//--------------------------------------------------------------------------
//This function validates the date for MM/DD/YYYY format.
//--------------------------------------------------------------------------
function isValidDate(dateStr) {

 // Checks for the following valid date formats:
 // MM/DD/YYYY
 // Also separates date into month, day, and year variables
 var datePat = /^(\d{2,2})(\/)(\d{2,2})\2(\d{4}|\d{4})$/;
 
 var matchArray = dateStr.match(datePat); // is the format ok?
 if (matchArray == null) {
  alert("Date must be in MM/DD/YYYY format")
  return false;
 }
 
 month = matchArray[1]; // parse date into variables
 day = matchArray[3];
 year = matchArray[4];
 if (month < 1 || month > 12) { // check month range
  alert("Month must be between 1 and 12");
  return false;
 }
 if (day < 1 || day > 31) {
  alert("Day must be between 1 and 31");
  return false;
 }
 if ((month==4 || month==6 || month==9 || month==11) && day==31) {
  alert("Month "+month+" doesn't have 31 days!")
  return false;
 }
 if (month == 2) { // check for february 29th
  var isleap = (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
  if (day>29 || (day==29 && !isleap)) {
   alert("February " + year + " doesn't have " + day + " days!");
   return false;
    }
 }
 return true;  // date is valid
}