Demonstration of async map reduce using promises

async-map-reduce.js

var Promise = require("bluebird");
var fileParts = ["http://myfiles.com/file1/part1", 
		"http://myfiles.com/file1/part2", 
		"http://myfiles.com/file1/part3"];

var fetchPart = function(partUrl) {
  // returns the promise of the part of a file
};

var filePartPromises = fileParts.map(fetchPart);
var file = [];

filePartPromises
  .reduce(function(acc, part) {
    return acc
      .then(function() {
        file.push(part);
      })
      .catch(console.log);
    }, q.resolve())
  .then(function() {
    console.log("complete file ", file);
});