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Simple ES6-based pub-sub service

A simple 0.8KB pub-sub-based event library that lets you send custom message within and cross the window! It's written in ES6 and makes use of the awesome Broadcast Channel API.

Demo: pub-sub.lekschas.de

Install

npm -i -D pub-sub-es

Get Started

import createPubSub from 'pub-sub-es';

// Creates a new pub-sub event listener stack.
const pubSub = createPubSub();

// Subscribe to an event
const myEmojiEventHandler = msg => console.log(`🎉 ${msg} 😍`);
pubSub.on('my-emoji-event', myEmojiEventHandler);

// Publish an event
pubSub.publish('my-emoji-event', 'Yuuhuu');  // >> 🎉 Yuuhuu 😍

// Unsubscribe
pubSub.unsubscribe('my-emoji-event', myEmojiEventHandler);

API

pub-sub-es exports the factory function (createPubSub) for creating a new pub-sub service by default and a global pub-sub service (globalPubSub). The API is the same for both.

`createPubSub(stack = { times: {} })`

Creates a new pub-sub instances

stack is an object holding for holding the event listeners and defaults to a new stack when being omitted.

Returns: a new pub-sub service

`pubSub.publish(event, news)`

Publishes or broadcasts an event with some news or payload

event is the name of the event to be published.
news is an arbitrary value that is being broadcasted.

`pubSub.subscribe(event, handler, times)`

Subscribes a handler to a specific event

event is the name of the event to be published.
handler is the handler function that is being called together with the broadcasted value.
times is the number of times the handler is invoked before it's automatically unsubscribed.

Returns: an object of form { event, handler }. This object can be used to automatically unsubscribe, e.g., pubSub.unsubscribe(pubSub.subscribe('my-event', myHandler)).

`pubSub.unsubscribe(event)`

Unsubscribes a handler from listening to an event

event is the name of the event to be published. Optionally, unsubscribe accepts an object of form { event, handler} coming from subscribe.

`pubSub.clear()`

Removes all currently active event listeners and unsets the event times.

Note: this endpoint is not available on the global pub-sub because it could have undesired side effects. You need to unsubscribe global event listeners manually instead.

Between-context messaging

The global pub-sub instance is created when pub-sub-es.js is loaded and provides a way for global messaging within and between contexts. It utilizes the Broadcast Channel API, which is currently not available in all browsers. If you need to support more browsers you have to load a polyfill. PubSubES is not taking care of that! Also, when sending sending objects from one context to another you have to make sure that they are clonable. For example, trying to broadcast a reference to a DOM element will fail.