1 function shade(){
2
3 var div = document.getElementById("shade");
4 div.className = "s";
5 div.style.display = "block";
6 }
7 function shadeDisplay(){
8
9 var div = document.getElementById("shade");
10 div.style.display = "none";
11 }
12 </script>
13 <style type="text/css">
14 #box{
15 width:400px;
16 height:300px;
17 margin:0px auto;
18 border:1px solid #000;
19 /*使子元素的坐标以父元素的左上角坐标为远点(0,0)*/
20 position:relative;
21 }
22 .s{
23 width:400px;
24 height:300px;
25 background-color:gray;
26 position:absolute;
27 left:0px;
28 top:0px;
29 z-index:999;
30 -moz-opacity:0.5;/*Firefox*/
31 opacity:0.5;/*Opera*/
32 filter:alpha(opacity=50); /*IE*/
33 }
34 </style>
35 </head>
36
37 <body>
38 <div id="box">
39 <a href="javascript:shade()">遮罩</a>
40 <div id="shade"></div>
41 </div>
42 <a href="javascript:shadeDisplay()">遮罩消失</a>
43
44 </body>