@eolthar/events

A lightweight, high-performance event emitter for fast and scalable projects.

npm i @eolthar/events

Benchmark

Category	@eolthar/events	tseep	EventEmitter3	NanoEvents	mitt
1. Mass subscription and emit	4 151 932	3 875 026	3 225 172	3 774 587	3 276 026
2. Unsubscribe	6 198 889	6 286 916	4 384 381	7 885 637	5 295 300
3. on → emit → off	2 348 937	2 727 954	2 509 048	3 543 034	2 744 207
4. emit (0 arguments)	10 397 673	8 126 418	6 837 431	8 565 591	6 764 343
5. emit (5 arguments)	9 915 638	8 080 340	6 901 530	7 531 209	6 454 089
6. emit (10 arguments)	9 183 703	7 561 947	4 503 834	6 767 050	6 023 215

Usage

const { Emitter } = require("@eolthar/events");

const emitter = new Emitter();

function handler(name) {
    console.log(`Hello, ${name}!`);
}

// Subscribe to an event
emitter.on("hello", handler);

// Emit an event
emitter.emit("hello", "Alice"); // Hello, Alice!

// Unsubscribe from the event
emitter.off("hello", handler);

// Emitting again won't call the listener
emitter.emit("hello", "Bob"); // nothing happens

API

new Emitter()

Creates a new event emitter instance.

emitter.on(event, listener)

Subscribes a listener to a named event.

emitter.on("data", (value) => console.log(value));

emitter.off(event, listener)

Removes a specific listener from an event.

function handler(value) {
    console.log(value);
}

emitter.on("data", handler);
emitter.off("data", handler);

emitter.once(event, listener)

Subscribes a listener that is automatically removed after the first call. Returns the internal wrapper function, which can be passed to off to manually remove the listener before it fires.

emitter.once("connect", () => console.log("connected!"));
emitter.emit("connect"); // connected!
emitter.emit("connect"); // nothing happens

emitter.emit(event, ...args)

Emits the specified event, calling all registered listeners in the order they were added.

emitter.emit("data", 1, 2, 3);

emitter.clear(event?)

Removes all listeners for a specific event. If no event is provided, clears all events.

emitter.clear("data"); // removes all listeners for "data"
emitter.clear(); // removes everything

License

MIT