Cookie Expiration

Cookie Expiration Overview

Cookie Expiration lets you structure authentication work so it stays readable, testable, and easy to scale. Instead of ad-hoc code, you follow a clear pattern that other developers can recognise immediately.

The key is to keep cookie expiration focused and predictable. Start from the minimal example here, then layer in only the complexity your feature actually needs.

import session from 'express-session';

app.use(session({
  secret: process.env.SESSION_SECRET,
  resave: false,
  saveUninitialized: false,
  cookie: { httpOnly: true, secure: true, sameSite: 'lax', maxAge: 3600000 },
}));

app.post('/login', (req, res) => {
  req.session.userId = user.id;
  res.json({ ok: true });
});

Session auth stores a server-side session and sends the user a secure, httpOnly cookie.

Cookie Expiration Example

// verify the caller on every protected request
function authenticate(req, res, next) {
  const token = req.headers.authorization?.replace('Bearer ', '');
  req.user = verifyToken(token); // throws if invalid
  next();
}

• Start from a minimal Cookie Expiration example and grow it only as needed.
• Keep configuration explicit so Cookie Expiration behaves the same in every environment.
• Name things clearly so teammates understand your Cookie Expiration at a glance.
• Add tests around Cookie Expiration early to lock in expected behaviour.

Authentication Cheatsheet

Quick authentication reference related to cookie expiration.

How Cookie Expiration Works

Cookie Expiration is part of proving who a user is and what they are allowed to do. Authentication verifies identity, while authorization decides access — and cookie expiration plays a specific role in that flow.

Session auth stores a server-side session and sends the user a secure, httpOnly cookie.

• Never store or log plain-text passwords or secrets.
• Prefer short-lived tokens with refresh over long-lived ones.
• Always send credentials over HTTPS.
• Fail closed: deny access when anything is uncertain.

Security Guidance for Cookie Expiration

Security is the whole point of cookie expiration. Small mistakes — weak hashing, tokens in localStorage, missing rate limits — are exactly what attackers look for, so follow proven defaults.

Common Mistakes

• Skipping error handling and edge cases when wiring up cookie expiration.
• Leaving cookie expiration untested, so regressions slip into production.
• Over-engineering cookie expiration before you actually need the extra flexibility.
• Ignoring documentation, which makes cookie expiration hard for the next developer to change.

Key Takeaways

• Cookie Expiration is a core part of working effectively with authentication.
• Start small and keep cookie expiration focused on a single responsibility.
• Apply consistent patterns so cookie expiration scales across your project.
• Test and document cookie expiration to keep it maintainable over time.