support serializing objects without prototype (#145)

* add failing test

* consider null-prototype object a "plain" object

Co-authored-by: Simon Knott <info@simonknott.de>

src/index.test.ts

@@ -936,3 +936,13 @@ test('regression #108: Error#stack should not be included by default', () => {
  ) as any;
  expect(thatShouldExist).toEqual(input.stack);
 });
+
+test('regression: `Object.create(null)` / object without prototype', () => {
+ const input: Record<string, unknown> = Object.create(null);
+ input.date = new Date();
+
+ const stringified = SuperJSON.stringify(input);
+ const parsed: any = SuperJSON.parse(stringified);
+
+ expect(parsed.date).toBeInstanceOf(Date);
+});

src/is.test.ts

@@ -9,6 +9,7 @@ import {
  isString,
  isSymbol,
  isUndefined,
+ isPlainObject,
 } from './is';
 
 test('Basic true tests', () => {
@@ -68,3 +69,8 @@ test('Primitive tests', () => {
 test('Date exception', () => {
  expect(isDate(new Date('_'))).toBe(false);
 });
+
+test('Regression: null-prototype object', () => {
+ expect(isPlainObject(Object.create(null))).toBe(true);
+ expect(isPrimitive(Object.create(null))).toBe(false);
+});

src/is.ts

@@ -10,6 +10,7 @@ export const isPlainObject = (
  payload: any
 ): payload is { [key: string]: any } => {
  if (getType(payload) !== 'Object') return false;
+ if (Object.getPrototypeOf(payload) === null) return true;
  return (
  payload.constructor === Object &&
  Object.getPrototypeOf(payload) === Object.prototype