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

  reason += validateVistor(theForm.visitor);
  reason += validateVisitormail(theForm.visitormail);
  reason += validatePhone(theForm.phone);
  reason += validateEmpty(theForm.from);

  reason += validateMailsubject(theForm.mailsubject);
  reason += validateNotes(theForm.notes);
    

      
  if (reason != "") {
    alert("Some fields need correction:\n" + reason);
    return false;
  }

  alert("All fields are filled correctly");
  return false;
}
function validateEmpty(fld) {
    var error = "";
 
    if (fld.value.length == 0) {
        fld.style.background = 'Yellow'; 
        error = "The required field has not been filled in.\n"
    } else {
        fld.style.background = 'White';
    }
    return error;  
}
function validateVisitor(fld) {
    var error = "";
    var illegalChars = /\W/; // allow letters, numbers, and underscores
 
    if (fld.value == "") {
        fld.style.background = 'Yellow'; 
        error = "You didn't enter a name.\n";
    } else {
        fld.style.background = 'White';
    }
    return error;
}



function validateMailsubject(fld) {
    var error = "";
    var illegalChars = /\W/; // allow letters, numbers, and underscores
 
    if (fld.value == "") {
        fld.style.background = 'Yellow'; 
        error = "You didn't enter a subject.\n";
    } else {
        fld.style.background = 'White';
    }
    return error;
}

function validateNotes(fld) {
    var error = "";
    var illegalChars = /\W/; // allow letters, numbers, and underscores
 
    if (fld.value == "") {
        fld.style.background = 'Yellow'; 
        error = "You didn't enter a message.\n";
    } else {
        fld.style.background = 'White';
    }
    return error;
}




function trim(s)
{
  return s.replace(/^\s+|\s+$/, '');
}
function validateVisitormail(fld) {
    var error="";
    var tfld = trim(fld.value);                        // value of field with whitespace trimmed off
    var emailFilter = /^[^@]+@[^@.]+\.[^@]*\w\w$/ ;
    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;
}
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 = 'Yellow';
    } else if (isNaN(parseInt(stripped))) {
        error = "The phone number contains illegal characters.\n";
        fld.style.background = 'Yellow';
    } else if (!(stripped.length == 10)) {
        error = "The phone number is the wrong length. Make sure you included an area code.\n";
        fld.style.background = 'Yellow';
    }
    return error;
}