About

Node is great

                    
const http = require('http');

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

const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello World\n');
});

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

EventEmitter

const EventEmitter = require('events');

class MyEmitter extends EventEmitter {}

const myEmitter = new MyEmitter();
myEmitter.on('event', () => {
  console.log('an event occurred!');
});
myEmitter.emit('event');
                

Asynchronous NodeJS

Multithreading

V8

Garbage collection

An object is considered garbage collectable if there is zero reference pointing at this object.

                    
var user = {
  name: "Вася"
};
user = null;
                    
                

                    
var vasya = {};
var petya = {};
vasya.friend = petya;
petya.friend = vasya;

vasya = petya = null;
                    
                

Two types of garbage collection

Memory leaks

Solution

Chrome Developer Tools

                    
theThing = null
                    
                

About tools

Npm once more

Node Package manager

Express

var express = require('express');
var app = express();

app.get('/', function (req, res) {
  res.send('Hello World!');
});

app.listen(3000, function () {
  console.log('Example app listening on port 3000!');
});

                

Express generator

express --view=jade myapp

├── app.js
├── bin
│   └── www
├── package.json
├── public
│   ├── images
│   ├── javascripts
│   └── stylesheets
│       └── style.css
├── routes
│   ├── index.js
│   └── users.js
└── views
    ├── error.jade
    ├── index.jade
    └── layout.jade

7 directories, 9 files
                

socket.io

• WebSocket
• Adobe Flash Socket
• AJAX long polling
• AJAX multipart streaming
• Forever Iframe
• JSONP Polling

socket.io and Express

var io = require('socket.io');
var express = require('express');

var app = express.createServer()
var io = io.listen(app);

app.listen(80);

io.sockets.on('connection', function (socket) {
  socket.emit('news', { hello: 'world' });
  socket.on('my other event', function (data) {
    console.log(data);
  });
  socket.on('disconnect', function () {
    console.log('user disconnected');
  });
});
                

MongoDB

Mongoose

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/test');

var Cat = mongoose.model('Cat', { name: String });

var kitty = new Cat({ name: 'Zildjian' });
kitty.save(function (err) {
  if (err) {
    console.log(err);
  } else {
    console.log('meow');
  }
});
                

Electron

Example

const {app, BrowserWindow} = require('electron')
const path = require('path')
const url = require('url')

let win

function createWindow () {
  win = new BrowserWindow({width: 800, height: 600})

  win.loadURL(url.format({
    pathname: path.join(__dirname, 'index.html'),
    protocol: 'file:',
    slashes: true
  }))

  win.webContents.openDevTools()

  win.on('closed', () => {
    win = null
  })
}

app.on('ready', createWindow)

app.on('window-all-closed', () => {
  if (process.platform !== 'darwin') {
    app.quit()
  }
})

app.on('activate', () => {
  if (win === null) {
    createWindow()
  }
})
                

Result

Good job!