本文转自:http://www.cnblogs.com/youcai/archive/2011/11/17/2252878.html

很久以前写过一遍文章js弹出层居中可移动出现的问题比较多,最重要的一个是在第二次弹出层关闭之后,后面的置灰背景还是存在。今天偶然想起来,于是修正了,出现这个问题的主要原因是上一次在点击关闭按钮之后没有将置灰层删除,而是隐藏了。以下是修正后的代码:
<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd“>
<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<meta http-equiv=”Content-Type” content=”text/html; charset=utf-8″ />
<META NAME=”Author” CONTENT=””>
<META NAME=”Keywords” CONTENT=””>
<META NAME=”Description” CONTENT=””>
<style type=”text/css”>
*
{
padding:0px;
margin:0px;
}
#Idiv
{
width:300px;
height:100px;
position:absolute;
z-index:1000;
border:2px solid #ffffff;
background:#ffffff;
}
</style>
<script langue=”javascript”>
 
function show()
{
var Idiv=document.getElementById(“Idiv”);
Idiv.style.display=”block”;
//以下部分要将弹出层居中显示
Idiv.style.left=(document.documentElement.clientWidth-Idiv.clientWidth)/2+document.documentElement.scrollLeft+”px”;
Idiv.style.top=(document.documentElement.clientHeight-Idiv.clientHeight)/2+document.documentElement.scrollTop-50+”px”;
 
 
//以下部分使整个页面至灰不可点击
var procbg = document.createElement(“div”); //首先创建一个div
procbg.setAttribute(“id”,”mybg”); //定义该div的id
procbg.style.background = “#000000”;
procbg.style.width = “100%”;
procbg.style.height = “100%”;
procbg.style.position = “fixed”;
procbg.style.top = “0”;
procbg.style.left = “0”;
procbg.style.zIndex = “500”;
procbg.style.opacity = “0.6”;
procbg.style.filter = “Alpha(opacity=70)”;
 
//以上部分也可以用csstext代替
// procbg.style.cssText=”background:#000000;width:100%;height:100%;position:fixed;top:0;left:0;zIndex:500;opacity:0.6;filter:Alpha(opacity=70);”;
//背景层加入页面
document.body.appendChild(procbg);
document.body.style.overflow = “hidden”; //取消滚动条
 
 
//以下部分实现弹出层的拖拽效果
var posX;
var posY;
Idiv.onmousedown=function(e)
{
if(!e) e = window.event; //IE
posX = e.clientX – parseInt(Idiv.style.left);
posY = e.clientY – parseInt(Idiv.style.top);
document.onmousemove = mousemove;
}
document.onmouseup = function()
{
document.onmousemove = null;
}
function mousemove(ev)
{
if(ev==null) ev = window.event;//IE
Idiv.style.left = (ev.clientX – posX) + “px”;
Idiv.style.top = (ev.clientY – posY) + “px”;
}
 
}
function closeDiv() //关闭弹出层
{
var Idiv=document.getElementById(“Idiv”);
Idiv.style.display=”none”;
document.body.style.overflow = “auto”; //恢复页面滚动条
var body = document.getElementsByTagName(“body”);
var mybg = document.getElementById(“mybg”);
body[0].removeChild(mybg);
}
 
</script>
</HEAD>
 
<BODY>
<div><a href=”javascript:void(0)” id=”show” onclick=”show()”>点击打开弹出层!</a></div>
<div id=”Idiv” style=”display:none;”><a href=”javascript:void(0)” onclick=”closeDiv()”>点击关闭层</a></div>
相关链接:http://blog.csdn.net/mathewsking/article/details/4539997 (关于document.body 和 document.documentElement 的区别 )
 
</BODY>
</HTML>
还有什么问题欢迎大家批评指正~~