Wie bei Firefox Portable nach ein paar Minuten Inaktivität bestimmte Internetseite aufrufen

<script type="text/javascript">  
function idleTimer() {
    var t;
    //window.onload = resetTimer;
    window.onmousemove = resetTimer; // catches mouse movements
    window.onmousedown = resetTimer; // catches mouse movements
    window.onclick = resetTimer;     // catches mouse clicks
    window.onscroll = resetTimer;    // catches scrolling
    window.onkeypress = resetTimer;  //catches keyboard actions

    function backtomainsite() {
        window.location.href = '/start';  //  
    }

   function resetTimer() {
        clearTimeout(t);
        t = setTimeout(backtomainsite, 1800000);  // time is in milliseconds (1000 is 1 second)
    }
}
idleTimer();
</script>