How to check whether session is null or not in javascript?

Question

How to check whether session is null or not in javascript?It is right way?

if ('<%=Session["Time"] == null%>')
{
    alert('null session');
}

Answer 1

Here's a solution that will test every 500 milliseconds if the user session has expired.

 function CheckSession() {
            var session = '<%=Session["username"] != null%>';
            if (session == false) {
                alert("Your Session has expired");
                window.location = "login.aspx";
            }
        }

setInterval(CheckSession(),500);