js 实现网站右侧广告浮动

 $(function () {
            var aaa = $("#div_OnlineTalk").css("margin-top").toString();
            var bbb = parseInt(aaa.replace("px",""));
            documentHeight = $(document).height();
            $(window).scroll(function () {

                $("#div_OnlineTalk").stop().animate({

                    marginTop: $(window).scrollTop() + bbb

                },1000);
            });

        });