Refer: Medium - Trim

Describe

Implement Trim<T> which takes an exact string type and returns a new string with the whitespace from both ends removed.

For example

code snippetCopytypescript
type trimed = Trim<'  Hello World  '> // expected to be 'Hello World'

Test Cases

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

type cases = [
  Expect<Equal<Trim<'str'>, 'str'>>,
  Expect<Equal<Trim<' str'>, 'str'>>,
  Expect<Equal<Trim<'     str'>, 'str'>>,
  Expect<Equal<Trim<'str   '>, 'str'>>,
  Expect<Equal<Trim<'     str     '>, 'str'>>,
  Expect<Equal<Trim<'   \n\t foo bar \t'>, 'foo bar'>>,
]

Solution

code snippetCopytypescript
type Trim<S extends string> = S extends `${' ' | '\n' | '\t'}${infer P}` | `${infer P}${' ' | '\n' | '\t'}`
  ? Trim<P>
  : S