Trim

In this medium-level challenge, you'll implement Trim<T> which takes an exact string type and returns a new string with the whitespace from both ends removed.

type trimmed = Trim<'  Hello World  '> // expected to be 'Hello World'

Detailed Explanation

type Whitespace = ' ' | '\n' | '\t'
 
type Trim<S extends string> = S extends `${Whitespace}${infer After}`
  ? Trim<After>
  : S extends `${infer Before}${Whitespace}`
    ? Trim<Before>
    : S

How it works:

• First, we define a type Whitespace that represents all whitespace characters
• Next, we constrain the type S to be a string with extends string
• S extends ${Whitespace}${infer After} matches the string type and captures the rest of the string into After
• ? Trim<After> recursively calls Trim with the rest of the string
• : S returns the string if it doesn't start or end with a whitespace character (base case)

This challenge helps you understand TypeScript's template literal types and how to apply this concept in real-world scenarios.