function toggleLayer(whichLayer)
{
if (document.getElementById)
{
// this is the way the standards work
var style2 = document.getElementById(whichLayer).style;
style2.display = style2.display? "":"block";
}
else if (document.all)
{
// this is the way old msie versions work
var style2 = document.all[whichLayer].style;
style2.display = style2.display? "":"block";
}
else if (document.layers)
{
// this is the way nn4 works
var style2 = document.layers[whichLayer].style;
style2.display = style2.display? "":"block";
}
}
// Check that a string contains only letters and numbers
function isAlphanumeric(string, ignoreWhiteSpace) {
   if (string.search) {
      if ((ignoreWhiteSpace && string.search(/[^\w\s]/) != -1) || (!ignoreWhiteSpace && string.search(/\W/) != -1)) return false;
   }
   return true;
}
// Check that a string contains only letters
function isAlphabetic(string, ignoreWhiteSpace) {
   if (string.search) {
      if ((ignoreWhiteSpace && string.search(/[^a-zA-Z\s]/) != -1) || (!ignoreWhiteSpace && string.search(/[^a-zA-Z]/) != -1)) return false;
   }
   return true;
}
// Check that a string contains only numbers
function isNumeric(string, ignoreWhiteSpace) {
   if (string.search) {
      if ((ignoreWhiteSpace && string.search(/[^\d\s]/) != -1) || (!ignoreWhiteSpace && string.search(/\D/) != -1)) return false;
   }
   return true;
}

function toggle_checkbox (checkbox) {
	checkbox . checked = ! checkbox . checked;
}
//function to check valid email address
function isValidEmail(strEmail){
  validRegExp = /^[^@]+@[^@]+.[a-z]{2,}$/i;

   // search email text for regular exp matches
    if (strEmail.search(validRegExp) == -1) 
   {
      return false;
    } 
    return true; 
}