@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