JWT Token Auth

// First: npm install jsonwebtoken
const jwt = require('jsonwebtoken');

// A secure secret key (normally stored in a .env file)
const SECRET_KEY = "my_super_secret_password_do_not_share";

// 1. Logging in: Creating a Token
function loginUser() {
  const payload = { userId: 42, username: 'Alex' };
  
  // Sign the token to expire in 1 hour
  const token = jwt.sign(payload, SECRET_KEY, { expiresIn: '1h' });
  console.log("Generated Token:", token);
  return token;
}

// 2. Accessing private data: Verifying the Token
function verifyUserRequest(token) {
  try {
    const decoded = jwt.verify(token, SECRET_KEY);
    console.log("Access Granted! Welcome User ID:", decoded.userId);
  } catch (error) {
    console.error("Access Denied. Invalid or expired token.");
  }
}

const userToken = loginUser();
verifyUserRequest(userToken);