Type Alias IsNullable<T>

IsNullable<T>: Extract<T, null | undefined> extends never
? false
: true

Checks if type T is possibly null or undefined.

Type Parameters

T
The type to check if it is nullable.

Example: Usage

import { assertType, IsNullable } from "@std/testing/types";

assertType<IsNullable<string | null>>(true);
assertType<IsNullable<string | undefined>>(true);
assertType<IsNullable<null | undefined>>(true);

assertType<IsNullable<string>>(false);
assertType<IsNullable<any>>(false);
assertType<IsNullable<never>>(false);