Moving title

<script type="text/javascript">
var rev = "fwd";
function titlebar(val)
{
        var msg  = "YOUR TITLE HERE";
        var res = "F ";
        var speed = 100;
        var pos = val;
        msg = "YOUR TITLE HERE";
        var le = msg.length;
        if(rev == "fwd"){
                if(pos < le){
                pos = pos+1;
                scroll = msg.substr(0,pos);
                document.title = scroll;
                timer = window.setTimeout("titlebar("+pos+")",speed);
                }
                else{
                rev = "bwd";
                timer = window.setTimeout("titlebar("+pos+")",speed);
                }
        }
        else{
                if(pos > 0){
                pos = pos-1;
                var ale = le-pos;
                scrol = msg.substr(ale,le);
                document.title = scrol;
                timer = window.setTimeout("titlebar("+pos+")",speed);
                }
                else{
                rev = "fwd";
                timer = window.setTimeout("titlebar("+pos+")",speed);
                }
        }
}
titlebar(0);
</script>