The factory pattern is a way to create objects of some type, leaving the decision of which concrete object to create to the specific factory that creates that object:
See [[Typescript has separate namespaces for values and for types and the companion object pattern]], we declare a type Shoe and a value Shoe with the same name:
type Shoe = {
purpose: string
}
class BalletFlat implements Shoe {
purpose = 'dancing'
}
class Boot implements Shoe {
purpose = 'woodcutting'
}
class Sneaker implements Shoe {
purpose = 'walking'
}
let Shoe = {
create(type: 'balletFlat' | 'boot' | 'sneaker'): Shoe {
switch(type) {
case 'balletFlat': return new BalletFlat;
case 'boot': return new Boot;
case 'sneaker': return new Sneaker;
}
}
}
Shoe.create('boot');