4484 - IsTuple

4484 - IsTuple

by jiangshan (@jiangshanmeta) #中等 #tuple

题目

Implement a type IsTuple, which takes an input type T and returns whether T is tuple type.

For example:

type case1 = IsTuple<[number]> // true
type case2 = IsTuple<readonly [number]> // true
type case3 = IsTuple<number[]> // false

在 Github 上查看：https://tsch.js.org/4484/zh-CN

代码

/* _____________ 你的代码 _____________ */

type IsTuple<T> = [T] extends [never]
  ? false
  : T extends readonly any[]
    ? number extends T['length']
      ? false
      : true
    : false

测试用例

/* _____________ 测试用例 _____________ */
import type { Equal, Expect } from '@type-challenges/utils'

type cases = [
  Expect<Equal<IsTuple<[]>, true>>,
  Expect<Equal<IsTuple<[number]>, true>>,
  Expect<Equal<IsTuple<readonly [1]>, true>>,
  Expect<Equal<IsTuple<{ length: 1 }>, false>>,
  Expect<Equal<IsTuple<number[]>, false>>,
  Expect<Equal<IsTuple<never>, false>>,
]

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