Authentication Do's and Don'ts

Do's and Don'ts Overview

At its core, do's and don'ts is about doing one thing well inside your authentication project. Once you understand the pattern, you can apply it consistently across features and teams.

Good do's and don'ts pays off across the whole codebase: fewer surprises, easier testing, and smoother onboarding. The snippet below is a solid starting point.

import express from 'express';
import jwt from 'jsonwebtoken';

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

function authenticate(req, res, next) {
  const token = req.headers.authorization?.replace('Bearer ', '');
  try {
    req.user = jwt.verify(token, process.env.JWT_SECRET);
    next();
  } catch {
    res.status(401).json({ error: 'Unauthorized' });
  }
}

Authentication middleware verifies the caller's identity before protected handlers run.

Do's and Don'ts 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 Do's and Don'ts example and grow it only as needed.
• Keep configuration explicit so Do's and Don'ts behaves the same in every environment.
• Name things clearly so teammates understand your Do's and Don'ts at a glance.
• Add tests around Do's and Don'ts early to lock in expected behaviour.

Authentication Cheatsheet

Quick authentication reference related to do's and don'ts.

How Do's and Don'ts Works

Do's and Don'ts is part of proving who a user is and what they are allowed to do. Authentication verifies identity, while authorization decides access — and do's and don'ts plays a specific role in that flow.

Authentication middleware verifies the caller's identity before protected handlers run.

• 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 Do's and Don'ts

Security is the whole point of do's and don'ts. Small mistakes — weak hashing, tokens in localStorage, missing rate limits — are exactly what attackers look for, so follow proven defaults.

Common Mistakes

• Copying do's and don'ts snippets without understanding what each line does.
• Skipping error handling and edge cases when wiring up do's and don'ts.
• Leaving do's and don'ts untested, so regressions slip into production.
• Over-engineering do's and don'ts before you actually need the extra flexibility.

Key Takeaways

• Do's and Don'ts is a core part of working effectively with authentication.
• Start small and keep do's and don'ts focused on a single responsibility.
• Apply consistent patterns so do's and don'ts scales across your project.
• Test and document do's and don'ts to keep it maintainable over time.