js弹出窗(背景是蒙板)

function alertWin(title, msg, w, h){ 
	var titleheight = "22px";//提示窗口标题高度 
	var bordercolor = "#0051AA";//提示窗口的边框颜色 
	var titlecolor = "#FFFFFF";//提示窗口的标题颜色 
	var titlebgcolor = "#0051AA";//提示窗口的标题背景色
	var bgcolor = "#FFFFFF";//提示内容的背景色
	var iWidth = document.documentElement.clientWidth; 
	var iHeight = document.documentElement.clientHeight; 
	var bgObj = document.createElement("div"); 
	bgObj.style.cssText = "position:absolute;left:0px;top:0px;width:"+iWidth+"px;height:"+Math.max(document.body.clientHeight, iHeight)+"px;filter:Alpha(Opacity=30);opacity:0.3;background-color:#000000;z-index:101;";
	document.body.appendChild(bgObj); 
	var msgObj=document.createElement("div");
	msgObj.style.cssText = "position:absolute;font:14px '宋体';top:"+(iHeight-h)/2+"px;left:"+(iWidth-w)/2+"px;width:"+w+"px;height:"+h+"px;text-align:center;border:1px solid "+bordercolor+";background-color:"+bgcolor+";padding:1px;line-height:22px;z-index:102;";
	document.body.appendChild(msgObj);
	var table = document.createElement("table");
	msgObj.appendChild(table);
	table.style.cssText = "margin:0px;border:0px;padding:0px;";
	table.cellSpacing = 0;
	var tr = table.insertRow(-1);
	var titleBar = tr.insertCell(-1);
	titleBar.style.cssText = "width:100%;height:"+titleheight+"px;text-align:left;padding:3px;margin:0px;font:bold 13px '宋体';color:"+titlecolor+";border:1px solid " + bordercolor + ";cursor:move;background-color:" + titlebgcolor;
	titleBar.style.paddingLeft = "10px";
	titleBar.innerHTML = title;
	var moveX = 0;
	var moveY = 0;
	var moveTop = 0;
	var moveLeft = 0;
	var moveable = false;
	var docMouseMoveEvent = document.onmousemove;
	var docMouseUpEvent = document.onmouseup;
	titleBar.onmousedown = function() {
		var evt = getEvent();
		moveable = true; 
		moveX = evt.clientX;
		moveY = evt.clientY;
		moveTop = parseInt(msgObj.style.top);
		moveLeft = parseInt(msgObj.style.left);
		document.onmousemove = function() {
			if (moveable) {
				var evt = getEvent();
				var x = moveLeft + evt.clientX - moveX;
				var y = moveTop + evt.clientY - moveY;
				if ( x > 0 &&( x + w < iWidth) && y > 0 && (y + h < iHeight) ) {
					msgObj.style.left = x + "px";
					msgObj.style.top = y + "px";
				}
			}	
		};
		document.onmouseup = function () { 
			if (moveable) { 
				document.onmousemove = docMouseMoveEvent;
				document.onmouseup = docMouseUpEvent;
				moveable = false; 
				moveX = 0;
				moveY = 0;
				moveTop = 0;
				moveLeft = 0;
			} 
		};
	}
	var closeBtn = tr.insertCell(-1);
	//得到是从哪来的，关闭窗口后跳回。
	var path =document.getElementById("pathMsg").value;
	
	closeBtn.style.cssText = "cursor:pointer; padding:2px;background-color:" + titlebgcolor;
	closeBtn.innerHTML = "<span style='font-size:15px; color:"+titlecolor+";'>×</span>";
	closeBtn.onclick = function(){ 
		document.body.removeChild(bgObj); 
		document.body.removeChild(msgObj);
		//关闭窗口后跳回。
		window.location.href =path;
	} 
	var msgBox = table.insertRow(-1).insertCell(-1);
	msgBox.style.cssText = "font:14px '宋体';";
	msgBox.colSpan  = 2;
	msgBox.innerHTML = "<table>"
		             + "<tr>"
		             + "<td><img src='/imgs/cl_2.gif'></td>"
		             + "<td style='text-align:left;'>"+msg+"</td>"
	                 + "</tr>"
	                 + "</table>";
    //获得事件Event对象，用于兼容IE和FireFox
    function getEvent() {
	    return window.event || arguments.callee.caller.arguments[0];
    }
}