TypeScript: RemoveUndefined Type

removeUndefined.ts

type RemoveUndefined<T extends any[]> = 
  T extends (infer R | undefined)[]
  ? R[]
  : T

// OK
type ArrayWithoutUndefined1 = RemoveUndefined<(string | number | undefined | Date)[]>
type ArrayWithoutUndefined2 = RemoveUndefined<(string | number | Date)[]>
type ArrayWithoutUndefined3 = RemoveUndefined<["hello", 1, 2, undefined, Date, {}]> // order is not maintained
type ArrayWithoutUndefined4 = RemoveUndefined<["hello", 1, 2, Date, {}]> // order is not maintained

const arr1 = [undefined, 1, 2, 3, "hello", "world", new Date()];
type ArrayWithoutUndefined5 = RemoveUndefined<typeof arr1>

const arr2 = [1, 2, 3, "hello", "world", new Date()];
type ArrayWithoutUndefined6 = RemoveUndefined<typeof arr2>

type ArrayWithoutUndefined7 = RemoveUndefined<[]>

// Not OK

type FailedArrayWithoutUndefined1 = RemoveUndefined<number>;
type FailedArrayWithoutUndefined2 = RemoveUndefined<string>;