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);