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

  reason += validateFirstname(theForm.first_name);
  reason += validateLastname(theForm.last_name);
  reason += validateEmail(theForm.email);
  reason += validatePhone(theForm.phone);
  reason += validateCompany(theForm.company);
      
  if (reason != "") {
    alert("Some fields need correction:\n" + reason);
    return false;
  }

  return true;
}


function validateFirstname(fld) {
    var error = "";
	
    if (fld.value == "") {
        fld.style.background = 'Yellow'; 
        error = "Please enter your first name.\n";
    } else {
        fld.style.background = 'White';
    } 
    return error;
}
function validateLastname(fld) {
    var error = "";
	
    if (fld.value == "") {
        fld.style.background = 'Yellow'; 
        error = "Please enter your last name.\n";
    } else {
        fld.style.background = 'White';
    } 
    return error;
}

function validateCompany(fld) {
    var error = "";
    
    if (fld.value == "") {
        fld.style.background = 'Yellow'; 
        error = "Please enter your company name.\n";
    } else if (fld.value.length < 2) {
        fld.style.background = 'Yellow'; 
        error = "Your company name is too short. Please re-enter.\n";
    } else {
        fld.style.background = 'White';
    } 
    return error;
}



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 = 'Yellow';
        error = "Please enter your 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 = "Your 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 = "Please enter your phone number.\n";
        fld.style.background = 'Yellow';
    } else if (isNaN(parseInt(stripped))) {
        error = "Your phone number contains illegal characters.\n";
        fld.style.background = 'Yellow';
    }  
    return error;
}