L0v3ch4n

外观

MergeAll

约 185 字小于 1 分钟

2026-02-11

题目

Merge variadic number of types into a new type. If the keys overlap, its values should be merged into an union.

For example:

type Foo = { a: 1; b: 2 }
type Bar = { a: 2 }
type Baz = { c: 3 }

type Result = MergeAll<[Foo, Bar, Baz]> // expected to be { a: 1 | 2; b: 2; c: 3 }

解题思路

待补充

答案

type MergeAll<XS> = any

验证

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

type cases = [
  Expect<Equal<MergeAll<[]>, {} >>,
  Expect<Equal<MergeAll<[{ a: 1 }]>, { a: 1 }>>,
  Expect<Equal<
    MergeAll<[{ a: string }, { a: string }]>,
    { a: string }
>
  >,
  Expect<Equal<
    MergeAll<[{ }, { a: string }]>,
    { a: string }
>
  >,
  Expect<Equal<
    MergeAll<[{ a: 1 }, { c: 2 }]>,
    { a: 1, c: 2 }
>
  >,
  Expect<Equal<
    MergeAll<[{ a: 1, b: 2 }, { a: 2 }, { c: 3 }]>,
    { a: 1 | 2, b: 2, c: 3 }
>
  >,
  Expect<Equal<MergeAll<[{ a: 1 }, { a: number }]>, { a: number }>>,
  Expect<Equal<MergeAll<[{ a: number }, { a: 1 }]>, { a: number }>>,
  Expect<Equal<MergeAll<[{ a: 1 | 2 }, { a: 1 | 3 }]>, { a: 1 | 2 | 3 }>>,
]

参考

无