Type Alias UnionHas<U, T>

UnionHas: [T] extends [U] ? true : false

Check if a union type includes a specific type.

Type Parameters

U
A union type
T
The type to check for membership in the union

Remarks

Evaluates to true if the type T is assignable to the union U, otherwise evaluates to false.

Example

type U = string | number | boolean;
type HasString = UnionHas< U, string >;  // true
type HasDate = UnionHas< U, Date >;      // false