EventEmitterX

A cross-platform EventEmitter implementation for Node.js and browsers, with an advanced reactive signals system (EventSignal) deeply integrated with React.

Online documentation and Demo ↗

Key Features

EventEmitterX

• ✅ Full Node.js EventEmitter API compatibility
• 🌐 Works in browsers without polyfills
• 🔒 listenerOncePerEventType — prevent duplicate listeners per event
• 📊 emitCounter — count emit calls for monitoring
• ⏱️ Enhanced static once() — Promise-based with filter, timeout, AbortSignal, multiple event names, and both EventEmitter/EventTarget support
• 🔄 static on() — async iterator for event streams with value transformation
• 🧹 destructor() / Symbol.dispose — safe resource cleanup
• 🐛 isDebugTraceListeners — attach call stacks to listeners for debugging

EventSignal

• ⚡ Reactive computed values with automatic dependency tracking
• 🔀 Sync and async computations
• ⚛️ Deep React integration: use(), useListener(), direct JSX rendering
• 🎭 Component type system for polymorphic rendering (registerReactComponentForComponentType)
• 📡 Source emitters — subscribe to external EventEmitter/EventTarget events
• ⏰ Triggers — clock, emitter, or signal-based recomputation
• 🎯 createMethod — typed action methods bound to signals
• 📦 Subscription objects with suspend()/resume()
• 🔮 Promise API and async iteration (for await...of)

Quick Start

import { EventEmitterX } from '@termi/eventemitterx/modules/events';
import { EventSignal } from '@termi/eventemitterx/modules/EventEmitterEx/EventSignal';

// --- EventEmitterX ---
const emitter = new EventEmitterX();

// Promise-based once with filter and timeout
const [data] = await EventEmitterX.once(emitter, 'data', {
  filter: (event, value) => value > 10,
  timeout: 5000,
});

// Async iterator
for await (const [tick] of EventEmitterX.on(emitter, 'tick')) {
  console.log(tick);
}

// --- EventSignal ---
const counter$ = new EventSignal(0);
const doubled$ = new EventSignal(0, () => counter$.get() * 2);

counter$.set(5);
console.log(doubled$.get()); // 10

// React integration
EventSignal.initReact(React);

function App() {
  const count = counter$.use();
  return <div>{count}</div>;
}

Documentation

Document	Description
Project Analysis	Full project overview and architecture
Module Index	Brief overview of all modules
EventEmitterX API	Detailed API reference with examples
EventSignal API	Detailed API reference with examples
Improvements	Potential improvements and roadmap

📖 Russian versions (_RU.md) are available for all documentation files.

Demo Applications

EventSignal React Demo

A React + Vite application demonstrating EventSignal features: counters, computed values, async data fetching, i18n, component switching, and more.

cd demo/eventSignals-test-app ; pnpm i ; pnpm run dev

Clicker (Full-Stack)

A real-time multiplayer clicker game with Fastify backend, Prisma ORM, and SSE-based updates.

cd demo/clicker ; ./bash/run_dev_backend_frontend.sh

Installation

pnpm install

Build

pnpm run build        # CJS + ESM
pnpm run build:cjs    # CommonJS only
pnpm run build:esm    # ES Modules only

License

ISC