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<html lang="en" xml:lang="en" xmlns="http://www.w3.org/1999/xhtml"><head>
<meta http-equiv="content-type" content="text/html;charset=UTF-8">
<link rel="icon" type="image/gif" href="/favicon.gif">
<link rel="apple-touch-icon" sizes="120x120" href="touch-icon-iphone-retina.png">
<link rel="apple-touch-icon" sizes="152x152" href="touch-icon-ipad-retina.png">
<title>Interpreted Languages: JavaScript & Ruby (Sheet One) - Hyperpolyglot</title>
<style type="text/css" id="internal-style">
@import url(style/hyperpolyglot.css);
</style>
<meta http-equiv="content-type" content="text/html;charset=UTF-8">
<meta http-equiv="content-language" content="en">
</head>
<body>
<div id="container-wrap-wrap">
<div id="container-wrap">
<div id="container">
<div id="header">
<h1><a href="/"><span>Hyperpolyglot (Ruby & JS Only Fork)</span></a></h1>
</div>
<div id="content-wrap">
<div id="main-content">
<div id="page-title">
Interpreted Languages: JavaScript and Ruby (Sheet One)
</div>
<div id="page-content">
<p><a name="top" id="top"></a><em>a side-by-side reference sheet</em></p>
<p><strong>sheet one:</strong> <a href="#version">version</a> | <a href="#grammar-execution">grammar and execution</a> | <a href="#var-expr">variables and expressions</a> | <a href="#arithmetic-logic">arithmetic and logic</a> | <a href="#strings">strings</a> | <a href="#regexes">regexes</a> | <a href="#dates-time">dates and time</a> | <a href="#resizable-arrays">resizable arrays</a> | <a href="#dictionaries">dictionaries</a> | <a href="#functions">functions</a> | <a href="#execution-control">execution control</a> | <a href="#exceptions">exceptions</a> | <a href="#concurrency">concurrency</a></p>
<p><strong><a href="index2.html">sheet two</a>:</strong> <a href="index2.html#file-handles">file handles</a> | <a href="index2.html#files">files</a> | <a href="index2.html#file-fmt">file formats</a> | <a href="index2.html#directories">directories</a> | <a href="index2.html#processes-environment">processes and environment</a> | <a href="index2.html#option-parsing">option parsing</a> | <a href="index2.html#libraries-namespaces">libraries and namespaces</a> | <a href="index2.html#objects">objects</a> | <a href="index2.html#inheritance-polymorphism">inheritance and polymorphism</a> | <a href="index2.html#reflection">reflection</a> | <a href="index2.html#net-web">net and web</a> | <a href="index2.html#unit-tests">unit tests</a> | <a href="index2.html#debugging-profiling">debugging and profiling</a> | <a href="index2.html#java-interop">java interop</a></p>
<table class="wiki-content-table"><tbody><tr><th colspan="5"><a name="version" id="version"></a><a href="#version-note">version</a></th>
</tr><tr><th></th>
<th><a href="#javascript">javascript</a></th>
<th><a href="#ruby">ruby</a></th>
</tr><tr><td><a name="version-used" id="version-used"></a><a href="#version-used-note">version used</a><br><span style="white-space: pre-wrap;"> </span></td>
<td></td>
<td><span style="color: gray"><em>1.9; 2.0</em></span></td>
</tr><tr><td><a name="version" id="version"></a><a href="#version-note">show version</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>$ node <span style="white-space: pre-wrap;">--</span>version</td>
<td>$ ruby <span style="white-space: pre-wrap;">--</span>version</td>
</tr><tr><td><a name="implicit-prologue" id="implicit-prologue"></a><a href="#implicit-prologue-note">implicit prologue</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><script src="underscore.js"><br>
</script></td>
<td><span style="color: gray"><em>none</em></span></td>
</tr><tr><th colspan="5"><a name="grammar-execution" id="grammar-execution"></a><a href="#grammar-execution-note">grammar and execution</a></th>
</tr><tr><th></th>
<th>javascript</th>
<th>ruby</th>
</tr><tr><td><a name="interpreter" id="interpreter"></a><a href="#interpreter-note">interpreter</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>$ node foo.js</td>
<td>$ ruby foo.rb</td>
</tr><tr><td><a name="repl" id="repl"></a><a href="#repl-note">repl</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>$ node</td>
<td>$ irb</td>
</tr><tr><td><a name="cmd-line-program" id="cmd-line-program"></a><a href="#cmd-line-program-note">command line program</a></td>
<td>$ node -e 'var sys = require("sys");<br>
sys.puts("hi world!");'</td>
<td>$ ruby -e 'puts "hi"'</td>
</tr><tr><td><a name="block-delimiters" id="block-delimiters"></a><a href="#block-delimiters-note">block delimiters</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>{}</td>
<td>{}<br><span style="color: purple">do end</span></td>
</tr><tr><td><a name="statement-separator" id="statement-separator"></a><a href="#statement-separator-note">statement separator</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>; or newline<br><br>
newline not separator inside (), [], {}, "", '', or after binary operator<br><br>
newline sometimes not separator when following line would not parse as a valid statement</em></span></td>
<td><span style="color: gray"><em>newline or</em></span> ;<br><br><span style="color: gray"><em>newlines not separators inside (), [], {}, <span style="white-space: pre-wrap;">``</span>, '', "", or after binary operator or backslash: <span style="white-space: pre-wrap;">\</span></em></span></td>
</tr><tr><td><a name="source-code-encoding" id="source-code-encoding"></a><a href="#source-code-encoding-note">source code encoding</a></td>
<td></td>
<td><span style="color: gray"><em>Ruby 2.0 source is UTF-8 by default</em></span><br><br><span style="color: gray"># -*- coding: utf-8 -*-</span></td>
</tr><tr><td><a name="eol-comment" id="eol-comment"></a><a href="#eol-comment-note">end-of-line comment</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><span style="white-space: pre-wrap;">//</span> comment</span></td>
<td><span style="color: gray"># comment</span></td>
</tr><tr><td><a name="multiple-line-comment" id="multiple-line-comment"></a><a href="#multiple-line-comment-note">multiple line comment</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray">/* line<br>
another line */</span></td>
<td><span style="color: gray">=begin<br>
comment line<br>
another line<br>
=end</span></td>
</tr><tr><th colspan="5"><a name="var-expr" id="var-expr"></a><a href="#var-expr-note">variables and expressions</a></th>
</tr><tr><th></th>
<th>javascript</th>
<th>ruby</th>
</tr><tr><td><a name="local-var" id="local-var"></a><a href="#local-var-note">local variable</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>var x = 1;<br><br>
var y = 2, z = 3;</td>
<td>v = <span style="color: peru">nil</span><br>
a, d = [], {}<br>
x = 1<br>
y, z = 2, 3</td>
</tr><tr><td><a name="local-scope-regions" id="local-scope-regions"></a><a href="#local-scope-regions-note">regions which define lexical scope</a></td>
<td><span style="color: gray"><em>top level:<br><span style="white-space: pre-wrap;"> </span>html page<br><br>
nestable:<br><span style="white-space: pre-wrap;"> </span>function</em></span></td>
<td><span style="color: gray"><em>top level:<br><span style="white-space: pre-wrap;"> </span>file<br><span style="white-space: pre-wrap;"> </span>class block<br><span style="white-space: pre-wrap;"> </span>module block<br><span style="white-space: pre-wrap;"> </span>method body<br><br>
nestable:<br><span style="white-space: pre-wrap;"> </span>anonymous function body<br><span style="white-space: pre-wrap;"> </span>anonymous block</em></span></td>
</tr><tr><td><a name="global-var" id="global-var"></a><a href="#global-var-note">global variable</a></td>
<td><span style="color: gray"><span style="white-space: pre-wrap;">//</span> assign without using var</span><br>
g = 1;<br><br>
function incr_global () { g++; }</td>
<td><span style="color: peru">$g1</span>, <span style="color: peru">$g2</span> = 7, 8<br><br><span style="color: purple">def</span> <span style="color: #0000cd">swap_globals</span><br><span style="white-space: pre-wrap;"> </span><span style="color: peru">$g1</span>, <span style="color: peru">$g2</span> = <span style="color: peru">$g2</span>, <span style="color: peru">$g1</span><br>
end</td>
</tr><tr><td><a name="const" id="const"></a><a href="#const-note">constant</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>none</em></span></td>
<td><span style="color: gray"># warning if capitalized<br>
# identifier is reassigned</span><br><span style="color: green">PI</span> = 3.14</td>
</tr><tr><td><a name="assignment" id="assignment"></a><a href="#assignment-note">assignment</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>x = 1;</td>
<td>v = 1</td>
</tr><tr><td><a name="parallel-assignment" id="parallel-assignment"></a><a href="#parallel-assignment-note">parallel assignment</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>none</em></span></td>
<td>x, y, z = 1, 2, 3<br><br><span style="color: gray"># 3 is discarded:</span><br>
x, y = 1, 2, 3<br><br><span style="color: gray"># z set to nil:</span><br>
x, y, z = 1, 2</td>
</tr><tr><td><a name="swap" id="swap"></a><a href="#swap-note">swap</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>tmp = x;<br>
x = y;<br>
y = tmp;</td>
<td>x, y = y, x</td>
</tr><tr><td><a name="compound-assignment" id="compound-assignment"></a><a href="#compound-assignment-note">compound assignment</a><br><span style="color: gray"><em>arithmetic, string, logical, bit</em></span></td>
<td>+= -= *= /= <span style="color: gray"><em>none</em></span> %=<br>
+=<br><span style="color: gray"><em>none</em></span><br><span style="white-space: pre-wrap;"><<= >>= </span>&= |= ^=</td>
<td>+= -= *= /= <span style="color: gray"><em>none</em></span> %= <span style="white-space: pre-wrap;">**</span>=<br>
+= *=<br>
&&= <span style="white-space: pre-wrap;">||</span>= ^=<br><span style="white-space: pre-wrap;"><<= >>= </span>&= |= ^=</td>
</tr><tr><td><a name="incr-decr" id="incr-decr"></a><a href="#incr-decr-note">increment and decrement</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>var x = 1;<br>
var y = ++x;<br>
var z = <span style="white-space: pre-wrap;">--</span>y;</td>
<td>x = 1<br><span style="color: gray"># x and y not mutated:</span><br>
y = x.succ<br>
z = y.pred</td>
</tr><tr><td><a name="null" id="null"></a><a href="#null-note">null</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>null</td>
<td><span style="color: peru">nil</span></td>
</tr><tr><td><a name="null-test" id="null-test"></a><a href="#null-test-note">null test</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>v === null</td>
<td>v == <span style="color: peru">nil</span><br>
v.nil?</td>
</tr><tr><td><a name="undef-var" id="undef-var"></a><a href="#undef-var-note">undefined variable</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>undefined</td>
<td><span style="color: gray"><em>raises</em> NameError</span></td>
</tr><tr><td><a name="conditional-expr" id="conditional-expr"></a><a href="#conditional-expr-note">conditional expression</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>x > 0 ? x : -x</td>
<td>x > 0 ? x : -x</td>
</tr><tr><th colspan="5"><a name="arithmetic-logic" id="arithmetic-logic"></a><a href="#arithmetic-logic-note">arithmetic and logic</a></th>
</tr><tr><th></th>
<th>javascript</th>
<th>ruby</th>
</tr><tr><td><a name="true-false" id="true-false"></a><a href="#true-false-note">true and false</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>true false</td>
<td><span style="color: peru">true false</span></td>
</tr><tr><td><a name="falsehoods" id="falsehoods"></a><a href="#falsehoods-note">falsehoods</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>false null undefined "" 0 NaN</td>
<td><span style="color: peru">false nil</span></td>
</tr><tr><td><a name="logical-op" id="logical-op"></a><a href="#logical-op-note">logical operators</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="white-space: pre-wrap;">&& ||</span> !</td>
<td>&& <span style="white-space: pre-wrap;">||</span> !<br><span style="color: gray"><em>lower precedence:</em></span><br><span style="color: purple">and or not</span></td>
</tr><tr><td><a name="relational-op" id="relational-op"></a><a href="#relational-op-note">relational operators</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="white-space: pre-wrap;">===</span> !== < > >= <=<br><br><span style="color: gray"><em>perform type coercion:</em></span><br><span style="white-space: pre-wrap;">==</span> !=</td>
<td>== != > < >= <=</td>
</tr><tr><td><a name="min-max" id="min-max"></a><a href="#min-max-note">min and max</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>Math.min(1, 2, 3)<br>
Math.max(1, 2, 3)<br><br>
Math.min.apply(Math, [1, 2, 3])<br>
Math.max.apply(Math, [1, 2, 3])</td>
<td>[1, 2, 3].min<br>
[1, 2, 3].max</td>
</tr><tr><td><a name="three-val-comparison" id="three-val-comparison"></a><a href="#three-val-comparison-note">three value comparison</a></td>
<td><span style="color: gray"><em>none</em></span></td>
<td>0 <=> 1<br><span style="color: maroon">"do"</span> <=> <span style="color: maroon">"re"</span></td>
</tr><tr><td><a name="arith-op" id="arith-op"></a><a href="#arith-op-note">arithmetic operators</a><br><span style="color: gray"><em>addition, subtraction, multiplication, float division, quotient, remainder</em></span></td>
<td>+ - * / <span style="color: gray"><em>none</em></span> %</td>
<td>+ - * x.fdiv(y) / %</td>
</tr><tr><td><a name="int-div" id="int-div"></a><a href="#int-div-note">integer division</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>Math.floor(x / y)</td>
<td>13 / 5</td>
</tr><tr><td><a name="divmod" id="divmod"></a><a href="#divmod-note">divmod</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>none</em></span></td>
<td>q, r = 13.divmod(5)</td>
</tr><tr><td><a name="int-div-zero" id="int-div-zero"></a><a href="#int-div-zero-note">integer division by zero</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>returns assignable value Infinity, NaN, or -Infinity depending upon whether dividend is positive, zero, or negative.<br><br>
There are literals for Infinity and NaN.</em></span></td>
<td><span style="color: gray"><em>raises</em> ZeroDivisionError</span></td>
</tr><tr><td><a name="float-div" id="float-div"></a><a href="#float-div-note">float division</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>13 / 5</td>
<td>13.to_f / 5 <span style="color: gray"><em>or</em></span><br>
13.fdiv(5)</td>
</tr><tr><td><a name="float-div-zero" id="float-div-zero"></a><a href="#float-div-zero-note">float division by zero</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>same behavior as for integers</em></span></td>
<td><span style="color: gray"><em>returns</em> -Infinity, NaN, <em>or</em> Infinity</span></td>
</tr><tr><td><a name="power" id="power"></a><a href="#power-note">power</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>Math.pow(2, 32)</td>
<td>2<span style="white-space: pre-wrap;">**</span>32</td>
</tr><tr><td><a name="sqrt" id="sqrt"></a><a href="#sqrt-note">sqrt</a></td>
<td>Math.sqrt(2)</td>
<td>include <span style="color: green">Math</span><br><br>
sqrt(2)</td>
</tr><tr><td><a name="sqrt-negative-one" id="sqrt-negative-one"></a><a href="#sqrt-negative-one-note">sqrt -1</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>NaN</td>
<td><span style="color: gray"><em>raises</em> Errno::EDOM</span></td>
</tr><tr><td><a name="transcendental-func" id="transcendental-func"></a><a href="#transcendental-func-note">transcendental functions</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>Math.exp Math.log Math.sin Math.cos Math.tan Math.asin Math.acos Math.atan Math.atan2</td>
<td>include <span style="color: green">Math</span><br><br>
exp log sin cos tan asin acos atan atan2</td>
</tr><tr><td><a name="transcendental-const" id="transcendental-const"></a><a href="#transcendental-const-note">transcendental constants</a><br><span style="color: gray"><em>π and e</em></span></td>
<td>Math.PI<br>
Math.E</td>
<td>include <span style="color: green">Math</span><br><br><span style="color: green">PI E</span></td>
</tr><tr><td><a name="float-truncation" id="float-truncation"></a><a href="#float-truncation-note">float truncation</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>none</em></span><br>
Math.round(3.1)<br>
Math.floor(3.1)<br>
Math.ceil(3.1)</td>
<td>x.to_i<br>
x.round<br>
x.ceil<br>
x.floor</td>
</tr><tr><td><a name="abs-val" id="abs-val"></a><a href="#abs-val-note">absolute value</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>Math.abs(-3)</td>
<td>x.abs</td>
</tr><tr><td><a name="int-overflow" id="int-overflow"></a><a href="#int-overflow-note">integer overflow</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>all numbers are floats</em></span></td>
<td><span style="color: gray"><em>becomes arbitrary length integer of type</em> Bignum</span></td>
</tr><tr><td><a name="float-overflow" id="float-overflow"></a><a href="#float-overflow-note">float overflow</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>Infinity</td>
<td><span style="color: green">Infinity</span></td>
</tr><tr><td><a name="rational-construction" id="rational-construction"></a><a href="#rational-construction-note">rational construction</a><br><span style="white-space: pre-wrap;"> </span></td>
<td></td>
<td>require <span style="color: maroon">'rational'</span><br><br>
x = <span style="color: green">Rational</span>(22, 7)</td>
</tr><tr><td><a name="rational-decomposition" id="rational-decomposition"></a><a href="#rational-decomposition-note">rational decomposition</a><br><span style="white-space: pre-wrap;"> </span></td>
<td></td>
<td>x.numerator<br>
x.denominator</td>
</tr><tr><td><a name="complex-construction" id="complex-construction"></a><a href="#complex-construction-note">complex construction</a><br><span style="white-space: pre-wrap;"> </span></td>
<td></td>
<td>require <span style="color: maroon">'complex'</span><br><br>
z = 1 + 1.414.im</td>
</tr><tr><td><a name="complex-decomposition" id="complex-decomposition"></a><a href="#complex-decomposition-note">complex decomposition</a><br><span style="color: gray"><em>real and imaginary component, argument, absolute value, conjugate</em></span></td>
<td></td>
<td>z.real<br>
z.imag<br>
z.arg<br>
z.abs<br>
z.conj</td>
</tr><tr><td><a name="random-num" id="random-num"></a><a href="#random-num-note">random number</a><br><span style="color: gray"><em>uniform integer, uniform float, normal float</em></span></td>
<td>Math.floor(Math.random() * 100)<br>
Math.random()<br><span style="color: gray"><em>none</em></span></td>
<td>rand(100)<br>
rand<br><span style="color: gray"><em>none</em></span></td>
</tr><tr><td><a name="random-seed" id="random-seed"></a><a href="#random-seed-note">random seed</a><br><span style="color: gray"><em>set, get, restore</em></span></td>
<td><span style="color: gray"><em>none</em></span></td>
<td>srand(17)<br><br>
seed = srand<br>
srand(seed)</td>
</tr><tr><td><a name="bit-op" id="bit-op"></a><a href="#bit-op-note">bit operators</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="white-space: pre-wrap;"><< >> & | ^ ~</span></td>
<td><span style="white-space: pre-wrap;"><< >> & | ^ ~</span></td>
</tr><tr><td><a name="binary-octal-hex-literals" id="binary-octal-hex-literals"></a><a href="#binary-octal-hex-literals-note">binary, octal, and hex literals</a></td>
<td><span style="color: gray"><em>none</em></span><br>
052 <span style="color: gray"><span style="white-space: pre-wrap;">//</span> deprecated</span><br>
0x2a</td>
<td>0b101010<br>
052<br>
0x2a</td>
</tr><tr><td><a name="radix" id="radix"></a><a href="#radix-note">radix</a><br><span style="color: gray"><em>convert integer to and from string with radix</em></span></td>
<td>(42).toString(7)<br><span style="color: gray"><em>??</em></span></td>
<td>42.to_s(7)<br><span style="color: maroon">"60"</span>.to_i(7)</td>
</tr><tr><th colspan="5"><a name="strings" id="strings"></a><a href="#strings-note">strings</a></th>
</tr><tr><th></th>
<th>javascript</th>
<th>ruby</th>
</tr><tr><td><a name="str-type" id="str-type"></a><a href="#str-type-note">string type</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>String</td>
<td>String</td>
</tr><tr><td><a name="str-literal" id="str-literal"></a><a href="#str-literal-note">string literal</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>"don't say \"no\""<br>
'don\'t say "no"'</td>
<td><span style="color: maroon">"don't say \"no\""</span><br><span style="color: maroon">'don\'t say "no"'</span><br><span style="color: maroon">"don't "</span> <span style="color: maroon">'say "no"'</span></td>
</tr><tr><td><a name="newline-in-str-literal" id="newline-in-str-literal"></a><a href="#newline-in-str-literal-note">newline in literal</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>yes</em></span></td>
<td><span style="color: maroon">'first line<br>
second line'<br><br>
"first line<br>
second line"</span></td>
</tr><tr><td><a name="str-literal-esc" id="str-literal-esc"></a><a href="#str-literal-esc-note">literal escapes</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>single and double quotes:</em></span><br>
\b \f \n \r \t \v \uhhhh \xhh \" \' \\</td>
<td><span style="color: gray"><em>double quoted:</em></span><br>
\a \b \c<span style="color: gray"><em>x</em></span> \e \f \n \r \s \t \v \x<span style="color: gray"><em>hh</em></span> \<span style="color: gray"><em>ooo</em></span> \u<span style="color: gray"><em>hhhh</em></span> \u{<span style="color: gray"><em>hhhhh</em></span>}<br><br><span style="color: gray"><em>single quoted:</em></span><br>
\' \\</td>
</tr><tr><td><a name="here-doc" id="here-doc"></a><a href="#here-doc-note">here document</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>none</em></span></td>
<td>word = <span style="color: maroon">"amet"</span><br><br>
s = <span style="color: maroon"><span style="white-space: pre-wrap;"><<</span>EOF<br>
lorem ipsum<br>
dolor sit</span> <span style="color: peru">#{word}</span><br><span style="color: maroon">EOF</span></td>
</tr><tr><td><a name="var-interpolation" id="var-interpolation"></a><a href="#var-interpolation-note">variable interpolation</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><span style="white-space: pre-wrap;">//</span> None; use string concatenation.<br><span style="white-space: pre-wrap;">//</span> Both of these expressions are '11':</span><br>
1 + "1"<br>
"1" + 1</td>
<td>count = 3<br>
item = <span style="color: maroon">"ball"</span><br>
puts <span style="color: maroon">"</span><span style="color: peru">#{count} #{item}</span><span style="color: maroon">s"</span></td>
</tr><tr><td><a name="expr-interpolation" id="expr-interpolation"></a><a href="#expr-interpolation-note">expression interpolation</a></td>
<td><span style="color: gray"><em>none</em></span></td>
<td><span style="color: maroon">"1 + 1 = #{1 + 1}"</span></td>
</tr><tr><td><a name="format-str" id="format-str"></a><a href="#format-str-note">format string</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><span style="white-space: pre-wrap;">//</span> None; use string concatenation.<br><span style="white-space: pre-wrap;">//</span> Evaluates to "12.35":</span><br>
12.3456.toFixed(2)</td>
<td><span style="color: maroon">"lorem %s %d %f"</span> % [<span style="color: maroon">"ipsum"</span>, 13, 3.7]</td>
</tr><tr><td><a name="mutable-str" id="mutable-str"></a><a href="#mutable-str-note">are strings mutable?</a></td>
<td><span style="color: gray"><em>no</em></span></td>
<td>s = <span style="color: maroon">"bar"</span><br>
s2 = s<br><span style="color: gray"># sets s and s2 to "baz":</span><br>
s[2] = <span style="color: maroon">"z"</span></td>
</tr><tr><td><a name="copy-str" id="copy-str"></a><a href="#copy-str-note">copy string</a></td>
<td><span style="color: gray"><em>none</em></span></td>
<td>s = <span style="color: maroon">"bar"</span><br>
s2 = s.clone<br><span style="color: gray"># s2 is not altered:</span><br>
s[2] = <span style="color: maroon">"z"</span></td>
</tr><tr><td><a name="str-concat" id="str-concat"></a><a href="#str-concat-note">concatenate</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>s = "Hello, " + "World!";</td>
<td>s = <span style="color: maroon">"Hello, "</span><br>
s2 = s + <span style="color: maroon">"World!"</span><br><br><span style="color: gray"># juxtaposition can be used to<br>
# concatenate literals:</span><br>
s2 = <span style="color: maroon">"Hello, " 'World!'</span></td>
</tr><tr><td><a name="str-replicate" id="str-replicate"></a><a href="#str-replicate-note">replicate</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>var hbar = Array(80).join("-");</td>
<td>hbar = <span style="color: maroon">"-"</span> * 80</td>
</tr><tr><td><a name="translate-case" id="translate-case"></a><a href="#translate-case-note">translate case</a><br><span style="color: gray"><em>to upper, to lower</em></span></td>
<td>"lorem".toUpperCase()<br>
"LOREM".toLowerCase()</td>
<td><span style="color: maroon">"lorem"</span>.upcase<br><span style="color: maroon">"LOREM"</span>.downcase</td>
</tr><tr><td><a name="capitalize" id="capitalize"></a><a href="#capitalize-note">capitalize</a><br><span style="color: gray"><em>string, words</em></span></td>
<td><span style="color: gray"><em>none</em></span></td>
<td><span style="color: maroon">"lorem"</span>.capitalize<br><span style="color: gray"><em>none</em></span></td>
</tr><tr><td><a name="trim" id="trim"></a><a href="#trim-note">trim</a><br><span style="color: gray"><em>both sides, left, right</em></span></td>
<td>" lorem ".trim()<br><span style="color: gray"># some browsers:</span><br>
" lorem".trimLeft()<br>
"lorem ".trimRight()</td>
<td><span style="color: maroon">" lorem "</span>.strip<br><span style="color: maroon">" lorem"</span>.lstrip<br><span style="color: maroon">"lorem "</span>.rstrip</td>
</tr><tr><td><a name="pad" id="pad"></a><a href="#pad-note">pad</a><br><span style="color: gray"><em>on right, on left, centered</em></span></td>
<td><span style="color: gray"><em>none</em></span></td>
<td><span style="color: maroon">"lorem"</span>.ljust(10)<br><span style="color: maroon">"lorem"</span>.rjust(10)<br><span style="color: maroon">"lorem"</span>.center(10)</td>
</tr><tr><td><a name="num-to-str" id="num-to-str"></a><a href="#num-to-str-note">number to string</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>"value: " + 8</td>
<td><span style="color: maroon">"value: "</span> + 8.to_s</td>
</tr><tr><td><a name="str-to-num" id="str-to-num"></a><a href="#str-to-num-note">string to number</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>7 + parseInt("12", 10)<br>
73.9 + parseFloat(".037")<br><br><span style="color: gray"><span style="white-space: pre-wrap;">//</span> 12:</span><br>
parseInt("12A")<br><span style="color: gray"><span style="white-space: pre-wrap;">//</span> NaN:</span><br>
parseInt("A")</td>
<td>7 + <span style="color: maroon">"12"</span>.to_i<br>
73.9 + <span style="color: maroon">".037"</span>.to_f<br><br><span style="color: gray"># 12:</span><br><span style="color: maroon">"12A"</span>.to_i<br><span style="color: gray"># 0:</span><br><span style="color: maroon">"A"</span>.to_i</td>
</tr><tr><td><a name="str-join" id="str-join"></a><a href="#str-join-note">string join</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>["do", "re", "mi"].join(" ")</td>
<td>%w(do re mi fa).join(<span style="color: maroon">' '</span>)<br><br><span style="color: gray"># implicitly converted to strings:</span><br>
[1, 2, 3].join(<span style="color: maroon">' '</span>)</td>
</tr><tr><td><a name="split" id="split"></a><a href="#split-note">split</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><span style="white-space: pre-wrap;">//</span> [ "do", "re", "", "mi", "" ]:</span><br>
"do re<span style="white-space: pre-wrap;"> </span>mi ".split(" ")<br><br><span style="color: gray"><span style="white-space: pre-wrap;">//</span> [ "do", "re", "mi", "" ]:</span><br>
"do re<span style="white-space: pre-wrap;"> </span>mi ".split(/\s+/)</td>
<td><span style="color: gray"># ["do", "re", "", "mi"]:</span><br><span style="color: maroon">"do re<span style="white-space: pre-wrap;"> </span>mi "</span>.split(<span style="color: maroon">/ /</span>)<br><br><span style="color: gray"># ["do", "re", "mi"]:</span><br><span style="color: maroon">"do re<span style="white-space: pre-wrap;"> </span>mi "</span>.split</td>
</tr><tr><td><a name="split-in-two" id="split-in-two"></a><a href="#split-in-two-note">split in two</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>none</em></span></td>
<td><span style="color: maroon">"do re mi fa"</span>.split(<span style="color: maroon">/\s+/</span>, 2)</td>
</tr><tr><td><a name="split-keep-delimiters" id="split-keep-delimiters"></a><a href="#split-keep-delimiters-note">split and keep delimiters</a></td>
<td><span style="color: gray"><em>none</em></span></td>
<td><span style="color: maroon">"do re mi fa"</span>.split(<span style="color: maroon">/(\s+)/</span>)</td>
</tr><tr><td><a name="prefix-suffix-test" id="prefix-suffix-test"></a><a href="#prefix-suffix-test-note">prefix and suffix test</a></td>
<td>"foobar".startsWith("foo")<br>
"foobar".endsWith("bar")</td>
<td>'foobar'.start_with?('foo')<br>
'foobar'.end_with?('bar')</td>
</tr><tr><td><a name="str-len" id="str-len"></a><a href="#str-len-note">length</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>"lorem".length</td>
<td><span style="color: maroon">"lorem"</span>.length<br><span style="color: maroon">"lorem"</span>.size</td>
</tr><tr><td><a name="index-substr" id="index-substr"></a><a href="#index-substr-note">index of substring</a><br><span style="color: gray"><em>first, last</em></span></td>
<td><span style="color: gray"><span style="white-space: pre-wrap;">//</span> returns -1 if not found:</span><br>
"lorem ipsum".indexOf("ipsum")</td>
<td><span style="color: gray"># returns nil if not found:</span><br><span style="color: maroon">"do re re"</span>.index(<span style="color: maroon">"re"</span>)<br><span style="color: maroon">"do re re"</span>.rindex(<span style="color: maroon">"re"</span>)</td>
</tr><tr><td><a name="extract-substr" id="extract-substr"></a><a href="#extract-substr-note">extract substring</a><br><span style="color: gray"><em>by start and length, by start and end, by successive starts</em></span></td>
<td>"lorem ipsum".substr(6, 5)<br>
"lorem ipsum".substring(6, 11)</td>
<td><span style="color: maroon">"lorem ipsum"</span>[6, 5]<br><span style="color: maroon">"lorem ipsum"</span>[6<span style="white-space: pre-wrap;">..</span>10]<br><span style="color: maroon">"lorem ipsum"</span>[6<span style="white-space: pre-wrap;">...</span>11]</td>
</tr><tr><td><a name="lookup-char" id="lookup-char"></a><a href="#lookup-char-note">character lookup</a></td>
<td>"lorem ipsum"[6]</td>
<td><span style="color: maroon">"lorem ipsum"</span>[6]</td>
</tr><tr><td><a name="chr-ord" id="chr-ord"></a><a href="#chr-ord-note">chr and ord</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>String.fromCharCode(65)<br>
"A".charCodeAt(0)</td>
<td>65.chr<br><span style="color: maroon">"A"</span>.ord<br><br>
0x3bb.chr(<span style="color: maroon">'UTF-8'</span>)<br><span style="color: maroon">"\u03bb"</span>.codepoints.first</td>
</tr><tr><td><a name="str-to-char-array" id="str-to-char-array"></a><a href="#str-to-char-array-note">to array of characters</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>"abcd".split("")</td>
<td><span style="color: maroon">"abcd"</span>.split(<span style="color: maroon">""</span>)</td>
</tr><tr><td><a name="translate-char" id="translate-char"></a><a href="#translate-char-note">translate characters</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>none</em></span></td>
<td><span style="color: maroon">"hello"</span>.tr(<span style="color: maroon">"a-z"</span>, <span style="color: maroon">"n-za-m"</span>)</td>
</tr><tr><td><a name="delete-char" id="delete-char"></a><a href="#delete-char-note">delete characters</a></td>
<td><span style="color: gray"><em>none</em></span></td>
<td><span style="color: maroon">"disemvowel me"</span>.delete(<span style="color: maroon">"aeiou"</span>)</td>
</tr><tr><td><a name="squeeze-char" id="squeeze-char"></a><a href="#squeeze-char-note">squeeze characters</a></td>
<td><span style="color: gray"><em>none</em></span></td>
<td><span style="color: maroon">"too<span style="white-space: pre-wrap;"> </span>much<span style="white-space: pre-wrap;"> </span>space"</span>.squeeze(<span style="color: maroon">" "</span>)</td>
</tr><tr><th colspan="5"><a name="regexes" id="regexes"></a><a href="#regexes-note">regular expressions</a></th>
</tr><tr><th></th>
<th>javascript</th>
<th>ruby</th>
</tr><tr><td><a name="regex-literal" id="regex-literal"></a><a href="#regex-literal-note">literal, custom delimited literal</a></td>
<td>/lorem|ipsum/</td>
<td><span style="color: maroon">/lorem|ipsum/<br>
%r(/etc/hosts)</span></td>
</tr><tr><td><a name="char-class-abbrev" id="char-class-abbrev"></a><a href="#char-class-abbrev-note">character class abbreviations</a></td>
<td>. \d \D \s \S \w \W</td>
<td>. \d \D \h \H \s \S \w \W</td>
</tr><tr><td><a name="regex-anchors" id="regex-anchors"></a><a href="#regex-anchors-note">anchors</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>^ $ \b \B</td>
<td>^ $ \A \b \B \z \Z</td>
</tr><tr><td><a name="regex-test" id="regex-test"></a><a href="#regex-test-note">match test</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>if (s.match(/1999/)) {<br><span style="white-space: pre-wrap;"> </span>alert("party!");<br>
}</td>
<td><span style="color: purple">if</span> <span style="color: maroon">/1999/</span>.match(s)<br><span style="white-space: pre-wrap;"> </span>puts <span style="color: maroon">"party!"</span><br><span style="color: purple">end</span></td>
</tr><tr><td><a name="case-insensitive-regex" id="case-insensitive-regex"></a><a href="#case-insensitive-regex-note">case insensitive match test</a></td>
<td>"Lorem".match(/lorem/i)</td>
<td><span style="color: maroon">/lorem/</span>i.match(<span style="color: maroon">"Lorem"</span>)</td>
</tr><tr><td><a name="regex-modifiers" id="regex-modifiers"></a><a href="#regex-modifiers-note">modifiers</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>g i m</td>
<td>i o m x</td>
</tr><tr><td><a name="subst" id="subst"></a><a href="#subst-note">substitution</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>s = "do re mi mi mi";<br>
s.replace(/mi/g, "ma");</td>
<td>s = <span style="color: maroon">"do re mi mi mi"</span><br>
s.gsub!(<span style="color: maroon">/mi/</span>, <span style="color: maroon">"ma"</span>)</td>
</tr><tr><td><a name="match-prematch-postmatch" id="match-prematch-postmatch"></a><a href="#match-prematch-postmatch-note">match, prematch, postmatch</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: per">m</span> = /\d{4}/.exec(s);<br>
if (m) {<br><span style="white-space: pre-wrap;"> </span>match = m[0];<br><span style="white-space: pre-wrap;"> </span><span style="color: gray"># no prematch or postmatch</span><br>
}</td>
<td>m = <span style="color: maroon">/\d{4}/</span>.match(s)<br><span style="color: purple">if</span> m<br><span style="white-space: pre-wrap;"> </span>match = m[0]<br><span style="white-space: pre-wrap;"> </span>prematch = m.pre_match<br><span style="white-space: pre-wrap;"> </span>postmatch = m.post_match<br><span style="color: purple">end</span></td>
</tr><tr><td><a name="group-capture" id="group-capture"></a><a href="#group-capture-note">group capture</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>rx = /^(\d{4})-(\d{2})-(\d{2})$/;<br>
m = rx.exec('2009-06-03');<br>
yr = m[1];<br>
mo = m[2];<br>
dy = m[3];</td>
<td>rx = <span style="color: maroon">/(\d{4})-(\d{2})-(\d{2})/</span><br>
m = rx.match(<span style="color: maroon">"2010-06-03"</span>)<br>
yr, mo, dy = m[1..3]</td>
</tr><tr><td><a name="named-group-capture" id="named-group-capture"></a><a href="#named-group-capture-note">named group capture</a></td>
<td><span style="color: gray"><em>none</em></span></td>
<td>rx = <span style="color: maroon">/^(?<file>.+)\.(?<suffix>.+)$/</span><br>
m = rx.match(<span style="color: maroon">'foo.txt'</span>)<br><br>
m[<span style="color: maroon">"file"</span>]<br>
m[<span style="color: maroon">"suffix"</span>]</td>
</tr><tr><td><a name="scan" id="scan"></a><a href="#scan-note">scan</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>var a = "dolor sit amet".match(/\w+/g);</td>
<td>a = <span style="color: maroon">"dolor sit amet"</span>.scan(<span style="color: maroon">/\w+/</span>)</td>
</tr><tr><td><a name="backreference" id="backreference"></a><a href="#backreference-note">backreference in match and substitution</a></td>
<td>/(\w+) \1/.exec("do do")<br><br>
"do re".replace(/(\w+) (\w+)/, '$2 $1')</td>
<td><span style="color: maroon">/(\w+) \1/</span>.match(<span style="color: maroon">"do do"</span>)<br><br><span style="color: maroon">"do re"</span>.sub(<span style="color: maroon">/(\w+) (\w+)/</span>, <span style="color: maroon">'\2 \1'</span>)</td>
</tr><tr><td><a name="recursive-regex" id="recursive-regex"></a><a href="#recursive-regex-note">recursive regex</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><em>none</em></span></td>
<td><span style="color: maroon">/(?<foo>\(([^()]*|\g<foo>)*\))/</span></td>
</tr><tr><th colspan="5"><a name="dates-time" id="dates-time"></a><a href="#dates-time-note">dates and time</a></th>
</tr><tr><th></th>
<th>javascript</th>
<th>ruby</th>
</tr><tr><td><a name="broken-down-datetime-type" id="broken-down-datetime-type"></a><a href="#broken-down-datetime-type-note">broken-down datetime type</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: green">Date</span></td>
<td><span style="color: green">Time</span></td>
</tr><tr><td><a name="current-datetime" id="current-datetime"></a><a href="#current-datetime-note">current datetime</a></td>
<td><span style="color: purple">var</span> <span style="color: peru">t</span> = <span style="color: purple">new</span> <span style="color: green">Date</span>();</td>
<td>t = <span style="color: green">Time</span>.now<br>
utc = <span style="color: green">Time</span>.now.utc</td>
</tr><tr><td><a name="current-unix-epoch" id="current-unix-epoch"></a><a href="#current-unix-epoch-note">current unix epoch</a></td>
<td>(<span style="color: purple">new</span> <span style="color: green">Date</span>()).getTime() / 1000</td>
<td>epoch = <span style="color: green">Time</span>.now.to_i</td>
</tr><tr><td><a name="broken-down-datetime-to-unix-epoch" id="broken-down-datetime-to-unix-epoch"></a><a href="#broken-down-datetime-to-unix-epoch-note">broken-down datetime to unix epoch</a></td>
<td>Math.round(t.getTime() / 1000)</td>
<td>epoch = t.to_i</td>
</tr><tr><td><a name="unix-epoch-to-broken-down-datetime" id="unix-epoch-to-broken-down-datetime"></a><a href="#unix-epoch-to-broken-down-datetime-note">unix epoch to broken-down datetime</a></td>
<td><span style="color: purple">var</span> <span style="color: peru">epoch</span> = 1315716177;<br><span style="color: purple">var</span> <span style="color: peru">t2</span> = <span style="color: purple">new</span> <span style="color: green">Date</span>(epoch * 1000);</td>
<td>t = <span style="color: green">Time</span>.at(1304442000)</td>
</tr><tr><td><a name="fmt-datetime" id="fmt-datetime"></a><a href="#fmt-datetime-note">format datetime</a></td>
<td><span style="color: gray"><em>none</em></span></td>
<td>t.strftime(<span style="color: maroon">"%Y-%m-%d %H:%M:%S"</span>)</td>
</tr><tr><td><a name="parse-datetime" id="parse-datetime"></a><a href="#parse-datetime-note">parse datetime</a></td>
<td><span style="color: gray"><em>none</em></span></td>
<td>require <span style="color: maroon">'date'</span><br><br>
s = <span style="color: maroon">"2011-05-03 10:00:00"</span><br>
fmt = <span style="color: maroon">"%Y-%m-%d %H:%M:%S"</span><br>
t = <span style="color: green">DateTime</span>.strptime(s, fmt).to_time</td>
</tr><tr><td><a name="parse-datetime-without-fmt" id="parse-datetime-without-fmt"></a><a href="#parse-datetime-without-fmt-note">parse datetime w/o format</a></td>
<td><span style="color: purple">var</span> <span style="color: peru">t</span> = <span style="color: purple">new</span> <span style="color: green">Date</span>(<span style="color: maroon">"July 7, 1999"</span>);</td>
<td>require <span style="color: maroon">'date'</span><br><br>
s = <span style="color: maroon">"July 7, 1999"</span><br>
t = <span style="color: green">Date</span>.parse(s).to_time</td>
</tr><tr><td><a name="date-parts" id="date-parts"></a><a href="#date-parts-note">date parts</a></td>
<td>t.getFullYear()<br>
t.getMonth() + 1<br>
t.getDate() <span style="color: gray"># getDay() is day of week</span></td>
<td>t.year<br>
t.month<br>
t.day</td>
</tr><tr><td><a name="time-parts" id="time-parts"></a><a href="#time-parts-note">time parts</a></td>
<td>t.getHours()<br>
t.getMinutes()<br>
t.getSeconds()</td>
<td>t.hour<br>
t.min<br>
t.sec</td>
</tr><tr><td><a name="build-datetime" id="build-datetime"></a><a href="#build-datetime-note">build broken-down datetime</a></td>
<td><span style="color: purple">var</span> <span style="color: peru">yr</span> = 1999;<br><span style="color: purple">var</span> <span style="color: peru">mo</span> = 9;<br><span style="color: purple">var</span> <span style="color: peru">dy</span> = 10;<br><span style="color: purple">var</span> <span style="color: peru">hr</span> = 23;<br><span style="color: purple">var</span> <span style="color: peru">mi</span> = 30;<br><span style="color: purple">var</span> <span style="color: peru">ss</span> = 0;<br><span style="color: purple">var</span> <span style="color: peru">t</span> = <span style="color: purple">new</span> <span style="color: green">Date</span>(yr, mo - 1, dy, hr, mi, ss);</td>
<td>yr = 1999<br>
mo = 9<br>
dy = 10<br>
hr = 23<br>
mi = 30<br>
ss = 0<br>
t = <span style="color: green">Time</span>.new(yr, mo, dy, hr, mi, ss)</td>
</tr><tr><td><a name="datetime-subtraction" id="datetime-subtraction"></a><a href="#datetime-subtraction-note">datetime subtraction</a></td>
<td><span style="color: gray">number <em>containing time difference in milliseconds</em></span></td>
<td><span style="color: gray">Float <em>containing time difference in seconds</em></span></td>
</tr><tr><td><a name="add-duration" id="add-duration"></a><a href="#add-duration-note">add duration</a></td>
<td><span style="color: purple">var</span> <span style="color: peru">t1</span> = <span style="color: purple">new</span> <span style="color: green">Date</span>();<br><span style="color: purple">var</span> <span style="color: peru">delta</span> = (10 * 60 + 3) * 1000;<br><span style="color: purple">var</span> <span style="color: peru">t2</span> = <span style="color: purple">new</span> <span style="color: green">Date</span>(t1.getTime() + delta);</td>
<td>require <span style="color: maroon">'date/delta'</span><br><br>
s = <span style="color: maroon">"10 min, 3 s"</span><br>
delta = <span style="color: green">Date</span>::<span style="color: green">Delta</span>.parse(s).in_secs<br>
t = <span style="color: green">Time</span>.now + delta</td>
</tr><tr><td><a name="local-tmz-determination" id="local-tmz-determination"></a><a href="#local-tmz-determination-note">local time zone determination</a></td>
<td></td>
<td><span style="color: gray"><em>if no time zone is specified the local time zone is used</em></span></td>
</tr><tr><td><a name="nonlocal-tmz" id="nonlocal-tmz"></a><a href="#nonlocal-tmz-note">nonlocal time zone</a></td>
<td></td>
<td><span style="color: gray"># gem install tzinfo</span><br>
require <span style="color: maroon">'tzinfo'</span><br><br>
tmz = <span style="color: gr4een">TZInfo</span>::<span style="color: green">Timezone</span>.get(<span style="color: maroon">"Asia/Tokyo"</span>)<br>
jp_time = tmz.utc_to_local(<span style="color: green">Time</span>.now.utc)</td>
</tr><tr><td><a name="tmz-info" id="tmz-info"></a><a href="#tmz-info-note">time zone info</a><br><br><span style="color: gray"><em>name and UTC offset</em></span></td>
<td></td>
<td>t.zone<br>
t.utc_offset / 3600</td>
</tr><tr><td><a name="daylight-savings-test" id="daylight-savings-test"></a><a href="#daylight-savings-test-note">daylight savings test</a></td>
<td></td>
<td>t.dst?</td>
</tr><tr><td><a name="microseconds" id="microseconds"></a><a href="#microseconds-note">microseconds</a></td>
<td></td>
<td>t.usec</td>
</tr><tr><td><a name="sleep" id="sleep"></a><a href="#sleep-note">sleep</a></td>
<td><span style="color: gray"><em>none</em></span></td>
<td>sleep(0.5)</td>
</tr><tr><td><a name="timeout" id="timeout"></a><a href="#timeout-note">timeout</a></td>
<td></td>
<td>require <span style="color: maroon">'timeout'</span><br><br><span style="color: purple">begin</span><br><span style="white-space: pre-wrap;"> </span><span style="color: green">Timeout</span>.timeout(5) <span style="color: purple">do</span><br><span style="white-space: pre-wrap;"> </span><span style="white-space: pre-wrap;"> </span>might_take_too_long<br><span style="white-space: pre-wrap;"> </span><span style="color: purple">end</span><br><span style="color: purple">rescue</span> <span style="color: green">Timeout</span>::<span style="color: green">Error</span><br><span style="color: purple">end</span></td>
</tr><tr><th colspan="5"><a name="resizable-arrays" id="resizable-arrays"></a><a href="#resizable-arrays-note">resizable arrays</a></th>
</tr><tr><th></th>
<th>javascript</th>
<th>ruby</th>
</tr><tr><td><a name="array-literal" id="array-literal"></a><a href="#array-literal-note">literal</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>a = [1, 2, 3, 4]</td>
<td>a = [1, 2, 3, 4]<br><br><span style="color: gray"># a = ['do', 're', 'mi']</span><br>
a = %w(do re mi)</td>
</tr><tr><td><a name="array-size" id="array-size"></a><a href="#array-size-note">size</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>a.length</td>
<td>a.size<br>
a.length <span style="color: gray"># same as size</span></td>
</tr><tr><td><a name="array-empty" id="array-empty"></a><a href="#array-empty-note">empty test</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><span style="white-space: pre-wrap;">//</span> TypeError if a is null or undefined:</span><br>
a.length === 0</td>
<td><span style="color: gray"># NoMethodError if a is nil:</span><br>
a.empty?</td>
</tr><tr><td><a name="array-lookup" id="array-lookup"></a><a href="#array-lookup-note">lookup</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>a[0]</td>
<td>a[0]<br><br><span style="color: gray"># returns last element:</span><br>
a[-1]</td>
</tr><tr><td><a name="array-update" id="array-update"></a><a href="#array-update-note">update</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>a[0] = "lorem"</td>
<td>a[0] = <span style="color: maroon">"lorem"</span></td>
</tr><tr><td><a name="array-out-of-bounds" id="array-out-of-bounds"></a><a href="#array-out-of-bounds-note">out-of-bounds behavior</a></td>
<td><span style="color: gray"><em>returns</em> undefined</span></td>
<td>a = []<br><span style="color: gray"># evaluates as nil:</span><br>
a[10]<br><span style="color: gray"># increases array size to 11:</span><br>
a[10] = <span style="color: maroon">"lorem"</span></td>
</tr><tr><td><a name="array-element-index" id="array-element-index"></a><a href="#array-element-index-note">element index</a><br><br><span style="color: gray"><em>first and last occurrence</em></span></td>
<td><span style="color: gray"><span style="white-space: pre-wrap;">//</span> return -1 if not found:</span><br>
[6, 7, 7, 8].indexOf(7)<br>
[6, 7, 7, 8].lastIndexOf(7)</td>
<td>a = %w(x y y z)<br><br><span style="color: gray"># return nil if not found:</span><br>
a.index(<span style="color: maroon">'y'</span>)<br>
a.rindex(<span style="color: maroon">'y'</span>)</td>
</tr><tr><td><a name="array-slice" id="array-slice"></a><a href="#array-slice-note">slice</a><br><span style="color: gray"><em>by endpoints, by length</em></span><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><span style="white-space: pre-wrap;">//</span> select 3rd and 4th elements:</span><br>
["a", "b", "c", "d"].slice(2, 4)<br><span style="color: gray"><em>none</em></span></td>
<td><span style="color: gray"># select 3rd and 4th elements:</span><br>
a[2..3]<br>
a[2, 2]</td>
</tr><tr><td><a name="array-slice-to-end" id="array-slice-to-end"></a><a href="#array-slice-to-end-note">slice to end</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>["a", "b", "c", "d"].slice(1)</td>
<td>a[1..-1]</td>
</tr><tr><td><a name="array-back" id="array-back"></a><a href="#array-back-note">manipulate back</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>a = [6, 7, 8];<br>
a.push(9);<br>
i = a.pop();</td>
<td>a = [6, 7, 8]<br>
a.push(9)<br>
a <span style="white-space: pre-wrap;"><<</span> 9 <span style="color: gray"># same as push</span><br>
a.pop</td>
</tr><tr><td><a name="array-front" id="array-front"></a><a href="#array-front-note">manipulate front</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>a = [6, 7, 8];<br>
a.unshift(5);<br>
i = a.shift();</td>
<td>a = [6, 7, 8]<br>
a.unshift(5)<br>
a.shift</td>
</tr><tr><td><a name="array-concatenation" id="array-concatenation"></a><a href="#array-concatenation-note">concatenate</a></td>
<td>a = [1, 2, 3].concat([4, 5, 6]);</td>
<td>a = [1, 2, 3]<br>
a2 = a + [4, 5, 6]<br>
a.concat([4, 5, 6])</td>
</tr><tr><td><a name="replicate-array" id="replicate-array"></a><a href="#replicate-array-note">replicate</a></td>
<td><span style="color: gray"><em>none</em></span></td>
<td>a = [<span style="color: peru">nil</span>] * 10<br>
a = <span style="color: green">Array</span>.new(10, <span style="color: peru">nil</span>)</td>
</tr><tr><td><a name="array-copy" id="array-copy"></a><a href="#array-copy-note">copy</a><br><span style="color: gray"><em>address copy, shallow copy, deep copy</em></span></td>
<td>a = [1, 2, [3, 4]];<br>
a2 = a;<br>
a3 = a.slice(0);<br>
a4 = JSON.parse(JSON.stringify(a));</td>
<td>a = [1,2,[3,4]]<br>
a2 = a<br>
a3 = a.dup<br>
a4 = <span style="color: green">Marshal</span>.load(<span style="color: green">Marshal</span>.dump(a))</td>
</tr><tr><td><a name="array-as-func-arg" id="array-as-func-arg"></a><a href="#array-as-func-arg-note">array as function argument</a></td>
<td><span style="color: gray"><em>parameter contains address copy</em></span></td>
<td><span style="color: gray"><em>parameter contains address copy</em></span></td>
</tr><tr><td><a name="iterate-over-array" id="iterate-over-array"></a><a href="#iterate-over-array-note">iterate over elements</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>_.each([1, 2, 3], function(n) {<br><span style="white-space: pre-wrap;"> </span>alert(n);<br>
})</td>
<td>[1, 2, 3].each { |i| puts i }</td>
</tr><tr><td><a name="indexed-array-iteration" id="indexed-array-iteration"></a><a href="#indexed-array-iteration-note">iterate over indices and elements</a></td>
<td>var len = a.length;<br>
for (var i = 0; i < len; i++ ) {<br><span style="white-space: pre-wrap;"> </span>alert(a[i]);<br>
}</td>
<td>a = %w(do re mi fa)<br>
a.each_with_index do |s, i|<br><span style="white-space: pre-wrap;"> </span>puts <span style="color: maroon">"</span><span style="color: peru">#{s}</span> <span style="color: maroon">at index</span> <span style="color: peru">#{i}</span><span style="color: maroon">"</span><br>
end</td>
</tr><tr><td><a name="range-iteration" id="range-iteration"></a><a href="#range-iteration-note">iterate over range</a></td>
<td><span style="color: gray"><em>not space efficient; use C-style for loop</em></span></td>
<td>(1..1_000_000).each <span style="color: purple">do</span> |i|<br><span style="white-space: pre-wrap;"> </span><span style="color: gray"><em>code</em></span><br><span style="color: purple">end</span></td>
</tr><tr><td><a name="range-array" id="range-array"></a><a href="#range-array-note">instantiate range as array</a></td>
<td>var a = _.range(1, 10);</td>
<td>a = (1..10).to_a</td>
</tr><tr><td><a name="array-reverse" id="array-reverse"></a><a href="#array-reverse-note">reverse</a><br><span style="color: gray"><em>non-destructive, in-place</em></span></td>
<td>var a = [1, 2, 3];<br>
a.reverse();</td>
<td>a = [1, 2, 3]<br><br>
a.reverse<br>
a.reverse!</td>
</tr><tr><td><a name="array-sort" id="array-sort"></a><a href="#array-sort-note">sort</a><br><span style="color: gray"><em>non-destructive,<br>
in-place,<br>
custom comparision</em></span></td>
<td>var a = [3, 1, 4, 2];<br>
a.sort();</td>
<td>a = %w(b A a B)<br><br>
a.sort<br>
a.sort!<br>
a.sort <span style="color: purple">do</span> |x, y|<br><span style="white-space: pre-wrap;"> </span>x.downcase <=> y.downcase<br><span style="color: purple">end</span></td>
</tr><tr><td><a name="array-dedupe" id="array-dedupe"></a><a href="#array-dedupe-note">dedupe</a><br><span style="color: gray"><em>non-destructive, in-place</em></span></td>
<td>var a = [1, 2, 2, 3];<br><br>
var a2 = _.uniq(a);<br>
a = _.uniq(a);</td>
<td>a = [1, 2, 2, 3]<br><br>
a2 = a.uniq<br>
a.uniq!</td>
</tr><tr><td><a name="membership" id="membership"></a><a href="#membership-note">membership</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>_.contains(a, 7)</td>
<td>a.include?(7)</td>
</tr><tr><td><a name="intersection" id="intersection"></a><a href="#intersection-note">intersection</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>_.intersection([1, 2], [2, 3, 4])</td>
<td>[1, 2] & [2 ,3, 4]</td>
</tr><tr><td><a name="union" id="union"></a><a href="#union-note">union</a><br><span style="white-space: pre-wrap;"> </span></td>
<td>_.union([1, 2], [2, 3, 4])</td>
<td>[1, 2] | [2, 3, 4]</td>
</tr><tr><td><a name="set-diff" id="set-diff"></a><a href="#set-diff-note">relative complement, symmetric difference</a></td>
<td>_.difference([1, 2, 3], [2])<br><span style="color: gray"><em>none</em></span></td>
<td>require <span style="color: maroon">'set'</span><br><br>
[1, 2, 3] - [2]<br><span style="color: green">Set</span>[1, 2] ^ <span style="color: green">Set</span>[2 ,3, 4]</td>
</tr><tr><td><a name="map" id="map"></a><a href="#map-note">map</a><br><span style="white-space: pre-wrap;"> </span></td>
<td><span style="color: gray"><span style="white-space: pre-wrap;">//</span> callback gets 3 args:<br><span style="white-space: pre-wrap;">//</span> value, index, array</span><br>
a.map(function(x) { return x * x })</td>