.php";
}