jquery下实现overlay遮罩层代码

/*
模态遮罩层单例对象
opacity:背景透明度
1. show()
2. close()
*/
Q.Overlay = function(opacity) {
var self = this;
self._createDiv = function() {

if (self._overlay) return;
self._overlay = $("<div></div>");

var overlayCss = {
width: 100%,
min-height: 100%,
position: fixed,
top: 0,
left: 0,
z-index: Q.Overlay.zindex,
background: #ccc,
text-align: center,
opacity: opacity
};

if ($.browser.msie && $.browser.version.substr(0, 1) < 7) {
overlayCss.position = "absolute";
overlayCss.height = Q.dom.pageHeight();
}
self._overlay.css(overlayCss);
$(document.body).append(self._overlay);
};
self.show = function() {
self._createDiv();
Q.Overlay.zindex++;
self._overlay.show();
};
self.close = function() {
self._overlay.hide();
self._overlay.remove();
self._overlay = undefined;
};
}
Q.Overlay.zindex = 1000;

/*统一ajax错误处理*/
Q.initAjaxErrorHandler = function() {
var overlay = new Q.Overlay(0.0);
$(document.body).ajaxStart(function() { overlay.show(); });
$(document.body).ajaxSuccess(function() { overlay.close(); });
$(document.body).ajaxError(function() { Q.alert("请求出错，请刷新页面并稍候再试！") });
}