// employer.js
function verify(f) {
	var msg;
  var validSerialNumber = true;
  var validKey = true;
  // check SerialNumber fields
  if ((f.sn1.value.length != 3) || (f.sn2.value.length != 3) || (f.sn3.value.length != 3))
    validSerialNumber = false;
  if (validSerialNumber) { 
    if (!isNumeric(f.sn1.value) || !isNumeric(f.sn2.value) || !isNumeric(f.sn3.value))
      validSerialNumber = false;
    else
      f.serialNumber.value = f.sn1.value + f.sn2.value + f.sn3.value;
  }
  // check ActivationKey fields
  if ((f.key1.value.length != 4) || (f.key2.value.length != 4) || (f.key3.value.length != 4))
    validKey = false;
  if (validKey) { 
    if (!isNumeric(f.key1.value) || !isNumeric(f.key2.value) || !isNumeric(f.key3.value))
      validKey = false;
    else
      f.activationKey.value = f.key1.value + "-" + f.key2.value + "-" + f.key3.value;
  }
	if (validSerialNumber && validKey) return true;

  if (!validSerialNumber && validKey)
    msg = "The Serial Number you entered is invalid.\n" +
          "Please enter 3 digits in each Serial Number field."
  else if (validSerialNumber && !validKey)
    msg = "The Activation Key you entered is invalid.\n" +
          "Please enter 4 digits in each Activation Key field."
  else
    msg = "The Serial Number and Activation Key you entered are invalid.\n" + 
          "Please enter 3 digits in each Serial Number field and\n" + 
          "4 digits in each Activation Key field." 
	alert(msg);
	return false;
}

function isNumeric(strString)
{
	var strValidChars = "0123456789";
	var strChar;
	var bResult = true;
	for (i = 0; i < strString.length && bResult == true; i++) {
		strChar = strString.charAt(i);
		if (strValidChars.indexOf(strChar) == -1)
	  { bResult = false; }
	}
	return bResult;
}