javascript弹出窗和悬浮层的写法

 今天在写程序时要用弹出层，就复习和搜索了一下javascript弹出窗和悬浮层的写法，在网上找了代码然后修改了一下。把代码贴出来以后用得着：

<script type="text/javascript">

function $ () {
return document.getElementById(arguments[0]) || false;
}
function openNewDiv(_id,DivHtml,newDivWidth,newDivHeight)
{
var m = "mask";
if ($(_id)) document.body.removeChild($(_id));
if ($(m)) document.body.removeChild($(m));
//mask遮罩层
var newMask = document.createElement("div");
newMask.id = m;
newMask.style.position = "absolute";
newMask.style.zIndex = "1";
_scrollWidth = Math.max(document.body.scrollWidth,document.documentElement.scrollWidth);
_scrollHeight = Math.max(document.body.scrollHeight,document.documentElement.scrollHeight);
newMask.style.width = _scrollWidth + "px";
newMask.style.height = _scrollHeight + "px";
newMask.style.top = "0px";
newMask.style.left = "0px";
newMask.style.background = "#33393C";
newMask.style.filter = "alpha(opacity=40)";
newMask.style.opacity = "0.40";
document.body.appendChild(newMask);
//新弹出层
var newDiv = document.createElement("div");
newDiv.id = _id;
newDiv.style.position = "absolute";
newDiv.style.zIndex = "9999";
newDivWidth = newDivWidth||500;
newDivHeight = newDivHeight||250;
newDiv.style.width = newDivWidth + "px";
newDiv.style.height = newDivHeight + "px";
newDiv.style.top = (document.body.scrollTop + document.body.clientHeight/2 – newDivHeight/2) + "px";
newDiv.style.left = (document.body.scrollLeft + document.body.clientWidth/2 – newDivWidth/2) + "px";
newDiv.style.background = "#EFEFEF";
newDiv.style.border = "1px solid #860001";
newDiv.style.padding = "5px";
newDiv.innerHTML = DivHtml;
document.body.appendChild(newDiv);
//弹出层滚动居中
function newDivCenter()
{
newDiv.style.top = (document.body.scrollTop + document.body.clientHeight/2 – newDivHeight/2) + "px";
newDiv.style.left = (document.body.scrollLeft + document.body.clientWidth/2 – newDivWidth/2) + "px";
}
if(document.all)
{
window.attachEvent("onscroll",newDivCenter);
}
else
{
window.addEventListener(‘scroll’,newDivCenter,false);
}
//关闭新图层和mask遮罩层
var newA = document.createElement("a");
newA.href = "#";
newA.innerHTML = "关闭";
newA.onclick = function()
{
if(document.all)
{
window.detachEvent("onscroll",newDivCenter);
}
else
{
window.removeEventListener(‘scroll’,newDivCenter,false);
}
document.body.removeChild($(_id));
document.body.removeChild($(m));
return false;
}
newDiv.appendChild(newA);
}
</script>