TypeScript Coach

Awaited<Type>

Produces the type returned by a Promise object.

Awaited will recursively unwrap the result type of a Promise, in case the Promise result is another Promise.

type A = Awaited<Promise<string>>
type B = Awaited<Promise<Promise<number>>>
type C = Awaited<boolean | Promise<number>>
// A simple equivalent to Awaited
type MyAwaited<T> = T extends Promise<infer U> ? MyAwaited<U> : T
type D = MyAwaited<Promise<string>>

Awaited is especially useful when working with functions that return promises, where you want to extract the value that the promise resolves to.

async function fetchUser() {
    return { id: 1, name: "Alice" }
}
type User = Awaited<ReturnType<typeof fetchUser>>