Pop

In this medium-level challenge, you'll implement a generic Pop<T> that removes the last element from an array.

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]

// Video Solution: https://youtube.com/watch?v=95X2WKv9sPg

/* _____________ Your Code Here _____________ */

type Pop<T extends any[]> = any

/* _____________ Test Cases _____________ */
import type { Equal, Expect } from '../helpers'

type cases = [
  Expect<Equal<Pop<[3, 2, 1]>, [3, 2]>>,
  Expect<Equal<Pop<['a', 'b', 'c', 'd']>, ['a', 'b', 'c']>>,
  Expect<Equal<Pop<[]>, []>>,
]

Detailed Explanation

[object Object]

How it works:

• First we constrain the type T to be an array with extends unknown[]
• T extends [...infer Keep, infer Last] matches the array type and collects all elements except the last one into Keep
• ? Keep returns the array type with the last element removed
• we return T if the array is empty