How to use the socket.io.listen function in socket

exports.start = function() {
	setupRoutes();

	// Create our tiny little HTTP server.
	var server = http.createServer(handleRequest);

	server.listen(config.site.port, config.site.ip);

	// I don't like this. But it works, I think.
	exports.io = io.listen(server);

	// Since everything is loaded, let's celebrate!
	logger.log('info', 'Started on %s:%d', config.site.ip, config.site.port);
};

var http = require('http');

server = http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello World\n');
}).listen(1337, '127.0.0.1');

var io = require('socket.io').listen(server);

io.sockets.on('connection', function(socket) {
 socket.on('message', function(message) {
   socket.broadcast.emit('message', message);
 });
});

console.log('Server running at http://127.0.0.1:1337/');

var express = require('express');
var app = express();
var server = require('http').createServer(app);
var io = require('socket.io').listen(server);

server.listen(80); //for local test
//server.listen(process.env.PORT || 3000);//for publish to heroku

app.use("/", express.static(__dirname + '/public'));

io.sockets.on('connection', function (socket) {
  socket.on('msg', function (data) {
    io.sockets.emit('new', data);
  });
});

var http = require('http');
var fs   = require('fs');

var server = http.createServer(function(req, res) {
	fs.createReadStream('./websocket.html').pipe(res);
}).listen(8080);

var io = require('socket.io').listen(server);

io.sockets.on('connection', function (socket) {
	socket.emit('server/hello', { from: 'server' });
	socket.on('browser/move', function (data) {
		io.sockets.emit('browser/move', data);
	});
});

const app = require('./app');
const http = require('http');
const socketio = require('socket.io');

const server = http.createServer(app);
const io = socketio.listen(server);
require('./sockets')(io);
require('./database');

async function main() {
  await server.listen(app.get('port'));
  console.log(`server on port ${app.get('port')}`);
}

main();