Session TimeOut alert Popup & redirect to Login Page | Asp.net MVC

<sessionState timeout="2"></sessionState>

 <add key ="SessionWarning" value ="1"/>

<script language="javascript" type="text/javascript">        
     var sessionTimeoutWarning =@System.Configuration.ConfigurationSettings.AppSettings["SessionWarning"].ToString();
     var sessionTimeout = @Session.Timeout;
        var timeOnPageLoad = new Date();

        //For warning
        setTimeout('SessionWarning()', parseInt(sessionTimeoutWarning) * 60 * 1000);
        //To redirect to the welcome page
        setTimeout('RedirectToWelcomePage()',parseInt(sessionTimeout) * 60 * 1000);

        //Session Warning
        function SessionWarning() {
            //minutes left for expiry
            var minutesForExpiry =  (parseInt(sessionTimeout) -
                parseInt(sessionTimeoutWarning));
            var message = "Your session will expire in another " + minutesForExpiry +
            " mins! Please Save the data before the session expires";
            alert(message);
            var currentTime = new Date();
            //time for expiry
            var timeForExpiry = timeOnPageLoad.setMinutes(timeOnPageLoad.getMinutes()
                + parseInt(sessionTimeout));

            //Current time is greater than the expiry time
            if(Date.parse(currentTime) > timeForExpiry)
            {
                alert("Session expired. You will be redirected to welcome page");
                window.location = "/Home/Index";
            }
        }

        //Session timeout
        function RedirectToWelcomePage(){
            alert("Session expired. You will be redirected to welcome page");
            window.location = "/Home/Index";
        }
    </script>