async-it

async-it is a series of generic asynchronous parallel and serial iterators for node.js.

These iterators are based on the ES5 additions to Array (forEach, map, filter, some, any, reduce and reduceRight). reduce and reduceRight are available in serial mode only.

Indexes are only passed to the callback in the aptly-named forEachWithIndex for fear of crowding the callback with little used arguments.

Like their sync counterparts, these iterators work on any object which has a numeric length property.

Usage

See examples/example.js:

var path = require('path'),
    fs = require('fs'),
    asyncItParallel = require('async-it').parallel;

var files = ['foo.txt', 'bar.txt', 'does-not-exist.txt', 'baz.txt'];
files = files.map(function(file) {
  return path.join(__dirname, 'files', file);
});

// select existing files
asyncItParallel.filter(files, function(file, cont) {
  fs.exists(file, function(exists) {
    cont(null, exists);
  });
}, function(err, existingFiles) {
  // collect their content
  asyncItParallel.map(existingFiles, function(file, cont) {
    fs.readFile(file, 'utf8', cont);
  }, function(err, content) {
    // output the ordered content to the console
    console.log(content.join('\n'));
  });
});

// Hi, I'm foo!
// Hello World, this is bar.
// I'm baz.

License

Licensed under the MIT license, Copyright 2010 Tobie Langel.