一个非常好，代码很整齐的JS弹出层实例

function sAlert(str){ 
var msgw,msgh,bordercolor; 
msgw=400;//提示窗口的宽度 
msgh=100;//提示窗口的高度 
titleheight=25 //提示窗口标题高度 
bordercolor="#336699";//提示窗口的边框颜色 
titlecolor="#99CCFF";//提示窗口的标题颜色 
var sWidth,sHeight; 
sWidth=document.body.offsetWidth; 
sHeight=screen.height; 
var bgObj=document.createElement("div"); 
bgObj.setAttribute('id','bgDiv'); 
bgObj.style.position="absolute"; 
bgObj.style.top="0"; 
bgObj.style.background="#777"; 
bgObj.style.filter="progidXImageTransform.Microsoft.Alpha(style=3,opacity=25,finishOpacity=75"; 
bgObj.style.opacity="0.6"; 
bgObj.style.left="0"; 
bgObj.style.width=sWidth + "px"; 
bgObj.style.height=sHeight + "px"; 
bgObj.style.zIndex = "10000"; 
document.body.appendChild(bgObj); 
var msgObj=document.createElement("div") 
msgObj.setAttribute("id","msgDiv"); 
msgObj.setAttribute("align","center"); 
msgObj.style.background="white"; 
msgObj.style.border="1px solid " + bordercolor; 
msgObj.style.position = "absolute"; 
msgObj.style.left = "50%"; 
msgObj.style.top = "50%"; 
msgObj.style.font="12px/1.6em Verdana, Geneva, Arial, Helvetica, sans-serif"; 
msgObj.style.marginLeft = "-225px" ; 
msgObj.style.marginTop = -75+document.documentElement.scrollTop+"px"; 
msgObj.style.width = msgw + "px"; 
msgObj.style.height =msgh + "px"; 
msgObj.style.textAlign = "center"; 
msgObj.style.lineHeight ="25px"; 
msgObj.style.zIndex = "10001"; 
var title=document.createElement("h4"); 
title.setAttribute("id","msgTitle"); 
title.setAttribute("align","right"); 
title.style.margin="0"; 
title.style.padding="3px"; 
title.style.background=bordercolor; 
title.style.filter="progidXImageTransform.Microsoft.Alpha(startX=20, startY=20, finishX=100, finishY=100,style=1,opacity=75,finishOpacity=100);"; 
title.style.opacity="0.75"; 
title.style.border="1px solid " + bordercolor; 
title.style.height="18px"; 
title.style.font="12px Verdana, Geneva, Arial, Helvetica, sans-serif"; 
title.style.color="white"; 
title.style.cursor="pointer"; 
title.innerHTML="关闭"; 
title.onclick=function(){ 
document.body.removeChild(bgObj); 
document.getElementById("msgDiv").removeChild(title); 
document.body.removeChild(msgObj); 
} 
document.body.appendChild(msgObj); 
document.getElementById("msgDiv").appendChild(title); 
var txt=document.createElement("p"); 
txt.style.margin="1em 0" 
txt.setAttribute("id","msgTxt"); 
txt.innerHTML=str; 
document.getElementById("msgDiv").appendChild(txt); 
}

原帖地址：http://www.xszhy.cn/bbs/thread-5051-1-1.html