function validateFormOnSubmit(theForm) {
var reason = "";

  reason += validateEmail(theForm.email);
  reason += validatePhone(theForm.phone);
  reason += validateEmpty(theForm.enquiry);
  reason += validateEmptyFirstName(theForm.firstName);
  reason += validateEmptySurname(theForm.surname);
      
  if (reason != "") {
    alert("Some fields need correction:\n" + reason);
    return false;
  }

  return true;
}


//validate empty fields
function validateEmpty(fld) {
    var error = "";
  
    if (fld.value.length == 0) {
        fld.style.background = '#f1e48f'; 
        error = "Please tell us what you are enquiring about.\n"
    } else {
        fld.style.background = 'White';
    }
    return error;   
}

//validate empty fields
function validateEmptyFirstName(fld) {
    var error = "";
  
    if (fld.value.length == 0) {
        fld.style.background = '#f1e48f'; 
        error = "Please enter your first name.\n"
    } else {
        fld.style.background = 'White';
    }
    return error;   
}

//validate empty fields
function validateEmptySurname(fld) {
    var error = "";
  
    if (fld.value.length == 0) {
        fld.style.background = '#f1e48f'; 
        error = "Please enter your surname.\n"
    } else {
        fld.style.background = 'White';
    }
    return error;   
}

//validate email
function trim(s)
{
  return s.replace(/^\s+|\s+$/, '');
} 

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 = '#f1e48f';
        error = "You didn't enter an email address.\n";
    } else if (!emailFilter.test(tfld)) {              //test email for illegal characters
        fld.style.background = '#f1e48f';
        error = "The email address you entered is invalid.\n";
    } else if (fld.value.match(illegalChars)) {
        fld.style.background = '#f1e48f';
        error = "The email address you entered contains illegal characters.\n";
    } else {
        fld.style.background = 'White';
    }
    return error;
}


//validate phone
function validatePhone(fld) {
    var error = "";
    var stripped = fld.value.replace(/[\(\)\.\-\ ]/g, '');     

   if (fld.value == "") {
        error = "You didn't enter a phone number.\n";
        fld.style.background = '#f1e48f';
    } else if (isNaN(parseInt(stripped))) {
        error = "The phone number you entered contains illegal characters.\n";
        fld.style.background = '#f1e48f';
    } else if (!(stripped.length > 6)) {
        error = "The phone number you entered is too short.\n";
        fld.style.background = '#f1e48f';
    } 
    return error;
}