Jassif Team Institution

उदाहरण

let fs = require('fs');
let rs = fs.createReadStream('./demofile.txt');
rs.on('open', function () {
  console.log('The file is open');
});

// Import the events module
const EventEmitter = require('events');

// Create an event emitter instance
const myEmitter = new EventEmitter();

// Register an event listener
myEmitter.on('greet', () => {
  console.log('Hello there!');
});

// Emit the event
myEmitter.emit('greet'); // Outputs: Hello there!

let events = require('events');
let eventEmitter = new events.EventEmitter();

उदाहरण

let events = require('events');
let eventEmitter = new events.EventEmitter();

//Create an event handler:
let myEventHandler = function () {
  console.log('I hear a scream!');
}

//Assign the event handler to an event:
eventEmitter.on('scream', myEventHandler);

//Fire the 'scream' event:
eventEmitter.emit('scream');

const EventEmitter = require('events');
const emitter = new EventEmitter();

// Emit event with arguments
emitter.on('userJoined', (username, userId) => {
  console.log(`${username} (${userId}) has joined the chat`);
});

emitter.emit('userJoined', 'JohnDoe', 42);
// Outputs: JohnDoe (42) has joined the chat

const EventEmitter = require('events');
const emitter = new EventEmitter();

// This listener will be called only once
emitter.once('connection', () => {
  console.log('First connection established');
});

emitter.emit('connection'); // This will trigger the listener
emitter.emit('connection'); // This won't trigger the listener again

const EventEmitter = require('events');
const emitter = new EventEmitter();

// Always handle 'error' events
emitter.on('error', (err) => {
  console.error('An error occurred:', err.message);
});

// This will trigger the error handler
emitter.emit('error', new Error('Something went wrong'));

// Good practice: Always listen for 'error' events
myEmitter.on('error', (err) => {
  console.error('Error in event emitter:', err);
});

// Instead of anonymous functions
function handleData(data) {
  console.log('Received data:', data);
}

myEmitter.on('data', handleData);

// Add a listener
const listener = () => console.log('Event occurred');
myEmitter.on('event', listener);

// Later, remove the listener when no longer needed
myEmitter.off('event', listener);