Node.js EventEmitter Guide

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

Best Practices#

Event Design:
✓ Use descriptive event names
✓ Document event signatures
✓ Emit errors as 'error' event
✓ Keep payloads serializable

Memory:
✓ Remove listeners when done
✓ Use once() for one-time events
✓ Set appropriate maxListeners
✓ Clean up in stop/destroy

Patterns:
✓ Extend EventEmitter for OOP
✓ Use event bus for decoupling
✓ Promisify with once()
✓ Handle errors consistently

Avoid:
✗ Too many listeners per event
✗ Forgetting to clean up
✗ Synchronous heavy work in handlers
✗ Circular event emissions

EventEmitter enables powerful event-driven patterns in Node.js. Extend it for custom classes, use proper error handling, and clean up listeners to prevent memory leaks. The once() method and promisified events work well with async/await patterns.

Node.js EventEmitter Guide

Basic Usage#

Event Methods#

Extending EventEmitter#

Error Handling#

Async Events#

Event Patterns#

Configuration#

Memory Management#

Real-World Examples#

Best Practices#

Conclusion#

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