[Typescript] 102. Hard - String to Number

Convert a string literal to a number, which behaves like Number.parseInt.

 

/* _____________ Your Code Here _____________ */

type ToNumber<S extends string, ACC extends unknown[] = []> = S extends `${number}`
  ? S extends `${ACC['length']}`
    ? ACC['length']
    : ToNumber<S, [...ACC, unknown]>
  : never


/* _____________ Test Cases _____________ */
import type { Equal, Expect } from '@type-challenges/utils'

type cases = [
  Expect<Equal<ToNumber<'0'>, 0>>,
  Expect<Equal<ToNumber<'5'>, 5>>,
  Expect<Equal<ToNumber<'12'>, 12>>,
  Expect<Equal<ToNumber<'27'>, 27>>,
  Expect<Equal<ToNumber<'18@7_$%'>, never>>,
]