<!DOCTYPE html>
<html>
<head>
<style type="text/css">
.PAN
{
text-transform: uppercase;
}
.error
{
color: Red;
visibility: hidden;
}
</style>
<script type="text/javascript">
function ValidatePAN() {
var txtPANCard = document.getElementById("txtPANCard");
var lblPANCard = document.getElementById("lblPANCard")
var regex = /([A-Z]){5}([0-9]){4}([A-Z]){1}$/;
if (regex.test(txtPANCard.value.toUpperCase())) {
lblPANCard.style.visibility = "hidden";
return true;
} else {
lblPANCard.style.visibility = "visible";
return false;
}
}
</script>
</head>
<body>
PAN Card:
<input name="txtPANCard" type="text" id="txtPANCard" class="PAN" />
<span id="lblPANCard" class="error">Invalid PAN Number</span>
<br>
<input type="button" id="btnSubmit" value="Submit" onclick="ValidatePAN()" />
</body>
</html>