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PartialByKeys

提出詳細

type Simplify<T extends object> = {
  [P in keyof T]: T[P]
}

type PartialByKeys<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 06:50:12
問題	PartialByKeys
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 UserPartialName {
  name?: string
  age: number
  address: string
}

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

type cases = [
  Expect<Equal<PartialByKeys<User, 'name'>, UserPartialName>>,
  Expect<Equal<PartialByKeys<User, 'name' | 'unknown'>, UserPartialName>>,
  Expect<Equal<PartialByKeys<User, 'name' | 'age'>, UserPartialNameAndAge>>,
  Expect<Equal<PartialByKeys<User>, Partial<User>>>,
]