IfNull.md

typelab / conditions / IfNull

type IfNull<T, Then, Else> = _IfNotAnyOrNever<T, T extends null ? Then : Else, Else>;

Resolves to Then if the type T is null, 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 null.
Else	never	The type to return if T is not null. Defaults to never.

Returns

Then if T is null, Else otherwise.

Example

type Yes = IfNull<null, 'yes', 'no'>; // 'yes'
type No = IfNull<string, 'yes', 'no'>; // 'no'
type YesOrNo = IfNull<string | null, 'yes', 'no'>; // 'yes' | 'no'