IfIntersected.md

typelab / conditions / IfIntersected

type IfIntersected<T1, T2, Then, Else> = T1 & T2 extends never ? Else : Then;

Resolves to Then if T1 is intersected with T2, otherwise resolves to Else.

Type Parameters

Type Parameter	Default type	Description
T1	‐	The first type to compare.
T2	‐	The second type to compare.
Then	‐	The type to return if T1 is intersected with type T2.
Else	never	The type to return if T1 is not intersected with type T2. Defaults to never.

Returns

Then if T1 & T2 is not never, Else otherwise.

Example

type Yes = IfIntersected<'a' | 'c', 'a' | 'b', 'yes', 'no'>; // 'yes'
type No = IfIntersected<'c', 'a' | 'b', 'yes', 'no'>; // 'no'