CSS代码：  .backToTop {      display: none;      width: 18px;      line-height: 1.2;      padding: 5px 0;      background-color: #000;      color: #fff;      font-size: 12px;      text-align: center;      position: fixed;      _position: absolute;      right: 10px;      bottom: 100px;      _bottom: "auto";      cursor: pointer;      opacity: .6;      filter: Alpha(opacity=60);  }

JS代码：  (function() {      var $backToTopTxt = "返回顶部", $backToTopEle = $('').appendTo($("body"))          .text($backToTopTxt).attr("title", $backToTopTxt).click(function() {              $("html, body").animate({ scrollTop: 0 }, 120);      }), $backToTopFun = function() {          var st = $(document).scrollTop(), winh = $(window).height();          (st > 0)? $backToTopEle.show(): $backToTopEle.hide();             //IE6下的定位          if (!window.XMLHttpRequest) {              $backToTopEle.css("top", st + winh - 166);             }      };      $(window).bind("scroll", $backToTopFun);      $(function() { $backToTopFun(); });  })();