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

  reason += validateUsername(theForm.user);
  reason += validatePassword(theForm.pass);

  if (reason != "") {
    alert("Correction:\n" + reason);
    return false;
  }

  return true;
}
function validateUsername(fld) {
    var error = "";
    var illegalChars = /\W/; // allow letters, numbers, and underscores

    if (fld.value == "") {
        fld.style.background = 'Yellow';
        error = "Please enter a username.\n";
    } else if ((fld.value.length < 5) || (fld.value.length > 15)) {
        fld.style.background = 'Yellow';
        error = "The username is the wrong length.\n";
    } else if (illegalChars.test(fld.value)) {
        fld.style.background = 'Yellow';
        error = "The username contains illegal characters.\n";
    } else {
        fld.style.background = 'White';
    }
    return error;
}
function validatePassword(fld) {
    var error = "";
    var illegalChars = /[\W_]/; // allow only letters and numbers

    if (fld.value == "") {
        fld.style.background = 'Yellow';
        error = "Please enter a password.\n";
    } else if ((fld.value.length < 5) || (fld.value.length > 15)) {
        error = "The password is the wrong length. \n";
        fld.style.background = 'Yellow';
    } else if (illegalChars.test(fld.value)) {
        error = "The password contains illegal characters.\n";
        fld.style.background = 'Yellow';
    } else {
        fld.style.background = 'White';
    }
   return error;
}