Node JS¶

What is Node.js?¶

Short Answer: Javascript on the server side

Long Answer: Node.js is a platform built on Chrome’s JavaScript runtime. It’s used to build fast, scalable network applications. It uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, making it perfect for building real-time applications

Asynchronous I/O¶

Does not need to wait for one process to finish before starting the other (Non-Blocking)
Optimize throughput and scalability in web applications with many I/O operations
Event-Driven programming
This makes Node.js apps extremely fast and efficient

Event Loop¶

Single-threaded
Supports concurrency via events and callbacks
EventEmitter class is used to bind events and event listeners

Simple Example¶

var fs = require("fs");

fs.readFile('input.txt', function (err, data) {
  if (err){
    console.log(err.stack);
    return;
  }
  console.log(data.toString());
});
console.log("Program Ended");

Using Node¶

node -v: check node.js version node: Interact with Node Console node filename: Run a file with node

NPM¶

What is NPM?¶

NPM stands for Node Package Manager
The term package is used for back-end and is equivalent to library on the front-end
Online repositories for node.js packages/modules
Over 200,000 packages available

Using NPM¶

npm -v: check npm version npm init: create a package.json file (manifest file)

To install a package:

// Add -g: to install globally
// --save: to save info in package.json file
npm install express --save

Installed package can be found in node_modules folder

Then, include the package in a Javascript file

var express = require("express");

Types of Modules¶

Framworks - Express.js
Template Engines - Pug, EJS, Handlebars
Utilities - Path, OS, API modules, Compilers
Database ORM - Mongoose, Mongo.js

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