User registration flow in Express

Introduction

User registration flow helps new users create an account so they can use your app securely.

When you want to let people sign up for your website or app.

When you need to collect user information like email and password.

When you want to protect parts of your app for registered users only.

When you want to save user data in a database for future logins.

Syntax

Express

app.post('/register', (req, res) => {
  const { username, password } = req.body;
  // Validate input
  // Save user to database
  res.send('User registered');
});

Use app.post to handle form submissions securely.

Access user data from req.body after using middleware like express.json().

Examples

Basic registration using email and password.

Express

app.post('/register', (req, res) => {
  const { email, password } = req.body;
  // Save user
  res.send('Registered with email');
});

Registration with simple input validation.

Express

app.post('/register', (req, res) => {
  const { username, password } = req.body;
  if (!username || !password) {
    return res.status(400).send('Missing fields');
  }
  // Save user
  res.send('User registered');
});

Sample Program

This Express app lets users register by sending a POST request to /register with JSON containing username and password. It checks for missing fields and duplicate usernames, then saves the user in a simple array.

Express

import express from 'express';

const app = express();
app.use(express.json());

const users = [];

app.post('/register', (req, res) => {
  const { username, password } = req.body;
  if (!username || !password) {
    return res.status(400).send('Username and password are required');
  }
  const userExists = users.find(u => u.username === username);
  if (userExists) {
    return res.status(409).send('User already exists');
  }
  users.push({ username, password });
  res.status(201).send('User registered successfully');
});

app.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
});

Important Notes

Always validate user input to avoid errors and security issues.

In real apps, never store passwords as plain text; use hashing.

Use proper HTTP status codes to inform clients about success or errors.

Summary

User registration flow lets new users create accounts.

Use app.post with express.json() to handle registration data.

Validate input and check for existing users before saving.