\documentclass[10pt,a4paper]{article}

% Packages
\usepackage{fancyhdr}           % For header and footer
\usepackage{multicol}           % Allows multicols in tables
\usepackage{tabularx}           % Intelligent column widths
\usepackage{tabulary}           % Used in header and footer
\usepackage{hhline}             % Border under tables
\usepackage{graphicx}           % For images
\usepackage{xcolor}             % For hex colours
%\usepackage[utf8x]{inputenc}    % For unicode character support
\usepackage[T1]{fontenc}        % Without this we get weird character replacements
\usepackage{colortbl}           % For coloured tables
\usepackage{setspace}           % For line height
\usepackage{lastpage}           % Needed for total page number
\usepackage{seqsplit}           % Splits long words.
%\usepackage{opensans}          % Can't make this work so far. Shame. Would be lovely.
\usepackage[normalem]{ulem}     % For underlining links
% Most of the following are not required for the majority
% of cheat sheets but are needed for some symbol support.
\usepackage{amsmath}            % Symbols
\usepackage{MnSymbol}           % Symbols
\usepackage{wasysym}            % Symbols
%\usepackage[english,german,french,spanish,italian]{babel}              % Languages

% Document Info
\author{dwapi}
\pdfinfo{
  /Title (es6-ecmascript-2015-es2015-quick-reference.pdf)
  /Creator (Cheatography)
  /Author (dwapi)
  /Subject (ES6 / ECMAScript 2015 / ES2015 Quick Reference Cheat Sheet)
}

% Lengths and widths
\addtolength{\textwidth}{6cm}
\addtolength{\textheight}{-1cm}
\addtolength{\hoffset}{-3cm}
\addtolength{\voffset}{-2cm}
\setlength{\tabcolsep}{0.2cm} % Space between columns
\setlength{\headsep}{-12pt} % Reduce space between header and content
\setlength{\headheight}{85pt} % If less, LaTeX automatically increases it
\renewcommand{\footrulewidth}{0pt} % Remove footer line
\renewcommand{\headrulewidth}{0pt} % Remove header line
\renewcommand{\seqinsert}{\ifmmode\allowbreak\else\-\fi} % Hyphens in seqsplit
% This two commands together give roughly
% the right line height in the tables
\renewcommand{\arraystretch}{1.3}
\onehalfspacing

% Commands
\newcommand{\SetRowColor}[1]{\noalign{\gdef\RowColorName{#1}}\rowcolor{\RowColorName}} % Shortcut for row colour
\newcommand{\mymulticolumn}[3]{\multicolumn{#1}{>{\columncolor{\RowColorName}}#2}{#3}} % For coloured multi-cols
\newcolumntype{x}[1]{>{\raggedright}p{#1}} % New column types for ragged-right paragraph columns
\newcommand{\tn}{\tabularnewline} % Required as custom column type in use

% Font and Colours
\definecolor{HeadBackground}{HTML}{333333}
\definecolor{FootBackground}{HTML}{666666}
\definecolor{TextColor}{HTML}{333333}
\definecolor{DarkBackground}{HTML}{036327}
\definecolor{LightBackground}{HTML}{F7FAF8}
\renewcommand{\familydefault}{\sfdefault}
\color{TextColor}

% Header and Footer
\pagestyle{fancy}
\fancyhead{} % Set header to blank
\fancyfoot{} % Set footer to blank
\fancyhead[L]{
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{C}
    \SetRowColor{DarkBackground}
    \vspace{-7pt}
    {\parbox{\dimexpr\textwidth-2\fboxsep\relax}{\noindent
        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
    }
\end{tabulary}
\columnbreak
\begin{tabulary}{11cm}{L}
    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{ES6 / ECMAScript 2015 / ES2015 Quick Reference Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{dwapi} via \textcolor{DarkBackground}{\uline{cheatography.com/43665/cs/13100/}}}
\end{tabulary}
\end{multicols}}

\fancyfoot[L]{ \footnotesize
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{LL}
  \SetRowColor{FootBackground}
  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}dwapi \\
  \uline{cheatography.com/dwapi} \\
  \end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
  \SetRowColor{FootBackground}
  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Not Yet Published.\\
   Updated 17th October, 2017.\\
   Page {\thepage} of \pageref{LastPage}.
\end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
  \SetRowColor{FootBackground}
  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Sponsor}}  \\
  \SetRowColor{white}
  \vspace{-5pt}
  %\includegraphics[width=48px,height=48px]{dave.jpeg}
  Measure your website readability!\\
  www.readability-score.com
\end{tabulary}
\end{multicols}}




\begin{document}
\raggedright
\raggedcolumns

% Set font size to small. Switch to any value
% from this page to resize cheat sheet text:
% www.emerson.emory.edu/services/latex/latex_169.html
\footnotesize % Small font.

\begin{multicols*}{2}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Hoisting}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{//var declaration example \newline (function() \{ \newline   var foo = 1; \newline   console.log(foo + " " + bar); \newline   var bar = 2; \newline \})(); \newline // Alerts "1 undefined" instead of throwing an error.  \newline // It's aware of bar b/c the declaration was hoisted to top of function.   \newline // So no error, but the value is undefined until after the alert. \newline  \newline //function example \newline foo(); \newline  \newline function foo() \{ \newline   alert("Hello!"); \newline \} \newline // Same as above, the function declaration is hoisted above the call();} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{Hoisting is JavaScript's default behavior of moving all var and function declarations to the top of the current scope (to the top of the current script or the current function).}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Functions}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{// Arrow Function \newline setTimeout(() =\textgreater{} \{ console.log('delayed') \}, 1000) \newline  \newline // Scoped Functions \newline \{ \newline   let cue = 'Luke, I am your father' \newline   console.log(cue) \newline \} \newline \textgreater{}'Luke, I am your father' \newline  \newline // Scoped Function Equivalent with Immediately Invoked Function Expressions (IIFE) \newline (function () \{ \newline var cue = 'Luke, I am your father' \newline console.log(cue) // 'Luke, I am – \newline \}()) \newline console.log(cue) // Reference Error \newline  \newline // Default Params!! \newline function test(num = 1) \{  console.log(num)  \}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Promises}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{// Promise itself has three states:  Pending,  Fulfilled , Rejected \newline  \newline let example = new Promise((resolve, reject) =\textgreater{} \{ \newline     request.get(url, (error, response, body) =\textgreater{} \{ \newline       if (body) \{ \newline         \seqsplit{resolve(JSON.parse(body));} // fulfilled \newline       \} else \{ \newline         let reason = new Error('There wan an error'); \newline         reject(reason); // reject \newline       \} \newline     \}) \newline \}).then((val) =\textgreater{} console.log("fulfilled:", val))   \newline  .catch((err) =\textgreater{} console.log("rejected:", err)); \newline    \newline    \newline // Run multiple promises in parallel  \newline Promise.all({[} \newline   promise1, promise2, promise3 \newline {]}).then(() =\textgreater{} \{ \newline   // all tasks are finished \newline \})} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{If you want to use Promises for recurring values or events, there is a better mechanism/pattern for this scenario called streams.}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{x{4 cm} x{4 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{8.4cm}}{\bf\textcolor{white}{Let vs Var}}  \tn
% Row 0
\SetRowColor{LightBackground}
let variables are limited in scope to the block, statement, or expression on which it is used & var defines variables globally, or locally to an entire function regardless of block scope \tn 
% Row Count 5 (+ 5)
% Row 1
\SetRowColor{white}
Variables declared with let or const do not get hoisted & variables defined with var DO get hoisted \tn 
% Row Count 8 (+ 3)
% Row 2
\SetRowColor{LightBackground}
Can NOT be re-decalred.\{\{nl\}\}let a = 5; \{\{nl\}\}let a =6; // SyntaxError: redeclaration & CAN be re-decalred.\{\{nl\}\}var a = 5; \{\{nl\}\}var a = 6; // no error. a=6 \tn 
% Row Count 13 (+ 5)
% Row 3
\SetRowColor{white}
\mymulticolumn{2}{x{8.4cm}}{let is more performant, and better for Garbage Collection} \tn 
% Row Count 15 (+ 2)
% Row 4
\SetRowColor{LightBackground}
Support: \seqsplit{Severside=Everywhere}. Browsers IE11+ Android 56+ (altho you can use Babel transpiler) & Universal support \tn 
% Row Count 20 (+ 5)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{8.4cm}}{Hoisting is a bit of a quirk in JS. let behaves more like variable declarations in most other langs \newline Douglas Crockford advises to always use let.}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Maps and Sets}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{{\bf{What are Maps?}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}Basically a Object/hash with some advantages.} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Difference between Maps and Objects:}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}An Object has a prototype, so there are default keys in the map\{\{nl\}\}Maps preserve K-V in order they were added -{}- allows for iteration\{\{nl\}\}Keys in Objects are treated like Strings Object.keys(myHash) returns a bunch of strings.  They can be anything in a Map.} \tn 
% Row Count 9 (+ 7)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{{\bf{What is a WeakMap?}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}A Map where the keys are weak. Meaning if a key is deleted the value will be GC'd} \tn 
% Row Count 12 (+ 3)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{{\bf{What is a Set?}}} \tn 
\mymulticolumn{1}{x{8.4cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}Highly performant array that preserves order of insertion, but does not index.} \tn 
% Row Count 15 (+ 3)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{x{2.72 cm} x{5.28 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{8.4cm}}{\bf\textcolor{white}{Other New Features}}  \tn
% Row 0
\SetRowColor{LightBackground}
Template Literals & `My dog is \$\{age\} years old` \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
Default Params & function( greeting='Howdy' )\{  console.log(greeting) \} \tn 
% Row Count 5 (+ 3)
% Row 2
\SetRowColor{LightBackground}
Object literals & myHash = \{color, size\} // same as \{color: color, size: size\} \tn 
% Row Count 8 (+ 3)
% Row 3
\SetRowColor{white}
Spread Operator & {[}1, 2, ...more{]} or list.push(...{[}3, 4{]}) or new Date(...{[}2015,8,1{]}) \tn 
% Row Count 11 (+ 3)
% Row 4
\SetRowColor{LightBackground}
Generator Function(*) & function *foo() \{\} //These can be paused \& resumed later???? \tn 
% Row Count 14 (+ 3)
% Row 5
\SetRowColor{white}
const variable type & Block scoped, immutable reference (vals in arrays can change) \tn 
% Row Count 17 (+ 3)
% Row 6
\SetRowColor{LightBackground}
Symbol variable type & Immuteable (Unclear advantage of these over hash obj) \tn 
% Row Count 20 (+ 3)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Classes, Inheritance, Setters, Getters}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{class Rectangle extends Shape \{ \newline   constructor(id, x, y, w, h) \{ \newline     super(id, x, y) \newline     this.width = w \newline     this.height = h \newline   \} \newline   // Getter and setter \newline   set width(w) \{ \newline     this.\_width = w \newline   \} \newline   get width() \{ \newline     return this.\_width \newline   \} \newline \} \newline class Circle extends Shape \{ \newline   constructor(id, x, y, radius) \{ \newline     super(id, x, y) \newline     this.radius = radius \newline   \} \newline   do\_a(x) \{ \newline     let a = 12; \newline     super.do\_a(x + a); \newline   \} \newline   static do\_b() \{ ... \newline   \} \newline \} \newline Circle.do\_b()} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Spread Operator and Destructuring}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{\textgreater{} const {[} cat, dog, ...fish {]} = {[}'schroedinger', 'Laika', 'Nemo', 'Dori'{]} \newline \textgreater{} fish // -\textgreater{} {[}'Nemo', 'Dori'{]} \newline \textgreater{} cat // -\textgreater{} {[}'schroedinger'{]} \newline  \newline  \newline \textgreater{} let arr = {[}1, 2, 3{]} \newline \textgreater{} {[}...arr, 4, 5, 6{]} \newline \textgreater{} {[}1, 2, 3, 4, 5, 6{]}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}


% That's all folks
\end{multicols*}

\end{document}