求高人解答javascript问题

<!-- 轮播广告 -->
     <div  class="sy_zwL" id="gdtp" >
                <div class="sy_kongbai"><img id="gdimg" width="1024" height="170" onMouseOver="stopi();" onMouseOut="begini();" onClick="openurl();" src="images/2.1.jpg">
                <div class="pre"><img   onclick="pre()"  onmouseover="sbOn('pre')" onMouseOut="sbOff('pre')" src="images/index_btn01.png" ></div>
                <div class="next"><img  onclick="gudong()" onMouseOver="sbOn('next')"onmouseout="sbOff('next')" src="images/index_btn02.png" ></div>
                </div>
                <!--<div class="sy_ererbg"></div>-->
                <div class="sy_erer">
                  <div class="sy_gdtp_title" id="gdtp_title" onClick="openurl();"></div>
            <div class="sy_erer">
                  <div class="sy_gdtp_title" id="gdtp_title" onClick="openurl();"></div>
                  <div class="sy_zwi">
                
                 </div>
                </div>
                </div>
                  <ol  id="bannerCtrl" class="flex-control-nav flex-control-paging">
                  <li><img id="gdtpdian0" onClick="gudong2(0)" src="images/zw_16.png" ></li>
                  <li><img id="gdtpdian1" onClick="gudong2(1)" src="images/zw_14.png" ></li>
                  <li><img id="gdtpdian2" onClick="gudong2(2)" src="images/zw_14.png" ></li>
                 <!-- <li><img id="gdtpdian3" onClick="gudong2(3)" src="images/zw_14.png" tppabs="http://www.jxzj.gov.cn/jxzj/images/zw_14.png"></li>
                  <li><img id="gdtpdian4" onClick="gudong2(4)" src="images/zw_14.png" tppabs="http://www.jxzj.gov.cn/jxzj/images/zw_14.png"></li>-->
                  </ol>
    
              </div>
              
             
<script type="text/javascript">
$(function() {
    var bannerSlider = new Slider($('#banner_tabs'), {
        time: 3000,
        delay: 400,
        event: 'hover',
        auto: true,
        mode: 'fade',
        controller: $('#bannerCtrl'),
        activeControllerCls: 'active'
    });
    $('#banner_tabs .flex-prev').click(function() {
        bannerSlider.prev();
    });
    $('#banner_tabs .flex-next').click(function() {
        bannerSlider.next();
    });
});
</script>
              <!--滚动图片js开始-->
              <script language="javascript">
              var i=0;
              var pics="";
              var links="";
              var titles="";
            
            pics+="images/2.3.jpg|";
            titles+=" |";
            links+="#|";
            
            pics+="images/2.2.jpg|";
            titles+=" |";
            links+="#|";
            
            pics+="images/2.1.jpg|";
            titles+=" |";
            links+="#|";
            
        
              var pic=pics.split("|");
              var url=links.split("|");
              var doctitle=titles.split("|");
              function $$(id){
                  return document.getElementById(id);
              }              
              function gudong2(num){
                 $$("gdimg").src=pic[num];
                 //$$("gdtp").style.background="url("+pic[num]+")";
                 $$("gdtp").title=doctitle[num];
                 $$("gdtp").setAttribute("url",url[num]);
                 $$("gdtp_title").innerHTML=doctitle[num];
                 for(var k=0;k<3;k++){
                   if(k==num){
                      $$("gdtpdian"+k).src="images/zw_16.png";
                   }else{
                      $$("gdtpdian"+k).src="images/zw_14.png";
                   }
                 }
                 if(num<2){
                    i=num+1;
                 }else{
                    i=0;
                 }
              }
              function gudong(){
                 gudong2(i);
              }
              function pre(){
                if(i>1){
                  gudong2(i-2);
                 }else{
                   gudong2(2);
                   i=2;
                 }
              } 
              function openurl(){
                 window.open($$("gdtp").getAttribute("url"));
              }
              var Interval;
              function begini(){
                gudong(0);
                Interval=window.setInterval("gudong();",3000);
              }
              function stopi(){
                clearInterval(Interval);
              }
              function sbOn(id){
                if(id=='pre'){
                   $$(id).src="images/index_btn01.png";
                }else{
                   $$(id).src="images/index_btn02.png";
                }
              }
              function sbOff(id){
                if(id=='pre'){
                   $$(id).src="images/index_btn03.png";
                }else{
                   $$(id).src="images/index_btn04.png";
                }
              }
              </script><!--lunbo end-->

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不写问题，不知所谓？