Event Emitter

What is EventEmitter?

In Nodejs there is a special system called EventEmitter. It helps your program listen for something to happen and do something when it happens.

• One part emits (sends) an event
• Another part listens and reacts when that event happens

Why it is Used

Node.js is built on event-driven architecture. That means it reacts to events all the time.

Examples of events:

• When a file finishes reading
• When a user clicks something
• When data comes from a network

EventEmitter is the core of how Node.js handles many things.

Interview Answer

EventEmitter is a class in Node.js that helps create and handle custom events.

Key points:

• It works on the publish and subscribe model
• One part emits an event
• Other parts subscribe or listen to that event
• You use on to listen and emit to trigger
• It helps write clean and modular code