asynckit

What is asynckit?

The asynckit npm package provides a minimalistic asynchronous control flow kit that offers a set of utilities for working with asynchronous operations in Node.js. It allows for sequential and parallel execution of asynchronous functions, as well as other utilities for handling streams and iterable collections.

What are asynckit's main functionalities?

Serial execution of async tasks

Executes an array of async tasks one after another. Each task is started only after the preceding task has completed. The results are collected in an array that is passed to the final callback.

const asyncKit = require('asynckit');
const fs = require('fs');

asyncKit.serial([
  callback => fs.readFile('file1.txt', 'utf8', callback),
  callback => fs.readFile('file2.txt', 'utf8', callback)
], (err, results) => {
  if (err) throw err;
  console.log(results); // results is an array of the contents of the two files
});

Parallel execution of async tasks

Executes an array of async tasks in parallel. All tasks are started at the same time, and the final callback is called when all tasks have completed. The results are collected in an array.

const asyncKit = require('asynckit');
const fs = require('fs');

asyncKit.parallel([
  callback => fs.readFile('file1.txt', 'utf8', callback),
  callback => fs.readFile('file2.txt', 'utf8', callback)
], (err, results) => {
  if (err) throw err;
  console.log(results); // results is an array of the contents of the two files
});

Stream processing

Provides a way to pipe data from a readable stream to a writable stream with the ability to handle errors that may occur during the streaming process.

const asyncKit = require('asynckit');
const stream = require('stream');

const readable = new stream.Readable();
const writable = new stream.Writable();

// Implement _read and _write methods for the streams
// ...

asyncKit.stream(readable, writable, (err) => {
  if (err) throw err;
  console.log('Stream processing complete');
});

Other packages similar to asynckit

async

The 'async' package is a comprehensive collection of asynchronous control flow utilities. It offers a wide range of functions for parallel, series, and other complex flow controls. Compared to asynckit, 'async' is more feature-rich and widely used, but it is also larger in size.

bluebird

Bluebird is a fully-featured promise library that allows for converting callback-based APIs to promises. It includes utilities for sequential and parallel execution of tasks. While asynckit uses callbacks, Bluebird focuses on promises, which can lead to cleaner code with less nesting.

q

Q is another promise library that provides tools for creating and managing promises. It is similar to Bluebird in that it helps with asynchronous flow control but uses a different API. Asynckit is callback-based, whereas Q is promise-based.

README

asynckit

Minimal async jobs utility library.

compression	size
asynckit.js	3.47 kB
asynckit.min.js	1.19 kB
asynckit.min.js.gz	590 B

Install

$ npm install asynckit --save

Examples

Parallel Jobs

Runs iterator over provided array in parallel. Stores output in the result array, on the matching positions. In unlikely event of an error from one of the jobs, will terminate rest of the active jobs (if abort function is provided) and return error along with salvaged data to the main callback function.

var parallel = require('asynckit/parallel')
  , assert   = require('assert')
  ;

var source         = [ 1, 1, 4, 16, 64, 32, 8, 2 ]
  , expectedResult = [ 2, 2, 8, 32, 128, 64, 16, 4 ]
  , expectedTarget = [ 1, 1, 2, 4, 8, 16, 32, 64 ]
  , target         = []
  ;

parallel(source, asyncJob, function(err, result)
{
  assert.deepEqual(result, expectedResult);
  assert.deepEqual(target, expectedTarget);
});

// async job accepts one element from the array
// and a callback function
function asyncJob(item, cb)
{
  // different delays (in ms) per item
  var delay = item * 25;

  // pretend different jobs take different time to finish
  // and not in consequential order
  var timeoutId = setTimeout(function() {
    target.push(item);
    cb(null, item * 2);
  }, delay);

  // allow to cancel "leftover" jobs upon error
  // return function, invoking of which will abort this job
  return clearTimeout.bind(null, timeoutId);
}

Also it supports named jobs, listed via object.

var parallel = require('asynckit/parallel')
  , assert   = require('assert')
  ;

var source         = { first: 1, one: 1, four: 4, sixteen: 16, sixtyFour: 64, thirtyTwo: 32, eight: 8, two: 2 }
  , expectedResult = { first: 2, one: 2, four: 8, sixteen: 32, sixtyFour: 128, thirtyTwo: 64, eight: 16, two: 4 }
  , expectedTarget = [ 1, 1, 2, 4, 8, 16, 32, 64 ]
  , expectedKeys   = [ 'first', 'one', 'two', 'four', 'eight', 'sixteen', 'thirtyTwo', 'sixtyFour' ]
  , target         = []
  , keys           = []
  ;

parallel(source, asyncJob, function(err, result)
{
  assert.deepEqual(result, expectedResult);
  assert.deepEqual(target, expectedTarget);
  assert.deepEqual(keys, expectedKeys);
});

// supports full value, key, callback (shortcut) interface
function asyncJob(item, key, cb)
{
  // different delays (in ms) per item
  var delay = item * 25;

  // pretend different jobs take different time to finish
  // and not in consequential order
  var timeoutId = setTimeout(function() {
    keys.push(key);
    target.push(item);
    cb(null, item * 2);
  }, delay);

  // allow to cancel "leftover" jobs upon error
  // return function, invoking of which will abort this job
  return clearTimeout.bind(null, timeoutId);
}

Want to Know More?

More examples can be found in test folder.

Or open an issue with questions and/or suggestions.

License

AsyncKit is licensed under the MIT license.