往上滚动的JS

  $(function() {
            var shtml = $("#scroll_ul")[0].innerHTML;
            shtml += shtml;
            $("#scroll_ul")[0].innerHTML = shtml;
            var lisize = $("#scroll_ul li").size();
            var linghight = parseInt($("#scroll_ul li:first").css("height"));
            var num = 0;
            var scrollinterval = setInterval(scrollul, 100);
            $("#scroll_ul").hover(function() {
                clearInterval(scrollinterval);
            }, function() {
                scrollinterval = setInterval(scrollul, 100);
            })
            function scrollul() {
                if ((num / 10) < lisize / 2) {
                    num++;
                 
                    $("#scroll_ul").css("marginTop", -parseInt((num * linghight) / 10) + "px");

                }
                else {
                    num = 0;
                    $("#scroll_ul").css("marginTop", "0px");

                }
            }
        })