async-autotarget

Select a specific subtree (or union of subtrees) of required functions from an input object appropriate for async.auto(). The goal is to simplify writing async workflows with async.auto, replacing cases where otherwise code will conditionally mutate the input object or functions will check their preconditions before executing.

1. https://github.com/caolan/async#auto

example

var async = require('async');
var autotarget = require('async-autotarget');

// assume you have a bunch of functions which do IO to get you cool stuff,
// and some functions depend on the results of others
var everything = {
  'vase': getVase,
  'roses': ['vase', getRoses],
  'candles': ['roses', getCandles],
  'oysters': getOysters,
  'dessert': getDessert,
  'movie': getMovie,
  'popcorn': ['movie', getPopcorn] // no point in popcorn if you don't have a movie
};

// Some nights you want to have a lovely evening with all the fixings
function lovelyEvening(callback) {
  async.auto(everything, function(err, evening) {
    if (err) {
      process.stderr.write("It was not meant to be.\n");
      callback(err);
      return;
    }
    callback(null, evening);
  });
}

// Sometimes you really just want the movie and the popcorn, nothing wrong with that
function movieNight(callback) {
  // 'popcorn' requires 'movie' in `everything`, so just need to select 'popcorn' here
  async.auto(autotarget(everything, 'popcorn'), callback);
}

// You can pass an array to get the union of two or more subtrees
// (this lets you get dessert too)
function movieNightWithDessert(callback) {
  async.auto(autotarget(everything, ['popcorn', 'dessert']), callback);
}