nodejs-patterns

name	nodejs-patterns
description	Async control flow, error handling, module design, streams, and production hardening
metadata	{"author":"cosmicstack-labs","version":"1.0.0","category":"backend","tags":["nodejs","backend","javascript","async","server"]}

Node.js Patterns

Production-grade Node.js backend patterns.

Async Patterns

Prefer Async/Await

// Good
async function getUser(id) {
  const user = await db.findUser(id);
  return user;
}

// Avoid raw callbacks or.then() chains

Parallel Execution

// Sequential (slow)
const user = await fetchUser(id);
const posts = await fetchPosts(id);

// Parallel (fast)
const [user, posts] = await Promise.all([
  fetchUser(id),
  fetchPosts(id),
]);

Error Handling

Global Handler

process.on('uncaughtException', (err) => {
  console.error('Uncaught:', err);
  // Graceful shutdown
  server.close(() => process.exit(1));
});

process.on('unhandledRejection', (reason) => {
  console.error('Unhandled Rejection:', reason);
});

Express Error Middleware

app.use((err, req, res, next) => {
  const status = err.status || 500;
  res.status(status).json({
    error: err.message,
    ...(process.env.NODE_ENV === 'development' && { stack: err.stack }),
  });
});

Module Design

• Single responsibility per module
• Export a class or factory function, not plain objects
• Use dependency injection for testability
• Prefer CommonJS (require) or ESM (import), consistent throughout

Production Hardening

• Cluster mode for multi-core
• Process manager (PM2) with auto-restart
• Health check endpoints
• Graceful shutdown (SIGTERM handler)
• Memory limit monitoring
• Structured logging (pino/winston)