Alert Message Box Using Javascript Codebehind Asp.net. ~ Aspdotnet Studio

Demo:-

Design Code:-

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" EnableEventValidation="false" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>Aspdotnet Studio</title>
<script type="text/javascript">
function Showalert() {
alert('Alert from codebehind');
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Button ID="btnS" runat="server" Text="Show alert" onclick="btnS_Click" />
<asp:Button ID="btnC" runat="server" Text="Call JavaScript Function"
onclick="btnC_Click" />
</div>
</form>
</body>
</html>

Code Behind:-

using System;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void btnS_Click(object sender, EventArgs e)
{
ScriptManager.RegisterStartupScript(this,GetType(),"showalert","alert('This is Simple Alert Message');",true);
}
protected void btnC_Click(object sender, EventArgs e)
{
ScriptManager.RegisterStartupScript(this, GetType(), "displayalertmessage", "Showalert();", true);
}
}