ExtractPromise.md

typelab / utils / ExtractPromise

type ExtractPromise<T> = T extends Promise<infer U> ? U : never;

Extract the value type from a Promise type.

Type Parameters

Type Parameter	Description
T extends Promise<Any>	The input type which should be a Promise.

Returns

The type of the return value in the Promise, or never if T is not a Promise.

Example

type Valid = ExtractPromise<Promise<number>>; // number
type Invalid = ExtractPromise<number>> // never