jQuery实现可兼容IE6的遮罩功能详解

<div id="main"><a onclick="showBg();" href="#" rel="external nofollow" rel="external nofollow" >点击这里看 jQuery 遮罩层效果.</a></div><div id="fullbg"></div><div id="dialog"><p class="close"><a onclick="closeBg();" href="#" rel="external nofollow" rel="external nofollow" >关闭</a></p>正在加载，请稍后...</div>

body {  font-family: Arial, Helvetica, sans-serif;  font-size: 12px;  margin: 0;}#main {  height: 1800px;  padding-top: 90px;  text-align: center;}#fullbg {  background-color: Gray;  left: 0px;  opacity: 0.5;  position: absolute;  top: 0px;  z-index: 3;  filter: alpha(opacity=50); /* IE6 */  -moz-opacity: 0.5; /* Mozilla */  -khtml-opacity: 0.5; /* Safari */}#dialog {  background-color: #FFF;  border: 1px solid #888;  display: none;  height: 200px;  left: 50%;  margin: -100px 0 0 -100px;  padding: 12px;  position: fixed !important; /* 浮动对话框 */  position: absolute;  top: 50%;  width: 200px;  z-index: 5;}#dialog p {  margin: 0 0 12px;}#dialog p.close {  text-align: right;}

<script type="text/javascript" src="http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script><script type="text/javascript">//显示灰色 jQuery 遮罩层function showBg() {  var bh = $("body").height();  var bw = $("body").width();  $("#fullbg").css({    height:bh,    width:bw,    display:"block"  });  $("#dialog").show();}//关闭灰色 jQuery 遮罩function closeBg() {  $("#fullbg,#dialog").hide();}</script><!--[if lte IE 6]><script type="text/javascript">// 浮动对话框$(document).ready(function() {  var domThis = $('#dialog')[0];  var wh = $(window).height() / 2;  $("body").css({    "background-image": "url(about:blank)",    "background-attachment": "fixed"  });  domThis.style.setExpression('top', 'eval((document.documentElement).scrollTop + ' + wh + ') + "px"');});</script><![endif]-->