Session Timeout Warning

var timerPROMPT = 0;
var timerCLOSE = 0;

function EndApp()
{
//RateDeck.style.display = "none"
//spDeck.style.display = "none"
alert("Session ending !!!!");
}
function StopTiming()
{
if(timerPROMPT > 0)
window.clearTimeout(timerPROMPT)

if (confirm('Due to inactivity, your session is about to time out.') == 1)
{
if(timerCLOSE > 0)
window.clearTimeout(timerCLOSE)

timerPROMPT = window.setTimeout("StopTiming()",5000);
timerCLOSE = window.setTimeout("EndApp()",8000);
}
else
{
EndApp();
}
}
function window_activity()
{
alert("Window_activity");
if(timerPROMPT > 0)
window.clearTimeout(timerPROMPT)
if(timerCLOSE > 0)
window.clearTimeout(timerCLOSE)

timerPROMPT = window.setTimeout("StopTiming()",5000);
timerCLOSE = window.setTimeout("EndApp()",6000);
}

var sessionTimeout = 30;
function DisplaySessionTimeout()
{
//assigning minutes left to session timeout to Label
document.getElementById("sessioTimeOut").innerText = sessionTimeout;
sessionTimeout = sessionTimeout - 1;

//if session is not less than 0
if (sessionTimeout >= 0)
//call the function again after 1 minute delay
window.setTimeout("DisplaySessionTimeout()", 60000);
else
{
//show message box
alert("Your current Session is over.");
}
}