JuanMa juanmaguitar

Iterators (ES-2015)

Iterators

An object is an iterator when it knows how to access items from a collection one at a time, while keeping track of its current position within that sequence.

In JavaScript an iterator is an object that provides a next() method which returns the next item in the sequence. This method returns an object with two properties: done and `value.

Maps (ES2015)

The Map object is a simple key/value map. Any value (both objects and primitive values) may be used as either a key or a value.

> var animalSounds = new Map();
> animalSounds.set("dog", "woof");
Map {"dog" => "woof"}
> animalSounds.set("cat", "meow");

	let fibonacci = {
	[Symbol.iterator]() {
	let pre = 0, cur = 1
	return {
	next () {
	[ pre, cur ] = [ cur, pre + cur ]
	return { done: false, value: cur }
	}
	}
	},

	function *fibonacci() {
	let [prev, current] = [0, 1];
	while(true) {
	[prev, current] = [current, prev + current];
	yield current;
	}
	}

	let seq = fibonacci();

	/* ------------------------------------------------------- */
	/* GENERATORS USING PREV VALUES */
	/* ------------------------------------------------------- */

	function *foo(x) {
	var y = 2 * (yield (x + 1));
	var z = yield (y / 3);
	return (x + y + z);
	}

	// https://medium.com/@rdsubhas/es6-from-callbacks-to-promises-to-generators-87f1c0cd8f2e#.q7boouq4o

	/* Step 1: Callback hell — N levels deep */

	var request = require('request');
	var url1='http://httpbin.org/', url2=url1, url3=url1, url4=url1;

	function foo(finalCallback) {
	request.get(url1, function(err1, res1) {
	if (err1) { return finalCallback(err1); }

	# Generators - ES2015

	http://riadbenguella.com/how-es6-generators-are-changing-how-we-write-javascript/

	Generators are special functions that can be run, paused and resumed at different stages of their execution, thanks to the special keyword `yield`.

	```javascript
	function* myGenerator() {
	yield 'first';
	let input = yield 'second';


	function User ( name, username ) {

	var password = User.generatePassword(15);

	this.name = name;
	this.username = username;
	this.password = User.encryptPassword( password );

	console.log("Your password is : " + password)

	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="UTF-8">
	<title>First Component</title>
	</head>
	<body>

	<!-- container node -->
	<div id="app"></div>