Formation Node.JS

by Rodolphe Duterval

Rodolphe Duterval

32 🐳

Dev Web FullStack

Introduce yourself?

  • Why are you here?

  • What are your objectives?

  • How can I help you?

Mes stacks

  • HTML 5 / CSS 3
  • JS (ES6)
  • PHP
  • Ruby
  • C / C++
  • Angular 2 / React / Vue
  • Node.js
  • MongoDB / MySQL

RULES

  • Fautes d’orthographe tolérées
  • Mauvaise indentation non tolérée

  • Copiage bête non toléré

  • Code en français non toléré
  • Bavardage tolérés tant que c'est discret
  • On ferme les ordi quand c'est demandé

Conseils

  • Participez

  • Pratiquez chez vous

  • Allez au-delàs de ce qu'on vous demande

  • Si vous n'avez pas compris, dites-le !

  • Dormez

  • ne me prenez pas pour un con

What is NODE.JS ?

NODE.JS IS A JAVASCRIPT RUNTIME

BUILT ON GOOGLE'S OPEN-SOURCE 

V8 JAVASCRIPT ENGINE. 🤔

Why & When to use Node.js

NODE.JS PROS

USE NODE.JS

  • single-threaded, based on even driven, non-blocking I/O model
  • Perfect for building fast and scalabe data-intensive apps.
  • Companies like : netflix, uber, paypal, ebay have started using node in production
  • API with database behind it ( NoSQL)
  • Data streaming
  • Real-time chat app
  • server-side web app

Install Node.js

go on : http://nodejs.org & install it !

node -v
v13.8.0

mkdir node-farm

Core Modules - Node.JS

//index.js
const hello = 'Hello ESTIAM';
console.log(hello)

// lancer dans votre terminal 
// node index.js

Node.JS - FS read & write

//index.js
const fs = require('fs');
// create an folder with 2 files .txt [input, final]
fs.readFileSync('./txt/input.txt', 'utf-8');
const textIn = fs.readFileSync('./txt/input.txt', 'utf-8');
console.log(textIn);

// lancer dans votre terminal 
// node index.js

Node.JS - FS read & write

//index.js
const fs = require('fs');
// create an folder with 2 files .txt [input, final]
fs.readFileSync('./txt/input.txt', 'utf-8');
const textIn = fs.readFileSync('./txt/input.txt', 'utf-8');
console.log(textIn);

const textOut = `check this out : ${textIn}\nCreated on ${Date.now()}`;
fs.writeFileSync('./txt/output.txt', 'utf-8');
console.log('File written !')
// lancer dans votre terminal 
// node index.js

Synchrone

blocking 👎

Asynchrone

non-blocking 🤟

vs.

Do you know callback Hell 🔥🔥 ?

fs.readdir(source, function (err, files) {
  if (err) {
    console.log('Error finding files: ' + err)
  } else {
    files.forEach(function (filename, fileIndex) {
      console.log(filename)
      gm(source + filename).size(function (err, values) {
        if (err) {
          console.log('Error identifying file size: ' + err)
        } else {
          console.log(filename + ' : ' + values)
          aspect = (values.width / values.height)
          widths.forEach(function (width, widthIndex) {
            height = Math.round(width / aspect)
            console.log('resizing ' + filename + 'to ' + height + 'x' + height)
            this.resize(width, height).write(dest + 'w' + width + '_' + filename, function(err) {
              if (err) console.log('Error writing file: ' + err)
            })
          }.bind(this))
        }
      })
    })
  }
})

Asynchronous JavaScript, or JavaScript that uses callbacks, is hard to get right intuitively

 //Non-blocking, asynchronous way
 fs.readFile('./txt/start.txt', 'utf-8', (err, data1) => {
   if (err) return console.log('ERROR! 💥');

  fs.readFile(`./txt/${data1}.txt`, 'utf-8', (err, data2) => {
    console.log(data2);
    fs.readFile('./txt/append.txt', 'utf-8', (err, data3) => {
      console.log(data3);

       fs.writeFile('./txt/final.txt', `${data2}\n${data3}`, 'utf-8', err => {
         console.log('Your file has been written 😁');
       })
     });
   });
 });
 console.log('Will read file!');

👼🏼 SOLUTION ??? 👼🏼

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