How jquery operates dynamic switching between pictures and animations

<style type="text/css"> 
#banner 
{ 
padding: 5px; 
position: relative; 
width: 968px; 
height: 293px; /*border: 1px solid #666;*/ 
overflow: hidden; 
font-size: 16px; 
} 
#banner_list img 
{ 
border: 0px; 
} 
#banner_bg 
{ 
margin-bottom: 5px; 
position: absolute; 
bottom: 0; 
background-color: #000; 
height: 30px; 
filter: Alpha(Opacity=30); 
opacity: 0.3; 
z-index: 1000; 
cursor: pointer; 
width: 968px; 
} 
#banner_info 
{ 
position: absolute; 
bottom: 4px; 
left: 0px; 
height: 22px; 
color: #fff; 
z-index: 1001; 
cursor: pointer; 
} 
#banner_text 
{ 
position: absolute; 
width: 120px; 
z-index: 1002; 
right: 3px; 
bottom: 3px; 
} 
#banner ul 
{ 
position: absolute; 
list-style-type: none; 
filter: Alpha(Opacity=80); 
opacity: 0.8; 
z-index: 1002; 
margin: 0; 
padding: 0; 
bottom: 10px; 
right: 5px; 
height: 20px; 
} 
#banner ul li 
{ 
padding: 0 8px; 
line-height: 18px; 
float: left; 
display: block; 
color: #FFF; 
border: #e5eaff 1px solid; 
background-color: #6f4f67; 
cursor: pointer; 
margin: 0; 
font-size: 16px; 
} 
#banner_list a 
{ 
/* position: absolute;*/ 
width: 968px; 
height: 293px; 
margin: 0px; 
padding: 0px; 
} 
#banner_list 
{ 
margin: 0px; 
padding: 0px; 
width: 968px; 
height: 293px; 
border: #e7e7e7 1px solid; 
} 
</style>

<script type="text/javascript"> 
var t = n = 0, count; 
$(function () { 
count = $("#banner_list a").length; 
$("#banner_list a:not(
:first-child
)").hide(); 
$("#banner_info").html($("#banner_list a:first-child").find("img").attr(&#39;alt&#39;)); 
$("#banner_info").click(function () { 
window.open
($("#banner_list a:first-child").attr(&#39;href&#39;), "_blank") }); 
$("#banner li").click(function () { 
var i = $(this).text() - 1; //获取Li元素内的值，即1，2，3，4 
n = i; 
if (i >= count) return; 
$("#banner_info").html($("#banner_list a").eq(i).find("img").attr(&#39;alt&#39;)); 
$("#banner_info").unbind().click(function () { window.open($("#banner_list a").eq(i).attr(&#39;href&#39;), "_blank") }) 
$("#banner_list a").filter(":visible").fadeOut(500).parent().children().eq(i).fadeIn(1000); 
$(this).css({ "background": "#be2424", &#39;color&#39;: &#39;#000&#39; }).siblings().css({ "background": "#6f4f67", &#39;color&#39;: &#39;#fff&#39; }); 
}); 
t = setInterval("showAuto()", 4000); 
$("#banner").hover(function () { clearInterval(t) }, function () { t = setInterval("showAuto()", 4000); });//4秒钟切换一张图片}); 
function showAuto() { 
n = n >= (count - 1) ? 0 : ++n; 
$("#banner li").eq(n).trigger(&#39;click&#39;); 
} 
</script>

<p id="banner"> 
<p id="banner_bg"> 
</p> 
<!--标题背景--> 
<p id="banner_info"> 
</p> 
<!--标题--> 
<ul> 
<li>1</li> 
<li>2</li> 
<li>3</li> 
<li>4</li> 
</ul> 
<p id="banner_list"> 
<a href=&#39;<%:DicFlashImg!=null?DicFlashImg["PFI_FlashImgoneURL"]:""%>&#39; target="_blank"> 
<img src=&#39;<%:DicFlashImg!=null?DicFlashImg["PFI_FlashImgone"]:"Images/Singapore.jpg"%>&#39; 
title="" alt="" width="968px" height="293px" border="0" /></a> <a href=&#39;<%:DicFlashImg!=null?DicFlashImg["PFI_FlashImgtowURL"]:""%>&#39; 
target="_blank"> 
<img src=&#39;<%:DicFlashImg!=null?DicFlashImg["PFI_FlashImgtow"]:"Images/Malaysia.jpg"%>&#39; 
title="" alt="" width="968px" height="293px" border="0" /></a> <a href=&#39;<%:DicFlashImg!=null?DicFlashImg["PFI_FlashImgthreeURL"]:""%>&#39; 
target="_blank"> 
<img src=&#39;<%:DicFlashImg!=null?DicFlashImg["PFI_FlashImgthree"]:"Images/HongKong.jpg"%>&#39; 
title="" alt="" width="968px" height="293px" border="0" /></a> 
<a href=&#39;<%:DicFlashImg!=null?DicFlashImg["PFI_FlashImgfourURL"]:""%>&#39; target="_blank"> 
<img src=&#39;<%:DicFlashImg!=null?DicFlashImg["PFI_FlashImgfour"]:"Images/flash4.jpg"%>&#39; 
title="" alt="" width="968px" height="293px" border="0" /></a> 
</p> 
</p>