Node.js Best Practices

my-app/
├── src/
│   ├── controllers/    # Request handlers
│   ├── models/         # Database models
│   ├── routes/         # API routes
│   ├── middleware/      # Custom middleware
│   ├── services/       # Business logic
│   ├── utils/          # Helper functions
│   ├── config/         # Configuration
│   └── index.js        # Entry point
├── tests/              # Test files
├── .env                # Environment vars
├── .gitignore
├── package.json
└── README.md

// Custom error class
class AppError extends Error {
  constructor(message, statusCode) {
    super(message);
    this.statusCode = statusCode;
    this.isOperational = true;
  }
}

// Global error handler
app.use((err, req, res, next) => {
  const status = err.statusCode || 500;
  const message = err.isOperational
    ? err.message
    : "Internal Server Error";

  res.status(status).json({
    status: "error",
    message,
    ...(process.env.NODE_ENV === "development" && {
      stack: err.stack,
    }),
  });
});

// Compression
const compression = require("compression");
app.use(compression());

// Response time header
app.use((req, res, next) => {
  const start = Date.now();
  res.on("finish", () => {
    const duration = Date.now() - start;
    console.log(req.method, req.url, duration + "ms");
  });
  next();
});