Today, we'll go through the basics of integrating Bcrypt (popular library for password hashing in Node.js) into an Express.js application using an array to store users instead of a database. Additionally, we'll include a hands-on guide on how to install Bcrypt, create users, and authenticate using Postman.

Sample code:

const express = require('express');
const bcrypt = require('bcrypt');
const app = express();
app.use(express.json());

const PORT = 8000;

const users = [];

app.post('/register', (req, res) => {
	const { username, password } = req.body;
	const salt = bcrypt.genSaltSync(10);
	const passwordSalted = bcrypt.hashSync(password, salt);
	users.push({ username, password: passwordSalted });
	res.status(201).send('User registered');
});

app.post('/login', (req, res) => {
	const { username, password } = req.body;
	const user = users.find((user) => user.username === username);
	if (user && bcrypt.compareSync(password, user.password)) {
		res.send('User logged in');
	} else {
		res.status(401).send('Invalid credentials');
	}
});

app.listen(PORT, () => console.log(`Server running on port ${PORT}`));