Parray — An utility to handle array elements in parallel

Parray is an utility to handle array elements in parallel in Node environment.

Installing

$ npm install parray

Example

var parray = require('parray');

var results = [];
parray.forEach([1, 2, 3], function (element, i) {
  results[i] = element * 2;
}, function () {
  console.log(results); // 2, 4, 6
  console.log('done');
});

API

parray module provides following API.

forEach(Array array, Function worker(element, index, traversedArray), Function callback()) -> Void

A function to execute a provided function once per array element in parallel.

• array: Required. An array.
• worker: Required. A function being executed once per array element.
• element: Required. A current element.
• index: Required. An element index.
• traversedArray: Required. An array object being traversed.
• callback: Optional. A function being executed when all elements are handled.

forEach([Number concurrency]) -> Function

A function to accept a concurrency number and return another forEach function which executes a provided function once per array element in parallel with the specified cuncurrency. If you use another forEach function directly, default concurrency 10 is used.

• concurrency: Required. A number of concurrency.

More Examples

Concurrency

Use forEach(concurrency) function.

var parray = require('parray');

var results = [];
parray.forEach(1)([1, 2, 3], function (element, i) {
  results[i] = element * 2;
}, function () {
  console.log(results); // 2, 4, 6
  console.log('done');
});

Waiting

Use Gate to await asynchronous calls.

var gate = require('gate');
var parray = require('parray');
var fs = require('fs');

var files = ['file1', 'file2'];
var latch = gate.latch();
parray.forEach(files, function (file) {
  fs.readFile(file, 'utf8', latch({name: file, data: 1}));
}, function () {
  latch.await(function (err, results) {
    if (err) throw err;
    console.log(results[0]); // { name: 'file1', data: 'FILE1' }
    console.log(results[1]); // { name: 'file2', data: 'FILE2' }
    console.log('done');
  });
});