title: Socket.io keeps reconnecting, even i don't use socket.io now
body: <p>I've run the chatting server and delete it.</p>
  
  <p>So, I don't have any file which uses socket.io</p>
  
  <pre><code>'use strict'
  const
      express = require('express')
      ,mongoose = require('mongoose')
      ,logger = require('morgan')
  
  const
      app = express()
  
  
  // === db setting ===
  
  
  
  // === initial setting ===
  app.set('view engine', 'pug');
  app.set('views', './views');
  app.use(express.static('public'));
  
  
  // === 3rd party middlewares ===
  app.use(logger('dev'));
  
  
  // === router ===
  app.get('/', (req, res, next) =&gt; {
      res.send('hello world');
  });
  
  
  // === error handler ===
  
  
  // === server running ===
  app.listen(8000, () =&gt; {
      console.log('=== server is running ===');
  });
  </code></pre>
  
  <p>However when i run the new server, it keeps showing me this message below. </p>
  
  <p>How can i fix this?</p>
  
  <p><a href="https://i.stack.imgur.com/S58VS.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/S58VS.png" alt="enter image description here"></a></p>