matthewp / leni

Yet another web worker library by me!

leni

A small library for communication between the main thread and workers.

The Problem

Web Workers are a cool way to offload expensive work to another thread. However, all communication is done through a single message event. If you want your worker to do more than 1 thing, a lot of boilerplate is required to reroute messages to the correct handler.

The Solution

This is a small library that create instances of event emitters that run both in the window and worker contexts. This makes it easy to send a message to one specific emitter, allowing you to have as many different handlers as you want.

window.js

import { connect } from 'https://unpkg.com/leni/leni.js';

let worker = new Worker('./worker.js');
let emitter = connect('app', worker);

emitter.addEventListener('anything-here', function(resp){
  console.log(resp); // Hi Matthew!
});

emitter.post('say-hi', { name: 'Matthew' });

worker.js

importScripts('https://unpkg.com/leni/leni.js');

function onApp(emitter) {
  emitter.addEventListener('say-hi', data => {
    let msg = `Hi ${data.name}!`;
    emitter.post('anything-here', msg);
  });
}

leni.subscribe('app', onApp);

That's it!

Installation

You can install with npm or yarn:

> npm install leni --save

> yarn add leni

Or better yet, use directly from unpkg:

import { connect } from 'https://unpkg.com/leni/leni.js';

// Use it!

If you plan on using leni throughout your app you can create a wrapper module like so:

leni.js

export * from 'https://unpkg.com/leni/leni.js';

app.js

import { connect } from './leni.js';

License

BSD-2-Clause

leni's Issues

Multiple emitters will all handle the same message

There is bug where having 2 emitters within the worker will cause both of them to handle the same messages if the types are the same.

function onMsg(emitter) {
  emitter.addEventListener('foo' => {
    console.log("oops");
  });
}

leni.subscribe('thing1', onMsg);
leni.subscribe('thing2', onMsg);