NodeJS

NodeJS

From Internshala Training NodeJS Course

Require

• Import node module

  .jsx

  const { readFs } = require("fs");
  const { readHttps } = require("https");
  

• Input the string in console.log.

  .jsx

  st readLine = require("readline").createInterface({
    output: process.stdout,
    input: process.stdin,
  });
  
  readLine.question("What is your name?\n", (name) => {
    console.log(`Welcome ${name}`);
    readLine.close();
  });
  
  // What is your name?
  // Jimmin <= Ask to input here
  // Welcome Jimmin
  

Module

• Process

  The process object in Node.js is a global object that can be accessed inside any module without requiring it.

  • process.on

    .jsx

    process.on('beforeExit', (code) => {
    console.log('Process beforeExit event with code: ', code);
    });
    // Process beforeExit event with code:  0                                                                                             /0.3s
    

  • Process expressions

    .jsx

    console.log(process.ppid);
    // 21321
    console.log(process.argv);
    // [
    //  '/snap/node/5148/bin/node',
    //  '/home/kurama/Documents/Projects/Node JS/app.js'
    //]
    console.log(`Reports are compact? ${process.report.compact}`);
    // Reports are compact? false                                                                                                         /0.3s
    

• Module

  The module is same as process but you can only access within the file information.

• Event

  • EventEmitter

    .jsx

    const events = require("events");
    const eEmitter = new events.EventEmitter();
    
    const getParty = function () {
      console.log("Time to party");
      const ran = Math.ceil(Math.random() * 10);
      console.log(`Party starts in ${ran}`);
      tester(ran);
    };
    
    eEmitter.on("music", getParty);
    
    tester(2);
    
    function tester(val) {
      setTimeout((e) => {
        eEmitter.emit("music");
      }, val * 1000);
    }
    
    // Time to party
    // Party starts in 5
    // Time to party
    // Party starts in 8
    // Time to party
    // Party starts in 3
    // Time to party
    // Party starts in 9