Validate OTP using JavaScript in ASP.Net

Hi sambath,

Please refer below sample.

HTML

<script type="text/javascript">
    function Check() {
        var message = '<%=Session["otp"] %>';
        var otp = document.getElementById('txtOTP').value;
        var countdigit = otp.length;
        if (countdigit == 4) {
            if (otp == message) {
                document.getElementById('lblMessage').innerHTML = "Correct OTP";
            }
            else {
                document.getElementById('lblMessage').innerHTML = "Incorrect OTP";
            }
        }
        else {
            document.getElementById('lblMessage').innerHTML = "";
        }
        return false;
    }
</script>
<div>
    Enter OTP:
    <asp:TextBox ID="txtOTP" class="otp" runat="server" MaxLength="4" TextMode="Password"
        onkeyup="Check();" />
    <br />
    <asp:Label ID="lblMessage" runat="server" />
</div>

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        Session["Otp"] = "1234";
    }
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Session("Otp") = "1234"
    End If
End Sub

Screenshot