MERN Stack New Batch

  const events = require ( 'events' ) ; const e = new events .EventEmitter() ; e. setMaxListeners ( 3 ) ; //=========== e. on ( 'event1' ,function (name , message) { console . log ( 'event1' ) ; console . log ( ` ${name} ${message} ` ) ; }) e. emit ( 'event1' , 'nayan' , 'Hello' ) ;

const events = require ( 'events' ) ; const e = new events .EventEmitter() ; e. setMaxListeners ( 3 ) ; //=========== e. on ( 'event1' ,function (name , message) { console . log ( 'event1' ) ; console . log ( ` ${name} ${message} ` ) ; }) e. emit ( 'event1' , 'nayan' , 'Hello' ) ;

  const events = require ( 'events' ) ; const e = new events .EventEmitter() ; e. setMaxListeners ( 4 ) ; //===========Example1 e. on ( 'event1' ,function () { console . log ( 'event1' ) ; }) e. on ( 'event1' ,function () { console . log ( 'event2' ) ; }) e. on ( 'event1' ,function () { console . log ( 'event3' ) ; }) e. on ( 'event1' ,function () { console . log ( 'event4' ) ; }) //==============call //e.emit('event1'); //i want output Like //event1 //event3 let a=e. listeners ( 'event1' ) ; a. forEach ((item , index)=>{ if (index === 0 || index === 2 ) { item() ; // 👉 This actually CALLS the function } })

  const events = require ( 'events' ) ; const e = new events .EventEmitter() ; e. setMaxListeners ( 3 ) ; //===========Example1 e. on ( 'event1' ,function () { console . log ( 'event1' ) ; }) e. on ( 'event1' ,function () { console . log ( 'event2' ) ; }) e. on ( 'event1' ,function () { console . log ( 'event3' ) ; }) // e.on('event1',function () { // console.log('event4'); // }) //==============call e. emit ( 'event1' ) ;

  const events = require ( 'events' ) ; const e = new events .EventEmitter() ; function Event1CallBackFun () { console . log ( 'Event1' ) ; } e. on ( 'Event1' , Event1CallBackFun ) e. on ( 'Event1' ,function () { console . log ( `new no call back function.` ) ; }) e. on ( 'Event2' ,function () { console . log ( 'Event2' ) ; }) //====call== e. emit ( 'Event1' ) ; /* * Event1 new no call back function. * */ e. emit ( 'Event2' ) ; //Event2 //==Remove Event1 try { e. removeAllListeners ( 'Event1' ) ; } catch (e) { console . log (e) } //e.removeListener('Event1',Event1CallBackFun) //====call== e. emit ( 'Event1' ) ; //no outpute e. emit ( 'Event2' ) ; //only show Event2

  const events = require ( 'events' ) ; const e = new events .EventEmitter() ; e. on ( 'click' , () => console . log ( 'Click 1' )) ; e. on ( 'click' , () => console . log ( 'Click 2' )) ; e. emit ( 'click' ) ; // Output: Click 1\nClick 2 //e.removeAllListeners('click'); try { e. removeListener () ; } catch (e) { console . log ( `Error : ${e} ` ) ; } e. emit ( 'click' ) ; // No output

  let events = require ( 'events' ) ; let e= new events .EventEmitter() ; function T () { console . log ( 'Line 7' ) ; } e. on ( 'Click' , T ) e. emit ( 'Click' ) ; //=========NOt Work // e.removeListener('Click',function () { // console.log('remove') // }); //e.removeListener('Click',T); e. emit ( 'Click' ) ; //=========Re Assign Click Event function TT () { console . log ( `Line 22` ) ; } e. on ( 'Click' , TT ) ; e. emit ( 'Click' ) ;

let events = require ( 'events' ) ; let e= new events .EventEmitter() ; function test () { console . log ( 'test function' ) ; } e. on ( 'click' , test ) ; e. emit ( 'click' ) ; //fire

  let fs = require ( "fs" ) ; // let data=fs.readFileSync('covid.csv'); // console.log('=========Data========'); // console.log(data.toString()); // console.log('=========Data========'); // console.log('=========Program End========'); fs . readFile ( 'covid.csv' ,function (error , data) { console . log ( '=========Data========' ) ; console . log (data. toString ()) ; console . log ( '=========Data========' ) ; }) ; console . log ( '=========Program End========' ) ;

let http = require ( 'http' ) http . createServer ((req , res)=>{ res.writeHead( 200 , { contentType : "application/json" }) ; res.end( "<h1>Computer Test</h1>" ) ; }). listen ( 8080 ) ;

  import React from "react" ; import "bootstrap/dist/css/bootstrap.min.css" ; import { BrowserRouter as Router , Link , Routes , Route } from "react-router-dom" ; import { Helmet } from "react-helmet" ; // 🔥 Give your main App a name (not anonymous export) export default function App () { return ( <Router> <Navigation /> <Routes> <Route path ="/" element = { <Home /> } /> <Route path ="/about" element = { <About /> } /> <Route path ="/contact" element = { <Contact /> } /> </Routes> </Router> ) ; } // ✅ SEO Helmet Component const SeoHelmet = ({ title , description , keywords , image , url }) => { return ( <Helmet> <title> {title} </title> <meta name ="title" content = {title}...

  import React , { useCallback } from "react" ; export default function TestCallBack () { // function TestChildFunction() { // alert("Success"); // } const TestChildFunction= useCallback (()=>{ alert ( "Success" ) ; }) return <> <TestChild onClickFun = {TestChildFunction} /> </> } const TestChild= React . memo (({onClickFun})=>{ return <> <button onClick = {onClickFun} > Call Function Parent </button> </> })

  import React , { forwardRef , useId , useImperativeHandle , useRef , useState } from "react" ; export default function (){ const uniqId= useId () ; const video= useRef () ; const childRef= useRef () ; function getInfo () { alert ( ` ${childRef. current . Title } ` ) ; alert ( ` ${childRef. current .Price} ` ) ; alert ( ` ${childRef. current .Description} ` ) ; } function setInfo () { childRef. current . ChangePrice ( 134 ) ; } return <> <h1> {uniqId} </h1> <button onClick = {()=>{video. current . play () ; }} > Play </button> <button onClick = {()=>{video. current . pause () ; }} > Stop </button> <video ref = {video} > <source src = { "https://www.w3schools.com/html/mov_bbb.mp4" } /> </video> <button > Get Product Information </button> <Product img = { ...

  import React , { forwardRef , useId , useImperativeHandle , useRef , useState } from "react" ; export default function (){ const uniqId= useId () ; const video= useRef () ; const childRef= useRef () ; function getInfo () { alert ( ` ${childRef. current . Title } ` ) ; alert ( ` ${childRef. current . Price } ` ) ; alert ( ` ${childRef. current .Description} ` ) ; } function setInfo () { childRef. current . Price = 145 ; } return <> <h1> {uniqId} </h1> <button onClick = {()=>{video. current . play () ; }} > Play </button> <button onClick = {()=>{video. current . pause () ; }} > Stop </button> <video ref = {video} > <source src = { "https://www.w3schools.com/html/mov_bbb.mp4" } /> </video> <button > Get Product Information </button> <Product img = { "h...