@haskou/value-objects

A TypeScript library for validated, immutable primitive wrappers and small utility value objects.

It provides ready-to-use objects for strings, numbers, identifiers, dates, coordinates, hashes, media, collections, and cryptographic payload helpers. Validation happens when an object is created, so code receiving one of these objects can rely on its shape.

Documentation

Full documentation is available at https://haskou.github.io/value-objects/.

The documentation includes installation, quick start, examples, error handling, serialization notes, and one reference page per exported class.

Reusable agent instructions and engineering skills are available at https://github.com/haskou/ddd-engineer-skills.

Installation

npm install @haskou/value-objects

yarn add @haskou/value-objects

Quick start

import { Color, Email, Hour, PositiveNumber } from '@haskou/value-objects';

const email = new Email('user@example.com');
const price = new PositiveNumber(29.99);
const color = new Color('#FF0000');
const hour = new Hour('09:30');

console.log(email.valueOf()); // 'user@example.com'
console.log(price.valueOf()); // 29.99
console.log(color.toString()); // '#FF0000'
console.log(hour.addMinutes(45).toString()); // '10:15'

Invalid values throw specific errors.

import { Email, InvalidEmailError } from '@haskou/value-objects';

try {
  new Email('not-an-email');
} catch (error) {
  if (error instanceof InvalidEmailError) {
    console.error('Invalid email');
  }
}

Available categories

Category	Examples
Base	ValueObject, NullObject, Enum
Strings	StringValueObject, Password, Email, Color
Numbers	NumberValueObject, Integer, PositiveNumber
IDs	ShortId, UUID
Time	Timestamp, CalendarDay, Hour, Duration, MonthOfYear
Coordinates	Latitude, Longitude, Coordinates
Hashes	MD5Hash, SHA256Hash, SHA512Hash
Media	Media
Collections	UniqueObjectArray
Crypto helpers	KeyPair, PrivateKey, PublicKey, SymmetricKey, encrypted payload objects

See the complete API reference in the documentation: https://haskou.github.io/value-objects/reference/

Documentation development

# Start local docs server
yarn docs:dev

# Build static documentation
yarn docs:build

# Preview the built site
yarn docs:preview

Package development

yarn install
yarn test
yarn build

Release branches

Publishing is handled by CI when a pull request is merged into the default branch.

Branch prefix	npm bump
fix/*	Patch
feat/*	Minor
break/*	Major

Branches without one of these prefixes still run CI, but they do not publish to npm.

License

MIT. See LICENSE.txt.