div弹出层，待优化

function getCurrentStyle(ele,name){ 
            if(typeof(ele)=="string")
            {
                ele=document.getElementById(ele);
            }
            if(document.all)
            {               
                return ele.currentStyle[name];
            }
            return  document.defaultView.getComputedStyle(ele, null)[name];
        }
        
        function update()
        {
            show("layer");   
        }
        
        //弹出层
        function show(divID,relativeTop,relativeLeft,width,height) {
            lock();
            if(!width)
            {
                width=300;
            }
            if(!height)
            {
                height=150;
            }
            var divLayer = document.getElementById("divLayer");    
            if (divLayer) {
                divLayer.style.display = "block";

                var arr = divLayer.getElementsByTagName("div");
                for (var i = 0; i < arr.length; i++) {
                    arr[i].style.display = "block";
                }
            } else {
                divLayer = document.createElement("div");
                divLayer.id = "divLayer";//border-color: #E78F08 #E78F08 #EAA12A;border-style: solid;border-width: 1px
                divLayer.innerHTML="<h4 id='divLayer_h' style='background:none repeat scroll 0 0 #F7B64B;padding:2px 10px;color:white;height:18px;line-height:18px;margin:0;font-size:14px;border-color: #E78F08 #E78F08 #EAA12A;border-style: solid;border-width: 1px;'><a href='javascript:divClose();' style='text-align:center;text-decoration:none;background-color:white;color:#C77405;font-size:14px;font-family:arial;height:14px;line-height:14px;overflow:hidden;float:right;width:14px;' title='关闭窗口'>&times;</a>提示</h4>";
                divLayer.innerHTML +="<div style='border: 1px solid #CCCCCC;' id='divLayer_Content'>"+document.getElementById(divID).innerHTML+"</div>";    
                divLayer.style.width=width+"px";
                divLayer.style.height=height+"px";        
                divLayer.style.backgroundColor="white";
                divLayer.style.boxShadow="1px 2px 2px #555555";
                divLayer.style.zIndex=parseInt(document.getElementById("divLock").style.zIndex)+1;
                divLayer.style.position="absolute";  
                divLayer.style.border="medium none";                
                //设置弹出层与页面顶部的距离
                if(relativeTop)
                {
                    divLayer.style.top=relativeTop+"px";
                }else
                {   
                    divLayer.style.top="50%";
                    divLayer.style.marginTop="-"+height*0.5+"px";
                    
                }   
                //设置弹出层与页面左侧的距离
                if(relativeLeft)
                {
                    divLayer.style.left=relativeLeft+"px";
                }else
                {    
                    divLayer.style.left="50%";    
                    divLayer.style.marginLeft="-"+width*0.5+"px";                    
                }   
                insertLayer(divLayer,document.body);   
                
                
                /*
                var contentHeight=getIntByPx(getCurrentStyle(divLayer,"height"))-getIntByPx(getCurrentStyle("divLayer_h","height"))-getIntByPx(getCurrentStyle("divLayer_h","paddingTop"))-getIntByPx(getCurrentStyle("divLayer_h","paddingBottom"));
                alert(contentHeight);
                */
                var contentHeight=getIntByPx(getCurrentStyle(divLayer,"height"))-document.getElementById("divLayer_h").offsetHeight-2;            
                document.getElementById("divLayer_Content").style.height=contentHeight+"px";
            }
        }


        function getIntByPx(px)
        {
            return parseInt(px.substring(0,px.length-2))
        }
        
        //关闭弹出层
        function divClose() {
            var divLayer = document.getElementById("divLayer");    
            var divLock = document.getElementById("divLock");    
            if (divLayer) {
                divLayer.style.display = "none";
                divLock.style.display = "none";
            }
        }
        
        //遮盖层
        function lock() {
            var divLock = document.getElementById("divLock");
            if (divLock) {
                divLock.style.display = "block";
            } else {
                divLock = document.createElement("div");
                divLock.id="divLock";
                divLock.style.width = Math.max(document.body.scrollWidth,document.documentElement.scrollWidth)+"px"
                divLock.style.height = getBodyHeight()+"px";
                divLock.style.verticalAlign="middle";
                divLock.style.position = "absolute";
                divLock.style.backgroundColor = "black";
                divLock.style.filter = "alpha(Opacity=40)";
                divLock.style.top = "0px";
                divLock.style.left = "0px";
                divLock.style.opacity = " 0.4";        
                divLock.style.zIndex = "1";
                document.body.appendChild(divLock);                
            }
        }  
        
        //获取body的高度
        function getBodyHeight()
        {
             //如果是IE
             if(document.all)
             {
                return  Math.max(document.body.scrollHeight, document.documentElement.scrollHeight,document.documentElement.clientHeight);
             }
             return Math.max(document.body.scrollHeight, document.documentElement.scrollHeight);
        }  
        
        function insertLayer(divLayer,parent)
        {
            //将此div插入到指定父元素的第一个元素之前
            if(parent.childNodes[0])
            {                   
                parent.insertBefore(divLayer,parent.childNodes[0]);
            }else
            {
                parent.appendChild(divLayer);
            }
        }