JavaScript

freecodecamp

JavaScript

JavaScript

let duck = {
  name: "Aflac",
  numLegs: 2
};
 

name Aflac numLegs 2

let duck = {
  name: "Aflac",
  numLegs: 2
};
console.log(duck.name);
 

method

duck

let duck = {
  name: "Aflac",
  numLegs: 2,
  sayName: function() {return "The name of this duck is " + duck.name + ".";}
};
duck.sayName();
 

this

sayName: function() {return "The name of this duck is " + duck.name + ".";}
 

let duck = {
  name: "Aflac",
  numLegs: 2,
  sayName: function() {return "The name of this duck is " + this.name + ".";}
};
 

this

duck

function Bird() {
  this.name = "Albert";
  this.color = "blue";
  this.numLegs = 2;
}
 

Albert blue 2

• constructors

• this
  this

Bird

function Bird() {
  this.name = "Albert";
  this.color  = "blue";
  this.numLegs = 2;
}

let blueBird = new Bird();
 

this

JavaScript Bird new

blueBird.name;
blueBird.color;
blueBird.numLegs;
 

blueBird.name = 'Elvira';
blueBird.name;
 

let swan = new Bird();
swan.name = "Carlos";
swan.color = "white";
 

Bird

function Bird(name, color) {
  this.name = name;
  this.color = color;
  this.numLegs = 2;
}
 

Bruce red numLegs 2

cardinal.name
cardinal.color
cardinal.numLegs
 

JavaScript

instanceof

instance JavaScript

let Bird = function(name, color) {
  this.name = name;
  this.color = color;
  this.numLegs = 2;
}

let crow = new Bird("Alexis", "black");

crow instanceof Bird;
 

let canary = {
  name: "Mildred",
  color: "Yellow",
  numLegs: 2
};

canary instanceof Bird;
 

function Bird(name) {
  this.name  = name;
  this.numLegs = 2;
}

let duck = new Bird("Donald");
let canary = new Bird("Tweety");
 

let ownProps = [];

for (let property in duck) {
  if(duck.hasOwnProperty(property)) {
    ownProps.push(property);
  }
}

console.log(ownProps);
 

Bird.prototype.numLegs = 2;
 

Bird numLegs

console.log(duck.numLegs);
console.log(canary.numLegs);
 

" " JavaScript

:

function Bird(name) {
  this.name = name; //own property
}

Bird.prototype.numLegs = 2;//prototype property

let duck = new Bird("Donald");
 

let ownProps = [];
let prototypeProps = [];

for (let property in duck) {
  if(duck.hasOwnProperty(property)) {
    ownProps.push(property);
  } else {
    prototypeProps.push(property);
  }
}

console.log(ownProps);
console.log(prototypeProps);
 

let duck = new Bird();
let beagle = new Dog();

console.log(duck.constructor === Bird); 
console.log(beagle.constructor === Dog);
 

function joinBirdFraternity(candidate) {
  if (candidate.constructor === Bird) {
    return true;
  } else {
    return false;
  }
}
 

constructor instanceof

Bird.prototype.numLegs = 2;
 

Bird.prototype.eat = function() {
  console.log("nom nom nom");
}

Bird.prototype.describe = function() {
  console.log("My name is " + this.name);
}
 

Bird.prototype = {
  numLegs: 2, 
  eat: function() {
    console.log("nom nom nom");
  },
  describe: function() {
    console.log("My name is " + this.name);
  }
};
 

constructor

duck.constructor === Bird;
duck.constructor === Object;
duck instanceof Bird;
 

Bird.prototype = {
  constructor: Bird,
  numLegs: 2,
  eat: function() {
    console.log("nom nom nom");
  },
  describe: function() {
    console.log("My name is " + this.name); 
  }
};
 

function Bird(name) {
  this.name = name;
}

let duck = new Bird("Donald");
 

Bird.prototype.isPrototypeOf(duck);
 

JavaScript

function Bird(name) {
  this.name = name;
}

typeof Bird.prototype;
 

Object.prototype.isPrototypeOf(Bird.prototype);
 

let duck = new Bird("Donald");
duck.hasOwnProperty("name"); 
 

Don't Repeat Yourself DRY

Bird.prototype = {
  constructor: Bird,
  describe: function() {
    console.log("My name is " + this.name);
  }
};

Dog.prototype = {
  constructor: Dog,
  describe: function() {
    console.log("My name is " + this.name);
  }
};
 

DRY

function Animal() { };

Animal.prototype = {
  constructor: Animal, 
  describe: function() {
    console.log("My name is " + this.name);
  }
};
 

function Animal() { }

Animal.prototype.eat = function() {
  console.log("nom nom nom");
};
 

new

let animal = new Animal();
 

let animal = Object.create(Animal.prototype);
 

animal.eat();
animal instanceof Animal;
 

Bird.prototype = Object.create(Animal.prototype);
 

let duck = new Bird("Donald");
duck.eat();
 

function Bird() { }
Bird.prototype = Object.create(Animal.prototype);
let duck = new Bird();
duck.constructor
 

Bird.prototype.constructor = Bird;
duck.constructor
 

function Animal() { }
Animal.prototype.eat = function() {
  console.log("nom nom nom");
};
function Bird() { }
Bird.prototype = Object.create(Animal.prototype);
Bird.prototype.constructor = Bird;
 

Bird.prototype.fly = function() {
  console.log("I'm flying!");
};
 

let duck = new Bird();
duck.eat();
duck.fly();
 

ChildObject.prototype = Object.create(ParentObject.prototype);
 

ChildObject.prototype.methodName = function() {...};
 

-

function Animal() { }
Animal.prototype.eat = function() {
  return "nom nom nom";
};
function Bird() { }

Bird.prototype = Object.create(Animal.prototype);

Bird.prototype.eat = function() {
  return "peck peck peck";
};
 

JavaScript

1. duck
   =>
   eat()
2. Bird
   =>
   eat()
   =>
3. Animal
   =>
   eat()
   JavaScript
4. Object
   =>
   JavaScript

Mixin

mixins mixin

let flyMixin = function(obj) {
  obj.fly = function() {
    console.log("Flying, wooosh!");
  }
};
 

let bird = {
  name: "Donald",
  numLegs: 2
};

let plane = {
  model: "777",
  numPassengers: 524
};

flyMixin(bird);
flyMixin(plane)
 

bird.fly();
plane.fly();
 

bird name bird

bird.name = "Duffy";
 

name

function Bird() {
  let hatchedEgg = 10;

  this.getHatchedEggCount = function() { 
    return hatchedEgg;
  };
}
let ducky = new Bird();
ducky.getHatchedEggCount();
 

JavaScript

IIFE

JavaScript

(function () {
  console.log("Chirp, chirp!");
})();
 

immediately invoked function expression) IIFE

IIFE

IIFE module mixin

function flyMixin(obj) {
  obj.fly = function() {
    console.log("Flying, wooosh!");
  };
}

 

mixin

let motionModule = (function () {
  return {
    flyMixin: function(obj) {
      obj.fly = function() {
        console.log("Flying, wooosh!");
      };
    }
  }
})();
 

IIFE

mixin module

motionModule.flyMixin(duck);
duck.fly();