description: Zero-dependency typed event bus with subscribe/emit, wait(), async streams, AbortSignal support, and test helpers. package: eventit category: events keywords: [event-bus, typed-events, pub-sub, reactive, decoupled, async-streams] related: [stateit, routeit, workit] exports: [createBus, createTestBus]

@vielzeug/eventit

Zero-dependency typed event bus with subscribe/emit, wait(), async streams, AbortSignal support, and test helpers.

Package: @vielzeug/eventit  ·  Category: Events

Key exports: createBus, createTestBus

When to use: Zero-dependency typed event bus with subscribe/emit, wait(), async streams, AbortSignal support, and test helpers.

Related: @vielzeug/stateit · @vielzeug/routeit · @vielzeug/workit

@vielzeug/eventit is part of Vielzeug and ships as a zero-dependency TypeScript package with ESM+CJS output.

Installation

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

Quick Start

import { BusDisposedError, createBus } from '@vielzeug/eventit';

type AppEvents = {
  'user:login': { userId: string; email: string };
  'user:logout': void;
};

const bus = createBus<AppEvents>();

bus.on('user:login', ({ userId }) => {
  console.log('Logged in:', userId);
});

bus.emit('user:login', { email: '[email protected]', userId: '42' });
bus.emit('user:logout');

const nextLogin = await bus.wait('user:login');
const nextSessionEvent = await bus.waitAny(['user:login', 'user:logout'] as const);

if (nextSessionEvent.event === 'user:login') {
  console.log(nextSessionEvent.payload.userId);
}

try {
  await bus.wait('user:login', AbortSignal.timeout(1_000));
} catch (err) {
  if (err instanceof BusDisposedError) {
    console.log('Bus was disposed');
  }
}

Documentation

• Overview
• Usage Guide
• API Reference
• Examples

License

MIT © Helmuth Saatkamp — part of the Vielzeug monorepo.