alert的美化，并且随滚动条滚动

onclick="sAlert('${vo.courseName}');" 

<script type="text/javascript" language="javascript">
function getScroll() {
var top, left, width, height;
if (document.documentElement && document.documentElement.scrollTop) {
top = document.documentElement.scrollTop;
left = document.documentElement.scrollLeft;
width = document.documentElement.scrollWidth;
height = document.documentElement.scrollHeight;
}
else if (document.body) {
top = document.body.scrollTop;
left = document.body.scrollLeft;
width = document.body.scrollWidth;
height = document.body.scrollHeight;
}
return { top: top, left: left, width, height: height };
}
function scall(){
var v = getScroll();
var bgDiv = document.getElementById("bgDiv");
var msgDiv = document.getElementById("msgDiv");
var msgTitle = document.getElementById("msgTitle");
if(bgDiv != null){

bgDiv.style.top = ((v.top) + 0) + "px";
}
if(msgDiv != null){ //重新设置滚动条的位置
msgDiv.style.left = "50%";
msgDiv.style.top = "50%";
msgDiv.style.font="12px/1.6em Verdana, Geneva, Arial, Helvetica, sans-serif";
msgDiv.style.marginLeft = "-225px" ;
msgDiv.style.marginTop = (-75+(v.top))+"px";
}
if(msgTitle != null){
msgTitle.style.top = ((v.top) + 50) + "px";
}
}
window.onload = scall ;
window.onscroll = scall ;
</script>

<script type="text/javascript" language="javascript">
function sAlert(str){
var top = document.body.scrollTop;//得到滚动条的高度
var msgw,msgh,bordercolor;
msgw=500;//提示窗口的宽度
msgh=300;//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="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"; //设置第一次点击时消息框的位置
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+top+"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>

<script type="text/javascript">

$(function(){
scall();

})

</script>