1.3.实现Awaited #15
Description
/* _____________ 你的代码 _____________ */
type MyAwaited<T> = T extends Promise<infer U>
? MyAwaited<U>
: T extends { then: (p: (arg: infer K) => any) => any }
? K
: T;
/* _____________ 测试用例 _____________ */
import type { Equal, Expect } from '@type-challenges/utils';
type X = Promise<string>;
type Y = Promise<{ field: number }>;
type Z = Promise<Promise<string | number>>;
type Z1 = Promise<Promise<Promise<string | boolean>>>;
type T = { then: (onfulfilled: (arg: number) => any) => any };
type cases = [
Expect<Equal<MyAwaited<X>, string>>,
Expect<Equal<MyAwaited<Y>, { field: number }>>,
Expect<Equal<MyAwaited<Z>, string | number>>,
Expect<Equal<MyAwaited<Z1>, string | boolean>>,
Expect<Equal<MyAwaited<T>, number>>
];
// @ts-expect-error
type error = MyAwaited<number>;