Factory Function

Motivating Factory Functions

There are three ways to create objects:
- Constructor Functions
- Classes
- Factory Functions
In JavaScript, each function is a function object
An object is a collection of properties
A property is an association between a name (or key) and a value
Each of these approaches stores methods on a shared prototype
Implying, these approaches offer most of the same features

Creating Objects with Constructor Functions

// constructor
function ConstructorCar() {}

ConstructorCar.prototype.drive = function () {
  console.log('Vroom!');
};

const car1 = new ConstructorCar();
console.log(car1.drive());

Creating Objects with Classes

// class
class ClassCar {
  drive () {
    console.log('Vroom!');
  }
}

const car2 = new ClassCar();
console.log(car1.drive());

Creating Objects with Factory Functions

// factory
const proto = {
  drive () {
    console.log('Vroom!');
  }
};

const factoryCar = () => Object.create(proto);

const car3 = factoryCar();
console.log(car3.drive());

Comparing Classes to Constructors

Prototype functions have been around before ES6
Classes were included in the ES6 release
ES6 classes desugar constructor functions

Benefits of Factories and Constructors

Inheritance is easier with prototypes
Private properties better suited for factories

References

Previous

Next

Prototype

Function Closures