关于实现banner轮换的问题，如何修改

最近遇到了这样的问题，本来banner都是gif格式的，但是现在要求上传图片格式为jpg时，运用JS实现动画效果，原来的也能用。

aspx:

 <div id="bh" runat="server" class="banner" style="margin:0 auto; width:950px;margin-bottom:5px;"> <a href='http://www.3456.tv/business/<%=companyoname %>/' target="_blank"> <img src ="<%=companybanner %>" alt="<%=companyname %>" title="<%=companyname %>"  height="<%=imgheight%>"/> </a> </div>
      <SCRIPT language=javascript type=text/javascript>
    var imgUrl = new Array();
    var Com_Banners = '<%=topImg%>';
    var strs = new Array(); //定义一数组
    strs = Com_Banners.split("|"); //字符分割 
    for (var i = 0; i <= strs.length - 1; i++) {
        imgUrl[i + 1] = strs[i];
    }
    var picNum = 1;
    var counts = strs.length;
    //自动切换图片代码  
    function NextPic() {
        var pic = document.getElementById("ShowImg");
        var button = document.getElementById("banner").getElementsByTagName("div");
        if (document.all) {
            pic.filters.revealTrans.Transition = Math.floor(Math.random() * 23);
            pic.filters.revealTrans.apply();
            pic.filters.revealTrans.play();
        }
        pic.src = imgUrl[picNum];
        picNum++;
        if (picNum > counts) {
            picNum = 1;
        }
        //设置翻页时间
        theTimer = setTimeout("NextPic()", 3000);
    }
 </SCRIPT>
  <div id="banner" runat="server" style="margin:0 auto; width:950px;display:<%=backdis%>;">
        <a href='http://www.3456.tv/business/<%=companyoname %>/' target="_blank"><img style="FILTER:revealTrans(duration=2,Transition=5)" id="ShowImg" width="950" src="<%=showImg%>" alt="<%=companyname%>"/></a>
     </div>
<SCRIPT type=text/javascript>NextPic();</SCRIPT>

aspx.cs:

        //头部banner
            if (companybanner.Equals(""))
            {
                bh.Visible = false;
                banner.Visible = false;
            }

            else
            {
                companybanner = dt.Rows[0]["BusBanner"].ToString();
                string[] arraylist = companybanner.Split('|');
                if (arraylist.Length > 1)
                {
                    topImg = dt.Rows[0]["BusBanner"].ToString();
                    showImg = topImg.Substring(0, topImg.IndexOf("|"));
                    banner.Visible = true;
                    bh.Visible = false;
                }
                else
                {
                    topImg = dt.Rows[0]["BusBanner"].ToString();
                    string houzhui = topImg.Substring(companybanner.LastIndexOf(".") + 1).ToLower().ToString();
                    if (houzhui == "jpg")
                    {
                        bh.Visible = false;
                        //imgHeight = "200";
                        backdis = "none";
                        banner.Visible = true;
                    }
                    else
                        bh.Visible = true;
                    banner.Visible = false;
                }
            }
        }
        else
            Response.Redirect("http://www.3456.tv/404.htm");
        if (topImg != "")
        {
            topImg = dt.Rows[0]["BusBanner"].ToString();
            //判断
            string[] arraylist = topImg.Split('|');
            if (arraylist.Length > 1)
            {
                banner.Visible = true;
                bh.Visible = false;
            }
            else
            {
                string houzhui = topImg.Substring(companybanner.LastIndexOf(".") + 1).ToLower().ToString();
                if (houzhui == "jpg")
                {
                    bh.Visible = false;
                    //imgHeight = "200";
                    backdis = "none";
                    banner.Visible = true;
                }
                else
                    bh.Visible = true;
                    banner.Visible = false;
            }
            type = companyoname;
        }

修改后台文件时，注意声明好变量。