cyan33

// Use Gists to store code you would like to remember later on
console.log(window); // log the "window" object to the console

cyan33

In JavaScript, undefined means a variable has been declared but has not yet been assigned a value, such as:

 var TestVar;
 alert(TestVar); //shows undefined
 alert(typeof TestVar); //shows undefined
null is an assignment value. It can be assigned to a variable as a representation of no value:

 var TestVar = null;
 alert(TestVar); //shows null
 alert(typeof TestVar); //shows object

cyan33

// this assumes that you have jquery, or any ajax utils like `isomorphic-fetch`

function storeDataCb(username, password) {
  if (!window.localStorage) return
  
  localStorage.username = username
  localStorage.password = password
}

function logIn() {

cyan33

/*
 * I got this inspiration from the source code of redux.
 * Essentially, compose(f, g, h) equals to (arg) => f(g(h(arg)))
 */

function compose(...funcs) {
  if (!funcs.length)  return (arg) => arg
  if (funcs.length === 1) return funcs[0]
  
  return funcs.reduce((a, b) => (...args) => a(b(...args)))

cyan33

// https://medium.com/gitconnected/understand-javascript-promises-by-building-a-promise-from-scratch-84c0fd855720

class SimplePromise {
  constructor(executionFunction) {
    this.promiseChain = [];
    this.handleError = () => {};
    
    this.onResolve = this.onResolve.bind(this);
    this.onReject = this.onReject.bind(this);
    

cyan33

function optimizeCb(func, context, argCount) {
  if (!context) return func
  
  switch (argCount ? argCount : 3) {
    case 1: return function(val) {
      return func.call(context, val)
    }
    case 2: return function(val, other) {
      return func.call(context, val, other)
    }

cyan33

// a code snippets from underscore.js for type checking in JavaScript

_.each(['Arguments', 'Function', 'String', 'Number', 'Date', 'RegExp', 'Error'], function(name) {
  _['is' + name] = function(obj) {
    return toString.call(obj) === '[object ' + name + ']';
  };
});

function isObject(item) {
  const type = typeof item

cyan33

// in the namespace of `_`
// The simplest extend
function simpleExtend(obj, src) {
  for (let key in src) {
    obj[key] = src[key]
  }
  return obj
}

// the two different type of configuration of key assigners

cyan33

function promisify(fn) {
  return function(...args) {
    return new Promise((res, rej) => {
      fn(...args, function() {
        res(arguments)
      })
    })
  }
}

cyan33

function async(makeGenerator) {
  return (...args) => {
    var generator = makeGenerator.apply(this, args);

    function next(result) {
      // result => { done: [Boolean], value: [Object] }
      if (result.done) return Promise.resolve(result.value);

      return Promise.resolve(result.value).then((res) => {
        return next(generator.next(res.value));