「重学TS 2.0 」TS 练习题第四十题

[semlinker]

实现 AnyOf 工具类型，只要数组中任意元素的类型非 Falsy 类型、 {} 类型或 [] 类型，则返回 true，否则返回 false。如果数组为空的话，则返回 false。具体的使用示例如下所示：

type AnyOf<T extends any[]> = // 你的实现代码

type A0 = AnyOf<[]>; // false
type A1 = AnyOf<[0, '', false, [], {}]> // false
type A2 = AnyOf<[1, "", false, [], {}]> // true

请在下面评论你的答案

[zhaoxiongfei]

type NotEmptyObject<T> = T extends {} ? ({} extends T ? false : true) : true;
type Flasy = 0 | "" | false | [];
type AnyOf<T extends any[]> = T extends [infer First, ...infer Rest]
  ? First extends Flasy
    ? AnyOf<Rest>
    : NotEmptyObject<First>
  : false;

type A0 = AnyOf<[]>; // false
type A1 = AnyOf<[0, "", false, [], {}]>; // false
type A2 = AnyOf<[1, "", false, [], {}]>; // true

[sunboyZgz]

写得烂了点

type FaslyUnion = 0 | "" | false | 0n | null | undefined;
type AnyOfUnion = FaslyUnion | [];
type IsEmptyObject<T> = T extends {} ? ({} extends T ? true : false) : false;

type AnyOf<T extends any[]> = Len<T> extends 0
  ? false
  : T[0] extends AnyOfUnion
  ? AnyOf<Tail<T>>
  : IsEmptyObject<T[0]> extends true
  ? false
  : true;
type A02 = AnyOf<[]>; // false
type A12 = AnyOf<[0, "", false, [], {}]>; // false
type A22 = AnyOf<[1, "", false, [], {}]>; // true

[zhaoxiongfei]

type NotEmptyObject<T> = T extends {} ? ({} extends T ? false : true) : true;
type Flasy = 0 | "" | false | [];
type AnyOf<T extends any[]> = T extends [infer First, ...infer Rest]
  ? [First] extends [Flasy]
    ? AnyOf<Rest>
    : NotEmptyObject<First>
  : false;

type A0 = AnyOf<[]>; // false
type A1 = AnyOf<[0, '', false, [], {}]> // false
type A2 = AnyOf<[1, "", false, [], {}]> // true
type A3 = AnyOf<[0, "" | 2, false, [], {}]> // true

注意 元组中存在联合类型的问题。因此比对空对象的时候[] 转换成元组去extends比对，避免联合类型发生分布执行

[mingzhans]

type Falsy = {
    [p in PropertyKey]: never
} | [] | '' | "" | false | 0 | undefined | null
type AnyOf<T extends any[]> = T extends [infer A, ...infer Rest] ? (A extends Falsy ? AnyOf<Rest> : true) : false// 你的实现代码

type A0 = AnyOf<[]>; // false
type A1 = AnyOf<[0, '', false, [], {}]> // false
type A2 = AnyOf<[1, "", false, [], {}]> // true// true

基本类型也都属于对象类型

[jackwangwj]

// 先extends infer，判断是否空数组
// [infer first, ...infer rest]
// 判断first 是否 extends 0, '' false , [], keyof {} 为 never
type Zero = T extends 0 ? true : false;
type T1 = Zero<0>

type Trim = T extends '' ? true : false;
type T2 = Trim<''>

type EmptyArr = T extends [] ? true : false
type T31 = EmptyArr<[]>
type T32 = EmptyArr<[1]>
type T33 = EmptyArr<'1'>
type T34 = EmptyArr<{}>

type EmptyObj = keyof T extends never ? true : false
type T4 = EmptyObj<{}>
type T41 = EmptyObj<[]>

type isFalsy = Zero extends true
? true
: Trim extends true
? true
: EmptyArr extends true
? true
: EmptyObj extends true
? true
: T extends false
? true :
false

type AnyOf<T extends any[]> = EmptyArr extends true
? false
: T extends [infer First, ...infer Rest]
? isFalsy extends true
? AnyOf
: true
: false

// 你的实现代码

type A0 = AnyOf<[]>; // false
type A1 = AnyOf<[0, '', false, [], {}]> // false
type A2 = AnyOf<[1, "", false, [], {}]> // true