2.0.0 • Public • Published

Parallel 1D

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A light helper for parallel calculations on one-dimensional arrays. Web workers are alternative here for method.

Demo and Comparsion

You can see a live demo at The source code of this demo is available in the repository.

Example of usage: Griffeath's Machine .


Run in a project root to install the package

npm i parallel1d

Web worker needs an external file as a browsers limitation. Web worker always gets data property in onmessage function. Parallel 1D will also add from and to properties to divide work.

 * mock.worker.js

// just one calculation function for example
function double(n) {
  return n * 2

// it gets passed options for worker (i.e. `input`), and special props `from` and `to`
onmessage = function ({ data: { input, from, to } }) {
  const result = []

  for (let i = from; i < to; i++) {
    const n = input[i]



A worker should return the resulting array through the postMessage function.

The worker may be imported just by const myWorker = new Worker('mock.worker.js'), or with worker-loader in case of using Webpack.

 * index.js

import SampleWorker from 'worker-loader!./mock.worker.js'

You can run it as promise if we don't need to run the same workers with different data

import parallel from 'parallel1d/promisified'

const someNumbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

async function runWorkers() {
  const result = await parallel(SampleWorker, { input: someNumbers }, someNumbers.length)
  // it's possible to pass options as the 4th argument, check the Options section below

Or you can use the older approach

import Parallel from 'parallel1d'

const someNumbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
// pass worker constructor and callback to process resulting array
const workers = new Parallel(SampleWorker, console.log)
// pass any options for worker and length of array to divide it to workers
workers.start({ input: someNumbers }, someNumbers.length)

// You will see in console as result: [2, 4, 6, 8, 10, 12, 14, 16, 18, 20]


We can pass options as the 4th argument to a promisified version

const options = {
  // handler for errors, console by default
  onError: console.error,
  // how much workers will be spawned, number of logical processors by default or 4 if undefined
  numberOfWorkers: navigator.hardwareConcurrency || 4,
  // type of array to be returned from parallel1d and workers
  // may be typed array like Int32Array or Uint8ClampedArray, Array by default
  ArrayConstructor: Array,

await parallel(SampleWorker, { input }, input.length, options)

// Besides worker constructor and callback to process resulting array parallel1d constructor accepts options as well
const workers = new Parallel(SampleWorker, console.log, options)

Getting Info

import Parallel from 'parallel1d'

// Get and check defaults without calling constructor with `new`
console.log('Defaults:', Parallel.DEFAULTS)

const workers = new Parallel(SampleWorker, console.log)

// Get the `numberOfWorkers` set in options or by default from a `threads` property
console.log('Threads number:', workers.threads)

// Get is it already started or no?
console.log(workers.working ? 'Work in progress' : 'We need to start it first')


If you need to stop all workers immediately, call:

// the callback argument will be called after termination of workers

Small Size

With all (0) dependencies, minified and gzipped:

  • require('parallel1d') 505 B
  • require('parallel1d/promisified') 550 B

How to Run the Demo Locally

Run in a console:

git clone
cd parallel1d
npm install
npm run start



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