模拟弹出窗口效果，关闭层之前，不能选择后面的页内容_javascript技巧

<script type="text/javascript" language="javascript"> //more javascript from http://www.smallrain.net 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="#c51100";//提示窗口的边框颜色 titlecolor="#c51100";//提示窗口的标题颜色 var sWidth,sHeight; sWidth=screen.width; sHeight=screen.height; var bgObj=document.createElement("div"); bgObj.setAttribute('id','bgDiv'); bgObj.style.position="absolute"; bgObj.style.top="0"; bgObj.style.background="#cccccc"; bgObj.style.filter="progid:DXImageTransform.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="progid:DXImageTransform.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); } </script> <input type="button" value="点击这里" onclick="sAlert('test弹窗效果');">
[Ctrl+A 全选 注:如需引入外部Js需刷新才能执行]