function checkbooking() 
{ 
    valid = true;
    if (!check_booking_name (document.forms.reservation.name.value)) {
        valid = false;
        alert ('Please fill in your name.');
    }
    if (!check_booking_email (document.forms.reservation.e_mail.value)) {
        valid = false;
        alert ('Please fill in your email address.');
    }
    return valid;
}

function check_booking_name (a) {
    if (a=="")
        return false;
    else
        return true;
} 

function check_booking_email (b) {
    if (b=="")
        return false;
    else
        return true;
}