jquery animate实现鼠标放上去显示离开隐藏效果

@CHARSET "UTF-8";
* html .showbox,* html .overlay {
position: absolute;
top: expression(eval(document.documentElement.scrollTop) );
}
#AjaxLoading {
border: 1px solid #8CBEDA;
color: #37a;
font-size: 12px;
font-weight: bold;
}
#AjaxLoading div.loadingWord {
width: 180px;
height: 50px;
line-height: 50px;
border: 2px solid #D6E7F2;
background: #fff;
}
#AjaxLoading img {
margin: 10px 15px;
float: left;
display: inline;
}
.overlay {
position: fixed;
top: 0;
right: 0;
bottom: 0;
left: 0;
z-index: 998;
width: 100%;
height: 100%;
_padding: 0 20px 0 0;
background: #f6f4f5;
display: none;
}
.showbox {
position: fixed;
top: 0;
left: 50%;
z-index: 9999;
opacity: 0;
filter: alpha(opacity = 0);
margin-left: -80px;
}

/**
* 加载动画窗口
*
* @author dendy
* @since 2013-7-19 10:13:05
*/
function getLoadingHtml(msg) {
if(!msg) msg = "加载";
var html = "";
return html;
}
function ajaxLoadingInit(msg) {
var loadingDiv = getLoadingHtml(msg);
var h = $(document).height();
$(".overlay").css({"height": h});
var div = $("body").find("#loadingDiv");
div.remove();
$("body").append($(loadingDiv));
}
/**
* 开始显示loading，在ajax执行之前调用
* @param msg 操作消息，"加载", "保存", "删除"
*/
function startLoading(msg) {
ajaxLoadingInit(msg);
$(".overlay").css({'display':'block','opacity':'0.8'});
$(".showbox").stop(true).animate({'margin-top':'300px','opacity':'1'},200);
}
/**
* 加载完成后隐藏，在ajax执行完成后（complete）调用
*/
function endLoading() {
$(".showbox").stop(true).animate({'margin-top':'250px','opacity':'0'},400);
$(".overlay").css({'display':'none','opacity':'0'});
}

startLoading();
$.ajax({
type : "POST",
url : this.url,
dataType : "json",
data : this.args,
success : function (data) {

},
complete : function () {
if (self.showLoading == true) endLoading();
},
error : this.error
});