awesome-typescript 「重学TS 2.0 」TS 练习题第十四题

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实现一个 Unshift 工具类型，用于把指定类型 E 作为第一个元素添加到 T 数组类型中。具体的使用示例如下所示：

type Unshift<T extends any[], E> =  // 你的实现代码

// 测试用例
type Arr0 = Unshift<[], 1>; // [1]
type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

提示：该题目有多种解法，感兴趣小伙伴可以自行尝试一下。请在下面评论你的答案。

Sep 16 '21 12:09 semlinker

type Unshift<T extends any[], E> = [E, ...T];

// 测试用例
type Arr = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

Sep 16 '21 12:09 sunboyZgz

// 第四道
type Unshift<T extends any[], E> = T extends [...args: infer U] ? [E, ...U] : never;

// 测试用例
type Arr = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3

Sep 16 '21 14:09 zhaoxiongfei

type Unshift<T extends any[], E> = undefined extends T[0]? [E] : 
((h: E, ...t: T) => void) extends (...args: infer R) => void? R : never

// 测试用例
type Arr2 = Unshift<[], 1>; // [1]
type Arr3 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]
type Arr4 = Unshift<[1], 0>; // [0, 1]

Sep 17 '21 14:09 douhao1988

type Unshift<T extends any[], E> = T extends [...infer R] ? [E, ...R] : never// 你的实现代码

// 测试用例
type Arr0 = Unshift<[], 1>; // [1]
type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

Sep 21 '21 14:09 mingzhans

type Unshift<T extends any[], E> = [E, ...T] // 你的实现代码

// 测试用例
type Arr0 = Unshift<[], 1>; // [1]
type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

Sep 24 '21 06:09 wenye123

// type Unshift<T extends any[], E> = [E, ...T] type Unshift<T extends any[], E> = ((e:E, ...t:T) => void) extends ((...args: infer R) => void) ? R : never type Arr0 = Unshift<[], 1>; // [1] type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

Sep 26 '21 10:09 Suc5999

type Unshift<T extends any[], E> = [E, ...T]

// 测试用例
type Arr0 = Unshift<[], 1>; // [1]
type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

Sep 27 '21 12:09 Mrlgm

```ts
type Unshift<T extends any[], E> =  // 你的实现代码

// 测试用例
type Arr0 = Unshift<[], 1>; // [1]
type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

type Unshift<T extends any[], E> = [E, ...T]

Sep 27 '21 15:09 winfa

// 实现一个 Unshift 工具类型，用于把指定类型 E 作为第一个元素添加到 T 数组类型中。具体的使用示例如下所示：

type Unshift<T extends any[], E> =  [E, ...T];

// 测试用例
type Arr0 = Unshift<[], 1>; // [1]
type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

依然是注重array的形状，直接构造数组出来

Oct 01 '21 15:10 zhaoxiongfei

type Unshift<T extends any[], E> = [E, ...T]  // 你的实现代码

// 测试用例
type Arr0 = Unshift<[], 1>; // [1]
type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

Oct 21 '21 03:10 Flavour86

type Unshift<T extends any[], E> = T extends [U: infer f, ...arga: infer a] ? [E, f, ...a] : [E] // 你的实现代码

// 测试用例 type Arr0 = Unshift<[], 1>; // [1] type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

Nov 21 '21 02:11 rookiecdn

export default {}

// 实现一个 Unshift 工具类型，用于把指定类型 E 作为第一个元素添加到 T 数组类型中。具体的使用示例如下所示：

type Unshift<T extends any[], E> = T extends [...infer args] ? [E, ...args] : never

// 测试用例 type Arr0 = Unshift<[], 1>; // [1] type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

Dec 01 '21 22:12 a572251465

type Unshift<T extends any[], E> = T extends [...args: infer Args] ? [E, ...Args] : never;

// 测试用例 type Arr0 = Unshift<[], 1>; // [1] type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

Dec 31 '21 03:12 Ljp10086

type Unshift<T extends any[], E> = 
  T extends [...infer Arr]
    ? [E, ...Arr]
    : []
// 测试用例
type Arr0 = Unshift<[], 1>; // [1]
type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

Mar 14 '22 14:03 waleiwalei

// 解法1: 通过infer指代数组key列表, 然后再数组中扩展前一位
type Unshift<T extends any[], E> = T extends [...infer K] ? [E, ...K] : never

// 解法2: 直接扩展就好了
type Unshift1<T extends any[], E> = [E, ...T]

May 27 '22 06:05 ChangerHe

type ParametersArray<T extends any[]> = T extends [...args:infer P]?P:[]
type Unshift<T extends any[], E> = [E,...ParametersArray<T>]

Jun 02 '22 12:06 ChuTingzj

type Unshift<T extends any[], E> = T extends NonNullable<T> ? [E, ...T] : [E] // 你的实现代码

// 测试用例
type Arr0 = Unshift<[], 1>; // [1]
type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]
type Arr2 = Unshift<null, 0>
type Arr3 = Unshift<undefined, 0>

Jul 14 '22 03:07 liziqiang

type Unshift<T extends any[], E> = [E, ...T]; // 你的实现代码

// 测试用例
type Arr0 = Unshift<[], 1>; // [1]
type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

Aug 25 '22 14:08 fishcoderman

type Unshift<T extends any[], E> = [E, ...T];

// 测试用例
type Arr0 = Unshift<[], 1>; // [1]
type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

Oct 20 '22 07:10 LLDLZ

type Unshift<T extends any[], E> = [E, ...T];

// 测试用例
type Arr0 = Unshift<[], 1>; // [1]
type Arr1 = Unshift<[1, 2, 3], 0>; // [0, 1, 2, 3]

Dec 11 '23 10:12 SweeperDuan

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「重学TS 2.0 」TS 练习题第十四题

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