IfAsyncFunction.md

typelab / conditions / IfAsyncFunction

type IfAsyncFunction<T, Then, Else> = _IfNotAnyOrNever<T, T extends AsyncFn ? Then : Else, Else>;

Resolves to Then if the type T is an async function, otherwise resolves to Else.

Type Parameters

Type Parameter	Default type	Description
T	‐	The type to be checked.
Then	‐	The type to return if T is async function.
Else	never	The type to return if T is not async function. Defaults to never.

Returns

Then if T is async function, Else otherwise.

Example

type Yes = IfAsyncFunction<() => Promise<void>, 'yes', 'no'>; // 'yes'
type No = IfAsyncFunction<() => void, 'yes', 'no'>; // 'no'
type YesOrNo = IfAsyncFunction<(() => Promise<void>) | (() => void), 'yes', 'no'>; // 'yes' | 'no'