Animal.js #js

Animal.js

/**
 * ES6 Classes
 * Notes:
 *  - instead of adding methods to the prototype
 *    can add them directly to class.
 */
class Animal {
  constructor(name, age) {
    this._name = name;
    this._age = age;
  }
  get name() {
    return this._name;
  }
  get age() {
    return this._age;
  }

  eat() {

  }

  sleep() {

  }
}

// Extending classes
class Dog extends Animal {
  constructor(name, age, breed) {
    super(name,age); // equivalent to Animal.call(this, name, age);
    this.breed = breed;
  }
}

/**
 * Constructor Function without prototype
 * Notes:
 *  - inheriting methods from another object
 *  - Exclusion of new keyword
 *  */
const animalMethods = {
  eat(amount) {
    console.log(`${this.name} is eating.`)
    this.energy += amount;
  }
  play() {
    console.log(`${this.name} is playing`)
  }
}

function Animal(name, energy) {
  let animal = Object.create(animalMethods);
  animal.name = name;
  animal.age = age;
  animal.sleep = function(energy) {
    console.log('sleeping')
  }

  return animal;
}

// notice the exclusion of new keyword.
const snoop = Animal('snoop', 7);

/**
 * Constructor Function using prototype
 * Notes:
 *  - Using prototype
 *  - Exclusion of new keyword
 *  */
function Animal(name, energy) {
  let animal = Object.create(Animal.prototype);
  animal.name = name;
  animal.energy = energy;

  return animal;
}

Animal.prototype.eat = function(amount) {
  console.log(`${this.name} is eating.`)
  this.energy += amount;
}

// notice the exclusion of new keyword.
const snoop = Animal('snoop', 7);

/**
 * Constructor Function using prototype and new keyword
 * Notes:
 *  - Using prototype
 *  - new keyword
 *  */
 function AnimalWithNew(name, energy) {
  // let this = Object.create(Animal.prototype);
  this.name = name;
  this.energy = energy;
  // return this;
}

// notice the exclusion of new keyword.
const snoop = new Animal('snoop', 7);

/**
 * Constructor function with inheritance
 */
function Dog(name, energy, breed) {
  Animal.call(this, energy, breed);
  this.breed = breed;
}
Dog.prototype = Object.create(Animal.prototype);

Dog.prototype.bark = function() {
  console.log('bark bark!')
}

// Reset constructor to not point to Animal, but Dog
Dog.prototype.constructor = Dog