function validateFormOnSubmit(theForm) {
var reason = "";
  reason += validateEmpty(theForm.email);
  reason += validateEmpty(theForm.adult_name);
  reason += validateEmpty(theForm.child_name);
  reason += validateEmpty(theForm.child_age);
  reason += validateEmpty(theForm.attending);
  reason += validateEmpty(theForm.contact_number);
  if (reason != "") {
    alert("Some fields need correction:\n\n" + reason);
    return false;
  }
  return true;
}

function validateBookingFormOnSubmit(theForm) {
var reason = "";
  reason += validateEmpty(theForm.email);
  reason += validateEmpty(theForm.adult_name);
  reason += validateEmpty(theForm.contact_number);
  if (reason != "") {
    alert("Some fields need correction:\n\n" + reason);
    return false;
  }
  return true;
}

function validatePreBookingFormOnSubmit(theForm) {
var reason = "";
  reason += validateEmpty(theForm.email);
  reason += validateEmpty(theForm.adult_name);
  reason += validateEmpty(theForm.contact_number);
  if (reason != "") {
    alert("Some fields need correction:\n\n" + reason);
    return false;
  }
  return true;
}


function validateEmpty(fld) {
    var error = "";
    if (fld.value.length == 0) {
        fld.style.background = 'Yellow'; 
        error = "The required field '" + fld.id + "' has not been filled in.\n"
    } else {
        fld.style.background = 'White';
    }
    return error;  
}

function validateEmail(fld) {
    var error="";
    var tfld = trim(fld.value);                        // value of field with whitespace trimmed off
    var emailFilter = /^[^@]+@[^@.]+\.[^@]*\w\w$/ ;
    var illegalChars= /[\(\)\<\>\,\;\:\\\"\[\]]/ ;
    if (fld.value == "") {
        fld.style.background = 'Yellow';
        error = "You didn't enter an email address.\n";
    } else if (!emailFilter.test(tfld)) {              //test email for illegal characters
        fld.style.background = 'Yellow';
        error = "Please enter a valid email address.\n";
    } else if (fld.value.match(illegalChars)) {
        fld.style.background = 'Yellow';
        error = "The email address contains illegal characters.\n";
    } else {
        fld.style.background = 'White';
    }
    return error;
}