Credit card date expire validations

script type="text/javascript"
function ValidateCardNumber(sender, args) {
if ((args.Value.length < 13) || (args.Value.length > 16)) {
args.IsValid = false;
}
else {
args.IsValid = true;
}
}
function IsValidDate(Mn, Yr) {
if (Mn == 12)
Yr++;

var dt = new Date();
dt.setMonth(Mn);
dt.setDate(1);
dt.setFullYear(Yr);
var today = new Date();

if (today >= dt) {
return false;
}
return true;
}

function CallDateFun(sender, args) {
var m = document.getElementById('<%= mddlMM.ClientID %>').value
var y = document.getElementById('<%= mddlYY.ClientID %>').value;
//year=2000+parseInt(y);
if (m != 0 && y != 0) {
args.IsValid = IsValidDate(m, y);
}
}
/script