00116-medium-replace.ts

// ============= Test Cases =============
import type { Equal, Expect } from "./test-utils";

type cases = [
  Expect<Equal<Replace<"foobar", "bar", "foo">, "foofoo">>,
  Expect<Equal<Replace<"foobarbar", "bar", "foo">, "foofoobar">>,
  Expect<Equal<Replace<"foobarbar", "", "foo">, "foobarbar">>,
  Expect<Equal<Replace<"foobarbar", "bar", "">, "foobar">>,
  Expect<Equal<Replace<"foobarbar", "bra", "foo">, "foobarbar">>,
  Expect<Equal<Replace<"", "", "">, "">>
];

// ============= Your Code Here =============
type R = Replace<"foobarbar", "", "foo">;
type Replace<
  S extends string,
  From extends string,
  To extends string
> = From extends ""
  ? S
  : S extends `${infer Pre}${From}${infer Post}`
  ? `${Pre}${To}${Post}`
  : S;