Builder pattern using TypeScript interfaces

Question

I would like to do something like this:

interface IPoint {
    x : number;
    y : number;
    z? : number;
}
const diag : IPoint = IPoint.x(1)
                      


        

Answer 1

This handles the type:

interface IPoint {
    x: number;
    y: number;
    z?: number;
}

type IBuilder = {
    [k in keyof T]: (arg: T[k]) => IBuilder
} & { build(): T }


let builder = {} as IBuilder

const diag = builder.x(1).y(2).z(undefined).build()

But I don't know how will you create the actual Builder thou. :)

You can play around with it at the playground

EDIT: Vincent Peng has created a builder-pattern npm package our of this (as mentioned in the comment). Go and give it some love!