Nodejs

Training

Program

• Javascript course Basic and Advanced
• Nodejs core & Libraries
• Modejs Ecosystem, Framwork and Application

Day 1 : Javascript course Basic and Advanced

• Basic
• Native method
• Naming
• Workshop based on Nodeschool.io
• Heritage
• this
• bind, call and apply
• Wrokshop

Les 3 vies du Javascript

Dans les année 90 : DHTML (Dynamic HTML), servait à faire des "petits effets" sur les page web. (Netscape, IE 5.5, ...)

Dans les année 2000 : JQuery, propose des effets compatible sur tous les navigateurs. Une révolution !

A partir des 2010 : Google crée V8, le nouveau moteur d'interprétation du JS.

Javascript : Assignment

var i = 10;
var str = 'Hello';
var ing = 'word';

i += 1;
i -= 1;
i++;
i--;
++i;
--i;

var string = str;
string += ing;

string = str + ing;
string += ", How is it going ?"'

Javascript : Expression

Loops

for (var i = 0; i < 10; i++) {
 ...
}

var i = 0;
while (i < 10) {
 ...
 i++;
}

var i = 0;
do {
   i++;
   ...
} while (i < 10);

For

While

Do while

Javascript : Expression

Loops

for (var i = 0; i < 10; i++) {
    if (i % 2) continue;
    ...
}

var i = 0;
while (true) {
 if (i > 10) break;
 ...
 i++;
}

Continue

Break

Javascript : Type of value

Native

var foobar;
typeof foobar
// "undefined"

undefined

var isTrue = true;
var isFalse = false;
typeof isTrue
// "boolean"
typeof isFalse
// "boolean"

boolean

var age = true;
typeof age
// "number"

number

var name = "Edouard";
typeof name
// "string"

string

Javascript : Type of value

Object

var object1 = null;
typeof object1
// "object"
object1
// null

Null

var object2 = ['cat', 'dog'];
typeof object2
// "object"
object2
// ['cat', 'dog']

Array

var object3 = {flowers: 'roses'};
typeof object3
// "object"
object3
// Object {flowers: 'roses'}

Object

Javascript : RegExps

Syntaxe

var myTest = /^Hel.*rld$/;
myTest.test("Bonjour monde");
// false
myTest.test("Hello world");
// true

Test

var str = "Hello world";

var myTest = /^Hel(.*)rld$/;
myTest.exec(str);
// ["Hello world", "lo wo"]

Exec

Javascript : Function

Syntaxe

var myFunction = function () {
    console.log("Hello word");
}
myFunction()
// Hello word

Anonymous

var hello = "Hello word"
var myFunction = function (message) {
    console.log(message);
}
myFunction(hello)
// Hello word

Arguments

function myFunction() {
    console.log("Hello word");
}
myFunction()
// Hello word

Basic

Javascript : Function

Syntaxe

var myFunction = function () {
    return("Hello word");
}
console.log(myFunction());
// Hello word

Return

var myFunction = function (i, message) {
    console.log(arguments);
}
myFunction(10, "Hello word")
// { '0': 10, '1': 'Hello word' }

Arguments

Javascript : Function

Scopes

var message = "Hello word"
var myFunction = function () {
    console.log(message);
}
myFunction()
// Hello word

Variable are passing through anonymous function

var message = "Hello word"
var myFunction = function () {
   var mySecondFunction = function () {
      console.log(message);
   }
   mySecondFunction();
}
myFunction()
// Hello word

As long as you stay in the same file (= module)

var myFunction = function () {
    console.log(message);
}
var message = "Hello word"
myFunction()
// Hello word

Still works if variable message is set after

Javascript : Objects

var object1 = {};
var object2 = {"cat": {}, "dog": "wouf"};
var object3 = {cat: {}, dog: {}};
var object4 = {cat: {number:3, totalWeight: 21}, dog: {number:5, totalWeight: 104}};

Self declared

var object5 = { cat: { noise: function () { console.log("meow") } }
                , dog: { noise: function () { console.log("wouf") } }
              };
object5.cat.noise();
// meow

object5.lion = { noise: function () { console.log("grraou") };
object5.cat.noise();
// meow
object5.lion.noise();
// grraou

object5.cat.parent = object5;
object5.cat.parent.cat.parent.cat.noise();
// meow
console.log(object5);
// { cat: { noise: [Function], parent: [Circular] }, dog: { noise: [Function] } }

Javascript : Objects

var Animal = function () {
  var race;

  this.setRace = function (lRace) {
    race = lRace;
  };

  this.noise = function (m) {
    var	noise;
    if (race == 'cat') {
      noise = 'meow';
    } else if (race == 'dog') {
      noise = 'wouf';
    } else {
      noise = 'Error: Race need to be set';
    }

    console.log(noise);
  };
}

var animal = new Animal();
animal.setRace('cat')
animal.noise();

delete animal; // Only remove reference
animal = undefined;

new / delete

Javascript : Objects

var Animal = function (race) {
  this.noise = function () {
    var	noise;
    if (race == 'cat') {
      noise = 'meow';
    } else if (race == 'dog') {
      noise = 'wouf';
    } else {
      noise = 'Error: Race need to be set';
    }

    console.log(noise);
  };
}

var animal = new Animal('cat');
animal.noise();

delete animal;
animal = undefined;

constructor

Javascript : Objects

Heritage

Later ;-)

Javascript : Native method

String

var str = "good morning";
str.replace("morning", "after noon");
// good after noon

replace

var str = "good morning";
str.split(' ');
// [ 'good', 'norning' ]

replace

var str = "good morning";
str.indexOf("morning");
// 6
str.indexOf("o");
// 1

indexOf

You want more ? 
http://www.w3schools.com/jsref/jsref_obj_string.asp

Javascript : Native method

Array

var mArray = [1, 2, 3, "cat", "dog"];
// [ 1, 2, 3, 'cat', 'dog' ]

Create / push / pop / indexOf / splice

mArray.push("lion");
// [ 1, 2, 3, 'cat', 'dog', 'lion' ]

push

mArray.pop(); // return lion
// [ 1, 2, 3, 'cat', 'dog' ]

pop

mArray.splice(mArray.indexOf('cat'), 1);
// [ 1, 2, 3, 'dog' ]

indexOf / splice

Object

• instance
• map
• record
• array
  • list
  • stack

Naming

Variable

• parameter
• closure
• property

function

• constructor
• lambda
• method
• callback
• recursive

Let's train

power_iter / power_rec

javascript

heritage

Javascript : heritage

Remember

var cat = {
  message: "meow"
  , talk : function() {	console.log(message) }
};
console.log(cat.message); // meow
cat.talk(); // meow

Object inline declared

var Cat = function () {
  var message =	"meow";
  this.talk = function () {
    console.log(message);
  };
}
var cat	= new Cat();
console.log(cat.message); // undefined                                                                                                                    
cat.talk(); // meow     

Object self-declared

Javascript : heritage

Remember

var Cat = function () {
  var message =	"meow";
  this.talk = function () {
    console.log(message);
  };
}
var felix = new Cat();
var lili = new Cat();

console.log(felix == lili); // false

Each new create a new instance.

There are not sharing their value or method

Javascript : heritage

Constructor and prototype

var Cat = function () {};
console.log(Cat.prototype); // {}  
Cat.prototype.talk = function () { console.log("meow"); };

var felix = new Cat();
var lili = new Cat();

felix.talk(); lili.talk(); // meow meow    

console.log(felix.talk == lili.talk); // true   

Cat.prototype.talk = function () { console.log("graou"); }
felix.talk(); lili.talk(); // graou graou        

Create prototype

Instance share same prototype

If you change the prototype, both instances get the changement

Javascript : heritage

Constructor and prototype

felix.constructor.prototype.talk(); // graou

You can still access to the prototype

felix instanceof Cat; // true

Even if set a method, the instance is still from considering from the Object

felix.talk = function () { console.log("twit");	};
felix.talk(); lili.talk(); // twitt graou

But you can replace the prototype by set directly a method.

Javascript : heritage

Heritage overview

var Maincoon = function () {};
Maincoon.prototype = Cat.prototype;

Never do :

var Cat = function () {};
Cat.prototype.talk = function () {console.log("meow") };

var Maincoon = function () {};
for (var proto in Cat.prototype) {
  Maincoon.prototype[proto] = Cat.prototype[proto];
}
Maincoon.prototype.getWeight = function	() {
  console.log(12);
};

var symba = new Maincoon();
symba.talk();
symba.getWeight();

Copy prototype

Javascript : heritage

Heritage overview

var Cat = function () {};
Cat.prototype.talk = function () {console.log("meow") };

var Maincoon = function () {};
for (var proto in Cat.prototype) {
  Maincoon.prototype[proto] = Cat.prototype[proto];
}
Maincoon.prototype.getWeight = function () {
  console.log(12);
};

var symba = new Maincoon();
symba.talk();
symba.getWeight();

Cat.prototype.lick = function () { console.log("slurp !"); };
var cat = new Cat();
cat.lick(); // slurp !
symba.lick(); // TypeError: Object [object Object] has no method 'lick'

Hum, damned

console.log(symba instanceof Maincoon); // true
console.log(symba instanceof Cat); // false

Copy prototype : The limit !

Javascript : heritage

Heritage overview

var Cat = function () {};
Cat.prototype.talk = function () {console.log("meow") };

var Maincoon = function () {};
var Surrogate = function () {
  this.constructor = Maincoon;
};
Surrogate.prototype = Cat.prototype;
Maincoon.prototype = new Surrogate();
Maincoon.prototype.getWeight = function () {
  console.log(12);
};


var symba = new Maincoon();
symba.talk();
symba.getWeight();

Cat.prototype.lick = function () { console.log("slurp !"); };
var cat = new Cat();
cat.lick(); // slurp !
symba.lick(); // TypeError: Object [object Object] has no method 'lick'

Chained prototype

Javascript : heritage

Heritage overview

var Class = function() {
  this.initialize && this.initialize.apply(this, arguments);
};
Class.extend = function(childPrototype) { // defining a static method 'extend'
  var parent = this;
  var child = function() { // the child constructor is a call to its parent's
    return parent.apply(this, arguments);
  };
  child.extend = parent.extend; // adding the extend method to the child class
  var Surrogate = function() {}; // surrogate "trick" as seen previously
  Surrogate.prototype = parent.prototype;
  child.prototype = new Surrogate;
  for(var key in childPrototype){
    child.prototype[key] = childPrototype[key];
  }
  return child; // returning the child class
};

Chained prototype : real case

The same method is use by angular, backbone, ...

Javascript : heritage

Heritage overview

Chained prototype : real case

var Cat = Class.extend({
  initialize : function () {
    this.noise = 'meow';
  }
  , talk: function () { console.log(this.noise) }
});

var Maincoon = Cat.extend({
  getWeight: function () { console.log(12) }
});

var symba = new Maincoon();
symba.talk();
symba.getWeight();

var cat = new Cat();
console.log(Maincoon instanceof Cat);

Cat.prototype.lick = function () { console.log("slurp !"); };
symba.lick();

Let's train

merge_object

Day 2

Nodejs core & Libraries

Nodejs core & Libraries

• Runtime introduction: V8, callbacks, non-blocking IO, event-loop
• Module system: require, package.json, npm, node_modules
• EventEmitter
• Useful core modules
• Error handling: Exceptions, CPS, stack traces, try/catch, trycatch
• Asynchrony contracts: callbacks, promises and async generators
• Control-flow: stepup, async, q/bluebird
• Module lifetime: require, configure, initialize
• Assisted Nodeschool.io Workshops

NodeJS

2009 : Created by Ryan Dahl

NodeJS use V8 engine to execute the js code

2011 : NPM is created to publish and share libraries to the community

Windows work with on NodeJS to make it windows compliant

2012+ : Developpement of framework : Express.js, socket.io, ...

NodeJS : Technical

Threading : Node.js operates on a single thread, using non-blocking I/O calls, allowing it to support tens of thousands of concurrent connections without incurring the cost of thread context-switching

V8 is the JavaScript execution engine built for Google Chrome, open-sourced by Google in 2008. Written in C++, V8 compiles JavaScript source code to native machine code instead of interpreting it in real time.

npm is the pre-installed package manager for the Node.js server platform

Event Loop : Node.js registers itself with the operating system so that it is notified when a connection is made. When a connection is made, the operating system will issue a callback.

NodeJS

Callbacks

Nodejs : Callbacks

var callback = function () {
  console.log("Callback called");
}

setTimeout(callback, 1000);

var request = require('request');
console.log("Begin code");

var callback = function (error, response, body) {
  console.log("Awnser received, length : ", body.length);
  console.log(body.substr(0, 40));
};

request('http://www.google.com', callback);
console.log("Finish code");

Example 1

Example 2

NodeJS

 non-blocking IO

Blocking pathern

Download file 1
wait download finish
Download file 2
wait download finish

Download file 1
Download file 2
wait download finish file 1 and 2

Non-blocking pathern

NodeJS : Non-blocking IO

console.log("Begin code");

setInterval(function () {
  console.log("Bonjour");
}, 1000);

setInterval(function ()	{
  console.log("Hello");
}, 2000);

console.log("Finish code");

Example 1

NodeJS : Non-blocking IO

NodeJS : Event Loop

NodeJS is mono-thread !

NodeJS is synchrone !

And yes, NodeJS can handle millions of events

NodeJS : Event Loop

console.log("Begin code");
function tick() {
    console.log('tick');
}

setInterval(tick, 1000);
console.log('End code');

Example 1

console.log("Begin code");
setInterval(function () {
  console.log("tick");
}, 1000);

while (1) { };
console.log("End code");

Example 2

NodeJS : Event Loop

function asyncFake(data, callback) {        
    if(data === 'foo') callback(true);
    else callback(false);
}

asyncFake('bar', function(result) {
    // this callback is actually called synchronously!
});

Using callback != synchrone

V8 Event Loop is based on epool (man 2 epool)

• epool watch a fd
• The event loop check return (man 2 epool_wait)
• Asynchrone work only with fd 

Nodejs

 Module system

NodeJS :  Module system

Modules are libraries :

• Core library
• Community library
• Code library

Project module are manage by package.json

$ROOT/package.json

NodeJS :  Module system

Modules are libraries :

• Core library
• Community library
• Code library

Project module are manage by package.json

$ROOT/package.json

First http server

Bash $> node test_2.js

test_2.js

var http = require('http');

console.log("Set new http server");
var server = http.createServer(function(req, res) {
  res.writeHead(200);
  res.end('Good morning !');
});
server.listen(8080);
console.log("Server listening on http://localhost:8080");

Take your web browser and test it : http://localhost:8080

First use

Read-Eval-Print-Loop (REPL)

Bash $> node
> console.log("hello word");
hello word
undefined

Bash $> node
> var string = "hello world"
undefined
> console.log(string);
hello world
undefined

"dependencies": {
    "eventemitter3": "^1.1.1"
  }