IfFunction.md

typelab / conditions / IfFunction

type IfFunction<T, Then, Else> = _IfNotAnyOrNever<T, T extends Fn ? Then : Else, Else>;

Resolves to Then if the type T is a 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 function.
Else	never	The type to return if T is not function. Defaults to never.

Returns

Then if T is function, Else otherwise.

Example

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