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

  reason += validateFirstname(theForm.firstname);
  reason += validateLastname(theForm.lastname);
  reason += validateHearAbout(theForm.how_did_you_hear_about_us);
  reason += validateInterest(theForm.interest);
  reason += validateEmail(theForm.email);
      
  if (reason != "") {
    alert("Some fields need correction:\n" + reason);
    return false;
  }

  return true;
}

function validateEmpty(fld) {
    var error = "";
 
    if (fld.value.length == 0) {
        fld.style.background = '#ff9'; 
        error = "The required field has not been filled in.\n"
    } else {
        fld.style.background = '#ff9';
    }
    return error;  
}

function validateFirstname(fld) {
    var error = "";
    if (fld.value == "") {
        fld.style.background = '#ff9'; 
        error = "You didn't enter a first name.\n";
    } else {
        fld.style.background = 'White';
    }
    return error;
}

function validateLastname(fld) {
    var error = "";
    if (fld.value == "") {
        fld.style.background = '#ff9'; 
        error = "You didn't enter a last name.\n";
    } else {
        fld.style.background = 'White';
    }
    return error;
}

function validateHearAbout(fld) {
    var error = "";
    if (fld.value == "") {
        fld.style.background = '#ff9'; 
        error = "Please tell us how you heard about us.\n";
    } else {
        fld.style.background = 'White';
    }
    return error;
}

function validateInterest(fld) {
    var error = "";
    if (document.demo.interest.selectedIndex == 0) {
        fld.style.background = '#ff9'; 
        error = "Please tell us what if your area of interest.\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 = '#ff9';
        error = "You didn't enter an email address.\n";
    } else if (!emailFilter.test(tfld)) { //test email for illegal characters
        fld.style.background = '#ff9';
        error = "Please enter a valid email address.\n";
    } else if (fld.value.match(illegalChars)) {
        fld.style.background = '#ff9';
        error = "The email address contains illegal characters.\n";
    } else {
        fld.style.background = 'White';
    }
    return error;
}