function checkEmail (strng) {
	var error="";
	if (strng == "") {
	   error = "EMAIL ADDRESS is a required field.\n";
	}

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


// phone number - strip out delimiters and check for 10 digits

function checkPhone (strng) {
	var error = "";
	if (strng == "") {error = "PHONE NUMBER is a required field.\n";}

	var stripped = strng.replace(/[\(\)\.\-\ ]/g, ''); //strip out acceptable non-numeric characters

	if (isNaN(parseInt(stripped))) {error = "PHONE contains illegal characters."; }
	if (!(stripped.length == 10)) {error = "PHONE number is the wrong length. Make sure you included an area code.\n";} 
	if (stripped == '0000000000' || stripped == '1111111111' || stripped == '2222222222' || stripped == '3333333333' || stripped == '4444444444' || stripped == '5555555555' || stripped == '6666666666' || stripped == '7777777777' || stripped == '8888888888' || stripped == '9999999999' || stripped == '1234567890' || stripped == '9876543210' || stripped == '8584928002') {error = "PHONE is invalid.\n";} 

	document.getElementById('phone').value = stripped;
	return error;
	}


function checkZip (strng) {
var error = "";
if (strng == "") {
   error = "ZIP is a required field.\n";
}

var stripped = strng.replace(/[\(\)\.\-\ ]/g, ''); //strip out acceptable non-numeric characters
    if (isNaN(parseInt(stripped))) {
       error = "ZIP contains illegal characters.";
  
    }
    if (!(stripped.length == 5)) {
	error = "ZIP must be 5 digits long.\n";
    } 
return error;
}


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

function checkPassword (strng) {
var error = "";
if (strng == "") 
	{
	error = "PASSWORD is a required field.\n";
	}

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

if (strng.length > 15)
	{
	error = "Your password cannot be longer than 15 characters long.\n";
	}
else if (illegalChars.test(strng)) 
	{
	error = "The password contains illegal characters.\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,fld) {
var error = "";
  if (strng.length == 0) {
     error = fld+" is a required field.\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;
}

// valid selector from dropdown list

function checkDropdown(choice) {
var error = "";
    if (choice == 0) {
    error = "You didn't choose an option from the drop-down list.\n";
    }    
return error;
}