@mxttwoods/eventbus v1.0.0

@mxttwoods/eventbus

A tiny, fast, zero-dependency event bus for JavaScript.

Description

• Less than 500 bytes minified + zipped
• Zero dependencies
• Modern Syntax
• Fast
• Simple
• Typed

Installation

Just download index.js, or use npm:

yarn add @mxttwoods/eventbus

Usage

Create an EventBus instance.

const emitter = new EventBus();

Then, add handlers as you see fit.

emitter.on('my-event', (data) => {
  alert('got ' + data);
});

emitter.on('my-event', (data) => {
  console.log('got ' + data);
});

Remove handlers using off.

function myHandler(data) {
  console.log(data);
}

emitter.on('my-event', myHandler);
emitter.off('my-event', myHandler);

Trigger events using emit.

// the second parameter here is the data you wish to
// pass to the event handlers
emitter.emit('my-event', {foo: 'Bar'});

If you want a handler to only run once, you can do this:

emitter.on('my-event', function foo() {
  emitter.off('my-event', foo());
  console.log('it worked');
});

You can register for multiple events at once like this:

function myHandler(data) {
  console.log(data);
}

emitter.on('event1 event2 etc', myHandler);
emitter.off('event1 event2 etc', myHandler);

Stopping propagation isn't build into EventBus. You can work around this limitation by doing something like this:

function stopPropagation() {
  const superOn = EventBus.prototype.on;

  EvenBus.prototype.on = (names, fn) => {
    superOn.call(this, names, (data) => {
      if (!data.isCanceled) {
        return fn(data);
      }
      return true;
    });
  };
}
stopPropagation();

With the above patch in place, you can do something like this in your event handlers:

emitter.on('my-event', (data) => {
  data.isCanceled = true; // now, no downstream handlers should be invoked
});

Development

Install

yarn install

Build

yarn build

Test

yarn test

Author

Matthew Woods

• Website: https://matthew.codes
• Twitter: @mxttwoods
• GitHub: @mxttwoods
• LinkedIn: @matthew-t-woods

Chris Davies

• GitHub: @chrisdavies

License

Copyright © 2021 Matthew Woods.

This project is MIT licensed.