jquery实现的图片点击滚动效果

<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">
$(function(){
//alert($('#findclose').closest('div').attr('id'));
var pic_length = $('#gd li').length;
var n = 0;
$('#toleft').click(function(){
if (!$('#gd').is(':animated') && n)
{
$('#gd').animate({left:'+=120px'},500);
n--;
}
});
$('#toright').click(function(){
if (!$('#gd').is(':animated') && pic_length > n+5)
{
$('#gd').animate({left:'-=120px'},500);
n++;
}
});
})
</script>
<style type="text/css">
ul{
list-style:none;
margin:0px;
padding:0px;
text-align:center;
}
#gd li {
width:90px;
height:80px;
display:block;
float:left;
margin:9px 15px;
}
</style>
<div style="width:702px;height:100px;background:#ccc;margin:0 auto">
<div style="width:30px;height:30px;background:red;margin:35px 10px;float:left;cursor:pointer;" id="toleft"></div>
<div style="width:600px;height:98px;float:left;border:1px solid #777;overflow: hidden;">
<ul style="list-style: none outside none;height:98px;display:block;background:yellow;position:relative;width:9999em;" id="gd">
<li style="background:red"></li>
<li style="background:orange"></li>
<li style="background:green"></li>
<li style="background:navy"></li>
<li style="background:blue"></li>
<li style="background:purple"></li>
<li style="background:pink"></li>
<li style="background:gray"></li>
</ul>
</div>
<div style="width:30px;height:30px;background:red;margin:35px 10px;float:left;cursor:pointer;" id="toright"></div>
</div>