Type Alias UnionToIntersection<T>

UnionToIntersection: (T extends any ? (x: T) => any : never) extends (
    x: infer R,
) => any
    ? R
    : never

Converts a union of types into an intersection of those same types.

type Union = { size: string } | { color: string };
type Intersection = UnionToIntersection<Union>;
// => { size: string } & { color: string }