Artem Tyurin agentcooper

@kangax's ES6 quiz, explained

@kangax created a new interesting quiz, this time devoted to ES6 (aka ES2015). I found this quiz very interesting and quite hard (made myself 3 mistakes on first pass).

Here we go with the explanations:

Question 1:

(function(x, f = () =&gt; x) {

In all the discussions about ES6 one thing is bugging me. I'm picking one random comment here from this io.js issue but it's something that comes up over and over again:

There's sentiment from one group that Node should have full support for Promises. While at the same time another group wants generator syntax support (e.g. var f = yield fs.stat(...)).

People keep putting generators, callbacks, co, thunks, control flow libraries, and promises into one bucket. If you read that list and you think "well, they are all kind of doing the same thing", then this is to you.

Files

The basic structure of a React+Flux application (see other examples)

 - /src/actions/AppActions.js     - Action creators (Flux)
 - /src/components/Application.js - The top-level React component
 - /src/constants/ActionTypes.js  - Action types (Flux)
 - /src/core/Dispatcher.js        - Dispatcher (Flux)
 - /src/stores/AppStore.js        - The main store (Flux)

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

This is a plain-text version of Bret Victor’s reading list. It was requested by hf on Hacker News.

Highly recommended things!

This is my five-star list. These are my favorite things in all the world.

A few of these works have had an extraordinary effect on my life or way of thinking. They get a sixth star. ★

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns                     on recent CPU
L2 cache reference ........................... 7 ns                     14x L1 cache
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns                     20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs 4X memory

stopBefore.js

2min screencast

Examples

stopBefore(document, 'getElementById')
stopBefore('document.getElementById') // the same as the previous
stopBefore(Element.prototype, 'removeChild')

List comprehensions

Basic idea in theoretical programming: a notation for Set builders from math.

Basic idea in practical programming: syntactic sugar for "map + filter" functional methods:

Example of map and filter, ES6

let x = N.filter(x => x > 10).map(x => x * x);

	quicksort :: (Ord a) => [a] -> [a]
	quicksort [] = []
	quicksort (x:xs) =
	let smallerSorted = quicksort (filter (<=x) xs)
	biggerSorted = quicksort (filter (>x) xs)
	in smallerSorted ++ [x] ++ biggerSorted

	<!DOCTYPE html>

	<meta charset=utf-8 />
	<title>Defining JavaScript functions, the ES6 way</title>

	<h1>Defining JavaScript functions, the ES6 way</h1>

	<em>Use Firefox 22 (Firefox Nightly)</em>

	<script>