// firstname
function checkFirstname (strng)
	{
	var error = "";

	firstnameFilter = /[A-Za-z]{3,}-?[A-Za-z]?/;
	if(!firstnameFilter.test(strng))
		{
		error = "Please enter your first name \n";
		}
	return error;
	}

// lastname
function checkLastname (strng)
	{
	var error = "";
	lastnameFilter = /[A-Za-z]{3,}-?[A-Za-z]?/;
	if(!lastnameFilter.test(strng))
		{
		error = "Please enter your last name \n";
		}
	return error;
	}

// email
function checkEmail (strng)
	{
	var error ="";
    var emailFilter=/^.+@.+\..{2,3}$/;
	if (strng == "")
		{
		error = "Please enter a valid email address.\n";
		return error;
		}
    if (!(emailFilter.test(strng)))
    	{
       	error = "Please enter a valid email address.\n";
    	}
    else
    	{
       	var illegalChars= /[\(\)\<\>\,\;\:\\\"\[\]]/;		//test email for illegal characters
        if (strng.match(illegalChars))
        	{
          	error = "The email address contains illegal characters.\n";
       		}
    	}
	return error;
	}

// phone number - strip out delimiters and check for 11 digits

function checkPhone (strng)
	{
	var error = "";
	if (strng == "")
		{
   		error = "You didn't enter a phone number.\n";
		}
	var stripped = strng.replace(/[\(\)\.\-\ ]/g, ''); //strip out acceptable non-numeric characters
    if (isNaN(parseInt(stripped)))
    	{
       	error = "The phone number contains illegal characters.";
    	}
    if (!(stripped.length == 11))
    	{
		error = "Please enter your full telephone number.\n";
    	}
	return error;
	}

// valid selector from dropdown list

function checkDropdown(choice) {
var error = "";
    if (choice == 0) {
    error = "Please select an option from the required drop down list.\n";
    }
return error;
}

// password - between 6-8 chars, uppercase, lowercase, and numeral

function checkPassword (strng) {
var error = "";
if (strng == "") {
   error = "You didn't enter a password.\n";
}

    var illegalChars = /[\W_]/; // allow only letters and numbers

    if ((strng.length < 6) || (strng.length > 8)) {
       error = "The password is the wrong length.\n";
    }
    else if (illegalChars.test(strng)) {
      error = "The password contains illegal characters.\n";
    }
    else if (!((strng.search(/(a-z)+/)) && (strng.search(/(A-Z)+/)) && (strng.search(/(0-9)+/)))) {
       error = "The password must contain at least one uppercase letter, one lowercase letter, and one numeral.\n";
    }
return error;
}


// username - 4-10 chars, uc, lc, and underscore only.

function checkUsername (strng) {
var error = "";
if (strng == "") {
   error = "You didn't enter a username.\n";
}


    var illegalChars = /\W/; // allow letters, numbers, and underscores
    if ((strng.length < 4) || (strng.length > 10)) {
       error = "The username is the wrong length.\n";
    }
    else if (illegalChars.test(strng)) {
    error = "The username contains illegal characters.\n";
    }
return error;
}


// non-empty textbox

function isEmpty(strng) {
var error = "";
  if (strng.length == 0) {
     error = "The mandatory text area has not been filled in.\n"
  }
return error;
}

// was textbox altered

function isDifferent(strng) {
var error = "";
  if (strng != "Can\'t touch this!") {
     error = "You altered the inviolate text area.\n";
  }
return error;
}

// exactly one radio button is chosen

function checkRadio(checkvalue) {
var error = "";
   if (!(checkvalue)) {
       error = "Please check a radio button.\n";
    }
return error;
}