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Pop

介绍​

实现一个泛型Pop<T>，它接受一个数组T，并返回一个由数组T的前 N-1 项（N 为数组T的长度）以相同的顺序组成的数组。

额外：同样，您也可以实现Shift，Push和Unshift吗？

例如

ts
  type arr1 = ['a', 'b', 'c', 'd']
  type arr2 = [3, 2, 1]
  type re1 = Pop<arr1> // expected to be ['a', 'b', 'c']
  type re2 = Pop<arr2> // expected to be [3, 2]
ts
  type arr1 = ['a', 'b', 'c', 'd']
  type arr2 = [3, 2, 1]
  type re1 = Pop<arr1> // expected to be ['a', 'b', 'c']
  type re2 = Pop<arr2> // expected to be [3, 2]
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起点​

ts
/* _____________ Your Code Here _____________ */
 
type Pop<T> = any
 
/* _____________ Test Cases _____________ */
type cases = [
  Expect<Equal<Pop<[3, 2, 1]>, [3, 2]>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Pop<['a', 'b', 'c', 'd']>, ['a', 'b', 'c']>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Pop<[]>, []>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
]
 
ts
/* _____________ Your Code Here _____________ */
 
type Pop<T> = any
 
/* _____________ Test Cases _____________ */
type cases = [
  Expect<Equal<Pop<[3, 2, 1]>, [3, 2]>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Pop<['a', 'b', 'c', 'd']>, ['a', 'b', 'c']>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Pop<[]>, []>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
]
 
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解决方案​

Spoiler warning // Click to reveal answer
ts
//方案1
type Pop<T extends any[]> = T extends [...infer R, infer L] ? R : []
 
type Push<T extends any[], U> = [...T, U]
 
type Shift<T extends any[]> = T extends [infer L, ...infer R] ? R : []
 
type Unshift<T extends any[], U> = [U, ...T]
 
ts
//方案1
type Pop<T extends any[]> = T extends [...infer R, infer L] ? R : []
 
type Push<T extends any[], U> = [...T, U]
 
type Shift<T extends any[]> = T extends [infer L, ...infer R] ? R : []
 
type Unshift<T extends any[], U> = [U, ...T]
 
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