Added socket.io to back-end, it broke everything - node.js

Question

Well, as the title suggests, I broke everything using socket.io. Mainly because the way it calls express breaks everything else using express.
Here is my old way of doing it:
/*jshint esversion: 6*/
const express = require('express');
const http = require('http');
const bodyParser = require('body-parser');
const path = require('path');
const expressValidator = require('express-validator');
const flash = require('connect-flash');
const session = require('express-session');
const passport = require('passport');
const fs = require('fs');
const db = require('./config/db');
// Init App
app = express();
// View Engine
app.set('view engine', 'ejs');
app.set('views', path.join(__dirname, 'views'));
// Bodyparser middleware
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
extended: false,
}));
// Set Static path
app.use(express.static(path.join(__dirname, 'static')));
Which works wonders! It works, however adding socket.io like so:
/*jshint esversion: 6*/
const app = require('express')();
const http = require('http').Server(app);
const socket = require('socket.io')(http);
const bodyParser = require('body-parser');
const path = require('path');
const expressValidator = require('express-validator');
const flash = require('connect-flash');
const session = require('express-session');
const passport = require('passport');
const fs = require('fs');
const db = require('./config/db');
// Init App
// app = express();
// View Engine
app.set('view engine', 'ejs');
app.set('views', path.join(__dirname, 'views'));
// Bodyparser middleware
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
extended: false,
}));
// Set Static path
app.use(express.static(path.join(__dirname, 'static')));
Breaks everything using express.* because it is saying express is not defined. So my static path gets broken and of course the app crashes.I tried several solutions, but to no avail.
Oops forgot to add the error:
app.use(express.static(path.join(__dirname, 'static')));
^
ReferenceError: express is not defined

Answer 1

Try this. The idea is that you need to import express. Socket.io can be required once the rest is defined.
/*jshint esversion: 6*/
const express = require('express');
const http = require('http');
const bodyParser = require('body-parser');
const path = require('path');
const expressValidator = require('express-validator');
const flash = require('connect-flash');
const session = require('express-session');
const passport = require('passport');
const fs = require('fs');
const db = require('./config/db');
// Init App
const app = express();
// Init http server
const server = http.createServer(app);
// Init socket
const socket = require('socket.io').listen(server);
// View Engine
app.set('view engine', 'ejs');
app.set('views', path.join(__dirname, 'views'));
// Bodyparser middleware
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
extended: false,
}));
// Set Static path
app.use(express.static(path.join(__dirname, 'static')));