pick.ts

[huibu]

/*
4 - Pick

by Anthony Fu (@antfu) #easy #union #built-in

Question

Implement the built-in Pick<T, K> generic without using it.

Constructs a type by picking the set of properties K from T

For example:

interface Todo {
  title: string
  description: string
  completed: boolean
}

type TodoPreview = MyPick<Todo, 'title' | 'completed'>

const todo: TodoPreview = {
    title: 'Clean room',
    completed: false,
}

View on GitHub: https://tsch.js.org/4
*/

/* _____________ Your Code Here _____________ */

type MyPick<T, K extends keyof T> = { [Key in K]: T[Key] }

/* _____________ Test Cases _____________ */
import type { Equal, Expect } from '@type-challenges/utils'

type cases = [
Expect<Equal<Expected1, MyPick<Todo, 'title'>>>,
Expect<Equal<Expected2, MyPick<Todo, 'title' | 'completed'>>>,
// @ts-expect-error
MyPick<Todo, 'title' | 'completed' | 'invalid'>,
]

interface Todo {
title: string
description: string
completed: boolean
}

interface Expected1 {
title: string
}

interface Expected2 {
title: string
completed: boolean
}

/* _____________ Further Steps _____________ /
/

Share your solutions: https://tsch.js.org/4/answer
View solutions: https://tsch.js.org/4/solutions
More Challenges: https://tsch.js.org
*/