#nodejs

Javascript runtime environment with chrome V8 engine and C++ embedded in it

Allows javascript to work at backend. Handle client-server, authentication, file handling and stuff

<span style={{ color: 'rgb(116,62,228)' }}>#Create</span> a folder
npm init # -y for autocomplete
npm install express jsonwebtoken dotenv
npm install --global nodemon # install package globally
nodemon server.js # to watch and reload server on update

Simple HTTP Server

const { createServer } = require('node:http');

const hostname = '127.0.0.1';
const port = 3000;

const server = createServer((req, res) => {
    res.statusCode = 200;
    res.setHeader('Content-Type', 'text/html'); // display what? plain? html?
    res.end('<h1> Himanshu Aggarwal </h1>');
});

server.listen(port, hostname, () => {
    console.log(`Server running at <http:// $$>{hostname}:$$ {port}/`);
});

Node version manager (nvm) to manage and switch to different version of npm as per req.

CommonJS Module

uses require to import modules.

const { createServer } = require('node:http');

Loads the modules synchronously.
We can console __dirname, __filename to get file directory and name in CommonJS

Exporting Modules ( math.js )

function sum(a, b) {
    return a + b;
}
const diff = (a, b) => a - b;

module.exports = { sum, diff };
exports.mult = (a, b) => a * b;

Import Modules ( script.js )

const { sum, diff, mult } = require("./math.js");

console.log(sum(3, 5));  // 8
console.log(diff(10, 4)); // 6
console.log(mult(4, 6));  // 24

Package Configuration ( package.json )

{
  "type": "commonjs"
}

EcmaScripts Modules

ES6 is modern and uses import to import modules

import { createServer } from "http";

Loads asynchronously
We can import functions, variables using export (default) in ES6 modules

Exporting Modules ( math.js )

export function sum(a, b) {
    return a + b;
}
export const diff = (a, b) => a - b;
export default (a, b) => a * b;

Import Modules ( script.js )

import mult, { sum, diff } from "./math.mjs";

console.log(sum(3, 5));  // 8
console.log(diff(10, 4)); // 6
console.log(mult(4, 6));  // 24

Package Configuration ( package.json )

{
  "type": "module"
}

Nodejs Introduction

Simple HTTP Server

CommonJS Module

EcmaScripts Modules

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