实例代码如下，可直接复制使用：
$.fn.dialog=function(){ this.MaskDiv=function() 
...{ 
var wnd = $(window), doc = $(document); //alert(doc.height()); 
if(wnd.height() > doc.height())...{ //当高度少于一屏 wHeight = wnd.height(); }else...{//当高度大于一屏 wHeight = doc.height(); 
} //创建遮罩背景 $("body").append("<div ID=MaskID></div>"); $("body").find("#MaskID").width(wnd.width()).height(wHeight) .css(...{position:"absolute",top:"0px",left:"0px",background:"#ccc",filter:"Alpha(opacity=90);",opacity:"0.3",zIndex:"10000"}); } 
}