forEachAsync

forEachAsync

As I do every few years, I decided to rewrite FuturesJS. This year's remake is extremely lightweight.

v3.x - Diet Cola Edition (published on npm as beta, so you must use the @3.x - and don't worry, v2.x is still supported)

Analogous to [].forEach, but handles items asynchronously with a final callback passed to then.

This is the most essential piece of the ArrayAsync package.

Usage

It's as simple as you could guess:

  // an asynchronous web request
  function getPics(animal, cb) {
    var flickerAPI = "http://api.flickr.com/services/feeds/photos_public.gne?jsoncallback=?";
    $.getJSON(
      flickerAPI
    , { tags: thing
      , tagmode: "any"
      , format: "json"
      , success: function (data) {
          console.log('teh animals:', data);
        }
      , complete: cb
      }
    );
  }

  // waits for one request to finish before beginning the next
  forEachAsync(['dogs', 'cats', 'octocats'], function (next, element, index, array) {
    getPics(element, next);
  
  // then after all of the elements have been handled
  // the final callback fires to let you know it's all done
  }).then(function () {
    console.log('All requests have finished');
  });

Browser Installation

You can download and include forEachAsync.js:

<script src="https://raw.github.com/FuturesJS/forEachAsync/master/forEachAsync.js"></script>

(function () {
  'use strict';

  var forEachAsync = window.forEachAsync
    ;

  // do stuff ...
}());

Or you can build it alongside other libraries:

npm install -g pakmanager
npm install forEachAsync@3.x --save
pakmanager -e browser build

<script src="pakmanaged.js"></script>

(function () {
  'use strict';

  var forEachAsync = require('forEachAsync').forEachAsync
    ;

  // do stuff ...
}());

Node Installation

npm install --save forEachAsync@3.x

API

forEachAsync(array, callback[, thisArg])

Parameters

• array Array of elements to iterate over
• callback Function to execute for each element, takes 4 arguments
  • next the function to call when the current element has been dealt with
  • element a single element of the aforementioned array
  • index the index of the current element
  • array the same array mentioned above
• thisArg Object to use as this when executing callback

forEachAsync#then(done)

Parameters

• then is in the return value of forEachAsync and accepts a final done callback.
  • done called after forEachAsync is complete, takes no arguments

Internal API

forEachAsync.__BREAK

This is used internally for the purposes of the ArrayAsync library.

Please don't break stuff; use someAsync or everyAsync instead.