:skull::bulb: Dead simple PubSub and EventEmitter

Small, readable, almost-tweetable modules utilising classic patterns in modern language.

Features

• Small: PubSub: 127 bytes, EventEmitter: 138 bytes, together: 191 bytes (all gzipped)
• Best practices: Subscribe returns unsubscribe. So you can use anonymous functions.
• Readable: There is nothing magical in the code; except the simplicity.
• Modern: Uses new, yet well-supported features.
• Efficient: No memory leaks, no duplicate calls, no extra looping.
• Clean API: sub and pub (or on and emit), need no more, can't go less.
• Modular: Use only what you need.
• Typed TypeScript definitions are bundled

Install

Install using yarn or npm:

yarn add dead-simple
# or via npm
npm install --save dead-simple

Usage

import pubsub from "dead-simple/pubsub";
import eventEmitter from "dead-simple/eventEmitter";
// Alternatively:
// import { pubsub, eventEmitter } from 'dead-simple'

// === PubSub ======
const clicks = pubsub();

const unSub = clicks.sub((target) => console.log(`Clicked on ${target}!`));

clicks.pub("button");
// -> Clicked on button!

unSub();

clicks.pub("link");
// nothing

// === eventEmitter ===
// eventEmitter = named PubSub
const events = eventEmitter();

events.on("click", (target) => console.log(`Clicked on ${target}!`));

const unSubChange = events.on("change", (newValue) =>
  console.log(`Value is now ${newValue}!`)
);

events.emit("change", 1968);
// -> Value is now 1968!

unSubChange();

events.emit("change", 1968);
// nothing

events.emit("click", "button");
// -> Clicked on button!

Browser compatibility

Used ES6: const, arrow functions, Map, Set, object shorthand

| Chrome* | Edge | FF | IE | Opera | Safari | iOS | Node | | -------- | ---- | --- | --- | ----- | ------ | --- | ---- | | 38 | 12 | 13 | -* | 25 | 7.1 | 8 | 4 |

Notes:

• Chrome includes mobile Chrome (Android 4+).
• IE 11 does not support only syntax feature, arrow functions and object shorthand.
• The module needs to be bundled, of course.

Super small versions

This project started a pair of gists which included a hand minified version, too.

We were able to get down to 91B for PubSub:

export default (s = new Set()) => ({
  pub: (d) => s.forEach((f) => f(d)),
  sub: (f) => s.add(f).delete.bind(s, f),
});

And 139B for EventEmitter (p is PubSub):

export default (e) => (
  (e = new Map()),
  Object.freeze({
    on: (n, f) => (e.has(name) || e.set(n, p()), e.get(n).sub(f)),
    emit: (n, d) => e.has(n) && e.get(n).pub(d),
  })
);

These versions are for fun, more like a proof of concept and may not work in some browsers.