題目
中文
實作一個以 T 作為泛型引數的 IsNever型別.
如果 T 是never, 回傳 true, 否則回傳 false.
示例:
type A = IsNever<never>; // expected to be true
type B = IsNever<undefined>; // expected to be false
type C = IsNever<null>; // expected to be false
type D = IsNever<[]>; // expected to be false
type E = IsNever<number>; // expected to be false
English
Implement a type IsNever, which takes input type T.
If the type of resolves to never, return true, otherwise false.
For example:
type A = IsNever<never>; // expected to be true
type B = IsNever<undefined>; // expected to be false
type C = IsNever<null>; // expected to be false
type D = IsNever<[]>; // expected to be false
type E = IsNever<number>; // expected to be false
答案
type IsNever<T extends unknown> = [T] extends [never] ? true : false;
在線演示
作者：Laggage
出處：https://www.cnblogs.com/laggage/p/type-challenge-is-never.html
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標籤：.NET技术