div跟随页面滚动

$(document).ready(function(){
         var timer;
         $(window).scroll(function (){
                clearInterval(timer);
                var topScroll=getScroll();
                var topDiv="100px";
                var top=topScroll+parseInt(topDiv);
                timer=setInterval(function(){
                    //$(".test").css("top", top+"px");
                     $("#splitsuspend_div").stop(true).animate({"top":top},50);
                },50)
              })
        })
        function getScroll(){
             var bodyTop = 0;
             if (typeof window.pageYOffset != 'undefined') {
                 bodyTop = window.pageYOffset;
             } else if (typeof document.compatMode != 'undefined' && document.compatMode != 'BackCompat') {
                 bodyTop = document.documentElement.scrollTop;
             }
             else if (typeof document.body != 'undefined') {
                 bodyTop = document.body.scrollTop;
             }
             return bodyTop
        }