🎯 NowaraJS Typed Event Emitter

Working with EventEmitter in TypeScript is painful. You get zero autocomplete, typos in event names fail silently, and your listeners accept any because the types don't flow through. I built this to fix that.

Why this package?

The goal is simple: Make event-driven code actually type-safe.

This package wraps EventEmitter so that every event name and payload is validated at compile time. No more guessing, no more runtime surprises.

📌 Table of Contents

• Features
• Installation
• Usage
• API Reference
• License
• Contact

✨ Features

• 🔒 Full Type Safety: Event names and payloads are checked at compile time.
• 🧩 Generic Design: Define your own event maps for any use case.
• 🔄 Familiar API: Same on, emit, once you already know.
• 📦 Zero Dependencies: Pure TypeScript, nothing else.

🔧 Installation

bun add @nowarajs/typed-event-emitter

⚙️ Usage

Basic Usage

Define an event map interface, then pass it to TypedEventEmitter. Everything flows from there.

import { TypedEventEmitter } from '@nowarajs/typed-event-emitter';

interface MyEvents {
	userLogin: [{ userId: string; timestamp: Date }];
	userLogout: [{ userId: string }];
	error: [Error];
}

const emitter = new TypedEventEmitter<MyEvents>();

// `payload` is inferred as { userId: string; timestamp: Date }
emitter.on('userLogin', (payload) => {
	console.log(`User ${payload.userId} logged in at ${payload.timestamp}`);
});

// TypeScript will yell if you pass the wrong shape
emitter.emit('userLogin', {
	userId: 'user123',
	timestamp: new Date()
});

Multiple Parameters

Events can have multiple arguments, and each one is typed individually.

import { TypedEventEmitter } from '@nowarajs/typed-event-emitter';

interface Events {
	move: [x: number, y: number];
	click: [button: 'left' | 'right', x: number, y: number];
}

const input = new TypedEventEmitter<Events>();

// x and y are both numbers
input.on('move', (x, y) => {
	console.log(`Mouse moved to ${x}, ${y}`);
});

// button is 'left' | 'right', x and y are numbers
input.on('click', (button, x, y) => {
	console.log(`${button} click at ${x}, ${y}`);
});

input.emit('move', 100, 200);
input.emit('click', 'left', 50, 75);

📚 API Reference

Full docs: nowarajs.github.io/typed-event-emitter

⚖️ License

MIT - Feel free to use it.

📧 Contact

• Mail: [email protected]
• GitHub: NowaraJS