Awaited

Unwrap nested Promises to get their resolved types! 🎁

In this easy-level challenge, you'll implement a type that extracts the value type from Promises, even when they're nested multiple levels deep. This is similar to TypeScript's built-in Awaited type and is essential for working with asynchronous code at the type level.

You'll learn about conditional types with infer, recursive type definitions, and how to handle Promise-like objects with then methods. This challenge bridges the gap between TypeScript's type system and JavaScript's asynchronous patterns.

type ExampleType = Promise<string>
 
type Result = MyAwaited<ExampleType> // string

Detailed Explanation

To unwrap Promise types, we need to use conditional types with infer and handle recursion for nested Promises.

type MyAwaited<T> = T extends PromiseLike<infer Value> ? MyAwaited<Value> : T

How it works:

• PromiseLike<infer Value> matches any object with a then method and captures its resolved type
• If the unwrapped type is still a Promise, recursively unwrap it
• Otherwise, return the unwrapped type
• If T isn't Promise-like, return it unchanged

This handles all cases including Promise<string>, Promise<Promise<number>>, and custom thenable objects, making it a robust solution for async type unwrapping.