Optional

Provide one type to the Optional function and it will return a type guard that will check if the value conforms to the specified type, undefined, or null.

Note, this type is just a Union of the specified type, Undefined, and Null.

Usage

import { T } from "type-guarder";
 
T.Optional(T.Number()).conforms(undefined); // true
T.Optional(T.Number()).conforms(null); // true
T.Optional(T.Number()).conforms(3); // true
T.Optional(T.Number()).conforms("Hello, world"); // false
T.Optional(T.Number()).conforms(true); // false

Undefinable Value