Determine the expiration time of the Session. Use JavaScript to display how many seconds are left in real time

<%@LANGUAGE="VBSCRIPT" CODEPAGE="936"%>
<%=1440 'Unit (minutes) 1440=24 hours The parameter cannot be greater than 24 hours, that is, it cannot be greater than 1440 minutes%>
<%
if session("login")<>"88888" then'Judge whether the session is valid
("Session expired")
end if
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http:///TR/xhtml1/DTD/">
<html xmlns="http:///1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>Unt titled document</title>
<script>
var lefttime=6 //session time delivery
var tid
function x()
{
lefttime--
="Remaining:"+lefttime + "seconds"
if(lefttime==0) {clearInterval(tid);="Login timed out" }
}
tid = ("x()",1000)
</script>
</head>
<body>
<div id=xx></div>
https://
</body>
</html>
Can a warning pop up when the time comes, and then click to enter another screen?
<script>
var lefttime=3 //session time delivery
var tid
function x()
{
lefttime--
="Remaining:"+lefttime + "seconds"
if(lefttime==0)
{
(tid);
if(("Do you want to enter?"))
("https:///")
}
}
tid = ("x()",1000)
</script>
<body>
<div id=xx></div>
Don't open another page, open a new page on the original page.
Change ("https:///") to
="https://"