Jquery实现遮罩层的方法

<!-- Status Bar Start -->
<div id="warning-dialog" class="status warning center- no-display">
 <p class="closestatus"><a href="javascript:$().hideWarningDialog()" title="Close">x</a></p>
 <div class="clear"></div>
 <p><img src="images/icon_warning.png" alt="Warning" /><span id="warning-dialog-detail">Attention!</span></p>
 <div class="closes">
  <input type="hidden" id="refresh-after-warning" value="false" />
  <input name="" type="image" src="images/niu_qd.jpg" align="absmiddle" class="button_jl" onclick="javascript:$().hideWarningDialog()" />
 </div>
</div>
<!-- Status Bar End -->

var warning_dialog = $('#warning-dialog'), 
 warning_dialog_detail = $('#warning-dialog-detail'), 
 refresh_after_warning = $('#refresh-after-warning');
// 显示遮罩层
$.fn.showWarningDialog = function(detail, refresh) {
 if ($isIE6) {
  $(".menu_select").hide();
 }
 $.fn.mask();
 warning_dialog_detail.html(detail);
 refresh_after_warning.val(refresh);
 warning_dialog.css({
  "position" : "absolute",
  "left" : "50%",
  "" : "50%",
  "margin-left" : "-250px",
  "margin-" : "-100px",
  "border" : "solid 3px #c",
  "z-index" : 6000
 });
 warning_dialog.show();
}
// 去除遮罩层
$.fn.hideWarningDialog = function() {
 if ($isIE6) {
  $(".menu_select").show();
 }
 $.fn.unmask();
 if (refresh_after_warning.val() == "true") {
  $('#main').showLoading();
  location.reload(true);
 } else
  warning_dialog.hide();
}
// 显示遮罩效果
$.fn.mask = function() {
 this.unmask();
 // 参数
 var op = {
  bgcolor : '#c',
  z : 5100,
  opacity : 0.3
 };
 var position = {
   : 0,
  left : 0
 };
 var original = $("#main");
 // 创建一个 Mask 层，追加到对象中
 var maskDiv = $('<div class="maskdivgen">&nbsp;</div>');
 maskDiv.appendTo(original);
 var maskWidth = original.width();
 var maskHeight = original.height();
 maskDiv.css({
  position : 'absolute',
   : position.,
  left : position.left,
  'z-index' : op.z,
  width : maskWidth,
  height : maskHeight,
  'background-color' : op.bgcolor,
  opacity : 0
 });
 maskDiv.fadeIn('fast', function() {
  // 淡入淡出效果
  $(this).fadeTo('fast', op.opacity);
 });
 return maskDiv;
}
// 去除遮罩效果
$.fn.unmask = function() {
 var original = $("#main");
 if (this[0] && this[0] !== window.document) {
  original = $(this[0]);
 }
 original.find("> div.maskdivgen").fadeOut('fast', 0, function() {
  $(this).remove();
 });
}

/ 当前页面高度 /
 function pageHeight() {
  return document.body.scrollHeight;
 }
 / 当前页面宽度 /
 function pageWidth() {
  return document.body.scrollWidth;
 }

<script type="text/javascript">
 function init() {
  <?php
   if ($msg != "用户名输入错误") {
  ?>
   $.fn.showWarningDialog("<?php echo $msg; ?>", "false");
  <?php
   }
  ?> 
 }
 window.onload = function(){
  init();
 };
 </script>