var CAT = {
  //[{id: '', name: '', data: [{id: '', name: '', data:[{id: '', name: ''}]},{}, ...]}, {} ...]
  data: [],
  url: function(){
    return 'http://upload.taobao.com/auction/json/reload_cats.htm?t='+Math.random();
  },
  init: function(){
    var url = CAT.url(),
      post_data = 'path=all';
    CAT.ajax(url, post_data, CAT.first_r);
  },
  first_r: function(data){
    var rs = data[0]['data'],
      first_l, first_d, i, j, second_id, second_d, func;
    for(i=0;i<rs.length; i++){
      //保存一级分类
      first_d = rs[i]['data'];
      first_l = [];
      for(j=0; j<first_d.length; j++){
        //保存二级分类同时查询三级分类，并提供存储数据的容器
        second_id = first_d[j]['sid'];
        second_d = {
          'id': first_d[j]['sid'],
          'name': first_d[j]['name'],
          'spell': first_d[j]['spell'],
          'data': []
        };
        first_l.push(second_d);
        func = CAT.second_r(second_d['data']);
        CAT.ajax(CAT.url(), 'path=next&sid='+second_id, func);
      }
      CAT.data.push({
        'id': rs[i]['id'],
        'name': rs[i]['name'],
        'data': first_l
      })
    }
  },
  second_r: function(container){
    return function(data){
      if(data.length<1){
        return
      }
      var rs = data[0]['data'],
        i, j, here, third_d;
      for(i=0; i<rs.length; i++){
        third_d = rs[i]['data'];
        for(j=0; j<third_d.length; j++){
          here = third_d[j];
          container.push({
            'id': here['sid'],
            'name': here['name'],
            'spell': here['spell']
          });
        }
      }
    }
  },
  ajax: function(url, post_data, func){
    var xhr = new XMLHttpRequest(),
    result;
    xhr.open('POST', url, true);
    xhr.setRequestHeader("Content-type","application/x-www-form-urlencoded");
    xhr.send(post_data);
    xhr.onreadystatechange=function(){
      if (xhr.readyState==4 && xhr.status==200){
        result = JSON.parse(xhr.responseText);
        func(result);
      }else if(xhr.readyState==4 && (!xhr.status==200)){
        console.log('Ajax Return Error!');
      }
    }
  }
};
CAT.init();