function calculate_total(subtotal,shipping) {
	return subtotal + shipping;
}
function update_cart_total(total,shipping_price) {
	var shipping = shipping_price;
	$("shipping_price").innerHTML = shipping;
	$("total").innerHTML = calculate_total(total,shipping);
}
function is_ready_to_pay() {
	if ($('send_to_payment').value == 1) {
		return true;
	} else {
		return false;
	}
}
function validate_name_and_email() {
	var errors = {};
	var is_valid = null;
	if ($("name").value == '') {
		errors['name'] = 1;
		$("name").className = "checkout_inputs invalid_input";
		is_valid = false;
	} else {
		$("name").className = "checkout_inputs";
	}
	if ($("email_address").value == '') {
		errors['email_address'] = 1;
		$("email_address").className = "checkout_inputs invalid_input";
		is_valid = false;
	} else {
		$("email_address").className = "checkout_inputs";
	}
	return is_valid;
}