Js控制滚动条

//向上滑动显示
        var initTop = 0;
        var i = 1;
        $(window).scroll(function(){
             var scrollTop = $(document).scrollTop();
             if(scrollTop < initTop){
                 var top = document.documentElement.scrollTop + document.body.scrollTop;
                 if(top == 0){
                        i++;
                        showMessage(i,‘loadold‘);
                 }
                 
             }
         initTop = scrollTop;
        });

$(".alllist").scroll(function(){
              distanceScrollCount = $(this)[0].scrollHeight;
              distanceScroll = $(this)[0].scrollTop;
              distanceSum = distanceScroll + divHight + 35;
              if(distanceSum >= distanceScrollCount){
                i++;
                showMessage(i,‘loadold‘);
              }
        });