[Typescript] Handling a Truly Empty Object in TypeScript

declare const tag: unique symbol;
export type EmptyObject = { [tag]?: never }; // Record<PropertyKey, never>

const acceptOnlyEmptyObject = (input: EmptyObject) => {};

acceptOnlyEmptyObject({});

acceptOnlyEmptyObject({
  // @ts-expect-error
  a: 1,
});
acceptOnlyEmptyObject(
  // @ts-expect-error
  'hello'
);
acceptOnlyEmptyObject(
  // @ts-expect-error
  42
);
acceptOnlyEmptyObject(
  // @ts-expect-error
  true
);
acceptOnlyEmptyObject(
  // @ts-expect-error
  Symbol('foo')
);
acceptOnlyEmptyObject(
  // @ts-expect-error
  []
);
acceptOnlyEmptyObject(
  // @ts-expect-error
  () => {}
);
acceptOnlyEmptyObject(
  // @ts-expect-error
  /foo/
);
acceptOnlyEmptyObject(
  // @ts-expect-error
  new Error('foo')
);
acceptOnlyEmptyObject(
  // @ts-expect-error
  null
);
acceptOnlyEmptyObject(
  // @ts-expect-error
  undefined
);

 

posted @ 2024-07-04 02:23  Zhentiw  阅读(5)  评论(0编辑  收藏  举报