如何使用三点对打字稿中的类型进行解构

Question

in flow I usually use the following

type A = {|
  a: string
|}

// in another file, import type A
type B = {|
  ...A,
  b: string,
|}

But when I'm doing similar in typescripts, it gives me `Member 'A' implicitly has an 'any' type.ts(7008)

type A = {
  a: string
}

// in another file, import type A
type B = {
  ...A,
  b: string,
}

what can I do to make this right? Thanks.

Answer 1

Use an intersection type:

type B = A & {b: string}

Or you can use interfaces:

interface B extends A {
    b: string
}

The difference is that an interface can have fields added to it by other interface B declarations elsewhere, whereas type B = ... cannot be modified after it is declared. See the docs for more details.