function keepAlivePing()
{
   var img = document.createElement("img");
   img.src = "/KeepAlive.aspx?" + Math.floor(Math.random()*999999999);
}

keepAlivePing();

var cookieEnabled = (navigator.cookieEnabled) ? true : false;

if ( typeof navigator.cookieEnabled == "undefined" && !cookieEnabled )
{ 
   document.cookie = "testcookie";
   cookieEnabled = ( document.cookie.indexOf( "testcookie" ) != -1 ) ? true : false;
}

if ( cookieEnabled )
{
   window.setInterval( keepAlivePing, 45000 );
}