Javascript提示窗口并实现模式窗口功能

提示窗口的界面：

 
 img{
     border:0px;
 }
 
 #overlay{
     position: absolute;
     top: 0;
     left: 0;
     z-index: 99;
     width: 100%;
     height: 500px;
     background-color: #000;
     filter:alpha(opacity=70);
     -moz-opacity: 0.6;
     opacity: 0.6;
 }
 
 .floatDiv{
     padding:0 0 0 0;    
     position:absolute; 
     width:300px; 
     margin:0 0 0 0; 
     z-index:100;
     border:1px solid #DADADA; 
     background:#FFF; padding:1px;
 }
 
 .floatDiv .divTitle{
     background:#E0E0E0 url('../images/dragForm/title_bg.gif');
     background-position:top left;
     background-repeat:repeat-x;
     height:25px;
     line-height:25px;
     padding:0px 4px;
     cursor:default;
 }
 
 .floatDiv .divContent{
     padding:3px; 
     min-height:100px;
     height:auto; cursor:default;
 }
 
 .floatDiv .divFoot{
     background:#F0F0F0; 
     text-align:right; 
     padding:4px;
     background:#E0E0E0 url('../images/dragForm/bottom_bg.gif');
     background-position:top left;
     background-repeat:repeat-x;
 }
 
 .floatDiv input.divButton{
     background:#E0E0E0 url('../images/dragForm/button_bg.gif');
     background-position:top left;
     background-repeat:repeat-x;
     border:1px solid #D1D3D2;
     height:21px;
     font-size:12px;
     padding:2px 5px;
     color:#626264;
 }
 

function $(_sId)
{return document.getElementById(_sId);}
  
function moveDiv(event, _sId)
{
    var oObj = $(_sId);    
    oObj.onmousemove = mousemove;
    oObj.onmouseup = mouseup;
    oObj.setCapture ? oObj.setCapture() : function(){};
    oEvent = window.event ? window.event : event;
    var dragData = {x : oEvent.clientX, y : oEvent.clientY};
    var backData = {x : parseInt(oObj.style.top), y : parseInt(oObj.style.left)};
   
    function mousemove()
    {
        var oEvent = window.event ? window.event : event;
        var iLeft = oEvent.clientX - dragData["x"] + parseInt(oObj.style.left);
        var iTop = oEvent.clientY - dragData["y"] + parseInt(oObj.style.top);
        oObj.style.left = iLeft;
        oObj.style.top = iTop;
        dragData = {x: oEvent.clientX, y: oEvent.clientY};  
    }
   
    function mouseup()
    {
        var oEvent = window.event ? window.event : event;
        oObj.onmousemove = null;
        oObj.onmouseup = null;
        if(oEvent.clientX < 1 || oEvent.clientY < 1)
        {
            oObj.style.left = backData.y;
            oObj.style.top = backData.x;
        }
            oObj.releaseCapture ? oObj.releaseCapture() : function(){};
    }
}

function closeDiv(_sID)
{
    var oObj = $(_sID);
    var overlay = $("overlay");    
    if(overlay != null)
    {
        overlay.outerHTML = "";
    }
    oObj.style.display = "none";
    
}

function showDiv(_sID,event)
{
    var arrySize = getPageSize();
    var oObj = $(_sID);
    //创建一个DIV,改名为 overlay 这个是透明的层    
    var oDiv =document.createElement("div");
    oDiv.id = "overlay";
    document.body.appendChild(oDiv);
    var overlay = $("overlay");
    overlay.style.height = arrySize[1];
    overlay.style.width = arrySize[0];
    //alert(arrySize[1]);    
    if(event == null)
    {
        if(oObj.style.left == "")
        {
            oObj.style.left = arrySize[0] / 2 - 150 ;
        }
        
        if(oObj.style.top == "")
        {
            oObj.style.top =  arrySize[0] / 2;
        }        
    }
    else
    {        
        var iEvent= window.event ? window.event : event;        
        oObj.style.left = arrySize[0] / 2 - 150 ; // iEvent.clientX;
        oObj.style.top = arrySize[1] / 2 - 150 ;// iEvent.clientY;
        
    }
    
    oObj.style.display = "block";
    overlay.style.display = "block";
    overlay.style.zindex = oObj.style.zindex - 1;
}

//取得页面大小
function getPageSize(){
    
    var xScroll, yScroll;
    
    if (window.innerHeight && window.scrollMaxY) {    
        xScroll = document.body.scrollWidth;
        yScroll = window.innerHeight + window.scrollMaxY;
    } else if (document.body.scrollHeight > document.body.offsetHeight){ // all but Explorer Mac
        xScroll = document.body.scrollWidth;
        yScroll = document.body.scrollHeight;
    } else { // Explorer Macwould also work in Explorer 6 Strict, Mozilla and Safari
        xScroll = document.body.offsetWidth;
        yScroll = document.body.offsetHeight;
    }
    
    var windowWidth, windowHeight;
    if (self.innerHeight) {    // all except Explorer
        windowWidth = self.innerWidth;
        windowHeight = self.innerHeight;
    } else if (document.documentElement && document.documentElement.clientHeight) { // Explorer 6 Strict Mode
        windowWidth = document.documentElement.clientWidth;
        windowHeight = document.documentElement.clientHeight;
    } else if (document.body) { // other Explorers
        windowWidth = document.body.clientWidth;
        windowHeight = document.body.clientHeight;
    }    
    
    // for small pages with total height less then height of the viewport
    if(yScroll < windowHeight){
        pageHeight = windowHeight;
    } else { 
        pageHeight = yScroll;
    }

    // for small pages with total width less then width of the viewport
    if(xScroll < windowWidth){    
        pageWidth = windowWidth;
    } else {
        pageWidth = xScroll;
    }


    arrayPageSize = new Array(pageWidth,pageHeight,windowWidth,windowHeight) 
    return arrayPageSize;
}

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">

<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题 1</title>
<link href="styles/drag.css" rel="stylesheet" media="all" />
<script type="text/javascript" src="scripts/drag.js"></script>
</head>

<body>

<div id="main">
    <a href="javascript:showDiv('floatDiv');">show</a>
<input type="button" onclick="showDiv('floatDiv',event);" value="显示在这里" />

</div>
<div id="floatDiv" class="floatDiv" style="display:none;">
    <div class="divTitle" onmousedown="moveDiv(event,'floatDiv');">
        <div style="float:left; width:250px;">提示窗口</div>
        <div style="float:right;text-align:right; height:25px;" >
            <a href="javascript:;" onclick="closeDiv('floatdiv');"><img src="images/dragform/ico_close.gif" onmouseout="this.src='images/dragform/ico_close.gif';" onmousemove="this.src='images/dragform/ico_close1.gif';" align="absmiddle" alt="关闭" /></a>
        </div>        
    </div>
    <div class="divContent" >
        <p>以前自已也有一个博客，写了300多篇，后面工作以后就没有再写了。不知道是不是因为懒了，还是工作太忙的原因，呵呵 
cnBlogs的博客圈子不错，所以我也插进来，希望能够认识更多业内的朋友。 
    </p>
    </div>
    <div class="divFoot">
        <input type="button" class="divButton" value="确 定" /> <input type="button" class="divButton" onclick="closeDiv('floatdiv')" value="取 消" />
    </div>
</div>
</body>

</html>