javascript弹出层居中效果的制作

<!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=gb2312" /> 
<meta name="author" content="Stri" /> 
<title>javascript 弹出层居中效果的制作</title> 
<style type="text/css"> 
* { padding:0; margin:0; list-style:none; }

body { font-family:Verdana, Geneva, sans-serif; font-size:14px; }

#a { width:300px; height:80px; border:5px solid #d3d3d3; background-color:#f7f7f7; position:absolute; padding:10px; }

a.btn { display:block; width:80px; cursor:pointer; background-color:#f7f7f7; padding:2px 0px; border:1px solid #d5d5d5; vertical-align:middle; text-align:center; margin:50px auto 5px; text-decoration:none; }

a:hover { background-color:#333; color:#fff; font-weight:bold; } 
</style> 
<script language="javascript" type="text/javascript"> 
window.onload=function divcenter() 
{ var c=document.createElement("div");

document.body.appendChild(c); 
c.setAttribute("id","a"); 
    var divId=document.getElementById("a"); 
     divId.innerHTML+="对浏览器变形,刷新看是否居中"; 
divId.style.left=(document.documentElement.clientWidth-divId.clientWidth)/2+document.documentElement.scrollLeft+"px"; 
setTimeout(function(){divId.style.top=(document.documentElement.clientHeight-divId.clientHeight)/2+document.documentElement.scrollTop-50+"px";},200);

} 
</ script> 
</head> 
<body> 
<script type="text/javascript"> 
x:for(var i=1; i<100;i++){ 
    var a=document.createElement("div"); 
    a.innerHTML=""+i+""; 
    document.body.appendChild(a);} 
</ script> 
</body> 
</html>

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]

<!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=gb2312" /> 
<meta name="author" content="Stri" /> 
<title>javascript 弹出层居中效果的制作</title> 
<style type="text/css"> 
* { padding:0; margin:0; list-style:none; }

body { font-family:Verdana, Geneva, sans-serif; font-size:14px; }

#a { width:380px; height:80px; border:5px solid #d3d3d3; background-color:#f7f7f7; position:absolute; padding:10px; z-index:9999; }

a.btn { display:block; width:80px; cursor:pointer; background-color:#f7f7f7; padding:2px 0px; border:1px solid #d5d5d5; vertical-align:middle; text-align:center; margin:50px auto 5px; text-decoration:none; }

a:hover { background-color:#333; color:#fff; font-weight:bold; }

#aa { position:fixed; bottom:20px; right:10px; } 
</style> 
<script language="javascript" type="text/javascript"> 
var drg=true; 
var ns=(document.all) ? false : true; 
function divcenter() 
{remove(); 
var c=document.createElement("div"); 
document.body.appendChild(c); 
c.setAttribute("id","a"); 
        c.setAttribute("dragable","dragable"); 
        c.onmousedown=foo;

var divId=document.getElementById("a"); 
     divId.innerHTML+="出现代码异常!<br>错误编号:0015;";     
divId.style.left=(document.documentElement.clientWidth-divId.clientWidth)/2+document.documentElement.scrollLeft+"px"; 
setTimeout(function(){divId.style.top=(document.documentElement.clientHeight-divId.clientHeight)/2+document.documentElement.scrollTop-50+"px";},100);

} 
//移除 
function remove(){ 
    if(document.getElementById("a")) 
    {document.body.removeChild(document.getElementById("a")); 
        }} 
         
function foo(){

if(drg){ 
        if(document.getElementById("a")!=null) 
        { 
            obj=document.getElementById("a"); 
            document.onmousedown=m_d; 
            document.onmouseup=m_u; 
            } 
        } 
        else 
        { 
         
         document.onmousemove=no_f; 
         document.onmousedown=no_f; 
         document.onmouseup=no_f; 
         } 
} 
function m_d(e){

x:for(var i=1; i<100;i++){ 
var a=document.createElement("div"); 
a.innerHTML=""+i+""; 
document.body.appendChild(a);} 
</ script> 
</body> 
</html>