Generate level-2 menus using jquery

[Javascript] & lt; prename & quot; code & quot; class & quot; html & quot; & gt; & lt;/pre & gt; functions on the page & lt; pre & gt; & lt;/pre & gt; & lt; prename & quot; code & quot; class & quot; javascript & quot; & [javascript]

Functions on the page

 

Function querySub (id, sid/* selected item */){

            $.post('${path}/page/article/querySubChannelArticle.action', 
                {'channelId':id},function(data){ 
                    $('select[name="article.subChannel.subId"] option[value!=""]').remove(); 
                    var jsonObj = data;    
                    for ( var i = 0; i < jsonObj.length; i++) { 
                        var $option = $(''); 
                        $option.attr('value',jsonObj[i].subId); 
                        if(jsonObj[i].subId === sid){ 
                            $option.attr('selected',true); 
                        } 
                        $option.text(jsonObj[i].subName); 
                        $('select[name="article.subChannel.subId"]').append($option); 
                    } 
                }); 
        } 
         
        $(function(){ 
            querySub(
  
   ,
   
    ); 
    
        }); 
    

   
  

 

Page code:

 

 
Level 1 topic 
 

  ListValue = "channelName"
Key = "article. subChannel. channel. channelId"
Onchange = "querySub (this. value)"> 
 
 
 
Secondary topic 
 

   

   
 
 

 
 
 

 
 
Server
 
Server
 
   public String querySubChannelArticle(){ 
 
        HttpServletResponse response=getResponse(); 
        HttpServletRequest request=getRequest(); 
        response.setContentType("application/json; charset=UTF-8"); 
        PrintWriter out =null; 
        try { 
            out = response.getWriter(); 
             
            List
  
   > list = new LinkedList
   
    >(); 
    
            if(channelId!=null && !channelId.equals("")){ 
    
                Channel tmp = new Channel(); 
    
                tmp.setChannelId(Integer.parseInt(channelId)); 
    
                subChannelList = subChannelDAO.listSubChannel(tmp); 
    
                 
    
                for(Object oo:subChannelList){ 
    
                    Map
    
      obj = new HashMap
     
      (); 
      
                    SubChannel c = (SubChannel)oo; 
      
                    obj.put("subId", c.getSubId()); 
      
                    obj.put("subName", c.getSubName()); 
      
                    list.add(obj); 
      
                } 
      
            } 
      
            String outStr = JsonUtil.toJSONStr(list); 
      
            out.println(outStr); 
      
        }catch(Exception e){ 
      
        e.printStackTrace(); 
      
        } 
      
        out.flush(); 
      
        out.close(); 
      
        return null; 
      
    } 
      

     
    
   
  

 
Actually, it's quite concise.