How do I use multiple interfaces for one object in typescript-CodePudding

I have to check an object. That may have different signatures. It should accept type and svc or id. Therefore I have two interfaces:

interface A {
  type: string;
  svc: string;
}
interface B {
  id: string;
}

I saw an example, where they used a type and both interface combined with "or":

export type AB = A | B;

func(config: AB) {
  if (config.type ) {
    ...
  }
}

But this delivers an TS error in IDE:

TS2339: Property 'type' does not exist on type 'AB'. Property 'type' does not exist on type 'B'.

How is the correct way to implement this?

CodePudding user response：

You can change the check to

if ('type' in config) {
  //because config contains a type property
  //typescript knows config must be of type A in here
}