Discussion on: Learn about difference between Type & Interface in Typescript

[peerreynders]

FYI: A class implicitly exposes an interface that can be merged into - example:

type CompareFn = (lhs: number, rhs: number) => number;

const sortWith: (a: readonly number[], f: CompareFn) => number[] = (
  array,
  fn
) => array.slice().sort(fn);

const ascending: CompareFn = (lhs, rhs) => lhs - rhs;
const descending: CompareFn = (lhs, rhs) => rhs - lhs;

class Container {
  readonly #values: readonly number[];

  constructor(values: number[]) {
    this.#values = Object.freeze(values.slice());
  }

  get values(): readonly number[] {
    return this.#values;
  }
}

interface Container {
  ascending(): number[];
  descending(): number[];
}

function asc(this: Container): number[] {
  return sortWith(this.values, ascending);
}

function desc(this: Container): number[] {
  return sortWith(this.values, descending);
}

Container.prototype.ascending = asc;
Container.prototype.descending = desc;

const container = new Container([10, 45, 15, 39, 21, 26]);
console.log(container.values);
console.log(container.ascending());
console.log(container.descending());

playground

[Code Oz]

Nice remark I learn something thank you bro !