Nodejs implements obtaining the product classification of a certain product_node.js

I had nothing to do, so I was researching the e-commerce website. It happened that a friend was opening a certain treasure store, and I was very happy to see the dazzling variety of product categories. So I did a little research.

Getting product categories is all done by AJAX, and because I need to log in, I have no trouble, so I took the simplest method, go to the background and directly open the console, paste the code in and run it, hehe, all categories are run to CAT. in the data.

Rookie practicing, please give me some advice.

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();

The above is the entire content of this article, I hope you all like it.