Typescript implement interface with same keys but different types

Question

I have an interface

export interface Foo {
  a: string;
  b: string;
}

I want to have another class that implements all keys of the interface but in other types:

export class Bar implements keysof(Foo) {
  a: SomeNewType;
  b: SomeNewType2;
}

Is this possible in typescript?

Meirion Hughes · Accepted Answer · 2019-06-06 13:01:33Z

10

You could potentially do it with a key map.

export interface Foo {
  a: string;
  b: string;
}

type HasKeys<T> = {
  [P in keyof T]: any;
}

export class Bar implements HasKeys<Foo> {

}

this will complain that Bar is missing a and b but it will be fine if you define them with any type. i.e.

export class Bar implements HasKeys<Foo> {
  a: number;
  b: object;
}

answered Jun 6, 2019 at 13:01

Meirion Hughes

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