Null objects

ValueObject returns a null object when constructed with null or undefined.

import { NullObject, StringValueObject } from '@haskou/value-objects';

const value = new StringValueObject(undefined as never);

NullObject.isNullObject(value); // true
value.valueOf(); // undefined

Method calls

Null objects expose fake methods from the target class. Calling those methods throws NullObjectError.

const value = new StringValueObject(undefined as never);

value.isEmpty(); // throws NullObjectError

When to check

if (NullObject.isNullObject(value)) {
  // Handle missing value explicitly.
}

Use this when input can be absent and the calling code wants to preserve the value-object shape until a method is actually used.