Node.js EventEmitter Patterns

EventEmitter is the foundation of Node.js event-driven architecture. Here's how to use it effectively.

Real-World Example: File Watcher#

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Best Practices#

Design:
✓ Always handle 'error' events
✓ Use typed events in TypeScript
✓ Document event signatures
✓ Clean up listeners when done

Performance:
✓ Remove listeners when not needed
✓ Set appropriate max listeners
✓ Use once() for one-time events
✓ Avoid synchronous operations in handlers

Patterns:
✓ Emit events for state changes
✓ Use namespaced events for organization
✓ Return unsubscribe functions
✓ Consider async iteration for streams

EventEmitter enables loose coupling and async communication in Node.js. Use typed events for safety, handle errors properly, and clean up listeners to prevent memory leaks. It's ideal for building modular, event-driven architectures.

Node.js EventEmitter Patterns

Basic Usage#

Custom EventEmitter Class#

TypeScript Typed Events#

Error Handling#

Async Iteration#

Event Namespacing#

Pub/Sub Pattern#

Event Queuing#

Memory Management#

Real-World Example: File Watcher#

Best Practices#

Conclusion#

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