// email

function checkEmail (strng) {
var error="";
if (strng == "") {
   error = "Please enter your Email Address\n";
   return error;
}

    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;    
}


// Zip Code - 5 or 9 digits, leave in dash

function checkZip (strng) {
var error = "";
if (strng == "") {
   return "" ;
}

var stripped = strng.replace(/[\(\)\.\-\ ]/g, ''); //strip out acceptable non-numeric characters
    if (isNaN(parseInt(stripped))) {
       error = "Please enter a valid Zip Code\n";
  
    }
    if (!((stripped.length == 5)||(stripped.length == 9))) {
	error = "Please enter a valid 5 or 9 digit Zip Code\n";
    } 
return error;
}



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

function checkPhone (strng) {
var error = "";
if (strng == "") {
   error = "Please enter your Phone Number.\n";
}

var stripped = strng.replace(/[\(\)\.\-\ ]/g, ''); //strip out acceptable non-numeric characters
    if (isNaN(parseInt(stripped))) {
       error = "Please enter a valid Phone Number";
  
    }
    if (!(stripped.length == 10)) {
	error = "Please enter a valid Phone Number, including an area code\n";
    } 
return error;
}

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

function checkFax(strng) {
var error = "";
if (strng == "") {
   error = "Please enter your Fax Number.\n";
}

var stripped = strng.replace(/[\(\)\.\-\ ]/g, ''); //strip out acceptable non-numeric characters
    if (isNaN(parseInt(stripped))) {
       error = "Please enter a valid Fax Number";
  
    }
    if (!(stripped.length == 10)) {
	error = "Please enter a valid Fax Number, including an area code\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;
}  


// text only field - uc, lc, and underscore only.

function checkTextOnly(strng,field) {
var error = "";
    var illegalChars = /[^\w\-\'\s]/; // allow letters, numbers, and underscores
    if (illegalChars.test(strng)) {
    	error = field + " contains an illegal character\n";
    } 
return error;
}      


// non-empty textbox

function isEmpty(strng,field) {
var error = "";
  if (strng.length == 0) {
     error = "Please enter your " + 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 checkType(checkvalue,fieldtype) {
var error = "";
   if (!(checkvalue)) {
       error = "Please select a " + fieldtype +"\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;
}