ZhihaoLau

var fs = require('fs');

function readFile(filename) {
  return new Promise(function(resolve, reject) {
    fs.readFile(filename, {encoding: 'utf8'}, function(err, data) {
      if (err) {
        reject(err);
        return;
      }
      resolve(data);

ZhihaoLau

let promise = Promise.resolve('hello');

promise.then(function(data) {
  console.log(data);
});

// Or: ------------------------

let promise = Promise.reject('oops');

ZhihaoLau

function createIterator(items) {
  var i = 0;
  return {
    next: function() {
      // NZakas' way is really straight forward what 'done' and 'value' is.
      var done = (i >= items.length);
      var value = done ? undefined : items[i++];

      return {
        done: done,

ZhihaoLau

function *createIterator(items) {
  for(let i = 0; i < items.length; i++) {
    yield items[i];
  }
}

let it = createIterator([1, 2, 3]);

console.log(it.next());   // Object {value: 1, done: false}
console.log(it.next());   // Object {value: 2, done: false}

ZhihaoLau

let o = {
  *createIterator(items) {
    for (let i = 0; i < items.length; i++) {
      yield items[i];
    }
  }
};

let it = o.createIterator([1, 2, 3]);

ZhihaoLau

let categories = [
  { id: 'animals', 'parent': null },
  { id: 'mammals', 'parent': 'animals' },
  { id: 'cats', 'parent': 'mammals' },
  { id: 'dogs', 'parent': 'mammals' },
  { id: 'chihuahua', 'parent': 'dogs' },
  { id: 'persian', 'parent': 'cats' },
  { id: 'siamese', 'parent': 'cats' },
]

ZhihaoLau

// Ruby = 5.times { |i| puts i }
// JS   = (1).times(function(i){console.log(i);})
Number.prototype.times = function(cb) {
  var i = -1;

  while (++i < this) {
    cb(i);
  }

  return +this;

ZhihaoLau

var arr = [1, 2, 3, 4];


function handleNext(value) {
  return value * 2
}


Array.prototype.fakeMap = function(cb) {
  return this.reduce((accumulator, next, index) => {

ZhihaoLau

function configableLogger(format) {
  var re = /:(\w+)/g;
  return function(req, res, next) {
    var str = format.replace(re, (match, property) => {
      return req[property];
    });
    console.log(str);
    next();
  }
}

ZhihaoLau

// A thing I want to do
// This flow only involves **one** promise, for example an ajax call
// None of the subsequent `then` or `catch` calls, return new promises.



var explode = false;
var promise = new Promise(function(resolve, reject) {
  if (explode) {