type Unshift<T, U> = T extends any[] ? [U, ...T]: [];

Solution by dailyco #35207

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

Solution by IsaacYouKorea #35206

type Unshift<T extends unknown[], P> = [P, ...T]

Solution by ClarityOfMind #35003

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

Solution by raeyoung-kim #34946

type Unshift<T extends unknown[], U> = T extends never[] ? [U] : [U, ...T]

Solution by 56aiden90 #34887

type Unshift<T extends unknown[], U> = [U, ...T]

Solution by eunsukimme #34817

type Unshift<T extends unknown[], U> = [U, ...T]

Solution by Yuriy113 #34736

// your answers
type Unshift<T extends unknown[], U> = [U, ...T]

Solution by zeyuanHong0 #34726

type Unshift<T extends any[], U> = T["length"] extends 0 ? [U] : [U, ...T];

Solution by lephuthuc2001 #34708

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

Solution by Git-I985 #34706

type Unshift<T, U> = T extends any[] ? [U, ...T] : T

Solution by nathan2slime #34664

type Unshift<T extends unknown[], U> = [U, ...T]
// your answers

Solution by Rustamaha #34555

type Unshift<T extends unknown[], U> = [U,...T]

Solution by devshinthant #34550

type Unshift<T extends unknown[], U> = [U, ...T]

Solution by binhdv155127 #34474

// 여기 풀이를 입력하세요
type Unshift<T extends readonly unknown[], U> = [U, ...T];

Solution by LeeKangHyun #34465

We should add U at array T's first place. So, declare a new array(type) and add U. And, spread T's elements.

// your answers
type Unshift<T extends any[], U> = [U, ...T]

Solution by dev-jaemin #34459

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

Solution by ktim816 #34429

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

Solution by bkdragon0228 #34426

// your answers
type Unshift<T extends any[], U> = [U, ...T]

Solution by gobielJonathan #34400

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

Solution by wxh-cyber #34370

type Unshift<T extends unknown[], U> = [U, ...T]

Solution by souzaramon #34318

// 你的答案

type Unshift<T extends unknown[], U> =[U,...T]

Solution by W-fitTiger #34250

문제설명

Array.unshift의 타입 버전을 구현하세요.

type Result = Unshift<[1, 2], 0>; // [0, 1, 2]

풀이

크게 어려운 문제는 아니었습니다. 입력받은 U를 배열의 가장 앞순서에 배치하여 새로운 array 타입을 생성합니다.

Union 타입의 장점

사실 여담이지만 다음과 같이 배열로 선언한 타입은 활용도가 높지 않습니다.
유니언 타입은 배열보다 간단하고 명확합니다. 타입을 읽을 때, 배열보다 유니언 타입이 더 직관적이고 이해하기 쉽습니다.
유니언 타입은 TypeScript의 타입 시스템과 자연스럽게 통합됩니다.
예를 들어, 유니언 타입은 함수의 매개변수나 반환 값의 타입으로 쉽게 사용할 수 있습니다.

Solution

/* _____________ 여기에 코드 입력 _____________ */

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

/* _____________ 테스트 케이스 _____________ */
import type { Equal, Expect } from "@type-challenges/utils";

type cases = [
	Expect<Equal<Unshift<[], 1>, [1]>>,
	Expect<Equal<Unshift<[1, 2], 0>, [0, 1, 2]>>,
	Expect<Equal<Unshift<["1", 2, "3"], boolean>, [boolean, "1", 2, "3"]>>
];

Solution by adultlee #34115

type Unshift<T extends unknown[], U> = [U, ...T];

Solution by ProvorovOleksii #34084

type Unshift<T extends unknown[], U> = [U, ...T]

Solution by ouzexi #33974

type Unshift<T extends unknown[], U> = [U,...T]

Solution by hyojinLee-git #33947

type Unshift<T extends unknown[], U> = [U, ...T]

Solution by notsecret32 #33865

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

Solution by okasyun #33835

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

pushの回答をほぼ逆にしたのみ。 配列が登場する場合はだいたいexntends type[]を宣言した方が良さそう。 anyはできれば使いたくない。問題によっては使っている型が限られているので、もっと丁寧に宣言しても良いかも

Solution by okabe-yuya #33827

type Unshift<T extends readonly unknown[], U> = [U, ...T]

Solution by veralex #33758