server.js

const express = require('express');
require('dotenv').config();
const app = express();
const path = require('path');
const cors = require('cors');
const { logger } = require('./middleware/logEvents');
const errorHandler = require('./middleware/errorHandler');
const credentials = require('./middleware/credentials');
const verifyJWT = require('./middleware/verifyJWT');
const cookieParser = require('cookie-parser');
const mongoose = require('mongoose');
const connectDB = require('./config/dbConn');
const PORT = process.env.PORT || 8000;

// connect to mongoDB
connectDB();

// custom middleware logger
app.use(logger);

// Cross Origin Resource Sharing
const whitelist = [ 'https://www.yoursite.com', 'http://127.0.0.1:5500', 'http://localhost:3500' ];
const corsOptions = {
	origin: (origin, callback) => {
		if (whitelist.indexOf(origin) !== -1 || !origin) {
			callback(null, true);
		} else {
			callback(new Error('Not allowed by CORS'));
		}
	},
	optionsSuccessStatus: 200
};

// handle option credentials check before CORS
// and fetch cpokies credentials requirment
app.use(credentials);

app.use(cors(corsOptions));

// built-in middleware to handle urlencoded data
// in other words, form data:
// ‘content-type: application/x-www-form-urlencoded’
app.use(express.urlencoded({ extended: false }));

// built-in middleware for json
app.use(express.json());

// middlware for cookies
app.use(cookieParser());

//serve static files
app.use('/', express.static(path.join(__dirname, '/public')));
app.use('/subdir', express.static(path.join(__dirname, '/public')));

// routes
app.use('/', require('./routes/root'));
app.use('/subdir', require('./routes/subdir'));
app.use('/register', require('./routes/register'));
app.use('/login', require('./routes/auth'));
app.use('/refresh', require('./routes/refresh'));
app.use('/logout', require('./routes/logout'));

app.use(verifyJWT);
app.use('/employees', require('./routes/api/employees'));

app.all('*', (req, res) => {
	res.status(404);
	if (req.accepts('html')) {
		res.sendFile(path.join(__dirname, 'views', '404.html'));
	} else if (req.accepts('json')) {
		res.json({ error: '404 Not Found' });
	} else {
		res.type('txt').send('404 Not Found');
	}
});

app.use(errorHandler);

// mongoose emits event when it connects
mongoose.connection.once('open', () => {
	console.log('connected to mongodb');
	app.listen(PORT, () => console.log(`Server running on port ${PORT}`));
});