var scrollMoveObj = null, scrollPageY = 0, scrollY = 0; var scrollDivList = new Array(); // obj需要添加滚动条的对象 w滚动条宽度 className滚动条样式名称 // obj元素 必须指定高度，并设置overflow:hidden; // 如要兼容IE6 必须给obj元素 指定 overflow:hidden; function jsScroll(obj, w, className) {
       if(typeof(obj) == 'string')    {
           obj = document.getElementByIdx_x_x(obj);     }     //当内容未超出现在高度时，不添加滚动条        if(!obj || obj.scrollHeight <= obj.clientHeight || obj.clientHeight == 0) {
           return;     }     obj.scrollBarWidth = w||6;     obj.style.overflow = 'hidden';     obj.scrollBar = document_createElement_x_x('div');     document.body.a(obj.scrollBar);     obj.scrollBarIndex = document_createElement_x_x('div');     obj.scrollBar.a(obj.scrollBarIndex);     obj.scrollBar.style.position = 'absolute';     obj.scrollBarIndex.style.position = 'absolute';     obj.scrollBar.className = className || '';     if(!className) {
           obj.scrollBar.style.backgroundColor = '#ddd';         obj.scrollBarIndex.style.backgroundColor = '#aaa';     }         scrollDivList.push(obj);     scrollResetSize(obj);         //使用鼠标滚轮滚动     obj.scrollBar.scrollDiv = obj;     obj.scrollBarIndex.scrollDiv = obj;     obj.onmousewheel = scrollMove;     obj.scrollBar.onmousewheel = scrollMove;     obj.scrollBarIndex.onmousewheel = scrollMove;         //拖动滚动条滚动     obj.scrollBarIndex.onmousedown = function(evt){
           evt = evt || event;         scrollPageY = evt.clientY;         scrollY = this.scrollDiv.scrollTop;         isScrollMove = true;         document.body.onselectstart = function(){
   return false};         scrollMoveObj = this.scrollDiv;         if(this.scrollDiv.scrollBar.className == '') {
               this.scrollDiv.scrollBarIndex.style.backgroundColor = '#888';         }         return false;     } } //当页面大小发生变化时，重新计算滚动条位置 window.onresize = function(){
       for(var i=0; i         scrollResetSize(scrollDivList[i]);     } } //计算滚动条位置 function scrollResetSize(o) {
       if(o.scrollHeight <= o.clientHeight) {
           o.scrollTop = 0;         o.scrollBar.style.display = 'none';     } else {
           o.scrollBar.style.display = 'block';     }     var x=0, y=0;     var p = o;     while(p) {
           x += p.offsetLeft;         y += p.offsetTop;         p = p.offsetParent;     }     var borderTop = parseInt(o.style.borderTopWidth||0);     var borderBottom = parseInt(o.style.borderBottomWidth||0);     o.scrollBar.style.width = o.scrollBarWidth + 'px';     o.scrollBar.style.height = o.clientHeight + 'px';     o.scrollBar.style.top = y + borderTop + 'px';     o.scrollBar.style.left = x + o.offsetWidth - o.scrollBarWidth + 'px';     o.scrollBarIndex.style.width = o.scrollBarWidth + 'px';     var h = o.clientHeight - (o.scrollHeight - o.clientHeight);     //当滚动条滑块最小20个像素     if(h < 20) {
           h = 20;     }     o.scrollBarHeight = h;     o.scrollBarIndex.style.height = h + 'px';     o.scrollBarIndex.style.left = '0px';     setScrollPosition(o); } function setScrollPosition(o) {
       o.scrollBarIndex.style.top = (o.clientHeight - o.scrollBarHeight) * o.scrollTop / (o.scrollHeight - o.clientHeight) + 'px'; } document.documentElement.onmousemove = function(evt){
       if(!scrollMoveObj)return;     evt = evt || event;     var per = (scrollMoveObj.scrollHeight - scrollMoveObj.clientHeight) / (scrollMoveObj.clientHeight - scrollMoveObj.scrollBarHeight)     scrollMoveObj.scrollTop = scrollY - (scrollPageY - evt.clientY) * per;     setScrollPosition(scrollMoveObj); } document.documentElement.onmouseup = function(evt){
       if(!scrollMoveObj)return;     if(scrollMoveObj.scrollBar.className == '') {
           scrollMoveObj.scrollBarIndex.style.backgroundColor = '#aaa';     }     scrollMoveObj = null;     document.body.onselectstart = function(){
   return true}; } // 鼠标滚轮滚动 function scrollMove(evt){
       var div = this.scrollDiv || this;     if(div.scrollHeight <= div.clientHeight) return true;     evt = evt || event;     var step = 20;     if(evt.wheelDelta < 0) {
           if(div.scrollTop >= (div.scrollHeight - div.clientHeight)) return true;         div.scrollTop += step;     } else {
           if(div.scrollTop == 0) return true;         div.scrollTop -= step;     }     setScrollPosition(div);         return false; }