old_contents: var express = require('express');
  var path = require('path');
  var favicon = require('serve-favicon');
  var cookieParser = require('cookie-parser');
  var bodyParser = require('body-parser');
  var app = express();
  var index = require('./routes/index');
  var common_util = require('./utils/common');
  var fs = require('fs');
  var mongoclient = require('mongodb').MongoClient;
  
  var folder = path.join(__dirname, 'battle_history');
  var mongodb_url = '' // Insert your mongodb url here.
  var port = 2333;
  var server_start_time = common_util.date_formate((new Date()), 'yyyy-MM-dd hh:mm:ss');
  var db = (function() {
      mongoclient.connect(url, (err, db) => {
          if (err) {
              return null;
          } else  {
              return db;
          }
      });
  })();
  
  var battle_map = {
      curr_max_room_id: 1,
  };
  
  var battle_status_checker = {};
  
  function save_end_battle(battle_cnt, battle) {
      console.log('battle save', battle_cnt, server_start_time);
      if (db == null) {
          console.log('DB connect error');
      }
      db.collection('battle_history')
          .insert(battle, {}, (err) => {
              if (err) {
                  console.log((new Date()).getTime(), err);
              }
          });
  }
  
  var check_battle_status = () => {
      console.log('battle check', common_util.date_formate((new Date()), 'yyyy-MM-dd hh:mm:ss'));
      for (var i in battle_map) {
          if (i == "curr_max_room_id") continue;
          if (!battle_status_checker[i]) {
              battle_status_checker[i] = 1;
          } else {
              if (battle_map[i].status == 'end') {
                  save_end_battle(i, battle_map[i]);
              }
              delete battle_map[i];
          }
      }
  }
  
  setInterval(check_battle_status, 600000);
  
  app.set('views', path.join(__dirname, 'views'));
  app.set('view engine', 'ejs');
  
  app.use(bodyParser.json());
  app.use(bodyParser.urlencoded({ extended: false }));
  app.use('/static', express.static(path.join(__dirname, 'public')));
  app.use(cookieParser());
  app.use((req, res, next) => {
      req.battle_map = battle_map;
      next();
  });
  app.use('/', index);
  
  app.listen(port, () => {
      console.log('App is listening on ', port);
  });
new_contents: var express = require('express');
  var path = require('path');
  var favicon = require('serve-favicon');
  var cookieParser = require('cookie-parser');
  var bodyParser = require('body-parser');
  var app = express();
  var index = require('./routes/index');
  var common_util = require('./utils/common');
  var fs = require('fs');
  var mongoclient = require('mongodb').MongoClient;
  
  var folder = path.join(__dirname, 'battle_history');
  var mongodb_url = '' // Insert your mongodb url here.
  var port = 2333;
  var server_start_time = common_util.date_formate((new Date()), 'yyyy-MM-dd hh:mm:ss');
  var db = (function() {
      mongoclient.connect(mongodb_url, (err, db) => {
          if (err) {
              return null;
          } else  {
              return db;
          }
      });
  })();
  
  var battle_map = {
      curr_max_room_id: 1,
  };
  
  var battle_status_checker = {};
  
  function save_end_battle(battle_cnt, battle) {
      console.log('battle save', battle_cnt, server_start_time);
      if (db == null) {
          console.log('DB connect error');
      }
      db.collection('battle_history')
          .insert(battle, {}, (err) => {
              if (err) {
                  console.log((new Date()).getTime(), err);
              }
          });
  }
  
  var check_battle_status = () => {
      console.log('battle check', common_util.date_formate((new Date()), 'yyyy-MM-dd hh:mm:ss'));
      for (var i in battle_map) {
          if (i == "curr_max_room_id") continue;
          if (!battle_status_checker[i]) {
              battle_status_checker[i] = 1;
          } else {
              if (battle_map[i].status == 'end') {
                  save_end_battle(i, battle_map[i]);
              }
              delete battle_map[i];
          }
      }
  }
  
  setInterval(check_battle_status, 600000);
  
  app.set('views', path.join(__dirname, 'views'));
  app.set('view engine', 'ejs');
  
  app.use(bodyParser.json());
  app.use(bodyParser.urlencoded({ extended: false }));
  app.use('/static', express.static(path.join(__dirname, 'public')));
  app.use(cookieParser());
  app.use((req, res, next) => {
      req.battle_map = battle_map;
      next();
  });
  app.use('/', index);
  
  app.listen(port, () => {
      console.log('App is listening on ', port);
  });
subject: fix little bug