js弹出遮罩层

---css样式控制 #backgroungDiv

{ position: fixed; _position: absolute; 100%; height: 100%; left: 0; top: 0; background: #000; opacity: 0.5; -moz-opacity: 0.5; filter: alpha(opacity=60); z-index: 100; display: none; }

---定义层

<div id="backgroungDiv"></div>

---js控制弹出和隐藏

function showdiv()

 {   document.getElementById("backgroungDiv").style.display ="block"; }

function hidediv()

{ document.getElementById("backgroungDiv").style.display ='none'; }