In what situations is the factory pattern used in Javascript?

Question

JavaScript

What are some simple examples of the correct use of this pattern?

Answer 1

There are three main ways to use factories in JavaScript:

// Объявление фабрики объектов
function Idiot(name) {
  return { name: name };
}
// создание экземпляра объекта
var idiot1 = Idiot('Bill');
console.dir(idiot1);

// Объявление фабрики классов
function PhilosophySchool(schoolName) {
  return function Philosopher(name) {
    return { name: name, school: schoolName };
  };
}

// Создание класса
var Stoicism = PhilosophySchool('Stoicism');
var philosopher = Stoicism('Marcus Aurelius');
console.dir(philosopher);

// Объявление базового прототипа
function Engineer(specialization) {
  this.specialization = 'Software';
};

Engineer.prototype.getName = function() {
  return this.specialization + ' engineer ' + this.name; 
}

// Объявление фабрики
function University(specialization) {
  function factoryConstructor(name) {
    this.name = name;
  };
  factoryConstructor.prototype = new Engineer(specialization);
  return factoryConstructor;
}

// Создание конструктора инженеров-программистов
SoftwareEngineer = University('Software');

// Создание экземпляра инженера-программиста
var alex = new SoftwareEngineer('Alex');
console.dir(alex.getName());

Answer 2

In fact, the factory pattern, not to be confused with the abstract factory and I don’t remember now, but there is another one, it is used everywhere and is a very good example of OO. Its essence is to make the life of the recipient as comfortable as possible. Below is the simplest example, which shows how a button is assembled in a factory, about which the recipient only knows that it adds karma. If I make a lot of such buttons, and then decide to change its skin, then I will not have to run through the code and change it from everywhere, but I will only need to change the assembly at the factory.

var ButtonFactory = (function(){
  function ButtonFactory(){
    
  }
  
  ButtonFactory().prototype.getLikeButton = function(){
    	var likeButton = document.createElement('button');
    	likeButton.style.background = 'ff00ff';
    	likeButton.style.innerHTML = 'like';

        return likeButton;
  };
  
  return ButtonFactory;
})();

var buttonFactory = new ButtonFactory();

document.getElementsByTagName('body')[0].appendChild(buttonFactory.getLikeButton());