[How to] using async.js

using-async.js

var obj = {dev: "/dev.json", test: "/test.json", prod: "/prod.json"};
var configs = {};

async.forEachOf(obj, function (value, key, callback) {
  fs.readFile(__dirname + value, "utf8", function (err, data) {
    if (err) return callback(err);
    try {
      configs[key] = JSON.parse(data);
    } catch (e) {
      return callback(e);
    }
    callback();
  })
}, function (err) {
  if (err) console.error(err.message);
  // configs is now a map of JSON data
  doSomethingWith(configs);
})

//snippet originally from https://github.com/caolan/async