js创建新节点,创建层
    <script language="javascript">
function docEle(str){
    return document.getElementById(str);
}
function openNewDiv(_id) {
	var m = "mask";
	if (docEle(_id)) document.body.removeChild(docEle(_id));
	if (docEle(m)) document.body.removeChild(docEle(m));
	// 新激活图层
	var newDiv = document.createElement("div");
	newDiv.id = _id;
	newDiv.style.position = "absolute";
	newDiv.style.zIndex = "9999";//设置层叠次序,大于1即为离用户最近的
	newDiv.style.width = "500px";
	newDiv.style.height = "300px";
	newDiv.style.top = "50px";
	newDiv.style.left = (parseInt(document.body.scrollWidth) - 300) / 2 + "px"; 
         // 屏幕居中
		newDiv.style.background = "#A3F5F1";
		newDiv.style.border = "1px solid #860001";
		newDiv.style.padding = "5px";//属性设置元素的内边距,定义元素边框与元素内容之间的空间
		newDiv.innerHTML = "新激活图层";
		document.body.appendChild(newDiv);
		// mask图层,为了好看,可以不要中间层
		var newMask = document.createElement("div2");
		newMask.id = m;
		newMask.style.position = "absolute";
		newMask.style.zIndex = "1";
		newMask.style.width = document.body.scrollWidth + "px";
		newMask.style.height = document.body.scrollHeight + "px";
		newMask.style.top = "0px";
		newMask.style.left = "0px";
		newMask.style.background = "#000";
		//透明度
		newMask.style.filter = "alpha(opacity=40)";
		document.body.appendChild(newMask);
		// 关闭mask和新图层
		var newA = document.createElement("a");
		newA.href = "#";
		newA.innerHTML = "关闭";
		//newA.style.background = "#811C18";
		newA.onclick = function() {
			document.body.removeChild(docEle(_id));
			document.body.removeChild(docEle(m));
			return false;
		}
		newDiv.appendChild(newA);
}
</script>
<body>
<a href="#" onclick="openNewDiv('newDiv');return false;">激活新层</a>
</body>