fibb.js

var util = require('util');
var stream = require('stream');
var Readable = stream.Readable;
var Writable = stream.Writable;
var map = require('through2-map');

util.inherits(Producer, Readable);

function Producer () {
  if(!(this instanceof Producer)) return new Producer;
  Readable.call(this, {objectMode: true});
  var prev = 0;
  var curr = 1;

  this._read = function () {
    var next = prev + curr;
    this.push(curr);
    prev = curr;
    curr = next;
  }
}

util.inherits(Consumer, Writable);

function Consumer (delay) {
  if(!(this instanceof Consumer)) return new Consumer(delay);
  Writable.call(this, {objectMode: true});
  this._write = function (number, encoding, onWritten) {
    setTimeout(function () {
      console.log(number);
      onWritten();
    }, delay);
  };
}

Producer()
  .pipe(map.obj(function (value) { return value * 2 }))
  .pipe(Consumer(100))