Learn You The Node.js For Much Win

Learn You The Node.js
For Much Win

What is Node.js?

A simple platform for writing

    … network-centric

    … JavaScript applications

    … using event-driven, non-blocking I/O

For writing applications

Target platforms:

  • OSX
  • Linux
  • Solaris
  • Windows

Also: *BSD, Linux variants & ARM: Raspberry Pi, BeagleBone, Kindle, webOS

And Browserify

JavaScript

V8 (Chrome)

Single runtime target

Many familiar extras:

console.log()  // info, warn, error, dir,
               // time, timeEnd, trace, assert

setTimeout()   // setInterval, setImmediate

JSON           // of course

Network-centric

Node core:

  • ¼ platform
  • ¼ dev support
  • ¼ abstractions, OS, libs & filesystem
  • ¼ networking

TCP, UDP, HTTP, HTTPS, TLS, SSL, URLs, query strings

Event-driven, non-blocking I/O

Reactionary: callbacks & events everywhere. Call Me Maybe.

First-class functions FTW!

// callbacks
fs.readFile('data.txt', 'utf8', function (err, data) {
  var lines = data.split('\n').length
  console.log(lines + ' lines')
})

// events
server.on('connection', function (stream) {
  console.log('someone connected!')
})

Event-driven, non-blocking I/O

Scalability: kernel-level non-blocking socket I/O:
epoll or select

Concurrent: worker threads for file I/O

JavaScript thread only needs to block for JavaScript!

Unless you tell it otherwise

Event-driven, non-blocking I/O

// Synchronous (avoid this)
console.log('Reading file...')
var data = fs.readFileSync('data.txt', 'utf8')
var lines = data.split('\n').length
console.log(lines + ' lines')

// Asynchronous (embrace this)
fs.readFile('data.txt', 'utf8', function (err, data) {
  var lines = data.split('\n').length
  console.log(lines + ' lines')
})
console.log('Reading file...')
JavaScript Node core library  
C / C++ Node bindings
V8 libuv OpenSSL
zlib
http_parser
cares

Original version of this table by Bert Belder: http://www.youtube.com/watch?v=nGn60vDSxQ4

libuv and the event loop

JavaScript callbacks
Timers Sleep?
Socket I/O Filesystem I/O OS events

GIF analogy credit: http://nodejsreactions.tumblr.com/post/56979518608/the-node-js-event-loop

npm - the Node Package Manager

Makes publishing and using packages a breeze

Minimises dependency and version conflicts

Ease and simplicity of reuse has encouraged a culture of extreme modularity

Packages per day across popular platforms (source: www.modulecounts.com)

Chart credit: http://blog.nodejitsu.com/npm-innovation-through-modularity

var net     = require('net')
var sockets = {}
var server  = net.createServer(function (socket) {
  var id = socket.remoteAddress + ':' + socket.remotePort
  sockets[id] = socket
  socket.on('end', function () { delete sockets[id] })
  socket.on('data', function (data) {
    msg('<' + id + '> ' + data)
  })
  msg('* ' + id + ' joined the chat')
})
function msg (msg) {
  Object.keys(sockets).forEach(function (p) {
    try { sockets[p].write(msg.replace(/(\r?\n)+/g, '') + '\n') } catch (e) {}
  })
}
server.listen(1337)