\documentclass[10pt,a4paper]{article}

% Packages
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\usepackage{multicol}           % Allows multicols in tables
\usepackage{tabularx}           % Intelligent column widths
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\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{alex09998}
\pdfinfo{
  /Title (web-applications-01.pdf)
  /Creator (Cheatography)
  /Author (alex09998)
  /Subject (Web Applications 01 Cheat Sheet)
}

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% Commands
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% 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{Web Applications 01 Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{alex09998} via \textcolor{DarkBackground}{\uline{cheatography.com/137559/cs/42627/}}}
\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}alex09998 \\
  \uline{cheatography.com/alex09998} \\
  \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 4th March, 2024.\\
   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
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% 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}{General info}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{We use ES6 (EcmaScript standard version 6)} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{Runs natively on browsers AND on a computer (using Node.js).  Execution environments: Server \& CLI Node.js, Browser, learning aids (\{\{link="http://pythontutor.com/javascript.html"\}\}Python Tutor\{\{/link\}\}).} \tn 
% Row Count 6 (+ 5)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{JS engines (interpreters): V8, SpiderMonkey, JavaScriptCore.} \tn 
% Row Count 8 (+ 2)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Compatibility:}} \{\{nl\}\} \{\{fa-circle\}\} Backwards: https://babeljs.io/, Polyfilling \{\{nl\}\} \{\{fa-circle\}\} Strict mode disables dangerous old semantics} \tn 
% Row Count 11 (+ 3)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{First line of file is \{\{nl\}\} `"use strict" ;`  \{\{nl\}\} \{\{fa-circle\}\} Can't define properties/parameters with same name;} \tn 
% Row Count 14 (+ 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}{Control Structures}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{If conditions: `if - else if - else`, `switch (expr)`} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{Loops: `for (initial\_expr; cond; increment;)`, `do - while`, `while`} \tn 
% Row Count 4 (+ 2)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{Special {\bf{for}} statements: \{\{nl\}\} `for (var in object) \{\}`: iterates over all the enumerable {\bf{properties}} of an object. Do {\bf{not}} use to traverse an array. \{\{nl\}\} `for (var of iterable) \{\}`: iterates the variable over all values of an {\bf{iterable object}} (array, map, etc.) and returns {\bf{the values}}.} \tn 
% Row Count 11 (+ 7)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Exception handling}}: \{\{nl\}\} `try-catch-finally`. \{\{nl\}\} Ready to use throwables.} \tn 
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\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{The condition of the ifs causes an implicit conversion of whatever is written to a boolean. \newline  \newline The expression in the switch may also be a string. \newline  \newline In loops, we may use `break;` or `continue;`}  \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}{Expressions}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{Declare + initialize: \{\{nl\}\} `\{\{lang-js\}\}let variable = expression ;` \{\{nl\}\} Reassign: \{\{nl\}\} `\{\{lang-js\}\}variable = expression ;`} \tn 
% Row Count 3 (+ 3)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Comparison}}: \{\{nl\}\} convert and compare: `a == b` \{\{nl\}\} same type {\bf{and}} value: `a === b`} \tn 
% Row Count 5 (+ 2)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Conversions}}: \{\{nl\}\} any to boolean: \{\{nl\}\} `truthy-falsy rule, Boolean(a), !!a` \{\{nl\}\} String to Number: \{\{nl\}\} `Number(s), parseInt(s), parseFloat(s)` \{\{nl\}\} Number to String: \{\{nl\}\} `n.toString(), String(n), n+""`} \tn 
% Row Count 10 (+ 5)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{String {\bf{concatenation}}: \{\{nl\}\} `string1 + string2`} \tn 
% Row Count 12 (+ 2)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Default value}} assignment ({\emph{if a then a else b}}): \{\{nl\}\} `a || b`} \tn 
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\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
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\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Strings}}  \tn
% Row 0
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\mymulticolumn{1}{x{8.4cm}}{Immutable sequence of unicode characters. All {\bf{operations}} always return {\bf{new strings}}.} \tn 
% Row Count 2 (+ 2)
% Row 1
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\mymulticolumn{1}{x{8.4cm}}{Length = \# of characters (not bytes).  \{\{nl\}\} Empty string has length 0 and is a {\bf{falsy}}.} \tn 
% Row Count 4 (+ 2)
% Row 2
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\mymulticolumn{1}{x{8.4cm}}{{\bf{Operations}}: \{\{nl\}\} \{\{fa-arrow-right\}\} indexing `\{\{lang-js\}\} s{[}3{]}` \{\{nl\}\} \{\{fa-arrow-right\}\} concatenation `\{\{lang-js\}\} s1 + s2` \{\{nl\}\} \{\{fa-arrow-right\}\} \# of characters `\{\{lang-js\}\} s.length`} \tn 
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\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Template literals ("dynamic string concatenation")}} \{\{nl\}\} `\{\{lang-js\}\}let name = "Bill";` \{\{nl\}\} `\{\{lang-js\}\}let greeting = \textbackslash{}`Hello \$\{ name \}.\textbackslash{}`;`} \tn 
% Row Count 11 (+ 3)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{Some Unicode characters are represented by {\bf{two}} code units, so some string methods above FFFF might misbehave.}  \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}{Language Structure}}  \tn
% Row 0
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\mymulticolumn{1}{x{8.4cm}}{{\bf{One file = one JS program}}\{\{nl\}\} ((loaded independently but communicate w/ global state and modules)} \tn 
% Row Count 3 (+ 3)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{File is entirely {\bf{parsed}} and {\bf{then}} executed top to bottom.} \tn 
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% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{Written in {\bf{Unicode}}, case sensitive.} \tn 
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\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Types and Variables}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Values}} have {\bf{types}}: \{\{nl\}\} "type" is a property of a value. \{\{nl\}{]} \{\{nl\}\} {\bf{Variables}} DON'T have types: \{\{nl\}\} variables can contain any type, and ≠  types in ≠  moments.} \tn 
% Row Count 4 (+ 4)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{Boolean type: \{\{nl\}\} 'true' or 'false' literal values \{\{nl\}\} {\bf{Conversion:}} \{\{nl\}\}  {\bf{Truthies:}} `0, -0, NaN, undefined, null, ' '`  \{\{nl\}\}    {\bf{Falsies:}} `3, 'false', {[}{]}, \{\}, ...`} \tn 
% Row Count 8 (+ 4)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{Numbers:  \{\{nl\}\} \{\{fa-arrow-right\}\}  No distinction integers and reals   \{\{nl\}\} \{\{fa-arrow-right\}\}  {\bf{Automatic conversion}} according to operation} \tn 
% Row Count 11 (+ 3)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Nullish values}}:  \{\{nl\}\} \{\{fa-arrow-right\}\}  `undefined`: variable declared but not initialized. Returned by void functions.   \{\{nl\}\} \{\{fa-arrow-right\}\}    `null`: empty value} \tn 
% Row Count 15 (+ 4)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Variables}}:  \{\{nl\}\} \{\{fa-arrow-right\}\} They're   pure references: refer to a {\bf{value}} \{\{nl\}\} \{\{fa-arrow-right\}\}     Declare: {\bf{let}}, {\bf{const}}, var.  \{\{nl\}\} \{\{fa-arrow-right\}\}   `Let`: {\bf{yes}} reassign, no redeclare, block scope, no hoisting   \{\{nl\}\} \{\{fa-arrow-right\}\}  `Const`: {\bf{no}} reassign, no redeclare, block scope, no hoisting  \{\{nl\}\} \{\{fa-arrow-right\}\}   `Var`: yes reassign and redeclare, function/global scope, hoisting.  \{\{ln\}\} \{\{ln\}\} Block scope: variable exists only in defined and inner scopes. \{\{ln\}\} {\bf{Hoisting}}: declaration of var inside code is moved to top of scope.} \tn 
% Row Count 27 (+ 12)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{8.4cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{8.4cm}}{\bf\textcolor{white}{Arrays}}  \tn
% Row 0
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\mymulticolumn{1}{x{8.4cm}}{Elements do {\bf{not}} need to be of the same {\bf{type}}.} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{Have property `length` (automatic).} \tn 
% Row Count 3 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Create}} arrays using parameters: \{\{nl\}\} `let v = Array.of(1, 2, 3) ;`} \tn 
% Row Count 5 (+ 2)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Add elements}}: \{\{nl\}\} `let v = {[}{]} ; v{[}0{]} = "a" ; v{[}1{]} = 8 ;` \{\{nl\}\} `.push()` adds to end of array \{\{nl\}\} `.unshift()` adds to beginning of array. \{\{nl\}\} `.length` adjusts {\bf{automatically}}. \{\{nl\}\} \{\{nl\}\} {\bf{Removal}}: `.unshift()` and `.pop()`.} \tn 
% Row Count 10 (+ 5)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Copy of the reference}}: `let v = {[}{]}; let alias = v;` we establish `alias` as an alias of `v`, so if we modify `alias` we're actually modifying `v`.} \tn 
% Row Count 13 (+ 3)
% Row 5
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{{\bf{Shallow copy of arrays}}: \{\{nl\}\} `let copy = Array.from(v);`} \tn 
% Row Count 15 (+ 2)
% Row 6
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{{\bf{ Destructuring assignment }}: \{\{nl\}\} Value of the right are extracted and stored in the variables on the left. \{\{nl\}\} `{[}x,y{]} = {[}y,x{]};` {\bf{easy swap}}.} \tn 
% Row Count 19 (+ 4)
% Row 7
\SetRowColor{white}
\mymulticolumn{1}{x{8.4cm}}{{\bf{ Spread operator }}: \{\{nl\}\} \{\{fa-arrow-right\}\} "all the rest": `\{\{lang-js\}\}let {[}x, ...y{]} = {[}1,2,3,4{]};·` we obtain y == {[}2,3,4{]} \{\{nl\}\} \{\{fa-arrow-right\}\} "everything inside vector x". \{\{nl\}\} Can be used to {\bf{copy arrays by value}}: `\{\{lang-js\}\}const b = Array.of(...a)`, `const b = {[}...a{]}`} \tn 
% Row Count 25 (+ 6)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{8.4cm}}{Automatic expansion of array: `\{\{lang-js\}\}let v = {[}{]}; v{[}3{]} = "a"`. \newline  \newline Arrays are not values, they're {\bf{references}}.}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}


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

\end{document}