Typescript create interface having keys of another interface

Question

interface A{
    x: string;
    y: string;
    z: string;
    // maybe later something more
}
interface B{
    [K in keyof A]: Boolean;
}

Why isn't it working? I want to create something like that, but dynamically:

interface B{
    x: Boolean;
    y: Boolean;
    z: Boolean;
    // maybe later something more
}

Does this answer your question? TypeScript: Derive interface from other interface by re-using the keys but not the values — ford04
– ford04, Commented Jun 29, 2020 at 10:29

Titian Cernicova-Dragomir · Accepted Answer · 2020-06-29 10:20:05Z

12

Don't use Boolean use boolean.

Also mapped types only work with type not interface, there is little difference between the two, so this should work

type Bar = {
  [key in keyof A]: boolean
}

Also, this mapped type could be written using the redefined mapped type Record:

type Bar = Record<keyof A, boolean>

answered Jun 29, 2020 at 10:20

Titian Cernicova-Dragomir

253k37 gold badges464 silver badges394 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Rozrewolwerowany rewolwer Over a year ago

Why boolean is better? Could you give an example when it makes difference?

revelt Over a year ago

@MateuszKisielMateuszKisiel in short, referring to book "Effective TypeScript" by O'Reilly, Item 10: Avoid Object Wrapper Types (String, Number, Boolean, Symbol, BigInt), — otherwise mixup will happen — for example, string is assignable to String, but String is not assignable to string

julodnik · Accepted Answer · 2020-06-29 10:18:50Z

3

Try following:

interface A{
    x: string;
    y: string;
    z: string;
    // maybe later something more
}


type Bar = {
  [key in keyof A]: boolean
}

interface B extends Bar { }

answered Jun 29, 2020 at 10:18

julodnik

3772 silver badges8 bronze badges

Collectives™ on Stack Overflow

Typescript create interface having keys of another interface

2 Answers 2

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related