Reverse

In this medium-level challenge, you'll implement the type version of Array.reverse().

Medium

Implement the type version of Array.reverse

For example:

type a = Reverse<['a', 'b']> // ['b', 'a']
type b = Reverse<['a', 'b', 'c']> // ['c', 'b', 'a']

Change the following code to make the test cases pass (no type check errors).

Video Walkthrough

type Reverse<T extends unknown[]> = T extends [...infer Rest, infer Last]
  ? [Last, ...Reverse<Rest>]
  : T

How it works:

First we constrain the type T to be an array.
Then we use a conditional type to check if the tuple has members (T extends [...infer Rest, infer Last]), while capturing the rest of the tuple (infer Rest) and the last element (infer Last).
If it has members, we return a new tuple with the last element (Last) and the rest of the tuple recursively passed into Reverse<Rest> ([Last, ...Reverse<Rest>]).
If it doesn't have members, we return the original tuple (T).

This challenge helps you understand tuple manipulation and how to apply this concept in real-world scenarios.