practice


<!DOCTYPE HTML>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Object Oriented JavaScript</title>
</head>
<body>

<script type="text/javascript">

// A basic JavaScript object with properties and a method
var customer = {
  name: 'Tom Smith',
  speak: function(){

    // this allows you to reference a specific objects value
    // without knowing the objects name
    return "My name is " + this.name;
  },
  // Objects can contain other objects
  address: {
    street: '123 Main St',
    city: 'Pittsburgh',
    state: 'PA'
  }
};

document.write(customer.speak()+ "<br />");

// You access properties and object properties like this
document.write(customer.name + " lives at " + customer.address.street + "<br />");

// You can add properties
customer.address.country = "US";

document.write(customer.address.country + "<br />");

// Creating multiple objects of the same type with Constructor
// Functions. Constructors provide the functions that classes
// provide in other languages
function Person(name, street) {

  // this allows us to refer to an object even though we
  // don't know its name before it is created
  this.name = name;
  this.street = street;
  this.info = function(){
    return "My name is " + this.name + " and I live on " + this.street;
  }
}

// You call constructor functions with new
var bobSmith = new Person("Bob Smith", "234 Main St");

document.write(bobSmith.info() + "<br />");

// instanceof tells you if an object is of a certain type
document.write("Bob is a person : " + (bobSmith instanceof Person) + "<br />");

// You can pass an object to a function and change values
function changeName(person){
  person.name = "Sue Smith";
}
changeName(bobSmith);
document.write("Bob became " + bobSmith.name + "<br />");

// Objects are only equal if they reference the same object
var person1 = new Person("Paul", "123 Main");
var person2 = new Person("Paul", "123 Main");

document.write("Are they equal " + (person1 == person2) + "<br />");

// ---------- PROTOTYPE ----------
// Every function has a prototype property that contains an object
// You can add properties and methods to the prototype object
// and then when you call for them to execute they are used
// just as if they belonged to the object

function getSum(num1, num2){
  return num1 + num2;
}

// Get the number of function arguments
document.write("Num of arguments : " + getSum.length + "<br />");

// You can add properties and methods to this object
function Mammal(name){
  this.name = name;
  this.getInfo = function(){
    return "The mammals name is " + this.name;
  }
}

// Use prototype to add a property
Mammal.prototype.sound = "Grrrrr";

// Use it to add a method
Mammal.prototype.makeSound = function() {
  return this.name + " says " + this.sound;
};

var grover = new Mammal("Grover");

document.write(grover.makeSound() + "<br />");

// List all properties of an object
for( var prop in grover){
  document.write(prop + " : " + grover[prop] + "<br />");
}

// Check which property belongs to prototype vs. the object grover
document.write("name Property of Grover : " + grover.hasOwnProperty("name") + "<br />");

document.write("sound Property of Grover : " + grover.hasOwnProperty("sound") + "<br />");

// You can add methods to built in JS objects
Array.prototype.inArray = function inArray(value){
  for(i = 0; i < this.length; i++){
    if(this[i] === value){
      return true;
    }
  }
  return false;
}

var sampArray = [1,2,3,4,5];

document.write("3 in array : " + sampArray.inArray(3) + "<br />");

// ---------- PRIVATE PROPERTIES ----------
// All properties in an object are public in that any function
// can modify or delete these properties.
// You can make properties private by declaring them as
// variables in a constructor

function SecretCode(){
  // This value can't be accessed directly
  var secretNum = 78;

  // This function can access secretNum
  this.guessNum = function(num){
    if(num > 78){
      return "Lower";
    } else if(num < 78){
      return "Higher";
    } else {
      return "You Guessed It";
    }
  }
}

var secret = new SecretCode();

// Returns undefined
document.write("Value of secretNum : " + secret.secretNum + "<br />");

document.write("Is 70 the number : " + secret.guessNum(70) + "<br />");

// Even if we add another function it can't access the secretNum
SecretCode.prototype.getSecret = function(){
  return this.secretNum;
}

document.write("The secret number is " + secret.getSecret() + "<br />");

// ---------- GETTERS AND SETTERS ----------
// Getters and Setters can protect data, or provide useful
// ways to set its value
// I'll show you a bunch of getters and setters you may come
// in contact with
var address = {
    street: "No Street",
    city: "No City",
    state: "No State",

    // Provides styled data all at once
    get getAddress() {
        return this.street + ", " + this.city + ", " + this.state;
    },

    // Allows the user to set 3 values with 1
    set setAddress (theAddress) {
        var parts = theAddress.toString().split(", ");
        this.street = parts[0] || '';
        this.city = parts[1] || '';
        this.state = parts[2] || '';
    }
}

address.setAddress = "123 Main St, Pittsburgh, PA";
document.write("Address : " + address.getAddress + "<br />");
document.write("City : " + address.city + "<br />");

// ---------- CONSTRUCTOR GETTERS AND SETTERS ----------
// Still used even though it is (Deprecated)
function Coordinates(){
  this.latitude = 0.0;
  this.longitude = 0.0;
}

// Define the getter with the prototype to assign it to with
// the property name and the getter function
Object.__defineGetter__.call(Coordinates.prototype, "getCoords", function(){
    return "Lat : " + this.latitude + " Long: " + this.longitude;
});

// Define the setter with the prototype to assign it to with
// the property name and the setter function
Object.__defineSetter__.call(Coordinates.prototype, "setCoords", function(coords){
    var parts = coords.toString().split(", ");
    this.latitude = parts[0] || '';
    this.longitude = parts[1] || '';
});

var testCoords = new Coordinates();

testCoords.setCoords = "40.71, 74.00";

document.write("Coordinates : " + testCoords.getCoords + "<br />");

// ---------- GETTERS AND SETTERS WITH DEFINEPROPERTY ----------
function Point(){
  this.xPos = 0;
  this.yPos = 0;
}

// Use defineProperty to set getters and setters
// Pass the prototype to attach to along with the property name
// and define the functions to associate with get and set
Object.defineProperty(Point.prototype, "pointPos", {
  get: function(){
    return "X: " + this.xPos + " Y: " + this.yPos;
  },
  set: function(thePoint){
    var parts = thePoint.toString().split(", ");
    this.xPos = parts[0] || '';
    this.yPos = parts[1] || '';
  }
});

var aPoint = new Point();

aPoint.pointPos = "100, 200";

document.write("Point Position : " + aPoint.pointPos + "<br />");

// ---------- ECMASCRIPT 5.1 GETTERS AND SETTERS ----------

var Circle = function (radius) {
    this._radius  = radius;
};

Circle.prototype = {
    set radius(radius) { this._radius = radius; },
    get radius() { return this._radius; },
    get area() { return Math.PI * (this._radius * this._radius); }
};
var circ = new Circle(10);

circ.radius = 15;

document.write("A circle with radius " + circ.radius + " has an area of " + circ.area.toFixed(2) + "<br />");

// ---------- INHERITANCE ----------
// When we ask for a property if it isn't found in the main object
// then it is searched for in the prototype object. We are able
// to inherit methods and variables from any object in a
// chain of objects.

function Animal(){
  this.name = "Animal";

  // toString is a function in the main Object that every
  // object inherits from
  this.toString = function() {
    return "My name is : " + this.name;
  };
}

function Canine(){
  this.name = "Canine";
}

function Wolf(){
  this.name = "Wolf";
}

// Overwrite the prototype for Canine and Wolf
Canine.prototype = new Animal();
Wolf.prototype = new Canine();

// After you overwrite prototype its constructor points to the
// main object object so you have to reset the constructor after
Canine.prototype.constructor = Canine;
Wolf.prototype.constructor = Wolf;

var arcticWolf = new Wolf();

// Wolf inherits toString from Animal
document.write(arcticWolf.toString() + "<br />");

document.write("Wolf instance of Animal : " + (arcticWolf instanceof Animal) + "<br />");

// Properties added to any object in the chain is inherited
Animal.prototype.sound = "Grrrrr";

Animal.prototype.getSound = function(){
  return this.name + " says " + this.sound;
}

Canine.prototype.sound = "Woof";
Wolf.prototype.sound = "Grrrr Wooof";

document.write(arcticWolf.getSound() + "<br />");

// More often then not it makes more sense to just inherit the
// prototype to speed up the lookup process

function Rodent(){
  this.name = "Rodent";
}

function Rat(){
  this.name = "Rat";
}

Rodent.prototype = new Animal();
Rat.prototype = Rodent.prototype;
Rodent.prototype.constructor = Rodent;
Rat.prototype.constructor = Rat;

var caneRat = new Rat();

// Wolf inherits toString from Animal
document.write(caneRat.toString() + "<br />");

// ---------- INTERMEDIATE FUNCTION INHERITANCE ----------
function extend(Child, Parent){
  var Temp = function(){};

  Temp.prototype = Parent.prototype;

  Child.prototype = new Temp();

  Child.prototype.constructor = Child;

}

function Deer(){
  this.name = "Deer";
  this.sound = "Snort";
}

extend(Deer, Animal);

var elk = new Deer();

document.write(elk.getSound() + "<br />");

// ---------- CALL PARENT METHODS ----------
function Vehicle(name) {
  this.name = "Vehicle"
}

// Functions for the parent object
Vehicle.prototype = {
  drive: function(){
    return this.name + " drives forward";
  },
  stop: function(){
    return this.name + " stops";
  }
}

function Truck(name) {
  this.name = name
}

// Inherit from Vehicle
Truck.prototype = new Vehicle();
Truck.prototype.constructor = Truck;

// Overwrite drive parent method
Truck.prototype.drive = function(){

  // Call the parent method with apply so that the parent
  // method can access the Trucks name value
  var driveMsg = Vehicle.prototype.drive.apply(this);
  return driveMsg += " through a field";
}

var jeep = new Truck("Jeep");

document.write(jeep.drive() + "<br />");

document.write(jeep.stop() + "<br />");

// ---------- SINGLETON PATTERN ----------
// Singletons are used when you only ever want 1 object to
// be created
// Let's say you want to create a game character with fixed
// stats
function Hero(name){

  // Check if the object exists
  if(typeof Hero.instance === 'object'){

    // If it does return it
    return Hero.instance;
  }

  // if it doesn't then create the hero
  this.name = name;
  Hero.instance = this;

  return this;
}

var derekHero = new Hero("Derek");
document.write("Are hero is " + derekHero.name + "<br />");

// This won't change the name to Paul
var paulHero = new Hero("Paul");
document.write("Are hero is " + paulHero.name + "<br />");

// ---------- FACTORY PATTERN ----------
// The factory pattern can be used to generate different
// objects on request

function Sword(desc){
  this.weaponType = "Sword";
  this.metal = desc.metal || "Steel";
  this.style = desc.style || "Longsword";
  this.hasMagic = desc.hasMagic || false;
}

function Bow(desc){
  this.weaponType = "Bow";
  this.material = desc.material || "Wood";
  this.style = desc.style || "Longbow";
  this.hasMagic = desc.hasMagic || false;
}

function WeaponFactory(){};

WeaponFactory.prototype.makeWeapon = function(desc){
  var weaponClass = null;

  if(desc.weaponType === "Sword"){
    weaponClass = Sword;
  } else if (desc.weaponType === "Bow"){
    weaponClass = Bow;
  } else {
    return false;
  }

  return new weaponClass(desc);

}

var myWeaponFact = new WeaponFactory();

var bladeFist = myWeaponFact.makeWeapon({
  weaponType: "Sword",
  metal: "Dark Iron",
  style: "Scythe",
  hasMagic: true
});

document.write(bladeFist.weaponType + " of type " + bladeFist.style + " crafted from " + bladeFist.metal + "<br />");

// ---------- DECORATOR PATTERN ----------
// The decorator pattern allows you alter an object at run time
function Pizza(price){
  this.price = price || 10;
}

Pizza.prototype.getPrice = function(){
  return this.price;
}

function ExtraCheese(pizza){
  var prevPrice = pizza.price;

  pizza.price = prevPrice + 1;
}

var myPizza = new Pizza(10);

ExtraCheese(myPizza);

document.write("Cost of Pizza : $" + myPizza.price + "<br />");

// ---------- OBSERVER PATTERN ----------
// A single object notifies many objects (observers) when a
// state change occurs
var Observable = function() {
    this.subscribers = [];
}

Observable.prototype = {
    subscribe: function(subscriber) {
        // Add the subscriber object to the list
        this.subscribers.push(subscriber);
    },
    unsubscribe: function(unsubscriber) {

        // Cycle through the subscriber array and delete
        // the unsubscriber
        for (i = 0; i < this.subscribers.length; i++) {
            if (this.subscribers[i] === unsubscriber) {
                this.subscribers.splice(i, 1);

                // We assume it only subscribed once so we
                // leave after it is found
                return unsubscriber.name;
            }
        }
    },
    publish: function(data) {

        // Cycle through all subscribers and send them the update
        for (i = 0; i < this.subscribers.length; i++) {
            this.subscribers[i].receiveData(data);
        }
    }
};

var OrganFanny = {
  name: "Organ Fanny",
  receiveData: function(data){
    document.write(this.name + " received your info : " + data + "<br />");
  }
}

var BoldmanYaks = {
  name: "Boldman Yaks",
    receiveData: function(data){
      document.write(this.name + " received your info : " + data + "<br />");
    }
}

// Add subscribers and alert them
observable = new Observable();
observable.subscribe(OrganFanny);
observable.subscribe(BoldmanYaks);
observable.publish('IBM at $145.30');

document.write(observable.unsubscribe(OrganFanny) + " Unsubscribed<br />");

observable.publish('IBM at $145.33');


</script>

</body>
</html>
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<!DOCTYPE HTML>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Object Oriented JavaScript</title>
</head>
<body>
 
<script type="text/javascript">
 
// A basic JavaScript object with properties and a method
var customer = {
  name: 'Tom Smith',
  speak: function(){
 
    // this allows you to reference a specific objects value
    // without knowing the objects name
    return "My name is " + this.name;
  },
  // Objects can contain other objects
  address: {
    street: '123 Main St',
    city: 'Pittsburgh',
    state: 'PA'
  }
};
 
document.write(customer.speak()+ "<br />");
 
// You access properties and object properties like this
document.write(customer.name + " lives at " + customer.address.street + "<br />");
 
// You can add properties
customer.address.country = "US";
 
document.write(customer.address.country + "<br />");
 
// Creating multiple objects of the same type with Constructor
// Functions. Constructors provide the functions that classes
// provide in other languages
function Person(name, street) {
 
  // this allows us to refer to an object even though we
  // don't know its name before it is created
  this.name = name;
  this.street = street;
  this.info = function(){
    return "My name is " + this.name + " and I live on " + this.street;
  }
}
 
// You call constructor functions with new
var bobSmith = new Person("Bob Smith", "234 Main St");
 
document.write(bobSmith.info() + "<br />");
 
// instanceof tells you if an object is of a certain type
document.write("Bob is a person : " + (bobSmith instanceof Person) + "<br />");
 
// You can pass an object to a function and change values
function changeName(person){
  person.name = "Sue Smith";
}
changeName(bobSmith);
document.write("Bob became " + bobSmith.name + "<br />");
 
// Objects are only equal if they reference the same object
var person1 = new Person("Paul", "123 Main");
var person2 = new Person("Paul", "123 Main");
 
document.write("Are they equal " + (person1 == person2) + "<br />");
 
// ---------- PROTOTYPE ----------
// Every function has a prototype property that contains an object
// You can add properties and methods to the prototype object
// and then when you call for them to execute they are used
// just as if they belonged to the object
 
function getSum(num1, num2){
  return num1 + num2;
}
 
// Get the number of function arguments
document.write("Num of arguments : " + getSum.length + "<br />");
 
// You can add properties and methods to this object
function Mammal(name){
  this.name = name;
  this.getInfo = function(){
    return "The mammals name is " + this.name;
  }
}
 
// Use prototype to add a property
Mammal.prototype.sound = "Grrrrr";
 
// Use it to add a method
Mammal.prototype.makeSound = function() {
  return this.name + " says " + this.sound;
};
 
var grover = new Mammal("Grover");
 
document.write(grover.makeSound() + "<br />");
 
// List all properties of an object
for( var prop in grover){
  document.write(prop + " : " + grover[prop] + "<br />");
}
 
// Check which property belongs to prototype vs. the object grover
document.write("name Property of Grover : " + grover.hasOwnProperty("name") + "<br />");
 
document.write("sound Property of Grover : " + grover.hasOwnProperty("sound") + "<br />");
 
// You can add methods to built in JS objects
Array.prototype.inArray = function inArray(value){
  for(i = 0; i < this.length; i++){
    if(this[i] === value){
      return true;
    }
  }
  return false;
}
 
var sampArray = [1,2,3,4,5];
 
document.write("3 in array : " + sampArray.inArray(3) + "<br />");
 
// ---------- PRIVATE PROPERTIES ----------
// All properties in an object are public in that any function
// can modify or delete these properties.
// You can make properties private by declaring them as
// variables in a constructor
 
function SecretCode(){
  // This value can't be accessed directly
  var secretNum = 78;
 
  // This function can access secretNum
  this.guessNum = function(num){
    if(num > 78){
      return "Lower";
    } else if(num < 78){
      return "Higher";
    } else {
      return "You Guessed It";
    }
  }
}
 
var secret = new SecretCode();
 
// Returns undefined
document.write("Value of secretNum : " + secret.secretNum + "<br />");
 
document.write("Is 70 the number : " + secret.guessNum(70) + "<br />");
 
// Even if we add another function it can't access the secretNum
SecretCode.prototype.getSecret = function(){
  return this.secretNum;
}
 
document.write("The secret number is " + secret.getSecret() + "<br />");
 
// ---------- GETTERS AND SETTERS ----------
// Getters and Setters can protect data, or provide useful
// ways to set its value
// I'll show you a bunch of getters and setters you may come
// in contact with
var address = {
    street: "No Street",
    city: "No City",
    state: "No State",
 
    // Provides styled data all at once
    get getAddress() {
        return this.street + ", " + this.city + ", " + this.state;
    },
 
    // Allows the user to set 3 values with 1
    set setAddress (theAddress) {
        var parts = theAddress.toString().split(", ");
        this.street = parts[0] || '';
        this.city = parts[1] || '';
        this.state = parts[2] || '';
    }
}
 
address.setAddress = "123 Main St, Pittsburgh, PA";
document.write("Address : " + address.getAddress + "<br />");
document.write("City : " + address.city + "<br />");
 
// ---------- CONSTRUCTOR GETTERS AND SETTERS ----------
// Still used even though it is (Deprecated)
function Coordinates(){
  this.latitude = 0.0;
  this.longitude = 0.0;
}
 
// Define the getter with the prototype to assign it to with
// the property name and the getter function
Object.__defineGetter__.call(Coordinates.prototype, "getCoords", function(){
    return "Lat : " + this.latitude + " Long: " + this.longitude;
});
 
// Define the setter with the prototype to assign it to with
// the property name and the setter function
Object.__defineSetter__.call(Coordinates.prototype, "setCoords", function(coords){
    var parts = coords.toString().split(", ");
    this.latitude = parts[0] || '';
    this.longitude = parts[1] || '';
});
 
var testCoords = new Coordinates();
 
testCoords.setCoords = "40.71, 74.00";
 
document.write("Coordinates : " + testCoords.getCoords + "<br />");
 
// ---------- GETTERS AND SETTERS WITH DEFINEPROPERTY ----------
function Point(){
  this.xPos = 0;
  this.yPos = 0;
}
 
// Use defineProperty to set getters and setters
// Pass the prototype to attach to along with the property name
// and define the functions to associate with get and set
Object.defineProperty(Point.prototype, "pointPos", {
  get: function(){
    return "X: " + this.xPos + " Y: " + this.yPos;
  },
  set: function(thePoint){
    var parts = thePoint.toString().split(", ");
    this.xPos = parts[0] || '';
    this.yPos = parts[1] || '';
  }
});
 
var aPoint = new Point();
 
aPoint.pointPos = "100, 200";
 
document.write("Point Position : " + aPoint.pointPos + "<br />");
 
// ---------- ECMASCRIPT 5.1 GETTERS AND SETTERS ----------
 
var Circle = function (radius) {
    this._radius  = radius;
};
 
Circle.prototype = {
    set radius(radius) { this._radius = radius; },
    get radius() { return this._radius; },
    get area() { return Math.PI * (this._radius * this._radius); }
};
var circ = new Circle(10);
 
circ.radius = 15;
 
document.write("A circle with radius " + circ.radius + " has an area of " + circ.area.toFixed(2) + "<br />");
 
// ---------- INHERITANCE ----------
// When we ask for a property if it isn't found in the main object
// then it is searched for in the prototype object. We are able
// to inherit methods and variables from any object in a
// chain of objects.
 
function Animal(){
  this.name = "Animal";
 
  // toString is a function in the main Object that every
  // object inherits from
  this.toString = function() {
    return "My name is : " + this.name;
  };
}
 
function Canine(){
  this.name = "Canine";
}
 
function Wolf(){
  this.name = "Wolf";
}
 
// Overwrite the prototype for Canine and Wolf
Canine.prototype = new Animal();
Wolf.prototype = new Canine();
 
// After you overwrite prototype its constructor points to the
// main object object so you have to reset the constructor after
Canine.prototype.constructor = Canine;
Wolf.prototype.constructor = Wolf;
 
var arcticWolf = new Wolf();
 
// Wolf inherits toString from Animal
document.write(arcticWolf.toString() + "<br />");
 
document.write("Wolf instance of Animal : " + (arcticWolf instanceof Animal) + "<br />");
 
// Properties added to any object in the chain is inherited
Animal.prototype.sound = "Grrrrr";
 
Animal.prototype.getSound = function(){
  return this.name + " says " + this.sound;
}
 
Canine.prototype.sound = "Woof";
Wolf.prototype.sound = "Grrrr Wooof";
 
document.write(arcticWolf.getSound() + "<br />");
 
// More often then not it makes more sense to just inherit the
// prototype to speed up the lookup process
 
function Rodent(){
  this.name = "Rodent";
}
 
function Rat(){
  this.name = "Rat";
}
 
Rodent.prototype = new Animal();
Rat.prototype = Rodent.prototype;
Rodent.prototype.constructor = Rodent;
Rat.prototype.constructor = Rat;
 
var caneRat = new Rat();
 
// Wolf inherits toString from Animal
document.write(caneRat.toString() + "<br />");
 
// ---------- INTERMEDIATE FUNCTION INHERITANCE ----------
function extend(Child, Parent){
  var Temp = function(){};
 
  Temp.prototype = Parent.prototype;
 
  Child.prototype = new Temp();
 
  Child.prototype.constructor = Child;
 
}
 
function Deer(){
  this.name = "Deer";
  this.sound = "Snort";
}
 
extend(Deer, Animal);
 
var elk = new Deer();
 
document.write(elk.getSound() + "<br />");
 
// ---------- CALL PARENT METHODS ----------
function Vehicle(name) {
  this.name = "Vehicle"
}
 
// Functions for the parent object
Vehicle.prototype = {
  drive: function(){
    return this.name + " drives forward";
  },
  stop: function(){
    return this.name + " stops";
  }
}
 
function Truck(name) {
  this.name = name
}
 
// Inherit from Vehicle
Truck.prototype = new Vehicle();
Truck.prototype.constructor = Truck;
 
// Overwrite drive parent method
Truck.prototype.drive = function(){
 
  // Call the parent method with apply so that the parent
  // method can access the Trucks name value
  var driveMsg = Vehicle.prototype.drive.apply(this);
  return driveMsg += " through a field";
}
 
var jeep = new Truck("Jeep");
 
document.write(jeep.drive() + "<br />");
 
document.write(jeep.stop() + "<br />");
 
// ---------- SINGLETON PATTERN ----------
// Singletons are used when you only ever want 1 object to
// be created
// Let's say you want to create a game character with fixed
// stats
function Hero(name){
 
  // Check if the object exists
  if(typeof Hero.instance === 'object'){
 
    // If it does return it
    return Hero.instance;
  }
 
  // if it doesn't then create the hero
  this.name = name;
  Hero.instance = this;
 
  return this;
}
 
var derekHero = new Hero("Derek");
document.write("Are hero is " + derekHero.name + "<br />");
 
// This won't change the name to Paul
var paulHero = new Hero("Paul");
document.write("Are hero is " + paulHero.name + "<br />");
 
// ---------- FACTORY PATTERN ----------
// The factory pattern can be used to generate different
// objects on request
 
function Sword(desc){
  this.weaponType = "Sword";
  this.metal = desc.metal || "Steel";
  this.style = desc.style || "Longsword";
  this.hasMagic = desc.hasMagic || false;
}
 
function Bow(desc){
  this.weaponType = "Bow";
  this.material = desc.material || "Wood";
  this.style = desc.style || "Longbow";
  this.hasMagic = desc.hasMagic || false;
}
 
function WeaponFactory(){};
 
WeaponFactory.prototype.makeWeapon = function(desc){
  var weaponClass = null;
 
  if(desc.weaponType === "Sword"){
    weaponClass = Sword;
  } else if (desc.weaponType === "Bow"){
    weaponClass = Bow;
  } else {
    return false;
  }
 
  return new weaponClass(desc);
 
}
 
var myWeaponFact = new WeaponFactory();
 
var bladeFist = myWeaponFact.makeWeapon({
  weaponType: "Sword",
  metal: "Dark Iron",
  style: "Scythe",
  hasMagic: true
});
 
document.write(bladeFist.weaponType + " of type " + bladeFist.style + " crafted from " + bladeFist.metal + "<br />");
 
// ---------- DECORATOR PATTERN ----------
// The decorator pattern allows you alter an object at run time
function Pizza(price){
  this.price = price || 10;
}
 
Pizza.prototype.getPrice = function(){
  return this.price;
}
 
function ExtraCheese(pizza){
  var prevPrice = pizza.price;
 
  pizza.price = prevPrice + 1;
}
 
var myPizza = new Pizza(10);
 
ExtraCheese(myPizza);
 
document.write("Cost of Pizza : $" + myPizza.price + "<br />");
 
// ---------- OBSERVER PATTERN ----------
// A single object notifies many objects (observers) when a
// state change occurs
var Observable = function() {
    this.subscribers = [];
}
 
Observable.prototype = {
    subscribe: function(subscriber) {
        // Add the subscriber object to the list
        this.subscribers.push(subscriber);
    },
    unsubscribe: function(unsubscriber) {
 
        // Cycle through the subscriber array and delete
        // the unsubscriber
        for (i = 0; i < this.subscribers.length; i++) {
            if (this.subscribers[i] === unsubscriber) {
                this.subscribers.splice(i, 1);
 
                // We assume it only subscribed once so we
                // leave after it is found
                return unsubscriber.name;
            }
        }
    },
    publish: function(data) {
 
        // Cycle through all subscribers and send them the update
        for (i = 0; i < this.subscribers.length; i++) {
            this.subscribers[i].receiveData(data);
        }
    }
};
 
var OrganFanny = {
  name: "Organ Fanny",
  receiveData: function(data){
    document.write(this.name + " received your info : " + data + "<br />");
  }
}
 
var BoldmanYaks = {
  name: "Boldman Yaks",
    receiveData: function(data){
      document.write(this.name + " received your info : " + data + "<br />");
    }
}
 
// Add subscribers and alert them
observable = new Observable();
observable.subscribe(OrganFanny);
observable.subscribe(BoldmanYaks);
observable.publish('IBM at $145.30');
 
document.write(observable.unsubscribe(OrganFanny) + " Unsubscribed<br />");
 
observable.publish('IBM at $145.33');
 
 
</script>
 
</body>
</html>