Go7hic

JavaScript  15 hrs 55 mins █████████████▎░░░░░░░  63.4%
JSX         6 hrs 15 mins  █████▏░░░░░░░░░░░░░░░  24.9%
JSON        1 hr 3 mins    ▉░░░░░░░░░░░░░░░░░░░░   4.2%
LESS        57 mins        ▊░░░░░░░░░░░░░░░░░░░░   3.8%
HTML        28 mins        ▍░░░░░░░░░░░░░░░░░░░░   1.9%

Go7hic

@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 = () => x) {