Event Modules in Node js

 In Node.js, the Event module provides a way to handle and work with events. It is a core module that enables event-driven programming, which is central to Node.js's architecture.

Key Concepts of the Event Module

EventEmitter:
The EventEmitter class is the core of the event module. It allows you to create, listen to, and emit events.

Event Listeners:
You can register functions (listeners) to handle specific events when they are emitted.

Basic Usage

Here’s an example to illustrate how the Event module works:

Import the Event Module

const EventEmitter = require('events');

Create an EventEmitter Instance

const eventEmitter = new EventEmitter();

Add Event Listeners

// Adding a listener for the 'greet' event

eventEmitter.on('greet', (name) => {

    console.log(`Hello, ${name}!`);

});

Emit Events

// Emitting the 'greet' event

eventEmitter.emit('greet', 'Alice');

Common Methods

Adding Listeners

• on(eventName, listener): Attaches a listener to the event.
• once(eventName, listener): Attaches a one-time listener.

Removing Listeners

• removeListener(eventName, listener): Removes a specific listener.
• removeAllListeners([eventName]): Removes all listeners for the specified event.

Emitting Events

• emit(eventName, [...args]): Triggers the event and passes arguments to the listeners.

Other Utility Methods

• listenerCount(eventName): Returns the number of listeners for an event.
• eventNames(): Returns an array of event names.