<!--
function isValidDate(dateStr) {

var datePat = /^(\d{1,2})(\/|-)(\d{1,2})\2(\d{2}|\d{4})$/; 


var matchArray = dateStr.match(datePat); // is the format ok?
if (matchArray == null) {
alert(dateStr + " Date is not in a valid format.")
return false;
}
month = matchArray[3]; // parse date into variables
day = matchArray[1];
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;
}

function dateDiff(dateform) {
date1 = new Date();
date2 = new Date();
diff  = new Date();

if (isValidDate(dateform.from.value)) { // Validates first date 
date1temp = new Date(dateform.from.value);
date1.setTime(date1temp.getTime());
}
else return false; // otherwise exits

if (isValidDate(dateform.to.value)) { // Validates second date 
date2temp = new Date(dateform.to.value);
date2.setTime(date2temp.getTime());
}
else return false; // otherwise exits
}
//-->