Replace

In this medium-level challenge, you'll implement Replace<S, From, To> which replaces the string From with To in the given string S - but only once.

type replaced = Replace<'types are fun!', 'fun', 'awesome'> // expected to be 'types are awesome!'

Detailed Explanation

type Replace<
  S extends string,
  From extends string,
  To extends string,
> = From extends ''
  ? S
  : S extends `${infer Before}${From}${infer After}`
    ? `${Before}${To}${After}`
    : S

How it works:

• First, we constrain the types S, From and To to be strings with extends string
• From extends '' ? S returns the string if From is an empty string
• S extends ${infer Before}${From}${infer After} matches the string type and captures the before and after parts of the string
• ? ${Before}${To}${After} returns the string with the From replaced with To
• : S returns the string if it doesn't contain From

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