@rupertsworld/emitter

Typed event emitter with disposable subscriptions.

Install

npm install @rupertsworld/emitter

Usage

Extend Emitter with an event map to get a fully typed emitter. Subscriptions return a Disposable — call dispose() to unsubscribe.

import { Emitter } from "@rupertsworld/emitter";

type Events = {
  message: string;
  error: Error;
  close: undefined;
};

class Chat extends Emitter<Events> {
  send(text: string) {
    this.emit("message", text);
  }

  disconnect() {
    this.emit("close");
  }
}

const chat = new Chat();

const sub = chat.on("message", (text) => {
  console.log("received:", text);
});

chat.send("hello"); // logs "received: hello"
sub.dispose();      // unsubscribed
chat.send("world"); // nothing logged

One-time listeners

chat.once("close", () => {
  console.log("disconnected");
});

API

Emitter<T>

Base class. T is a Record<string, any> mapping event names to payload types. Use undefined for events with no payload.

| Method | Description | | --- | --- | | on(type, handler) | Subscribe to an event. Returns a Disposable. | | once(type, handler) | Subscribe to an event once. Returns a Disposable. | | off(type, handler) | Unsubscribe a handler. | | emit(type, payload) | Emit an event (protected — only available in subclasses). |

Wildcard '*' can be used with on and once to listen to all events.