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RequiredByKeys

提出詳細

type Simplify<T extends object> = { [P in keyof T]: T[P] }
type RequiredByKeys<T extends Object, K extends PropertyKey = keyof T> = Simplify<Omit<T, K> & {
  [P in keyof T as P extends K ? P : never]-?: T[P]
}>

提出日時	2025-09-16 07:55:30
問題	RequiredByKeys
ユーザー	balckowl
ステータス	Accepted

テストケース

import type { Equal, Expect } from '@type-challenges/utils'

interface User {
  name?: string
  age?: number
  address?: string
}

interface UserRequiredName {
  name: string
  age?: number
  address?: string
}

interface UserRequiredNameAndAge {
  name: string
  age: number
  address?: string
}

type cases = [
  Expect<Equal<RequiredByKeys<User, 'name'>, UserRequiredName>>,
  Expect<Equal<RequiredByKeys<User, 'name' | 'unknown'>, UserRequiredName>>,
  Expect<Equal<RequiredByKeys<User, 'name' | 'age'>, UserRequiredNameAndAge>>,
  Expect<Equal<RequiredByKeys<User>, Required<User>>>,
]