Callbacks & Callback Hell

const emitter = new EventEmitter();
emitter.on('data', callback);
emitter.emit('data', result);

Direct callback
Event-driven callback
This code demonstrates the event-driven callback pattern using EventEmitter: 1) Callbacks are registered as event listeners, 2) Multiple callbacks can listen for the same event, 3) Events can be emitted multiple times, 4) Provides loose coupling between event producers and consumers, 5) Common in Node.js for handling streams, user events, and long-running processes, 6) Allows for dynamic addition and removal of callbacks.
Promise callback
Timeout callback