var tbody = document.getElementById("ctl00_allclass2_DataList_ParClass").getElementsByTagName("tr");
  var tr;
  var ul;
  var span;
  var find = false;
  var firChiIndex=0
  if(navigator.userAgent.indexOf("MSIE")==-1)
  {
     firChiIndex=1;
  }
  
  for(var i=0;i<tbody.length;i++)
  {
     tr    = tbody[i];//第一个tr 
     ul    = tr.getElementsByTagName("ul")[0];//拿到第一个ul
     span  = tr.getElementsByTagName("span")[0];//拿到第一个span
    
     if(ul.childNodes.length >firChiIndex)//表示还有ui li（有数据）了
     {
       span.innerHTML = '<img src="http://s.yizimg.com/Skins3/SB2758Skin/images/plus.jpg"/>';
       span.mark = 'plus';
       if(location.href.toLowerCase().indexOf('firstcatalog') > -1)
       {
          if(!find)
          {       //它的父节点是<div class="ImgAllClass2">
             if(span.parentNode.getElementsByTagName("a")[0].href.toLowerCase() == location.href.toLowerCase() )
             {
               span.innerHTML ='<img src="http://s.yizimg.com/Skins3/SB2758Skin/images/minus.jpg"/>'
               span.mark = 'minus'; 
               span.parentNode.parentNode.getElementsByTagName("ul")[0].style.display = 'block';
               find = true;
             }
           }
       }
       if(location.href.toLowerCase().indexOf('secondcatalog') > -1)
       {
          if(!find)
          {
              var as = ul.getElementsByTagName('a');
              
              for(var j=0;j<as.length;j++)
              {
                 if( as[j].href.toLowerCase() == location.href.toLowerCase() )
                 {
                    span.innerHTML ='<img src="http://s.yizimg.com/Skins3/SB2758Skin/images/minus.jpg"/>';
                    span.mark = 'minus'; 
                    span.parentNode.parentNode.getElementsByTagName("ul")[0].style.display = 'block';
                    find = true;
                 }
              }
            
          }
       }
 
       span.onclick = function()
       {
           var ul=this.parentNode.parentNode.getElementsByTagName("ul")[0];           
           ul.style.display = ul.style.display == "block" ?"none":"block";
           
           if(this.mark == 'plus')
           {
               this.innerHTML ='<img src="http://s.yizimg.com/Skins3/SB2758Skin/images/minus.jpg"/>';
               this.mark = 'minus';
           }
           else
           {   
               this.innerHTML ='<img src="http://s.yizimg.com/Skins3/SB2758Skin/images/plus.jpg"/>';
               this.mark = 'plus';       
           }                    
       }
       
       
     }
     else
     {
        span.innerHTML = "&nbsp;&nbsp;"
        span.style.visibility="hidden";
     }
  }