@i-xi-dev/pubsub

A JavaScript Pub/Sub Broker.

Requirement

Broker requires AbortController and AggregateError.

Chrome	Edge	Firefox	Safari	Deno	Node.js
✅	✅	✅	✅ 14+	✅	✅ 15.0.0+

Installation

npm

$ npm i @i-xi-dev/pubsub@2.0.17

import { PubSub } from "@i-xi-dev/pubsub";

CDN

Example for Skypack

import { PubSub } from "https://cdn.skypack.dev/@i-xi-dev/pubsub@2.0.17";

Usage

Broker class

const broker = new PubSub.Broker();
const topic1 = Symbol();
const topic2 = Symbol();

const subscriber11 = [];
const subscriber12 = [];
const subscriber21 = [];


// subscribe(
//   topic: symbol | string,
//   callback: (message?: T) => Promise<void>,
//   options?: { once?: boolean, signal?: AbortSignal }
// ): void

broker.subscribe(topic1, (message) => {
  subscriber11.push(message);
});
const callback12 = (message) => {
  subscriber12.push(message);
};
broker.subscribe(topic1, callback12);
broker.subscribe(topic2, (message) => {
  subscriber21.push(message);
});


// publish(
//   topic: symbol | string,
//   message?: T
// ): Promise<void>
// rejects with AggregateError, if one or more callbacks failed.

await broker.publish(topic1, "X");
// → subscriber11: [ "X" ]
//   subscriber12: [ "X" ]
//   subscriber21: []


// unsubscribe(
//   topic: symbol | string,
//   callback: (message?: T) => Promise<void>
// ): void

broker.unsubscribe(topic1, callback12);
await broker.publish(topic1, "X");
// → subscriber11: [ "X", "X" ]
//   subscriber12: [ "X" ]
//   subscriber21: []


// clear(): void

broker.clear();
await broker.publish(topic1, "X");
// → subscriber11: [ "X", "X" ]
//   subscriber12: [ "X" ]
//   subscriber21: []

Subscribe options

once: boolean

let received = "";
broker.subscribe(topic1, (message) => {
  received = message;
}, {
  once: true,
});

await broker.publish(topic1, "Y1");
await broker.publish(topic1, "Y2");
// → received: "Y1"

signal: AbortSignal

const received = [];
const controller = new AbortController();
broker.subscribe(topic1, (message) => {
  received.push(message);
}, {
  signal: controller.signal,
});

await broker.publish(topic1, "Z1");
await broker.publish(topic1, "Z2");
controller.abort();
await broker.publish(topic1, "Z3");
// → received: [ "Z1", "Z2" ]