How do you handle uncaught exceptions and unhandled rejections in Node.js?

Question

Accepted Answer

**Uncaught exceptions** and **unhandled rejections** crash the process if not handled.

```javascript
// Uncaught synchronous exceptions
process.on("uncaughtException", (err, origin) => {
    console.error("Uncaught Exception:", err);
    // Log to monitoring service
    logger.fatal({ err, origin });
    // Graceful shutdown
    gracefulShutdown("uncaughtException");
});

// Unhandled promise rejections
process.on("unhandledRejection", (reason, promise) => {
    console.error("Unhandled Rejection:", reason);
    logger.error({ reason });
    // Graceful shutdown (Node 15+ crashes by default)
    gracefulShutdown("unhandledRejection");
});
```

**Best practices:**
- Always use try/catch with async/await.
- Always handle .catch() on promises.
- Use async error middleware in Express.
- Log errors before exiting.
- Use monitoring (Sentry, Datadog).
- Don't just catch and ignore — re-throw or exit.

Node.js: How do you handle uncaught exceptions and unhandled rejections in Node.js?