example.js

var floc = require('./floc');

function doAsync(value, cb) {
  setTimeout(function() {
    cb(null, value / 2);
  }, 1000);
}

var callback = floc(function (err, value) {
  this.valueMain = value;
  this.one(null, value);
})
.add('one', function(err, value) {
  this.valueOne = value;
  this.two(null, value * 2);
})
.add('two', function (err, value) {
  this.valueTwo = value;
  doAsync(value, this.three);
})
.add('three', function (err, value) {
  this.valueThree = value;
  console.log(this)
})
.set('foo2', 'bar2')

callback(null, 10);
callback(null, 20);

traditional.js

function doAsync(value, cb) {
  setTimeout(function() {
    cb(null, value / 2);
  }, 1000);
}

function callback(err, value) {
  var self = {};
  self.foo2 = 'bar2';
  self.valueMain = value;

  one(null, value);

  function one(err, value) {
    self.valueOne = value;
    two(null, value * 2);
  }

  function two(err, value) {
    self.valueTwo = value;
    doAsync(value, this.three);
  }

  function three(err, value) {
    self.valueThree = value;
    console.log(this);
  }
}

callback(null, 10);
callback(null, 20);