自定义滚动条

css：

.dumascroll {}        /*只需对需要渲染滚动条的div设置该class即可,div要固定高度，超出部分设置隐藏，显示纵向滚动条。*/.dumascroll_area {    height:100%;overflow:hidden;}.dumascroll_bar,.dumascroll_handle,.dumascroll_handle_a,.dumascroll_arrow_up,.dumascroll_arrow_up_a,.dumascroll_arrow_down,.dumascroll_arrow_down_a {    background-image:url(../images/un_bg_bar.gif);}.dumascroll_bar {    position:absolute;    top:0;    right:0;    z-index:9;    width:14px;    height:100%;    cursor:default;    -moz-user-select:none;    -khtml-user-select:none;    user-select:none;    background-repeat:repeat-y;    background-position:-42px 0;    float:left;}.dumascroll_arrow_up,.dumascroll_arrow_up_a,.dumascroll_handle,.dumascroll_handle_a,.dumascroll_arrow_down,.dumascroll_arrow_down_a {    position:absolute;    left:0;}.dumascroll_arrow_up,.dumascroll_arrow_up_a,.dumascroll_arrow_down,.dumascroll_arrow_down_a {    width:100%;    height:14px;    color:#fff;    text-align:center;}.dumascroll_arrow_up,.dumascroll_arrow_up_a { top:0; }.dumascroll_arrow_down,.dumascroll_arrow_down_a { bottom:0; }.dumascroll_handle,.dumascroll_handle_a { width:100%; background-repeat:repeat-y; }.dumascroll_arrow_up { background-position:0 0; }.dumascroll_arrow_up_a { background-position:-14px 0; }.dumascroll_handle { background-position:-28px 0; }.dumascroll_handle_a { background-position:-56px 0; }.dumascroll_arrow_down { background-position:-70px 0; }.dumascroll_arrow_down_a { background-position:-84px 0; }

js:

var duma = {    $:function(o){ if(document.getElementById(o)) {return document.getElementById(o);} },    getStyle:function(o) { return o.currentStyle||document.defaultView.getComputedStyle(o,null); },    getOffset:function(o) {        var t = o.offsetTop,h = o.offsetHeight;        while(o = o.offsetParent) { t += o.offsetTop; }        return { top:t, height:h };    },    bind:function(o,eType,fn) {        if(o.addEventListener) { o.addEventListener(eType,fn,false); }        else if(o.attachEvent) { o.attachEvent("on" + eType,fn); }        else { o["on" + eType] = fn; }    },    stopEvent:function(e) {        e = e || window.event;        e.stopPropagation && (e.preventDefault(),e.stopPropagation()) || (e.cancelBubble = true,e.returnValue = false);    },    setCookie:function(c_name,value,expiredays) {        var exdate = new Date();        exdate.setDate(exdate.getDate() + expiredays);        document.cookie = c_name + "=" + escape(value) + ((expiredays == null) ? "" : ";expires=" + exdate.toGMTString());    },    getCookie:function(c_name) {        if(document.cookie.length > 0) {            c_start = document.cookie.indexOf(c_name + "=");            if(c_start != -1) {                 c_start = c_start + c_name.length + 1;                 c_end = document.cookie.indexOf(";",c_start);                if(c_end == -1) { c_end = document.cookie.length; }                return unescape(document.cookie.substring(c_start,c_end));            }         }        return "";    }};duma.BeautifyScrollBar = function(obj,arrowUpCss,arrowUpActiveCss,handleCss,handleActiveCss,arrowDownCss,arrowDownActiveCss) {    this.arrowUpInterval;    this.arrowDownInterval;    this.barMouseDownInterval;    this.relY;    this.id = obj;    this.obj = duma.$(this.id);    this.setObjCss();        //预先设置父容器的css定位才能让接下来的属性设置起作用    this.obj.innerHTML = '<div id="' + obj + 'Area" class="dumascroll_area">' + this.obj.innerHTML + '</div><div id="' + obj + 'Bar" class="dumascroll_bar"><div class="dumascroll_arrow_up"></div><div class="dumascroll_handle"></div><div class="dumascroll_arrow_down"></div></div>';    this.area = duma.$(obj + "Area");    this.bar = duma.$(obj + "Bar");    this.barPos;    this.arrowUp = this.bar.getElementsByTagName("div")[0];    this.arrowUpCss = arrowUpCss;    this.arrowUpActiveCss = arrowUpActiveCss;    this.handle = this.bar.getElementsByTagName("div")[1];    this.handleCss = handleCss;    this.handleActiveCss = handleActiveCss;    this.arrowDown = this.bar.getElementsByTagName("div")[2];    this.arrowDownCss = arrowDownCss;    this.arrowDownActiveCss = arrowDownActiveCss;    this.handleMinHeight = 15;    this.arrowUpHeight = parseInt(duma.getStyle(this.arrowUp).height);    this.arrowDownHeight = parseInt(duma.getStyle(this.arrowDown).height);    this.areaScrollHeight = this.area.scrollHeight;    this.handleHeight = parseInt(this.area.offsetHeight/this.area.scrollHeight * (this.bar.offsetHeight - this.arrowUpHeight - this.arrowDownHeight));}duma.BeautifyScrollBar.prototype = {    setObjCss:function() {        duma.getStyle(this.obj).position == "static" ? this.obj.style.position = "relative" : duma.getStyle(this.obj).backgroundColor == "transparent" ? this.obj.style.backgroundColor = "#fff" : null;        //若容器本来就没有设position，则初始化为relative；若容器原来未设置背景色，则初始化为白色；    },    sethandle:function() {                //当内容超多时设置拖拽条子的最小高度        this.handle.style.top = this.arrowUpHeight + "px";        if(this.handleHeight > this.handleMinHeight) {            this.handleHeight < this.bar.offsetHeight - this.arrowUpHeight - this.arrowDownHeight ? this.handle.style.height = this.handleHeight + "px" : this.handle.style.display = "none";        }        else { this.handleHeight = this.handleMinHeight; this.handle.style.height = this.handleMinHeight + "px"; }    },    setBarPos:function() {                //将当前滚动的距离值存入cookie        this.barPos = this.area.scrollTop + "";        duma.setCookie(this.id + "CookieName",this.barPos,1);    },    getBarPos:function() {        this.barPos = duma.getCookie(this.id + "CookieName");        if(this.barPos!=null && this.barPos!="") {            this.area.scrollTop = this.barPos;            this.areaScroll();        }    },    clearArrowUpInterval:function() { clearInterval(this.arrowUpInterval); },    clearArrowDownInterval:function() { clearInterval(this.arrowDownInterval); },    clearBarMouseDownInterval:function() { clearInterval(this.barMouseDownInterval); },    areaScroll:function() {        this.handle.style.display != "none" ? this.handle.style.top = this.area.scrollTop/(this.area.scrollHeight - this.area.offsetHeight) * (this.bar.offsetHeight - this.handleHeight - this.arrowUpHeight - this.arrowDownHeight) + this.arrowUpHeight + "px" : null;    },    areakeydown:function(e) {            //支持键盘上下按键        var that = this;        document.onkeydown = function(event) {            var e = event || window.event,            ek = e.keyCode || e.which;            if(ek == 40) { that.area.scrollTop += 25 }            else if(ek == 38) { that.area.scrollTop -= 25 }            if(that.area.scrollTop > 0 && that.area.scrollTop < that.area.scrollHeight - that.area.offsetHeight){ duma.stopEvent(e); }            that.setBarPos();        }    },    handleMove:function(e) {        var e = e || window.event;        this.area.scrollTop = (e.clientY - this.relY - this.arrowUpHeight)/(this.bar.offsetHeight - this.handleHeight - this.arrowUpHeight - this.arrowDownHeight)*(this.area.scrollHeight - this.area.offsetHeight);        this.setBarPos();    },    handleMouseDown:function(e) {        var that = this,e = e || window.event;        that.relY = e.clientY - that.handle.offsetTop;        that.handle.setCapture ? that.handle.setCapture() : null;        that.handle.className = that.handleActiveCss;        document.onmousemove = function(event) { that.handleMove(event); };        document.onmouseup = function() {            that.handle.className = that.handleCss;            that.handle.releaseCapture ? that.handle.releaseCapture() : null;            document.onmousemove = null;        };    },    barScroll:function(e) {        var e = e || window.event,eDir;        //设置滚轮事件,e.wheelDelta与e.detail分别兼容IE、W3C，根据返回值的正负来判断滚动方向        if(e.wheelDelta) { eDir = e.wheelDelta/120; }        else if(e.detail) { eDir = -e.detail/3; }        eDir > 0 ? this.area.scrollTop -= 80 : this.area.scrollTop += 80;    //步长设80像素比较接近window滚动条的滚动速度        if(this.area.scrollTop > 0 && this.area.scrollTop < this.area.scrollHeight - this.area.offsetHeight){ duma.stopEvent(e); }        this.setBarPos();    },    barDown:function(e) {        var e = e || window.event,that = this,            eY = e.clientY,            mStep = this.bar.offsetHeight,            documentScrollTop = document.documentElement.scrollTop || document.body.scrollTop,            hOffset = duma.getOffset(this.handle),            bOffset = duma.getOffset(this.bar);        if(documentScrollTop + eY < hOffset.top) { this.barMouseDownInterval = setInterval(function(e){            that.area.scrollTop -= that.area.offsetHeight;            if(that.area.scrollTop <= (eY + documentScrollTop - bOffset.top - that.arrowUpHeight)/(that.bar.offsetHeight - that.arrowUpHeight - that.arrowDownHeight) * that.area.scrollHeight) { that.clearBarMouseDownInterval(); }            that.setBarPos();        },80); }        else if(documentScrollTop + eY > hOffset.top + hOffset.height) { this.barMouseDownInterval = setInterval(function(){            that.area.scrollTop += that.area.offsetHeight;            if(that.area.scrollTop >= (eY + documentScrollTop - bOffset.top - that.arrowUpHeight - hOffset.height)/(that.bar.offsetHeight - that.arrowUpHeight - that.arrowDownHeight) * that.area.scrollHeight) { that.clearBarMouseDownInterval(); }            that.setBarPos();        },80); }        duma.stopEvent(e);    },    arrowUpMouseDown:function(e) {        var that = this;        this.arrowUpInterval = setInterval(function(){ that.area.scrollTop -= 25; that.setBarPos(); },10);        this.arrowUp.className = this.arrowUpActiveCss;        duma.stopEvent(e);    },    arrowUpMouseUp:function() { this.clearArrowUpInterval(); this.arrowUp.className = this.arrowUpCss; },    arrowUpMouseOut:function() { this.clearArrowUpInterval(); this.arrowUp.className = this.arrowUpCss; },    arrowDownMouseDown:function(e) {        var that = this;        this.arrowDownInterval = setInterval(function(){ that.area.scrollTop += 25; that.setBarPos(); },10);        this.arrowDown.className = this.arrowDownActiveCss;        duma.stopEvent(e);    },    arrowDownMouseUp:function() { this.clearArrowDownInterval(); this.arrowDown.className = this.arrowDownCss; },    arrowDownMouseOut:function() { this.clearArrowDownInterval(); this.arrowDown.className = this.arrowDownCss; },    run:function(){        var that = this;        this.sethandle();        this.areaScroll();        this.getBarPos();        this.area.onscroll = function(){that.areaScroll()};        this.area.onmouseover = this.bar.onmouseover = function(event){that.areakeydown(event)};        this.area.onmouseout = this.bar.onmouseout = function(){document.onkeydown = null};        this.handle.onmousedown = function(event){that.handleMouseDown(event)};        this.bar.onmousedown = function(event){that.barDown(event)};        this.bar.onmouseup = function(){that.clearBarMouseDownInterval()};        this.bar.onmouseout = function(){that.clearBarMouseDownInterval()};        this.arrowUp.onmousedown = function(event){that.arrowUpMouseDown(event)};        this.arrowUp.onmouseup = function(){that.arrowUpMouseUp()};        this.arrowUp.onmouseout = function(){that.arrowUpMouseOut()};        this.arrowDown.onmousedown = function(event){that.arrowDownMouseDown(event)};        this.arrowDown.onmouseup = function(){that.arrowDownMouseUp()};        this.arrowDown.onmouseout = function(){that.arrowDownMouseOut()};        duma.bind(this.obj,"mousewheel",function(event){that.barScroll(event)});        duma.bind(this.obj,"DOMMouseScroll",function(event){that.barScroll(event)});    }}duma.BeautifyScrollBar.init = function() {    var o = document.getElementsByTagName("div"),        oLen = o.length,        dumascrollClass = /\bdumascroll\b/,        oArr = [],        oArrLen = oArr.length;    for(var i=0; i<oLen; i++) {        if(dumascrollClass.test(o[i].className)) {            oArr.push("dumaScrollAreaId_" + i);            oArrLen = oArr.length;            o[i].id = oArr[oArrLen - 1];        }    }    for(var j=0; j<oArrLen; j++) {        new duma.BeautifyScrollBar(oArr[j],"dumascroll_arrow_up","dumascroll_arrow_up_a","dumascroll_handle","dumascroll_handle_a","dumascroll_arrow_down","dumascroll_arrow_down_a").run();    }}duma.bind(window,"load",duma.BeautifyScrollBar.init);