@vielzeug/illusionist

Typed, deterministic, locale-aware fake data generator with seeded PRNG.

Installation

pnpm add @vielzeug/illusionist
npm install @vielzeug/illusionist
yarn add @vielzeug/illusionist

Quick Start

import { createIllusion } from '@vielzeug/illusionist';
import { en } from '@vielzeug/illusionist/locales';

const illusion = createIllusion({ seed: 12345, locale: en });

illusion.person.fullName();      // "Ashley Harris"
illusion.internet.email();       // "[email protected]"
illusion.commerce.price();       // Money<USD>
illusion.date.past({ years: 5 }); // Temporal.ZonedDateTime
illusion.finance.iban();         // "IT0649896243786776403271206"
illusion.location.city();        // "Denver"
illusion.lorem.paragraph();      // "Dolor in fugiat anim dolor aute officia irure sunt..."
illusion.system.semver();        // "7.4.0"

illusion.dispose();              // [Symbol.dispose]() also works

Entry Points

• @vielzeug/illusionist — curated root exports + createIllusion factory
• @vielzeug/illusionist/person — names, genders, job titles
• @vielzeug/illusionist/internet — emails, URLs, IPs, user agents
• @vielzeug/illusionist/commerce — product names, prices, departments
• @vielzeug/illusionist/date — past/future dates, birthdays, weekdays
• @vielzeug/illusionist/finance — IBANs, credit cards, crypto addresses
• @vielzeug/illusionist/location — cities, streets, coordinates
• @vielzeug/illusionist/lorem — lorem ipsum text generation
• @vielzeug/illusionist/system — file paths, semver, UUIDs, cron
• @vielzeug/illusionist/seed — createSeed, mulberry32 PRNG
• @vielzeug/illusionist/locales — locale objects (en, de); tree-shakeable, import only what you use

Seeded Determinism

Pass a seed for reproducible output — same seed always produces the same sequence across all categories. Omit seed for cryptographic randomness via crypto.getRandomValues.

const a = createIllusion({ seed: 'test-fixture', locale: en });
const b = createIllusion({ seed: 'test-fixture', locale: en });

a.person.fullName() === b.person.fullName(); // true

Locale Support

Initial locales are explicit, tree-shakeable objects exported from @vielzeug/illusionist/locales. Locale data ships only for locales you import; the root package includes no default locale.

import { de } from '@vielzeug/illusionist/locales';

const illusion = createIllusion({ seed: 42, locale: de });

illusion.person.firstName();  // "Mathilda"
illusion.location.city();     // "Bielefeld"

For dynamic app switching, load the locale before creating the synchronous instance:

const { de } = await import('@vielzeug/illusionist/locales');
const illusion = createIllusion({ locale: de });

Documentation

• Overview
• Usage Guide
• API Reference
• Examples

License

MIT © Helmuth Saatkamp — part of the Vielzeug monorepo.