Event-Emitter

Modern toolchains like Vite or bundlers targeting browsers no longer polyfill Node’s EventEmitter. @avensio/event-emitter fills that gap with a small, type-safe implementation that behaves the same in Node.js and the browser.

Install

pnpm add @avensio/event-emitter
# npm install @avensio/event-emitter

Highlights

• Typed events: declare an interface where each key maps to a tuple of argument types ({ data: [{ id: string }] }). The emitter enforces these signatures at compile time.
• Drop-in API: on, off, once, emit, with extras such as clearListeners and listenerCount for teardown and diagnostics.
• Zero dependencies: tiny footprint, no polyfills, no globals.
• Unified builds: ESM/CJS/IIFE bundles plus .d.ts declarations for framework and library authors.

How it works

import { EventEmitter } from '@avensio/event-emitter'

type GraphEvents = {
  ready: [void]
  data: [{ nodes: number }]
  error: [Error]
}

const emitter = new EventEmitter<GraphEvents>()
emitter.on('data', ({ nodes }) => console.log('nodes', nodes))
emitter.emit('data', { nodes: 42 })

Listeners run synchronously in registration order. Exceptions in a listener propagate to the caller of emit, so wrap handlers when you need isolation.

When to use it

• Framework or SDK internals needing type-safe hooks (ready, updated, error).
• Shared libraries that run both in Node.js (SSR, CLIs) and browsers.
• Replacement for the built-in emitter when targeting environments like Cloudflare Workers, Service Workers, or ESM-only bundlers.

Next steps

• Browse the API reference for signatures, overloads, and behavior.
• Check Usage patterns for recipes (bridging DOM events, composing emitters, automating teardown).
• Read Development workflow before contributing.