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, with streams support.

AsyncKit provides harness for parallel and serial iterators over list of items represented by arrays or objects. Optionally it accepts abort function (should be synchronously return by iterator for each item), and terminates left over jobs upon an error event. For specific iteration order built-in (ascending and descending) and custom sort helpers also supported, via asynckit.serialOrdered method.

It ensures async operations to keep behavior more stable and prevent Maximum call stack size exceeded errors, from sync iterators.

compression	size
asynckit.js	12.34 kB
asynckit.min.js	4.11 kB
asynckit.min.js.gz	1.47 kB

Install

$ npm install --save asynckit

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.

Input Array

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);
}

More examples could be found in test/test-parallel-array.js.

Input Object

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);
}

More examples could be found in test/test-parallel-object.js.

Serial Jobs

Runs iterator over provided array sequentially. Stores output in the result array, on the matching positions. In unlikely event of an error from one of the jobs, will not proceed to the rest of the items in the list and return error along with salvaged data to the main callback function.

Input Array

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

var source         = [ 1, 1, 4, 16, 64, 32, 8, 2 ]
  , expectedResult = [ 2, 2, 8, 32, 128, 64, 16, 4 ]
  , expectedTarget = [ 0, 1, 2, 3, 4, 5, 6, 7 ]
  , target         = []
  ;

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

// extended interface (item, key, callback)
// also supported for arrays
function asyncJob(item, key, cb)
{
  target.push(key);

  // it will be automatically made async
  // even it iterator "returns" in the same event loop
  cb(null, item * 2);
}

More examples could be found in test/test-serial-array.js.

Input Object

Also it supports named jobs, listed via object.

var serial = require('asynckit').serial
  , assert = require('assert')
  ;

var source         = [ 1, 1, 4, 16, 64, 32, 8, 2 ]
  , expectedResult = [ 2, 2, 8, 32, 128, 64, 16, 4 ]
  , expectedTarget = [ 0, 1, 2, 3, 4, 5, 6, 7 ]
  , target         = []
  ;

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, 4, 16, 64, 32, 8, 2 ]
  , target         = []
  ;


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

// shortcut interface (item, callback)
// works for object as well as for the arrays
function asyncJob(item, cb)
{
  target.push(item);

  // it will be automatically made async
  // even it iterator "returns" in the same event loop
  cb(null, item * 2);
}

More examples could be found in test/test-serial-object.js.

Note: Since object is an unordered collection of properties, it may produce unexpected results with sequential iterations. Whenever order of the jobs' execution is important please use serialOrdered method.

Ordered Serial Iterations

TBD

For example compare-property package.

Streaming interface

TBD

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.