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String Join

提出詳細

type Join<In extends string[], Sep extends string = ""> =
  In extends [infer L extends string, infer R extends string, ...infer Rest extends string[]]
  ? Join<[`${L}${Sep}${R}`, ...Rest], Sep>
  : In[0] extends string
  ? In[0]
  : ""

declare function join<Sep extends string>(delimiter: Sep): <T extends string[], S extends string = Sep>(...parts: T) => Join<T, S>
提出日時2024-09-12 08:03:23
問題String Join
ユーザーookkoouu
ステータスAccepted
テストケース
import type { Equal, Expect } from '@type-challenges/utils'

// Edge cases
const noCharsOutput = join('-')()
const oneCharOutput = join('-')('a')
const noDelimiterOutput = join('')('a', 'b', 'c')

// Regular cases
const hyphenOutput = join('-')('a', 'b', 'c')
const hashOutput = join('#')('a', 'b', 'c')
const twoCharOutput = join('-')('a', 'b')
const longOutput = join('-')('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h')

type cases = [
  Expect<Equal<typeof noCharsOutput, ''>>,
  Expect<Equal<typeof oneCharOutput, 'a'>>,
  Expect<Equal<typeof noDelimiterOutput, 'abc'>>,
  Expect<Equal<typeof twoCharOutput, 'a-b'>>,
  Expect<Equal<typeof hyphenOutput, 'a-b-c'>>,
  Expect<Equal<typeof hashOutput, 'a#b#c'>>,
  Expect<Equal<typeof longOutput, 'a-b-c-d-e-f-g-h'>>,
]