Node.js EventEmitter Patterns

The EventEmitter is central to Node.js architecture. Here's how to use it effectively.

Best Practices#

Design:
✓ Use semantic event names
✓ Document event payloads
✓ Keep events focused
✓ Consider event versioning

Memory:
✓ Remove listeners when done
✓ Watch maxListeners warnings
✓ Use once() for one-time events
✓ Clean up in destroy methods

Error Handling:
✓ Always add error listeners
✓ Handle async errors properly
✓ Use captureRejections
✓ Don't throw in listeners

Performance:
✓ Don't over-emit
✓ Batch related events
✓ Consider throttling
✓ Profile with many listeners

The EventEmitter pattern enables loose coupling and flexible architectures. Use it for async communication, state changes, and plugin systems. Always handle errors, manage memory properly, and document your event contracts.

Node.js EventEmitter Patterns

EventEmitter Basics#

Creating Custom Emitters#

Job Queue Pattern#

WebSocket-like Pattern#

Event Bus Pattern#

State Machine with Events#

Error Handling#

Memory Management#

Typed Events (TypeScript)#

Best Practices#

Conclusion#

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