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1737 lines
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HTML
1737 lines
106 KiB
HTML
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<!DOCTYPE html>
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html;charset=UTF-8" />
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<title>CoffeeScript</title>
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<link rel="stylesheet" type="text/css" href="documentation/css/docs.css" />
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<link rel="stylesheet" type="text/css" href="documentation/css/idle.css" />
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</head>
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<body>
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<div class="container">
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<h1><sub style="font-size: 100px;">☕</sub> CoffeeScript</h1>
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<p>
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CoffeeScript is a little language that compiles into JavaScript. Think
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of it as JavaScript's less ostentatious kid brother — the same genes,
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roughly the same height, but a different sense of style. Apart from a handful of
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bonus goodies, statements in CoffeeScript correspond one-to-one with their
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equivalent in JavaScript, it's just another way of saying it.
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</p>
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<p>
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<b>Disclaimer:</b>
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CoffeeScript is just for fun and seriously alpha. I'm sure that there are still
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plenty of holes in the walls and leaks in the roof. <i>There are no guarantees
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that the syntax won't change between versions.</i> That said,
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it compiles into clean JavaScript (the good parts) that can use existing
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JavaScript libraries seamlessly, and passes through
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<a href="http://www.jslint.com/">JSLint</a> without warnings. The compiled
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output is quite readable — pretty-printed, with comments
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preserved intact.
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</p>
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<p>
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<b>Latest Version:</b>
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<a href="http://gemcutter.org/gems/coffee-script">0.3.2</a>
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</p>
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<h2>Table of Contents</h2>
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<p>
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<a href="#overview">Mini Overview</a><br />
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<a href="#installation">Installation and Usage</a><br />
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<a href="#try_coffee">Try CoffeeScript</a><br />
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<a href="#whitespace">Significant Whitespace</a><br />
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<a href="#functions">Functions and Invocation</a><br />
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<a href="#assignment">Assignment</a><br />
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<a href="#objects_and_arrays">Objects and Arrays</a><br />
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<a href="#lexical_scope">Lexical Scoping and Variable Safety</a><br />
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<a href="#conditionals">Conditionals, Ternaries, and Conditional Assignment</a><br />
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<a href="#aliases">Aliases</a><br />
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<a href="#splats">Splats...</a><br />
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<a href="#arguments">Arguments are Arrays</a><br />
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<a href="#while">While Loops</a><br />
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<a href="#comprehensions">Comprehensions (Arrays, Objects, and Ranges)</a><br />
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<a href="#slice_splice">Array Slicing and Splicing with Ranges</a><br />
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<a href="#expressions">Everything is an Expression</a><br />
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<a href="#existence">The Existential Operator</a><br />
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<a href="#inheritance">Inheritance, and Calling Super from a Subclass</a><br />
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<a href="#pattern_matching">Pattern Matching</a><br />
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<a href="#fat_arrow">Function Binding</a><br />
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<a href="#embedded">Embedded JavaScript</a><br />
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<a href="#switch">Switch/When/Else</a><br />
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<a href="#try">Try/Catch/Finally</a><br />
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<a href="#comparisons">Chained Comparisons</a><br />
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<a href="#strings">Multiline Strings and Heredocs</a><br />
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<a href="#resources">Resources</a><br />
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<a href="#change_log">Change Log</a><br />
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</p>
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<h2 id="overview">Mini Overview</h2>
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<p><i>CoffeeScript on the left, compiled JavaScript output on the right.</i></p>
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<div class='code'><pre class="idle"><span class="Comment"><span class="Comment">#</span> Assignment:</span>
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<span class="FunctionName">number</span><span class="Keyword">:</span> <span class="Number">42</span>
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<span class="FunctionName">opposite_day</span><span class="Keyword">:</span> <span class="BuiltInConstant">true</span>
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<span class="Comment"><span class="Comment">#</span> Conditions:</span>
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<span class="FunctionName">number</span><span class="Keyword">:</span> <span class="Keyword">-</span><span class="Number">42</span> <span class="Keyword">if</span> opposite_day
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<span class="Comment"><span class="Comment">#</span> Functions:</span>
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<span class="FunctionName">square</span><span class="Keyword">:</span> <span class="FunctionArgument">(</span><span class="FunctionArgument">x</span><span class="FunctionArgument">)</span> <span class="Storage">-></span> x <span class="Keyword">*</span> x
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<span class="Comment"><span class="Comment">#</span> Arrays:</span>
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<span class="FunctionName">list</span><span class="Keyword">:</span> [<span class="Number">1</span>, <span class="Number">2</span>, <span class="Number">3</span>, <span class="Number">4</span>, <span class="Number">5</span>]
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<span class="Comment"><span class="Comment">#</span> Objects:</span>
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<span class="FunctionName">math</span><span class="Keyword">:</span> {
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<span class="FunctionName">root</span><span class="Keyword">:</span> Math.sqrt
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<span class="FunctionName">square</span><span class="Keyword">:</span> square
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<span class="FunctionName">cube</span><span class="Keyword">:</span> <span class="FunctionArgument">(</span><span class="FunctionArgument">x</span><span class="FunctionArgument">)</span> <span class="Storage">-></span> x <span class="Keyword">*</span> square x
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}
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<span class="Comment"><span class="Comment">#</span> Splats:</span>
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<span class="FunctionName">race</span><span class="Keyword">:</span> <span class="FunctionArgument">(</span><span class="FunctionArgument">winner, runners...</span><span class="FunctionArgument">)</span> <span class="Storage">-></span>
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print winner, runners
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<span class="Comment"><span class="Comment">#</span> Existence:</span>
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alert <span class="String"><span class="String">"</span>I knew it!<span class="String">"</span></span> <span class="Keyword">if</span> elvis<span class="Keyword">?</span>
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<span class="Comment"><span class="Comment">#</span> Array comprehensions:</span>
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<span class="FunctionName">cubed_list</span><span class="Keyword">:</span> math.cube num <span class="Keyword">for</span> num <span class="Keyword">in</span> list
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</pre><pre class="idle"><span class="Storage">var</span> __a, __b, __c, cubed_list, list, math, num, number, opposite_day, race, square;
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<span class="Comment"><span class="Comment">//</span> Assignment:</span>
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number <span class="Keyword">=</span> <span class="Number">42</span>;
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opposite_day <span class="Keyword">=</span> <span class="BuiltInConstant">true</span>;
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<span class="Comment"><span class="Comment">//</span> Conditions:</span>
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<span class="Keyword">if</span> (opposite_day) {
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number <span class="Keyword">=</span> <span class="Keyword">-</span><span class="Number">42</span>;
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}
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<span class="Comment"><span class="Comment">//</span> Functions:</span>
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square <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">square</span>(<span class="FunctionArgument">x</span>) {
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<span class="Keyword">return</span> x <span class="Keyword">*</span> x;
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};
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<span class="Comment"><span class="Comment">//</span> Arrays:</span>
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list <span class="Keyword">=</span> [<span class="Number">1</span>, <span class="Number">2</span>, <span class="Number">3</span>, <span class="Number">4</span>, <span class="Number">5</span>];
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<span class="Comment"><span class="Comment">//</span> Objects:</span>
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math <span class="Keyword">=</span> {
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root: <span class="LibraryClassType">Math</span>.sqrt,
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square: square,
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cube: <span class="Storage">function</span> <span class="FunctionName">cube</span>(<span class="FunctionArgument">x</span>) {
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<span class="Keyword">return</span> x <span class="Keyword">*</span> square(x);
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}
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};
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<span class="Comment"><span class="Comment">//</span> Splats:</span>
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race <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">race</span>(<span class="FunctionArgument">winner</span>) {
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<span class="Storage">var</span> runners;
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runners <span class="Keyword">=</span> <span class="LibraryClassType">Array</span>.<span class="LibraryConstant">prototype</span>.slice.<span class="LibraryFunction">call</span>(arguments, <span class="Number">1</span>);
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<span class="Keyword">return</span> <span class="LibraryFunction">print</span>(winner, runners);
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};
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<span class="Comment"><span class="Comment">//</span> Existence:</span>
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<span class="Keyword">if</span> ((<span class="Keyword">typeof</span> elvis <span class="Keyword">!</span><span class="Keyword">==</span> <span class="String"><span class="String">"</span>undefined<span class="String">"</span></span> <span class="Keyword">&</span><span class="Keyword">&</span> elvis <span class="Keyword">!</span><span class="Keyword">==</span> <span class="BuiltInConstant">null</span>)) {
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<span class="LibraryFunction">alert</span>(<span class="String"><span class="String">"</span>I knew it!<span class="String">"</span></span>);
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}
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<span class="Comment"><span class="Comment">//</span> Array comprehensions:</span>
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cubed_list <span class="Keyword">=</span> (<span class="Storage">function</span>() {
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__a <span class="Keyword">=</span> []; __b <span class="Keyword">=</span> list;
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<span class="Keyword">for</span> (__c <span class="Keyword">=</span> <span class="Number">0</span>; __c <span class="Keyword"><</span> __b.<span class="LibraryConstant">length</span>; __c<span class="Keyword">++</span>) {
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num <span class="Keyword">=</span> __b[__c];
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__a.<span class="LibraryFunction">push</span>(math.cube(num));
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}
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<span class="Keyword">return</span> __a;
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}).<span class="LibraryFunction">call</span>(<span class="Variable">this</span>);
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</pre><button onclick='javascript: var __a, __b, __c, cubed_list, list, math, num, number, opposite_day, race, square;
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// Assignment:
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number = 42;
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opposite_day = true;
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// Conditions:
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if (opposite_day) {
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number = -42;
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}
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// Functions:
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square = function square(x) {
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return x * x;
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};
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// Arrays:
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list = [1, 2, 3, 4, 5];
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// Objects:
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math = {
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root: Math.sqrt,
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square: square,
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cube: function cube(x) {
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return x * square(x);
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}
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};
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// Splats:
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race = function race(winner) {
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var runners;
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runners = Array.prototype.slice.call(arguments, 1);
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return print(winner, runners);
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};
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// Existence:
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if ((typeof elvis !== "undefined" && elvis !== null)) {
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alert("I knew it!");
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}
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// Array comprehensions:
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cubed_list = (function() {
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__a = []; __b = list;
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for (__c = 0; __c < __b.length; __c++) {
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num = __b[__c];
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__a.push(math.cube(num));
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}
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return __a;
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}).call(this);
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;alert(cubed_list);'>run: cubed_list</button><br class='clear' /></div>
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<p>
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For a longer CoffeeScript example, check out
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<a href="documentation/underscore.html">Underscore.coffee</a>, a port
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of the <a href="http://documentcloud.github.com/underscore/">Underscore.js</a>
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library of helper functions. Underscore.coffee can pass the entire Underscore.js
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test suite. The CoffeeScript version is faster than the original for a number
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of methods (in general, due to the speed of CoffeeScript's array comprehensions), and
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after being minified and gzipped, is only 241 bytes larger than the original
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JavaScript version.
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Additional examples are included in the source repository, inside the
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<a href="http://github.com/jashkenas/coffee-script/tree/master/examples/">examples</a> folder.
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</p>
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<h2 id="installation">Installation and Usage</h2>
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<p>
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The CoffeeScript compiler is written in pure Ruby, and is available
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as a Ruby Gem.
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</p>
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<pre>
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gem install coffee-script</pre>
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<p>
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Installing the gem provides the <tt>coffee</tt> command, which can
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be used to compile CoffeeScript <tt>.coffee</tt> files into JavaScript, as
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well as debug them. In conjunction with
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<a href="http://nodejs.org/">Node.js</a> (or <a href="http://narwhaljs.org/">Narwhal</a>), the <tt>coffee</tt>
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command also provides direct evaluation and an interactive REPL.
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When compiling to JavaScript, <tt>coffee</tt> writes the output
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as <tt>.js</tt> files in the same directory by default, but output
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can be customized with the following options:
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</p>
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<table>
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<tr>
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<td width="25%"><code>-i, --interactive</code></td>
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<td>
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Launch an interactive CoffeeScript session.
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Requires <a href="http://nodejs.org/">Node.js</a>,
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or <a href="http://narwhaljs.org/">Narwhal</a>, with <tt>--narwhal</tt>.
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</td>
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</tr>
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<tr>
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<td><code>-r, --run</code></td>
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<td>
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Compile and execute scripts without saving the intermediate
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JavaScript. Requires <a href="http://nodejs.org/">Node.js</a>,
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or <a href="http://narwhaljs.org/">Narwhal</a>, with <tt>--narwhal</tt>.
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</td>
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</tr>
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<tr>
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<td><code>-o, --output [DIR]</code></td>
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<td>
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Write out all compiled JavaScript files into the specified directory.
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</td>
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</tr>
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<tr>
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<td><code>-w, --watch</code></td>
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<td>
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Watch the modification times of the coffee-scripts, recompiling as
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soon as a change occurs.
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</td>
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</tr>
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<tr>
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<td><code>-p, --print</code></td>
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<td>
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Instead of writing out the JavaScript as a file, print it
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directly to <b>stdout</b>.
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</td>
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</tr>
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<tr>
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<td><code>-l, --lint</code></td>
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<td>
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If the <tt>jsl</tt> (JavaScript Lint) command is installed, use it
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to check the compilation of a CoffeeScript file. (Handy in
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conjunction with <tt>--watch</tt>)
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</td>
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</tr>
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<tr>
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<td><code>-e, --eval</code></td>
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<td>
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Compile and print a little snippet of CoffeeScript directly from the
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command line (or from <b>stdin</b>). For example:<br /><tt>coffee -e "square: (x) -> x * x"</tt>
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</td>
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</tr>
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<tr>
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<td><code>-t, --tokens</code></td>
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<td>
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Instead of parsing the CoffeeScript, just lex it, and print out the
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token stream: <tt>[:IDENTIFIER, "square"], [":", ":"], [:PARAM, "x"]</tt> ...
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</td>
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</tr>
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<tr>
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<td><code>-v, --verbose</code></td>
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<td>
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As the JavaScript is being generated, print out every step of code
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generation, including lexical scope and the nodes in the
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AST.
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</td>
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</tr>
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<tr>
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<td><code>-n, --no-wrap</code></td>
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<td>
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Compile the JavaScript without the top-level function safety wrapper.
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(Used for CoffeeScript as a Node.js module.)
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</td>
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</tr>
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<tr>
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<td><code>-g, --globals</code></td>
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<td>
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Suppress all variable declarations at the top-level, effectively adding
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those variables to the global scope. (Used by the REPL.)
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</td>
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</tr>
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<tr>
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<td><code>--install-bundle</code></td>
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<td>
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Install the TextMate bundle for CoffeeScript syntax highlighting.
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</td>
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</tr>
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</table>
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<p>
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<b>Examples:</b>
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</p>
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<pre>
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coffee path/to/script.coffee
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coffee --interactive
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coffee --watch --lint experimental.coffee
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coffee --print app/scripts/*.coffee > concatenation.js</pre>
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<h2 id="try_coffee">Try CoffeeScript</h2>
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<p>
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Here's a live version of the CoffeeScript compiler, running within
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your browser.<br /> Hit the <b>compile</b> button to generate JavaScript
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on the right-hand side.
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You can also paste in any of the examples from below.
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</p>
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<div class="code repl_wrapper">
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<textarea id="repl_source">reverse: (string) ->
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string.split('').reverse()
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print reverse 'tpircseeffoc'</textarea>
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<pre id="repl_results"></pre>
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<button onclick="javascript: repl_compile();">compile</button>
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<br class="clear" />
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</div>
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<h2>Language Reference</h2>
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<p>
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<i>
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This reference is structured so that it can be read from top to bottom,
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if you like. Later sections use ideas and syntax previously introduced.
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Familiarity with JavaScript is assumed.
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In all of the following examples, the source CoffeeScript is provided on
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the left, and the direct compilation into JavaScript is on the right.
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</i>
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</p>
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<p id="whitespace">
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<b class="header">Significant Whitespace</b>
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CoffeeScript uses Python-style significant whitespace: You don't need to
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use semicolons <tt>;</tt> to terminate expressions, ending
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the line will do just as well. Semicolons can still be used to fit
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multiple expressions onto a single line. Instead of using curly braces
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<tt>{ }</tt> to delimit blocks of code (like <a href="#functions">functions</a>,
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<a href="#conditionals">if-statements</a>,
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<a href="#switch">switch</a>, and <a href="#try">try/catch</a>),
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use indentation.
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</p>
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<p>
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You don't need to use parentheses to invoke a function, if you're passing
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arguments:<br /><tt>print "coffee"</tt>
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</p>
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<p>
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You can use newlines to break up your expression into smaller pieces,
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as long as CoffeeScript can determine that the line hasn't finished yet.
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</p>
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<p id="functions">
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<b class="header">Functions and Invocation</b>
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Functions are defined by a list of parameters, an arrow, and the
|
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function body. The empty function looks like this: <tt>-></tt>. All
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functions in CoffeeScript are named by default, for easier debugging.
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</p>
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<div class='code'><pre class="idle"><span class="FunctionName">square</span><span class="Keyword">:</span> <span class="FunctionArgument">(</span><span class="FunctionArgument">x</span><span class="FunctionArgument">)</span> <span class="Storage">-></span> x <span class="Keyword">*</span> x
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<span class="FunctionName">cube</span><span class="Keyword">:</span> <span class="FunctionArgument">(</span><span class="FunctionArgument">x</span><span class="FunctionArgument">)</span> <span class="Storage">-></span> square(x) <span class="Keyword">*</span> x
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</pre><pre class="idle"><span class="Storage">var</span> cube, square;
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square <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">square</span>(<span class="FunctionArgument">x</span>) {
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<span class="Keyword">return</span> x <span class="Keyword">*</span> x;
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};
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cube <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">cube</span>(<span class="FunctionArgument">x</span>) {
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<span class="Keyword">return</span> square(x) <span class="Keyword">*</span> x;
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};
|
|
</pre><button onclick='javascript: var cube, square;
|
|
square = function square(x) {
|
|
return x * x;
|
|
};
|
|
cube = function cube(x) {
|
|
return square(x) * x;
|
|
};
|
|
;alert(cube(5));'>run: cube(5)</button><br class='clear' /></div>
|
|
<p>
|
|
If you'd like to create an anonymous function, just wrap it in parentheses:
|
|
<tt>((x) -> x * x)</tt>
|
|
</p>
|
|
|
|
<p id="assignment">
|
|
<b class="header">Assignment</b>
|
|
Use a colon <tt>:</tt> to assign, as in
|
|
<a href="http://json.org">JSON</a>. Equal signs are only needed for
|
|
mathy things. While colons are preferred, the two may be used interchangeably,
|
|
even within object literals.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">greeting</span><span class="Keyword">:</span> <span class="String"><span class="String">"</span>Hello CoffeeScript<span class="String">"</span></span>
|
|
<span class="FunctionName">difficulty</span><span class="Keyword">:</span> <span class="Number">0.5</span>
|
|
</pre><pre class="idle"><span class="Storage">var</span> difficulty, greeting;
|
|
greeting <span class="Keyword">=</span> <span class="String"><span class="String">"</span>Hello CoffeeScript<span class="String">"</span></span>;
|
|
difficulty <span class="Keyword">=</span> <span class="Number">0.5</span>;
|
|
</pre><button onclick='javascript: var difficulty, greeting;
|
|
greeting = "Hello CoffeeScript";
|
|
difficulty = 0.5;
|
|
;alert(greeting);'>run: greeting</button><br class='clear' /></div>
|
|
<p>
|
|
Declaration of new variables are pushed up to the top of the nearest
|
|
lexical scope, so that assignment may always be performed within expressions.
|
|
</p>
|
|
|
|
<p id="objects_and_arrays">
|
|
<b class="header">Objects and Arrays</b>
|
|
Object and Array literals look very similar to their JavaScript cousins.
|
|
When you spread out each assignment on a separate line, the commas are
|
|
optional. In this way, assigning object properties looks the same as
|
|
assigning local variables, and can be moved around freely. Feel free to mix
|
|
and match the two styles.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">song</span><span class="Keyword">:</span> [<span class="String"><span class="String">"</span>do<span class="String">"</span></span>, <span class="String"><span class="String">"</span>re<span class="String">"</span></span>, <span class="String"><span class="String">"</span>mi<span class="String">"</span></span>, <span class="String"><span class="String">"</span>fa<span class="String">"</span></span>, <span class="String"><span class="String">"</span>so<span class="String">"</span></span>]
|
|
|
|
<span class="FunctionName">ages</span><span class="Keyword">:</span> {
|
|
<span class="FunctionName">max</span><span class="Keyword">:</span> <span class="Number">10</span>
|
|
<span class="FunctionName">ida</span><span class="Keyword">:</span> <span class="Number">9</span>
|
|
<span class="FunctionName">tim</span><span class="Keyword">:</span> <span class="Number">11</span>
|
|
}
|
|
|
|
<span class="FunctionName">matrix</span><span class="Keyword">:</span> [
|
|
<span class="Number">1</span>, <span class="Number">0</span>, <span class="Number">1</span>
|
|
<span class="Number">0</span>, <span class="Number">0</span>, <span class="Number">1</span>
|
|
<span class="Number">1</span>, <span class="Number">1</span>, <span class="Number">0</span>
|
|
]
|
|
</pre><pre class="idle"><span class="Storage">var</span> ages, matrix, song;
|
|
song <span class="Keyword">=</span> [<span class="String"><span class="String">"</span>do<span class="String">"</span></span>, <span class="String"><span class="String">"</span>re<span class="String">"</span></span>, <span class="String"><span class="String">"</span>mi<span class="String">"</span></span>, <span class="String"><span class="String">"</span>fa<span class="String">"</span></span>, <span class="String"><span class="String">"</span>so<span class="String">"</span></span>];
|
|
ages <span class="Keyword">=</span> {
|
|
max: <span class="Number">10</span>,
|
|
ida: <span class="Number">9</span>,
|
|
tim: <span class="Number">11</span>
|
|
};
|
|
matrix <span class="Keyword">=</span> [<span class="Number">1</span>, <span class="Number">0</span>, <span class="Number">1</span>, <span class="Number">0</span>, <span class="Number">0</span>, <span class="Number">1</span>, <span class="Number">1</span>, <span class="Number">1</span>, <span class="Number">0</span>];
|
|
</pre><button onclick='javascript: var ages, matrix, song;
|
|
song = ["do", "re", "mi", "fa", "so"];
|
|
ages = {
|
|
max: 10,
|
|
ida: 9,
|
|
tim: 11
|
|
};
|
|
matrix = [1, 0, 1, 0, 0, 1, 1, 1, 0];
|
|
;alert(song.join(","));'>run: song.join(",")</button><br class='clear' /></div>
|
|
|
|
<p id="lexical_scope">
|
|
<b class="header">Lexical Scoping and Variable Safety</b>
|
|
The CoffeeScript compiler takes care to make sure that all of your variables
|
|
are properly declared within lexical scope — you never need to write
|
|
<tt>var</tt> yourself.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">num</span><span class="Keyword">:</span> <span class="Number">1</span>
|
|
<span class="FunctionName">change_numbers</span><span class="Keyword">:</span> <span class="Storage">-></span>
|
|
<span class="FunctionName">new_num</span><span class="Keyword">:</span> <span class="Keyword">-</span><span class="Number">1</span>
|
|
<span class="FunctionName">num</span><span class="Keyword">:</span> <span class="Number">10</span>
|
|
<span class="FunctionName">new_num</span><span class="Keyword">:</span> change_numbers()
|
|
</pre><pre class="idle"><span class="Storage">var</span> change_numbers, new_num, num;
|
|
num <span class="Keyword">=</span> <span class="Number">1</span>;
|
|
change_numbers <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">change_numbers</span>() {
|
|
<span class="Storage">var</span> new_num;
|
|
new_num <span class="Keyword">=</span> <span class="Keyword">-</span><span class="Number">1</span>;
|
|
<span class="Keyword">return</span> num <span class="Keyword">=</span> <span class="Number">10</span>;
|
|
};
|
|
new_num <span class="Keyword">=</span> change_numbers();
|
|
</pre><button onclick='javascript: var change_numbers, new_num, num;
|
|
num = 1;
|
|
change_numbers = function change_numbers() {
|
|
var new_num;
|
|
new_num = -1;
|
|
return num = 10;
|
|
};
|
|
new_num = change_numbers();
|
|
;alert(new_num);'>run: new_num</button><br class='clear' /></div>
|
|
<p>
|
|
Notice how the all of the variable declarations have been pushed up to
|
|
the top of the closest scope, the first time they appear.
|
|
<b>num</b> is not redeclared within the inner function, because it's
|
|
already in scope; the <b>new_num</b> within the function, on the other hand,
|
|
should not be able to change the value of the external variable of the same name, and
|
|
therefore has a declaration of its own.
|
|
</p>
|
|
<p>
|
|
Although suppressed within this documentation for clarity, all
|
|
CoffeeScript output is wrapped in an anonymous function:
|
|
<tt>(function(){ ... })();</tt> This safety wrapper, combined with the
|
|
automatic generation of the <tt>var</tt> keyword, make it exceedingly difficult
|
|
to pollute the global namespace by accident.
|
|
</p>
|
|
<p>
|
|
If you'd like to create top-level variables for other scripts to use,
|
|
attach them as properties on <b>window</b>, or on the <b>exports</b>
|
|
object in CommonJS. The <b>existential operator</b> (below), gives you a
|
|
reliable way to figure out where to add them, if you're targeting both
|
|
CommonJS and the browser: <tt>root: exports ? this</tt>
|
|
</p>
|
|
|
|
<p id="conditionals">
|
|
<b class="header">Conditionals, Ternaries, and Conditional Assignment</b>
|
|
<b>If/else</b> statements can be written without the use of parentheses and
|
|
curly brackets. As with functions and other block expressions,
|
|
multi-line conditionals are delimited by indentation. There's also a handy
|
|
postfix form, with the <tt>if</tt> or <tt>unless</tt> at the end.
|
|
</p>
|
|
<p>
|
|
CoffeeScript will compile <b>if</b> statements using the ternary operator
|
|
when possible, to make it easier to use the result as an expression.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">mood</span><span class="Keyword">:</span> greatly_improved <span class="Keyword">if</span> singing
|
|
|
|
<span class="Keyword">if</span> happy <span class="Keyword">and</span> knows_it
|
|
claps_hands()
|
|
cha_cha_cha()
|
|
|
|
<span class="FunctionName">date</span><span class="Keyword">:</span> <span class="Keyword">if</span> friday <span class="Keyword">then</span> sue <span class="Keyword">else</span> jill
|
|
|
|
expensive <span class="Keyword">||</span><span class="Keyword">=</span> do_the_math()
|
|
</pre><pre class="idle"><span class="Storage">var</span> date, expensive, mood;
|
|
<span class="Keyword">if</span> (singing) {
|
|
mood <span class="Keyword">=</span> greatly_improved;
|
|
}
|
|
<span class="Keyword">if</span> (happy <span class="Keyword">&</span><span class="Keyword">&</span> knows_it) {
|
|
claps_hands();
|
|
cha_cha_cha();
|
|
}
|
|
date <span class="Keyword">=</span> friday ? sue : jill;
|
|
expensive <span class="Keyword">=</span> expensive <span class="Keyword">||</span> do_the_math();
|
|
</pre><br class='clear' /></div>
|
|
<p>
|
|
The conditional assignment operators are included: <tt>||=</tt>,
|
|
which only assigns a value to a variable if the variable's current value
|
|
is falsy, and <tt>&&=</tt>, which only replaces the value of
|
|
truthy variables.
|
|
</p>
|
|
|
|
<p id="aliases">
|
|
<b class="header">Aliases</b>
|
|
Because the <tt>==</tt> operator frequently causes undesirable coercion,
|
|
is intransitive, and has a different meaning than in other languages,
|
|
CoffeeScript compiles <tt>==</tt> into <tt>===</tt>, and <tt>!=</tt> into
|
|
<tt>!==</tt>.
|
|
In addition, <tt>is</tt> compiles into <tt>===</tt>,
|
|
and <tt>isnt</tt> into <tt>!==</tt>.
|
|
</p>
|
|
<p>
|
|
You can use <tt>not</tt> as an alias for <tt>!</tt>.
|
|
</p>
|
|
<p>
|
|
For logic, <tt>and</tt> compiles to <tt>&&</tt>, and <tt>or</tt>
|
|
into <tt>||</tt>.
|
|
</p>
|
|
<p>
|
|
Instead of a newline or semicolon, <tt>then</tt> can be used to separate
|
|
conditions from expressions, in <b>while</b>,
|
|
<b>if</b>/<b>else</b>, and <b>switch</b>/<b>when</b> statements.
|
|
</p>
|
|
<p>
|
|
As in <a href="http://yaml.org/">YAML</a>, <tt>on</tt> and <tt>yes</tt>
|
|
are the same as boolean <tt>true</tt>, while <tt>off</tt> and <tt>no</tt> are boolean <tt>false</tt>.
|
|
</p>
|
|
<p>
|
|
For single-line statements, <tt>unless</tt> can be used as the inverse of <tt>if</tt>.
|
|
</p>
|
|
<p>
|
|
As a shortcut for <tt>this.property</tt>, you can use <tt>@property</tt>.
|
|
</p>
|
|
<div class='code'><pre class="idle">launch() <span class="Keyword">if</span> ignition <span class="Keyword">is</span> <span class="BuiltInConstant">on</span>
|
|
|
|
<span class="FunctionName">volume</span><span class="Keyword">:</span> <span class="Number">10</span> <span class="Keyword">if</span> band <span class="Keyword">isnt</span> spinal_tap
|
|
|
|
let_the_wild_rumpus_begin() <span class="Keyword">unless</span> answer <span class="Keyword">is</span> <span class="BuiltInConstant">no</span>
|
|
|
|
<span class="Keyword">if</span> car.speed <span class="Keyword"><</span> speed_limit <span class="Keyword">then</span> accelerate()
|
|
|
|
print <span class="String"><span class="String">"</span>My name is <span class="String">"</span></span> <span class="Keyword">+</span> <span class="Variable">@name</span>
|
|
</pre><pre class="idle"><span class="Storage">var</span> volume;
|
|
<span class="Keyword">if</span> (ignition <span class="Keyword">===</span> <span class="BuiltInConstant">true</span>) {
|
|
launch();
|
|
}
|
|
<span class="Keyword">if</span> (band <span class="Keyword">!</span><span class="Keyword">==</span> spinal_tap) {
|
|
volume <span class="Keyword">=</span> <span class="Number">10</span>;
|
|
}
|
|
<span class="Keyword">if</span> (<span class="Keyword">!</span>(answer <span class="Keyword">===</span> <span class="BuiltInConstant">false</span>)) {
|
|
let_the_wild_rumpus_begin();
|
|
}
|
|
car.speed <span class="Keyword"><</span> speed_limit ? accelerate() : <span class="BuiltInConstant">null</span>;
|
|
<span class="LibraryFunction">print</span>(<span class="String"><span class="String">"</span>My name is <span class="String">"</span></span> <span class="Keyword">+</span> <span class="Variable">this</span>.<span class="LibraryConstant">name</span>);
|
|
</pre><br class='clear' /></div>
|
|
|
|
<p id="splats">
|
|
<b class="header">Splats...</b>
|
|
The JavaScript <b>arguments object</b> is a useful way to work with
|
|
functions that accept variable numbers of arguments. CoffeeScript provides
|
|
splats <tt>...</tt>, both for function definition as well as invocation,
|
|
making variable numbers of arguments a little bit more palatable.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">gold</span><span class="Keyword">:</span> <span class="FunctionName">silver</span><span class="Keyword">:</span> <span class="FunctionName">the_field</span><span class="Keyword">:</span> <span class="String"><span class="String">"</span>unknown<span class="String">"</span></span>
|
|
|
|
<span class="FunctionName">award_medals</span><span class="Keyword">:</span> <span class="FunctionArgument">(</span><span class="FunctionArgument">first, second, rest...</span><span class="FunctionArgument">)</span> <span class="Storage">-></span>
|
|
<span class="FunctionName">gold</span><span class="Keyword">:</span> first
|
|
<span class="FunctionName">silver</span><span class="Keyword">:</span> second
|
|
<span class="FunctionName">the_field</span><span class="Keyword">:</span> rest
|
|
|
|
<span class="FunctionName">contenders</span><span class="Keyword">:</span> [
|
|
<span class="String"><span class="String">"</span>Michael Phelps<span class="String">"</span></span>
|
|
<span class="String"><span class="String">"</span>Liu Xiang<span class="String">"</span></span>
|
|
<span class="String"><span class="String">"</span>Yao Ming<span class="String">"</span></span>
|
|
<span class="String"><span class="String">"</span>Allyson Felix<span class="String">"</span></span>
|
|
<span class="String"><span class="String">"</span>Shawn Johnson<span class="String">"</span></span>
|
|
<span class="String"><span class="String">"</span>Roman Sebrle<span class="String">"</span></span>
|
|
<span class="String"><span class="String">"</span>Guo Jingjing<span class="String">"</span></span>
|
|
<span class="String"><span class="String">"</span>Tyson Gay<span class="String">"</span></span>
|
|
<span class="String"><span class="String">"</span>Asafa Powell<span class="String">"</span></span>
|
|
<span class="String"><span class="String">"</span>Usain Bolt<span class="String">"</span></span>
|
|
]
|
|
|
|
award_medals contenders...
|
|
|
|
alert <span class="String"><span class="String">"</span>Gold: <span class="String">"</span></span> <span class="Keyword">+</span> gold
|
|
alert <span class="String"><span class="String">"</span>Silver: <span class="String">"</span></span> <span class="Keyword">+</span> silver
|
|
alert <span class="String"><span class="String">"</span>The Field: <span class="String">"</span></span> <span class="Keyword">+</span> the_field
|
|
</pre><pre class="idle"><span class="Storage">var</span> award_medals, contenders, gold, silver, the_field;
|
|
gold <span class="Keyword">=</span> (silver <span class="Keyword">=</span> (the_field <span class="Keyword">=</span> <span class="String"><span class="String">"</span>unknown<span class="String">"</span></span>));
|
|
award_medals <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">award_medals</span>(<span class="FunctionArgument">first, second</span>) {
|
|
<span class="Storage">var</span> rest;
|
|
rest <span class="Keyword">=</span> <span class="LibraryClassType">Array</span>.<span class="LibraryConstant">prototype</span>.slice.<span class="LibraryFunction">call</span>(arguments, <span class="Number">2</span>);
|
|
gold <span class="Keyword">=</span> first;
|
|
silver <span class="Keyword">=</span> second;
|
|
<span class="Keyword">return</span> the_field <span class="Keyword">=</span> rest;
|
|
};
|
|
contenders <span class="Keyword">=</span> [<span class="String"><span class="String">"</span>Michael Phelps<span class="String">"</span></span>, <span class="String"><span class="String">"</span>Liu Xiang<span class="String">"</span></span>, <span class="String"><span class="String">"</span>Yao Ming<span class="String">"</span></span>, <span class="String"><span class="String">"</span>Allyson Felix<span class="String">"</span></span>, <span class="String"><span class="String">"</span>Shawn Johnson<span class="String">"</span></span>, <span class="String"><span class="String">"</span>Roman Sebrle<span class="String">"</span></span>, <span class="String"><span class="String">"</span>Guo Jingjing<span class="String">"</span></span>, <span class="String"><span class="String">"</span>Tyson Gay<span class="String">"</span></span>, <span class="String"><span class="String">"</span>Asafa Powell<span class="String">"</span></span>, <span class="String"><span class="String">"</span>Usain Bolt<span class="String">"</span></span>];
|
|
award_medals.<span class="LibraryFunction">apply</span>(<span class="Variable">this</span>, contenders);
|
|
<span class="LibraryFunction">alert</span>(<span class="String"><span class="String">"</span>Gold: <span class="String">"</span></span> <span class="Keyword">+</span> gold);
|
|
<span class="LibraryFunction">alert</span>(<span class="String"><span class="String">"</span>Silver: <span class="String">"</span></span> <span class="Keyword">+</span> silver);
|
|
<span class="LibraryFunction">alert</span>(<span class="String"><span class="String">"</span>The Field: <span class="String">"</span></span> <span class="Keyword">+</span> the_field);
|
|
</pre><button onclick='javascript: var award_medals, contenders, gold, silver, the_field;
|
|
gold = (silver = (the_field = "unknown"));
|
|
award_medals = function award_medals(first, second) {
|
|
var rest;
|
|
rest = Array.prototype.slice.call(arguments, 2);
|
|
gold = first;
|
|
silver = second;
|
|
return the_field = rest;
|
|
};
|
|
contenders = ["Michael Phelps", "Liu Xiang", "Yao Ming", "Allyson Felix", "Shawn Johnson", "Roman Sebrle", "Guo Jingjing", "Tyson Gay", "Asafa Powell", "Usain Bolt"];
|
|
award_medals.apply(this, contenders);
|
|
alert("Gold: " + gold);
|
|
alert("Silver: " + silver);
|
|
alert("The Field: " + the_field);
|
|
;'>run</button><br class='clear' /></div>
|
|
|
|
<p id="arguments">
|
|
<b class="header">Arguments are Arrays</b>
|
|
If you reference the <b>arguments object</b> directly, it will be converted
|
|
into a real Array, making all of the
|
|
<a href="https://developer.mozilla.org/En/Core_JavaScript_1.5_Reference/Objects/Array">Array methods</a>
|
|
available.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">backwards</span><span class="Keyword">:</span> <span class="Storage">-></span>
|
|
alert arguments.reverse()
|
|
|
|
backwards <span class="String"><span class="String">"</span>stairway<span class="String">"</span></span>, <span class="String"><span class="String">"</span>to<span class="String">"</span></span>, <span class="String"><span class="String">"</span>heaven<span class="String">"</span></span>
|
|
</pre><pre class="idle"><span class="Storage">var</span> backwards;
|
|
backwards <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">backwards</span>() {
|
|
<span class="Storage">var</span> arguments <span class="Keyword">=</span> <span class="LibraryClassType">Array</span>.<span class="LibraryConstant">prototype</span>.slice.<span class="LibraryFunction">call</span>(arguments, <span class="Number">0</span>);
|
|
<span class="Keyword">return</span> <span class="LibraryFunction">alert</span>(arguments.<span class="LibraryFunction">reverse</span>());
|
|
};
|
|
backwards(<span class="String"><span class="String">"</span>stairway<span class="String">"</span></span>, <span class="String"><span class="String">"</span>to<span class="String">"</span></span>, <span class="String"><span class="String">"</span>heaven<span class="String">"</span></span>);
|
|
</pre><button onclick='javascript: var backwards;
|
|
backwards = function backwards() {
|
|
var arguments = Array.prototype.slice.call(arguments, 0);
|
|
return alert(arguments.reverse());
|
|
};
|
|
backwards("stairway", "to", "heaven");
|
|
;'>run</button><br class='clear' /></div>
|
|
|
|
<p id="while">
|
|
<b class="header">While Loops</b>
|
|
The only low-level loop that CoffeeScript provides is the <b>while</b> loop. The
|
|
main difference from JavaScript is that the <b>while</b> loop can be used
|
|
as an expression, returning an array containing the result of each iteration
|
|
through the loop.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="Comment"><span class="Comment">#</span> Econ 101</span>
|
|
<span class="Keyword">if</span> <span class="Variable">this</span>.studying_economics
|
|
<span class="Keyword">while</span> supply <span class="Keyword">></span> demand <span class="Keyword">then</span> buy()
|
|
<span class="Keyword">while</span> supply <span class="Keyword"><</span> demand <span class="Keyword">then</span> sell()
|
|
|
|
<span class="Comment"><span class="Comment">#</span> Nursery Rhyme</span>
|
|
<span class="FunctionName">num</span><span class="Keyword">:</span> <span class="Number">6</span>
|
|
<span class="FunctionName">lyrics</span><span class="Keyword">:</span> <span class="Keyword">while</span> num <span class="Keyword">-</span><span class="Keyword">=</span> <span class="Number">1</span>
|
|
num <span class="Keyword">+</span> <span class="String"><span class="String">"</span> little monkeys, jumping on the bed.</span>
|
|
<span class="String"> One fell out and bumped his head.<span class="String">"</span></span>
|
|
</pre><pre class="idle"><span class="Storage">var</span> __a, lyrics, num;
|
|
<span class="Comment"><span class="Comment">//</span> Econ 101</span>
|
|
<span class="Keyword">if</span> (<span class="Variable">this</span>.studying_economics) {
|
|
<span class="Keyword">while</span> (supply <span class="Keyword">></span> demand) {
|
|
buy();
|
|
}
|
|
<span class="Keyword">while</span> (supply <span class="Keyword"><</span> demand) {
|
|
sell();
|
|
}
|
|
}
|
|
<span class="Comment"><span class="Comment">//</span> Nursery Rhyme</span>
|
|
num <span class="Keyword">=</span> <span class="Number">6</span>;
|
|
lyrics <span class="Keyword">=</span> (<span class="Storage">function</span>() {
|
|
__a <span class="Keyword">=</span> [];
|
|
<span class="Keyword">while</span> (num <span class="Keyword">-</span><span class="Keyword">=</span> <span class="Number">1</span>) {
|
|
__a.<span class="LibraryFunction">push</span>(num <span class="Keyword">+</span> <span class="String"><span class="String">"</span> little monkeys, jumping on the bed. \</span>
|
|
<span class="String">One fell out and bumped his head.<span class="String">"</span></span>);
|
|
}
|
|
<span class="Keyword">return</span> __a;
|
|
}).<span class="LibraryFunction">call</span>(<span class="Variable">this</span>);
|
|
</pre><button onclick='javascript: var __a, lyrics, num;
|
|
// Econ 101
|
|
if (this.studying_economics) {
|
|
while (supply > demand) {
|
|
buy();
|
|
}
|
|
while (supply < demand) {
|
|
sell();
|
|
}
|
|
}
|
|
// Nursery Rhyme
|
|
num = 6;
|
|
lyrics = (function() {
|
|
__a = [];
|
|
while (num -= 1) {
|
|
__a.push(num + " little monkeys, jumping on the bed. \
|
|
One fell out and bumped his head.");
|
|
}
|
|
return __a;
|
|
}).call(this);
|
|
;alert(lyrics.join("\n"));'>run: lyrics.join("\n")</button><br class='clear' /></div>
|
|
<p>
|
|
Other JavaScript loops, such as <b>for</b> loops and <b>do-while</b> loops
|
|
can be mimicked by variations on <b>while</b>, but the hope is that you
|
|
won't need to do that with CoffeeScript, either because you're using
|
|
<b>each</b> (<b>forEach</b>) style iterators, or...
|
|
</p>
|
|
|
|
<p id="comprehensions">
|
|
<b class="header">Comprehensions (Arrays, Objects, and Ranges)</b>
|
|
For your looping needs, CoffeeScript provides array comprehensions
|
|
similar to Python's. They replace (and compile into) <b>for</b> loops, with
|
|
optional guard clauses and the value of the current array index.
|
|
Unlike for loops, array comprehensions are expressions, and can be returned
|
|
and assigned. They should be able to handle most places where you otherwise
|
|
would use a loop, <b>each</b>/<b>forEach</b>, <b>map</b>, or <b>select</b>/<b>filter</b>.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="Comment"><span class="Comment">#</span> Eat lunch.</span>
|
|
<span class="FunctionName">lunch</span><span class="Keyword">:</span> eat(food) <span class="Keyword">for</span> food <span class="Keyword">in</span> [<span class="String"><span class="String">'</span>toast<span class="String">'</span></span>, <span class="String"><span class="String">'</span>cheese<span class="String">'</span></span>, <span class="String"><span class="String">'</span>wine<span class="String">'</span></span>]
|
|
|
|
<span class="Comment"><span class="Comment">#</span> Naive collision detection.</span>
|
|
<span class="Keyword">for</span> roid <span class="Keyword">in</span> asteroids
|
|
<span class="Keyword">for</span> roid2 <span class="Keyword">in</span> asteroids <span class="Keyword">when</span> roid <span class="Keyword">isnt</span> roid2
|
|
roid.explode() <span class="Keyword">if</span> roid.overlaps roid2
|
|
</pre><pre class="idle"><span class="Storage">var</span> __a, __b, __c, __d, __e, __f, __g, food, lunch, roid, roid2;
|
|
<span class="Comment"><span class="Comment">//</span> Eat lunch.</span>
|
|
lunch <span class="Keyword">=</span> (<span class="Storage">function</span>() {
|
|
__a <span class="Keyword">=</span> []; __b <span class="Keyword">=</span> [<span class="String"><span class="String">'</span>toast<span class="String">'</span></span>, <span class="String"><span class="String">'</span>cheese<span class="String">'</span></span>, <span class="String"><span class="String">'</span>wine<span class="String">'</span></span>];
|
|
<span class="Keyword">for</span> (__c <span class="Keyword">=</span> <span class="Number">0</span>; __c <span class="Keyword"><</span> __b.<span class="LibraryConstant">length</span>; __c<span class="Keyword">++</span>) {
|
|
food <span class="Keyword">=</span> __b[__c];
|
|
__a.<span class="LibraryFunction">push</span>(eat(food));
|
|
}
|
|
<span class="Keyword">return</span> __a;
|
|
}).<span class="LibraryFunction">call</span>(<span class="Variable">this</span>);
|
|
<span class="Comment"><span class="Comment">//</span> Naive collision detection.</span>
|
|
__d <span class="Keyword">=</span> asteroids;
|
|
<span class="Keyword">for</span> (__e <span class="Keyword">=</span> <span class="Number">0</span>; __e <span class="Keyword"><</span> __d.<span class="LibraryConstant">length</span>; __e<span class="Keyword">++</span>) {
|
|
roid <span class="Keyword">=</span> __d[__e];
|
|
__f <span class="Keyword">=</span> asteroids;
|
|
<span class="Keyword">for</span> (__g <span class="Keyword">=</span> <span class="Number">0</span>; __g <span class="Keyword"><</span> __f.<span class="LibraryConstant">length</span>; __g<span class="Keyword">++</span>) {
|
|
roid2 <span class="Keyword">=</span> __f[__g];
|
|
<span class="Keyword">if</span> (roid <span class="Keyword">!</span><span class="Keyword">==</span> roid2) {
|
|
<span class="Keyword">if</span> (roid.overlaps(roid2)) {
|
|
roid.explode();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
</pre><br class='clear' /></div>
|
|
<p>
|
|
If you know the start and end of your loop, or would like to step through
|
|
in fixed-size increments, you can use a range to specify the start and
|
|
end of your comprehension. (The long line-breaking "for" definitions in
|
|
the compiled JS below allow ranges to count downwards, as well as upwards).
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">countdown</span><span class="Keyword">:</span> num <span class="Keyword">for</span> num <span class="Keyword">in</span> [<span class="Number">10</span>..<span class="Number">1</span>]
|
|
|
|
<span class="FunctionName">egg_delivery</span><span class="Keyword">:</span> <span class="Storage">-></span>
|
|
<span class="Keyword">for</span> i <span class="Keyword">in</span> [<span class="Number">0</span>...eggs.length] <span class="Keyword">by</span> <span class="Number">12</span>
|
|
<span class="FunctionName">dozen_eggs</span><span class="Keyword">:</span> eggs[i...i<span class="Keyword">+</span><span class="Number">12</span>]
|
|
deliver <span class="Keyword">new</span> <span class="TypeName">egg_carton</span>(dozen)
|
|
</pre><pre class="idle"><span class="Storage">var</span> __a, __b, __c, __d, __e, countdown, egg_delivery, num;
|
|
countdown <span class="Keyword">=</span> (<span class="Storage">function</span>() {
|
|
__a <span class="Keyword">=</span> []; __d <span class="Keyword">=</span> <span class="Number">10</span>; __e <span class="Keyword">=</span> <span class="Number">1</span>;
|
|
<span class="Keyword">for</span> (__c<span class="Keyword">=</span><span class="Number">0</span>, num<span class="Keyword">=</span>__d; (__d <span class="Keyword"><=</span> __e ? num <span class="Keyword"><=</span> __e : num <span class="Keyword">>=</span> __e); (__d <span class="Keyword"><=</span> __e ? num <span class="Keyword">+</span><span class="Keyword">=</span> <span class="Number">1</span> : num <span class="Keyword">-</span><span class="Keyword">=</span> <span class="Number">1</span>), __c<span class="Keyword">++</span>) {
|
|
__a.<span class="LibraryFunction">push</span>(num);
|
|
}
|
|
<span class="Keyword">return</span> __a;
|
|
}).<span class="LibraryFunction">call</span>(<span class="Variable">this</span>);
|
|
egg_delivery <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">egg_delivery</span>() {
|
|
<span class="Storage">var</span> __f, __g, __h, __i, __j, dozen_eggs, i;
|
|
__f <span class="Keyword">=</span> []; __i <span class="Keyword">=</span> <span class="Number">0</span>; __j <span class="Keyword">=</span> eggs.<span class="LibraryConstant">length</span>;
|
|
<span class="Keyword">for</span> (__h<span class="Keyword">=</span><span class="Number">0</span>, i<span class="Keyword">=</span>__i; (__i <span class="Keyword"><=</span> __j ? i <span class="Keyword"><</span> __j : i <span class="Keyword">></span> __j); (__i <span class="Keyword"><=</span> __j ? i <span class="Keyword">+</span><span class="Keyword">=</span> <span class="Number">12</span> : i <span class="Keyword">-</span><span class="Keyword">=</span> <span class="Number">12</span>), __h<span class="Keyword">++</span>) {
|
|
__f.<span class="LibraryFunction">push</span>((<span class="Storage">function</span>() {
|
|
dozen_eggs <span class="Keyword">=</span> eggs.<span class="LibraryFunction">slice</span>(i, i <span class="Keyword">+</span> <span class="Number">12</span>);
|
|
<span class="Keyword">return</span> deliver(<span class="Keyword">new</span> <span class="TypeName">egg_carton</span>(dozen));
|
|
}).<span class="LibraryFunction">call</span>(<span class="Variable">this</span>));
|
|
}
|
|
<span class="Keyword">return</span> __f;
|
|
};
|
|
</pre><button onclick='javascript: var __a, __b, __c, __d, __e, countdown, egg_delivery, num;
|
|
countdown = (function() {
|
|
__a = []; __d = 10; __e = 1;
|
|
for (__c=0, num=__d; (__d <= __e ? num <= __e : num >= __e); (__d <= __e ? num += 1 : num -= 1), __c++) {
|
|
__a.push(num);
|
|
}
|
|
return __a;
|
|
}).call(this);
|
|
egg_delivery = function egg_delivery() {
|
|
var __f, __g, __h, __i, __j, dozen_eggs, i;
|
|
__f = []; __i = 0; __j = eggs.length;
|
|
for (__h=0, i=__i; (__i <= __j ? i < __j : i > __j); (__i <= __j ? i += 12 : i -= 12), __h++) {
|
|
__f.push((function() {
|
|
dozen_eggs = eggs.slice(i, i + 12);
|
|
return deliver(new egg_carton(dozen));
|
|
}).call(this));
|
|
}
|
|
return __f;
|
|
};
|
|
;alert(countdown);'>run: countdown</button><br class='clear' /></div>
|
|
<p>
|
|
Comprehensions can also be used to iterate over the keys and values in
|
|
an object. Use <tt>of</tt> to signal comprehension over the properties of
|
|
an object instead of the values in an array.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">years_old</span><span class="Keyword">:</span> {<span class="FunctionName">max</span><span class="Keyword">:</span> <span class="Number">10</span>, <span class="FunctionName">ida</span><span class="Keyword">:</span> <span class="Number">9</span>, <span class="FunctionName">tim</span><span class="Keyword">:</span> <span class="Number">11</span>}
|
|
|
|
<span class="FunctionName">ages</span><span class="Keyword">:</span> <span class="Keyword">for</span> child, age <span class="Keyword">of</span> years_old
|
|
child <span class="Keyword">+</span> <span class="String"><span class="String">"</span> is <span class="String">"</span></span> <span class="Keyword">+</span> age
|
|
</pre><pre class="idle"><span class="Storage">var</span> __a, __b, age, ages, child, years_old;
|
|
<span class="Storage">var</span> __hasProp <span class="Keyword">=</span> <span class="LibraryClassType">Object</span>.<span class="LibraryConstant">prototype</span>.hasOwnProperty;
|
|
years_old <span class="Keyword">=</span> {
|
|
max: <span class="Number">10</span>,
|
|
ida: <span class="Number">9</span>,
|
|
tim: <span class="Number">11</span>
|
|
};
|
|
ages <span class="Keyword">=</span> (<span class="Storage">function</span>() {
|
|
__a <span class="Keyword">=</span> []; __b <span class="Keyword">=</span> years_old;
|
|
<span class="Keyword">for</span> (child <span class="Keyword">in</span> __b) {
|
|
age <span class="Keyword">=</span> __b[child];
|
|
<span class="Keyword">if</span> (__hasProp.<span class="LibraryFunction">call</span>(__b, child)) {
|
|
__a.<span class="LibraryFunction">push</span>(child <span class="Keyword">+</span> <span class="String"><span class="String">"</span> is <span class="String">"</span></span> <span class="Keyword">+</span> age);
|
|
}
|
|
}
|
|
<span class="Keyword">return</span> __a;
|
|
}).<span class="LibraryFunction">call</span>(<span class="Variable">this</span>);
|
|
</pre><button onclick='javascript: var __a, __b, age, ages, child, years_old;
|
|
var __hasProp = Object.prototype.hasOwnProperty;
|
|
years_old = {
|
|
max: 10,
|
|
ida: 9,
|
|
tim: 11
|
|
};
|
|
ages = (function() {
|
|
__a = []; __b = years_old;
|
|
for (child in __b) {
|
|
age = __b[child];
|
|
if (__hasProp.call(__b, child)) {
|
|
__a.push(child + " is " + age);
|
|
}
|
|
}
|
|
return __a;
|
|
}).call(this);
|
|
;alert(ages.join(", "));'>run: ages.join(", ")</button><br class='clear' /></div>
|
|
|
|
<p id="slice_splice">
|
|
<b class="header">Array Slicing and Splicing with Ranges</b>
|
|
CoffeeScript borrows Ruby's
|
|
<a href="http://ruby-doc.org/core/classes/Range.html">range syntax</a>
|
|
for extracting slices of arrays. With two dots (<tt>3..5</tt>), the range
|
|
is inclusive: the first argument is the index of the first element in
|
|
the slice, and the second is the index of the last one. Three dots signify
|
|
a range that excludes the end.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">numbers</span><span class="Keyword">:</span> [<span class="Number">0</span>, <span class="Number">1</span>, <span class="Number">2</span>, <span class="Number">3</span>, <span class="Number">4</span>, <span class="Number">5</span>, <span class="Number">6</span>, <span class="Number">7</span>, <span class="Number">8</span>, <span class="Number">9</span>]
|
|
|
|
<span class="FunctionName">three_to_six</span><span class="Keyword">:</span> numbers[<span class="Number">3</span>..<span class="Number">6</span>]
|
|
|
|
<span class="FunctionName">numbers_copy</span><span class="Keyword">:</span> numbers[<span class="Number">0</span>...numbers.length]
|
|
|
|
</pre><pre class="idle"><span class="Storage">var</span> numbers, numbers_copy, three_to_six;
|
|
numbers <span class="Keyword">=</span> [<span class="Number">0</span>, <span class="Number">1</span>, <span class="Number">2</span>, <span class="Number">3</span>, <span class="Number">4</span>, <span class="Number">5</span>, <span class="Number">6</span>, <span class="Number">7</span>, <span class="Number">8</span>, <span class="Number">9</span>];
|
|
three_to_six <span class="Keyword">=</span> numbers.<span class="LibraryFunction">slice</span>(<span class="Number">3</span>, <span class="Number">6</span> <span class="Keyword">+</span> <span class="Number">1</span>);
|
|
numbers_copy <span class="Keyword">=</span> numbers.<span class="LibraryFunction">slice</span>(<span class="Number">0</span>, numbers.<span class="LibraryConstant">length</span>);
|
|
</pre><button onclick='javascript: var numbers, numbers_copy, three_to_six;
|
|
numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
|
|
three_to_six = numbers.slice(3, 6 + 1);
|
|
numbers_copy = numbers.slice(0, numbers.length);
|
|
;alert(numbers_copy);'>run: numbers_copy</button><br class='clear' /></div>
|
|
<p>
|
|
The same syntax can be used with assignment to replace a segment of an
|
|
array with new values (to splice it).
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">numbers</span><span class="Keyword">:</span> [<span class="Number">0</span>, <span class="Number">1</span>, <span class="Number">2</span>, <span class="Number">3</span>, <span class="Number">4</span>, <span class="Number">5</span>, <span class="Number">6</span>, <span class="Number">7</span>, <span class="Number">8</span>, <span class="Number">9</span>]
|
|
|
|
numbers[<span class="Number">3</span>..<span class="Number">6</span>]<span class="Keyword">:</span> [<span class="Keyword">-</span><span class="Number">3</span>, <span class="Keyword">-</span><span class="Number">4</span>, <span class="Keyword">-</span><span class="Number">5</span>, <span class="Keyword">-</span><span class="Number">6</span>]
|
|
|
|
|
|
</pre><pre class="idle"><span class="Storage">var</span> numbers;
|
|
numbers <span class="Keyword">=</span> [<span class="Number">0</span>, <span class="Number">1</span>, <span class="Number">2</span>, <span class="Number">3</span>, <span class="Number">4</span>, <span class="Number">5</span>, <span class="Number">6</span>, <span class="Number">7</span>, <span class="Number">8</span>, <span class="Number">9</span>];
|
|
numbers.splice.<span class="LibraryFunction">apply</span>(numbers, [<span class="Number">3</span>, <span class="Number">6</span> <span class="Keyword">-</span> <span class="Number">3</span> <span class="Keyword">+</span> <span class="Number">1</span>].<span class="LibraryFunction">concat</span>([<span class="Keyword">-</span><span class="Number">3</span>, <span class="Keyword">-</span><span class="Number">4</span>, <span class="Keyword">-</span><span class="Number">5</span>, <span class="Keyword">-</span><span class="Number">6</span>]));
|
|
</pre><button onclick='javascript: var numbers;
|
|
numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
|
|
numbers.splice.apply(numbers, [3, 6 - 3 + 1].concat([-3, -4, -5, -6]));
|
|
;alert(numbers);'>run: numbers</button><br class='clear' /></div>
|
|
|
|
<p id="expressions">
|
|
<b class="header">Everything is an Expression (at least, as much as possible)</b>
|
|
You might have noticed how even though we don't add return statements
|
|
to CoffeeScript functions, they nonetheless return their final value.
|
|
The CoffeeScript compiler tries to make sure that all statements in the
|
|
language can be used as expressions. Watch how the <tt>return</tt> gets
|
|
pushed down into each possible branch of execution, in the function
|
|
below.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">grade</span><span class="Keyword">:</span> <span class="FunctionArgument">(</span><span class="FunctionArgument">student</span><span class="FunctionArgument">)</span> <span class="Storage">-></span>
|
|
<span class="Keyword">if</span> student.excellent_work
|
|
<span class="String"><span class="String">"</span>A+<span class="String">"</span></span>
|
|
<span class="Keyword">else</span> <span class="Keyword">if</span> student.okay_stuff
|
|
<span class="Keyword">if</span> student.tried_hard <span class="Keyword">then</span> <span class="String"><span class="String">"</span>B<span class="String">"</span></span> <span class="Keyword">else</span> <span class="String"><span class="String">"</span>B-<span class="String">"</span></span>
|
|
<span class="Keyword">else</span>
|
|
<span class="String"><span class="String">"</span>C<span class="String">"</span></span>
|
|
|
|
<span class="FunctionName">eldest</span><span class="Keyword">:</span> <span class="Keyword">if</span> <span class="Number">24</span> <span class="Keyword">></span> <span class="Number">21</span> <span class="Keyword">then</span> <span class="String"><span class="String">"</span>Liz<span class="String">"</span></span> <span class="Keyword">else</span> <span class="String"><span class="String">"</span>Ike<span class="String">"</span></span>
|
|
</pre><pre class="idle"><span class="Storage">var</span> eldest, grade;
|
|
grade <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">grade</span>(<span class="FunctionArgument">student</span>) {
|
|
<span class="Keyword">if</span> (student.excellent_work) {
|
|
<span class="Keyword">return</span> <span class="String"><span class="String">"</span>A+<span class="String">"</span></span>;
|
|
} <span class="Keyword">else</span> <span class="Keyword">if</span> (student.okay_stuff) {
|
|
<span class="Keyword">return</span> student.tried_hard ? <span class="String"><span class="String">"</span>B<span class="String">"</span></span> : <span class="String"><span class="String">"</span>B-<span class="String">"</span></span>;
|
|
} <span class="Keyword">else</span> {
|
|
<span class="Keyword">return</span> <span class="String"><span class="String">"</span>C<span class="String">"</span></span>;
|
|
}
|
|
};
|
|
eldest <span class="Keyword">=</span> <span class="Number">24</span> <span class="Keyword">></span> <span class="Number">21</span> ? <span class="String"><span class="String">"</span>Liz<span class="String">"</span></span> : <span class="String"><span class="String">"</span>Ike<span class="String">"</span></span>;
|
|
</pre><button onclick='javascript: var eldest, grade;
|
|
grade = function grade(student) {
|
|
if (student.excellent_work) {
|
|
return "A+";
|
|
} else if (student.okay_stuff) {
|
|
return student.tried_hard ? "B" : "B-";
|
|
} else {
|
|
return "C";
|
|
}
|
|
};
|
|
eldest = 24 > 21 ? "Liz" : "Ike";
|
|
;alert(eldest);'>run: eldest</button><br class='clear' /></div>
|
|
<p>
|
|
Even though functions will always return their final value, it's both possible
|
|
and encouraged to return early from a function body writing out the explicit
|
|
return (<tt>return value</tt>), when you know that you're done.
|
|
</p>
|
|
<p>
|
|
Because variable declarations occur at the top of scope, assignment can
|
|
be used within expressions, even for variables that haven't been seen before:
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">six</span><span class="Keyword">:</span> (<span class="FunctionName">one</span><span class="Keyword">:</span> <span class="Number">1</span>) <span class="Keyword">+</span> (<span class="FunctionName">two</span><span class="Keyword">:</span> <span class="Number">2</span>) <span class="Keyword">+</span> (<span class="FunctionName">three</span><span class="Keyword">:</span> <span class="Number">3</span>)
|
|
</pre><pre class="idle"><span class="Storage">var</span> one, six, three, two;
|
|
six <span class="Keyword">=</span> ((one <span class="Keyword">=</span> <span class="Number">1</span>)) <span class="Keyword">+</span> ((two <span class="Keyword">=</span> <span class="Number">2</span>)) <span class="Keyword">+</span> ((three <span class="Keyword">=</span> <span class="Number">3</span>));
|
|
</pre><button onclick='javascript: var one, six, three, two;
|
|
six = ((one = 1)) + ((two = 2)) + ((three = 3));
|
|
;alert(six);'>run: six</button><br class='clear' /></div>
|
|
<p>
|
|
Things that would otherwise be statements in JavaScript, when used
|
|
as part of an expression in CoffeeScript, are converted into expressions
|
|
by wrapping them in a closure. This lets you do useful things, like assign
|
|
the result of a comprehension to a variable:
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="Comment"><span class="Comment">#</span> The first ten global properties.</span>
|
|
|
|
<span class="FunctionName">globals</span><span class="Keyword">:</span> (name <span class="Keyword">for</span> name <span class="Keyword">of</span> window)[<span class="Number">0</span>...<span class="Number">10</span>]
|
|
</pre><pre class="idle"><span class="Storage">var</span> __a, __b, globals, name;
|
|
<span class="Storage">var</span> __hasProp <span class="Keyword">=</span> <span class="LibraryClassType">Object</span>.<span class="LibraryConstant">prototype</span>.hasOwnProperty;
|
|
<span class="Comment"><span class="Comment">//</span> The first ten global properties.</span>
|
|
globals <span class="Keyword">=</span> ((<span class="Storage">function</span>() {
|
|
__a <span class="Keyword">=</span> []; __b <span class="Keyword">=</span> <span class="LibraryClassType">window</span>;
|
|
<span class="Keyword">for</span> (name <span class="Keyword">in</span> __b) {
|
|
<span class="Keyword">if</span> (__hasProp.<span class="LibraryFunction">call</span>(__b, name)) {
|
|
__a.<span class="LibraryFunction">push</span>(name);
|
|
}
|
|
}
|
|
<span class="Keyword">return</span> __a;
|
|
}).<span class="LibraryFunction">call</span>(<span class="Variable">this</span>)).<span class="LibraryFunction">slice</span>(<span class="Number">0</span>, <span class="Number">10</span>);
|
|
</pre><button onclick='javascript: var __a, __b, globals, name;
|
|
var __hasProp = Object.prototype.hasOwnProperty;
|
|
// The first ten global properties.
|
|
globals = ((function() {
|
|
__a = []; __b = window;
|
|
for (name in __b) {
|
|
if (__hasProp.call(__b, name)) {
|
|
__a.push(name);
|
|
}
|
|
}
|
|
return __a;
|
|
}).call(this)).slice(0, 10);
|
|
;alert(globals);'>run: globals</button><br class='clear' /></div>
|
|
<p>
|
|
As well as silly things, like passing a <b>try/catch</b> statement directly
|
|
into a function call:
|
|
</p>
|
|
<div class='code'><pre class="idle">alert(
|
|
<span class="Keyword">try</span>
|
|
nonexistent <span class="Keyword">/</span> <span class="BuiltInConstant">undefined</span>
|
|
<span class="Keyword">catch</span> error
|
|
<span class="String"><span class="String">"</span>And the error is ... <span class="String">"</span></span> <span class="Keyword">+</span> error
|
|
)
|
|
</pre><pre class="idle"><span class="LibraryFunction">alert</span>((<span class="Storage">function</span>() {
|
|
<span class="Keyword">try</span> {
|
|
<span class="Keyword">return</span> nonexistent / undefined;
|
|
} <span class="Keyword">catch</span> (error) {
|
|
<span class="Keyword">return</span> <span class="String"><span class="String">"</span>And the error is ... <span class="String">"</span></span> <span class="Keyword">+</span> error;
|
|
}
|
|
}).<span class="LibraryFunction">call</span>(<span class="Variable">this</span>));
|
|
</pre><button onclick='javascript: alert((function() {
|
|
try {
|
|
return nonexistent / undefined;
|
|
} catch (error) {
|
|
return "And the error is ... " + error;
|
|
}
|
|
}).call(this));
|
|
;'>run</button><br class='clear' /></div>
|
|
<p>
|
|
There are a handful of statements in JavaScript that can't be meaningfully
|
|
converted into expressions, namely <tt>break</tt>, <tt>continue</tt>,
|
|
and <tt>return</tt>. If you make use of them within a block of code,
|
|
CoffeeScript won't try to perform the conversion.
|
|
</p>
|
|
|
|
<p id="existence">
|
|
<b class="header">The Existential Operator</b>
|
|
It's a little difficult to check for the existence of a variable in
|
|
JavaScript. <tt>if (variable) ...</tt> comes close, but fails for zero,
|
|
the empty string, and false. CoffeeScript's existential operator <tt>?</tt> returns true unless
|
|
a variable is <b>null</b> or <b>undefined</b>, which makes it analogous
|
|
to Ruby's <tt>nil?</tt>
|
|
</p>
|
|
<p>
|
|
It can also be used for safer conditional assignment than <tt>||=</tt>
|
|
provides, for cases where you may be handling numbers or strings.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">solipsism</span><span class="Keyword">:</span> <span class="BuiltInConstant">true</span> <span class="Keyword">if</span> mind<span class="Keyword">?</span> <span class="Keyword">and</span> <span class="Keyword">not</span> world<span class="Keyword">?</span>
|
|
|
|
speed <span class="Keyword">?</span><span class="Keyword">=</span> <span class="Number">140</span>
|
|
|
|
|
|
|
|
|
|
|
|
</pre><pre class="idle"><span class="Storage">var</span> solipsism, speed;
|
|
<span class="Keyword">if</span> ((<span class="Keyword">typeof</span> mind <span class="Keyword">!</span><span class="Keyword">==</span> <span class="String"><span class="String">"</span>undefined<span class="String">"</span></span> <span class="Keyword">&</span><span class="Keyword">&</span> mind <span class="Keyword">!</span><span class="Keyword">==</span> <span class="BuiltInConstant">null</span>) <span class="Keyword">&</span><span class="Keyword">&</span> <span class="Keyword">!</span>(<span class="Keyword">typeof</span> world <span class="Keyword">!</span><span class="Keyword">==</span> <span class="String"><span class="String">"</span>undefined<span class="String">"</span></span> <span class="Keyword">&</span><span class="Keyword">&</span> world <span class="Keyword">!</span><span class="Keyword">==</span> <span class="BuiltInConstant">null</span>)) {
|
|
solipsism <span class="Keyword">=</span> <span class="BuiltInConstant">true</span>;
|
|
}
|
|
speed <span class="Keyword">=</span> (<span class="Keyword">typeof</span> speed <span class="Keyword">!</span><span class="Keyword">==</span> <span class="String"><span class="String">"</span>undefined<span class="String">"</span></span> <span class="Keyword">&</span><span class="Keyword">&</span> speed <span class="Keyword">!</span><span class="Keyword">==</span> <span class="BuiltInConstant">null</span>) ? speed : <span class="Number">140</span>;
|
|
</pre><button onclick='javascript: var solipsism, speed;
|
|
if ((typeof mind !== "undefined" && mind !== null) && !(typeof world !== "undefined" && world !== null)) {
|
|
solipsism = true;
|
|
}
|
|
speed = (typeof speed !== "undefined" && speed !== null) ? speed : 140;
|
|
;alert(speed);'>run: speed</button><br class='clear' /></div>
|
|
<p>
|
|
The accessor variant of the existential operator <tt>?.</tt> can be used to soak
|
|
up null references in a chain of properties. Use it instead
|
|
of the dot accessor <tt>.</tt> in cases where the base value may be <b>null</b>
|
|
or <b>undefined</b>. If all of the properties exist then you'll get the expected
|
|
result, if the chain is broken, <b>undefined</b> is returned instead of
|
|
the <b>TypeError</b> that would be raised otherwise.
|
|
</p>
|
|
<div class='code'><pre class="idle">lottery.draw_winner()<span class="Keyword">?</span>.address<span class="Keyword">?</span>.zipcode
|
|
</pre><pre class="idle"><span class="Storage">var</span> __a;
|
|
((__a <span class="Keyword">=</span> lottery.draw_winner()) <span class="Keyword">==</span> undefined ? undefined : __a.address <span class="Keyword">==</span> undefined ? undefined : __a.address.zipcode);
|
|
</pre><br class='clear' /></div>
|
|
<p>
|
|
Soaking up nulls is similar to Ruby's
|
|
<a href="http://andand.rubyforge.org/">andand gem</a>, and to the
|
|
<a href="http://groovy.codehaus.org/Operators#Operators-SafeNavigationOperator%28%3F.%29">safe navigation operator</a>
|
|
in Groovy.
|
|
</p>
|
|
|
|
<p id="inheritance">
|
|
<b class="header">Inheritance, and Calling Super from a Subclass</b>
|
|
JavaScript's prototypal inheritance has always been a bit of a
|
|
brain-bender, with a whole family tree of libraries that provide a cleaner
|
|
syntax for classical inheritance on top of JavaScript's prototypes:
|
|
<a href="http://code.google.com/p/base2/">Base2</a>,
|
|
<a href="http://prototypejs.org/">Prototype.js</a>,
|
|
<a href="http://jsclass.jcoglan.com/">JS.Class</a>, etc.
|
|
The libraries provide syntactic sugar, but the built-in inheritance would
|
|
be completely usable if it weren't for a couple of small exceptions:
|
|
it's awkward to call <b>super</b> (the prototype object's
|
|
implementation of the current function), and it's awkward to correctly
|
|
set the prototype chain.
|
|
</p>
|
|
<p>
|
|
CoffeeScript provides <tt>extends</tt>
|
|
to help with prototype setup, <tt>::</tt> for quick access to an
|
|
object's prototype, and converts <tt>super()</tt> into a call against
|
|
the immediate ancestor's method of the same name.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">Animal</span><span class="Keyword">:</span> <span class="Storage">-></span>
|
|
|
|
<span class="FunctionName">Animal::move</span><span class="Keyword">:</span> <span class="FunctionArgument">(</span><span class="FunctionArgument">meters</span><span class="FunctionArgument">)</span> <span class="Storage">-></span>
|
|
alert <span class="Variable">@name</span> <span class="Keyword">+</span> <span class="String"><span class="String">"</span> moved <span class="String">"</span></span> <span class="Keyword">+</span> meters <span class="Keyword">+</span> <span class="String"><span class="String">"</span>m.<span class="String">"</span></span>
|
|
|
|
<span class="FunctionName">Snake</span><span class="Keyword">:</span> <span class="FunctionArgument">(</span><span class="FunctionArgument">name</span><span class="FunctionArgument">)</span> <span class="Storage">-></span>
|
|
<span class="Variable">@name</span><span class="Keyword">:</span> name
|
|
<span class="Variable">this</span>
|
|
|
|
Snake <span class="Variable">extends</span> Animal
|
|
|
|
<span class="FunctionName">Snake::move</span><span class="Keyword">:</span> <span class="Storage">-></span>
|
|
alert <span class="String"><span class="String">"</span>Slithering...<span class="String">"</span></span>
|
|
<span class="Variable">super</span> <span class="Number">5</span>
|
|
|
|
<span class="FunctionName">Horse</span><span class="Keyword">:</span> <span class="FunctionArgument">(</span><span class="FunctionArgument">name</span><span class="FunctionArgument">)</span> <span class="Storage">-></span>
|
|
<span class="Variable">@name</span><span class="Keyword">:</span> name
|
|
<span class="Variable">this</span>
|
|
|
|
Horse <span class="Variable">extends</span> Animal
|
|
|
|
<span class="FunctionName">Horse::move</span><span class="Keyword">:</span> <span class="Storage">-></span>
|
|
alert <span class="String"><span class="String">"</span>Galloping...<span class="String">"</span></span>
|
|
<span class="Variable">super</span> <span class="Number">45</span>
|
|
|
|
<span class="FunctionName">sam</span><span class="Keyword">:</span> <span class="Keyword">new</span> <span class="TypeName">Snake</span> <span class="String"><span class="String">"</span>Sammy the Python<span class="String">"</span></span>
|
|
<span class="FunctionName">tom</span><span class="Keyword">:</span> <span class="Keyword">new</span> <span class="TypeName">Horse</span> <span class="String"><span class="String">"</span>Tommy the Palomino<span class="String">"</span></span>
|
|
|
|
sam.move()
|
|
tom.move()
|
|
|
|
|
|
|
|
|
|
</pre><pre class="idle"><span class="Storage">var</span> Animal, Horse, Snake, __a, __b, sam, tom;
|
|
Animal <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">Animal</span>() { };
|
|
<span class="LibraryClassType">Animal</span>.<span class="LibraryConstant">prototype</span>.<span class="FunctionName">move</span> = <span class="Storage">function</span> <span class="FunctionName">move</span>(<span class="FunctionArgument">meters</span>) {
|
|
<span class="Keyword">return</span> <span class="LibraryFunction">alert</span>(<span class="Variable">this</span>.<span class="LibraryConstant">name</span> <span class="Keyword">+</span> <span class="String"><span class="String">"</span> moved <span class="String">"</span></span> <span class="Keyword">+</span> meters <span class="Keyword">+</span> <span class="String"><span class="String">"</span>m.<span class="String">"</span></span>);
|
|
};
|
|
Snake <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">Snake</span>(<span class="FunctionArgument">name</span>) {
|
|
<span class="Variable">this</span>.<span class="LibraryConstant">name</span> <span class="Keyword">=</span> name;
|
|
<span class="Keyword">return</span> <span class="Variable">this</span>;
|
|
};
|
|
<span class="FunctionName">__a</span> = <span class="Storage">function</span>(){};
|
|
<span class="LibraryClassType">__a</span>.<span class="LibraryConstant">prototype</span> = Animal.<span class="LibraryConstant">prototype</span>;
|
|
Snake.__superClass__ <span class="Keyword">=</span> Animal.<span class="LibraryConstant">prototype</span>;
|
|
<span class="LibraryClassType">Snake</span>.<span class="LibraryConstant">prototype</span> = <span class="Keyword">new</span> <span class="TypeName">__a</span>();
|
|
<span class="LibraryClassType">Snake</span>.<span class="LibraryConstant">prototype</span>.<span class="FunctionName">constructor</span> = Snake;
|
|
<span class="LibraryClassType">Snake</span>.<span class="LibraryConstant">prototype</span>.<span class="FunctionName">move</span> = <span class="Storage">function</span> <span class="FunctionName">move</span>() {
|
|
<span class="LibraryFunction">alert</span>(<span class="String"><span class="String">"</span>Slithering...<span class="String">"</span></span>);
|
|
<span class="Keyword">return</span> Snake.__superClass__.move.<span class="LibraryFunction">call</span>(<span class="Variable">this</span>, <span class="Number">5</span>);
|
|
};
|
|
Horse <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">Horse</span>(<span class="FunctionArgument">name</span>) {
|
|
<span class="Variable">this</span>.<span class="LibraryConstant">name</span> <span class="Keyword">=</span> name;
|
|
<span class="Keyword">return</span> <span class="Variable">this</span>;
|
|
};
|
|
<span class="FunctionName">__b</span> = <span class="Storage">function</span>(){};
|
|
<span class="LibraryClassType">__b</span>.<span class="LibraryConstant">prototype</span> = Animal.<span class="LibraryConstant">prototype</span>;
|
|
Horse.__superClass__ <span class="Keyword">=</span> Animal.<span class="LibraryConstant">prototype</span>;
|
|
<span class="LibraryClassType">Horse</span>.<span class="LibraryConstant">prototype</span> = <span class="Keyword">new</span> <span class="TypeName">__b</span>();
|
|
<span class="LibraryClassType">Horse</span>.<span class="LibraryConstant">prototype</span>.<span class="FunctionName">constructor</span> = Horse;
|
|
<span class="LibraryClassType">Horse</span>.<span class="LibraryConstant">prototype</span>.<span class="FunctionName">move</span> = <span class="Storage">function</span> <span class="FunctionName">move</span>() {
|
|
<span class="LibraryFunction">alert</span>(<span class="String"><span class="String">"</span>Galloping...<span class="String">"</span></span>);
|
|
<span class="Keyword">return</span> Horse.__superClass__.move.<span class="LibraryFunction">call</span>(<span class="Variable">this</span>, <span class="Number">45</span>);
|
|
};
|
|
sam <span class="Keyword">=</span> <span class="Keyword">new</span> <span class="TypeName">Snake</span>(<span class="String"><span class="String">"</span>Sammy the Python<span class="String">"</span></span>);
|
|
tom <span class="Keyword">=</span> <span class="Keyword">new</span> <span class="TypeName">Horse</span>(<span class="String"><span class="String">"</span>Tommy the Palomino<span class="String">"</span></span>);
|
|
sam.move();
|
|
tom.move();
|
|
</pre><button onclick='javascript: var Animal, Horse, Snake, __a, __b, sam, tom;
|
|
Animal = function Animal() { };
|
|
Animal.prototype.move = function move(meters) {
|
|
return alert(this.name + " moved " + meters + "m.");
|
|
};
|
|
Snake = function Snake(name) {
|
|
this.name = name;
|
|
return this;
|
|
};
|
|
__a = function(){};
|
|
__a.prototype = Animal.prototype;
|
|
Snake.__superClass__ = Animal.prototype;
|
|
Snake.prototype = new __a();
|
|
Snake.prototype.constructor = Snake;
|
|
Snake.prototype.move = function move() {
|
|
alert("Slithering...");
|
|
return Snake.__superClass__.move.call(this, 5);
|
|
};
|
|
Horse = function Horse(name) {
|
|
this.name = name;
|
|
return this;
|
|
};
|
|
__b = function(){};
|
|
__b.prototype = Animal.prototype;
|
|
Horse.__superClass__ = Animal.prototype;
|
|
Horse.prototype = new __b();
|
|
Horse.prototype.constructor = Horse;
|
|
Horse.prototype.move = function move() {
|
|
alert("Galloping...");
|
|
return Horse.__superClass__.move.call(this, 45);
|
|
};
|
|
sam = new Snake("Sammy the Python");
|
|
tom = new Horse("Tommy the Palomino");
|
|
sam.move();
|
|
tom.move();
|
|
;'>run</button><br class='clear' /></div>
|
|
|
|
<p id="pattern_matching">
|
|
<b class="header">Pattern Matching (Destructuring Assignment)</b>
|
|
To make extracting values from complex arrays and objects more convenient,
|
|
CoffeeScript implements ECMAScript Harmony's proposed
|
|
<a href="http://wiki.ecmascript.org/doku.php?id=harmony:destructuring">destructuring assignment</a>
|
|
syntax. When you assign an array or object literal to a value, CoffeeScript
|
|
breaks up and matches both sides against each other, assigning the values
|
|
on the right to the variables on the left. In the simplest case, it can be
|
|
used for parallel assignment:
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">bait</span><span class="Keyword">:</span> <span class="Number">1000</span>
|
|
<span class="FunctionName">and_switch</span><span class="Keyword">:</span> <span class="Number">0</span>
|
|
|
|
[bait, and_switch]<span class="Keyword">:</span> [and_switch, bait]
|
|
</pre><pre class="idle"><span class="Storage">var</span> __a, and_switch, bait;
|
|
bait <span class="Keyword">=</span> <span class="Number">1000</span>;
|
|
and_switch <span class="Keyword">=</span> <span class="Number">0</span>;
|
|
__a <span class="Keyword">=</span> [and_switch, bait];
|
|
bait <span class="Keyword">=</span> __a[<span class="Number">0</span>];
|
|
and_switch <span class="Keyword">=</span> __a[<span class="Number">1</span>];
|
|
</pre><button onclick='javascript: var __a, and_switch, bait;
|
|
bait = 1000;
|
|
and_switch = 0;
|
|
__a = [and_switch, bait];
|
|
bait = __a[0];
|
|
and_switch = __a[1];
|
|
;alert(bait);'>run: bait</button><br class='clear' /></div>
|
|
<p>
|
|
But it's also helpful for dealing with functions that return multiple
|
|
values.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">weather_report</span><span class="Keyword">:</span> <span class="FunctionArgument">(</span><span class="FunctionArgument">location</span><span class="FunctionArgument">)</span> <span class="Storage">-></span>
|
|
<span class="Comment"><span class="Comment">#</span> Make an Ajax request to fetch the weather...</span>
|
|
[location, <span class="Number">72</span>, <span class="String"><span class="String">"</span>Mostly Sunny<span class="String">"</span></span>]
|
|
|
|
[city, temp, forecast]<span class="Keyword">:</span> weather_report <span class="String"><span class="String">"</span>Berkeley, CA<span class="String">"</span></span>
|
|
</pre><pre class="idle"><span class="Storage">var</span> __a, city, forecast, temp, weather_report;
|
|
weather_report <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">weather_report</span>(<span class="FunctionArgument">location</span>) {
|
|
<span class="Comment"><span class="Comment">//</span> Make an Ajax request to fetch the weather...</span>
|
|
<span class="Keyword">return</span> [location, <span class="Number">72</span>, <span class="String"><span class="String">"</span>Mostly Sunny<span class="String">"</span></span>];
|
|
};
|
|
__a <span class="Keyword">=</span> weather_report(<span class="String"><span class="String">"</span>Berkeley, CA<span class="String">"</span></span>);
|
|
city <span class="Keyword">=</span> __a[<span class="Number">0</span>];
|
|
temp <span class="Keyword">=</span> __a[<span class="Number">1</span>];
|
|
forecast <span class="Keyword">=</span> __a[<span class="Number">2</span>];
|
|
</pre><button onclick='javascript: var __a, city, forecast, temp, weather_report;
|
|
weather_report = function weather_report(location) {
|
|
// Make an Ajax request to fetch the weather...
|
|
return [location, 72, "Mostly Sunny"];
|
|
};
|
|
__a = weather_report("Berkeley, CA");
|
|
city = __a[0];
|
|
temp = __a[1];
|
|
forecast = __a[2];
|
|
;alert(forecast);'>run: forecast</button><br class='clear' /></div>
|
|
<p>
|
|
Pattern matching can be used with any depth of array and object nesting,
|
|
to help pull out deeply nested properties.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">futurists</span><span class="Keyword">:</span> {
|
|
<span class="FunctionName">sculptor</span><span class="Keyword">:</span> <span class="String"><span class="String">"</span>Umberto Boccioni<span class="String">"</span></span>
|
|
<span class="FunctionName">painter</span><span class="Keyword">:</span> <span class="String"><span class="String">"</span>Vladimir Burliuk<span class="String">"</span></span>
|
|
<span class="FunctionName">poet</span><span class="Keyword">:</span> {
|
|
<span class="FunctionName">name</span><span class="Keyword">:</span> <span class="String"><span class="String">"</span>F.T. Marinetti<span class="String">"</span></span>
|
|
<span class="FunctionName">address</span><span class="Keyword">:</span> [
|
|
<span class="String"><span class="String">"</span>Via Roma 42R<span class="String">"</span></span>
|
|
<span class="String"><span class="String">"</span>Bellagio, Italy 22021<span class="String">"</span></span>
|
|
]
|
|
}
|
|
}
|
|
|
|
{<span class="FunctionName">poet</span><span class="Keyword">:</span> {<span class="FunctionName">name</span><span class="Keyword">:</span> poet, <span class="FunctionName">address</span><span class="Keyword">:</span> [street, city]}}<span class="Keyword">:</span> futurists
|
|
</pre><pre class="idle"><span class="Storage">var</span> __a, __b, __c, city, futurists, poet, street;
|
|
futurists <span class="Keyword">=</span> {
|
|
sculptor: <span class="String"><span class="String">"</span>Umberto Boccioni<span class="String">"</span></span>,
|
|
painter: <span class="String"><span class="String">"</span>Vladimir Burliuk<span class="String">"</span></span>,
|
|
poet: {
|
|
name: <span class="String"><span class="String">"</span>F.T. Marinetti<span class="String">"</span></span>,
|
|
address: [<span class="String"><span class="String">"</span>Via Roma 42R<span class="String">"</span></span>, <span class="String"><span class="String">"</span>Bellagio, Italy 22021<span class="String">"</span></span>]
|
|
}
|
|
};
|
|
__a <span class="Keyword">=</span> futurists;
|
|
__b <span class="Keyword">=</span> __a.poet;
|
|
poet <span class="Keyword">=</span> __b.<span class="LibraryConstant">name</span>;
|
|
__c <span class="Keyword">=</span> __b.address;
|
|
street <span class="Keyword">=</span> __c[<span class="Number">0</span>];
|
|
city <span class="Keyword">=</span> __c[<span class="Number">1</span>];
|
|
</pre><button onclick='javascript: var __a, __b, __c, city, futurists, poet, street;
|
|
futurists = {
|
|
sculptor: "Umberto Boccioni",
|
|
painter: "Vladimir Burliuk",
|
|
poet: {
|
|
name: "F.T. Marinetti",
|
|
address: ["Via Roma 42R", "Bellagio, Italy 22021"]
|
|
}
|
|
};
|
|
__a = futurists;
|
|
__b = __a.poet;
|
|
poet = __b.name;
|
|
__c = __b.address;
|
|
street = __c[0];
|
|
city = __c[1];
|
|
;alert(poet + " — " + street);'>run: poet + " — " + street</button><br class='clear' /></div>
|
|
|
|
<p id="fat_arrow">
|
|
<b class="header">Function binding</b>
|
|
The fat arrow <tt>=></tt> can be used to both define a function, and to bind
|
|
it to the current value of <tt>this</tt>, right on the spot. This is helpful
|
|
when using callback-based libraries like Prototype or jQuery, for creating
|
|
iterator functions to pass to <tt>each</tt>, or event-handler functions
|
|
to use with <tt>bind</tt>. Functions created with the fat arrow are able to access
|
|
properties of the <tt>this</tt> where they're defined.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">Account</span><span class="Keyword">:</span> <span class="FunctionArgument">(</span><span class="FunctionArgument">customer, cart</span><span class="FunctionArgument">)</span> <span class="Storage">-></span>
|
|
<span class="Variable">@customer</span><span class="Keyword">:</span> customer
|
|
<span class="Variable">@cart</span><span class="Keyword">:</span> cart
|
|
|
|
$(<span class="String"><span class="String">'</span>.shopping_cart<span class="String">'</span></span>).bind <span class="String"><span class="String">'</span>click<span class="String">'</span></span>, <span class="FunctionArgument">(</span><span class="FunctionArgument">event</span><span class="FunctionArgument">)</span> <span class="Storage">=></span>
|
|
<span class="Variable">@customer</span>.purchase <span class="Variable">@cart</span>
|
|
</pre><pre class="idle"><span class="Storage">var</span> Account;
|
|
Account <span class="Keyword">=</span> <span class="Storage">function</span> <span class="FunctionName">Account</span>(<span class="FunctionArgument">customer, cart</span>) {
|
|
<span class="Variable">this</span>.customer <span class="Keyword">=</span> customer;
|
|
<span class="Variable">this</span>.cart <span class="Keyword">=</span> cart;
|
|
<span class="Keyword">return</span> <span class="Keyword">$</span>(<span class="String"><span class="String">'</span>.shopping_cart<span class="String">'</span></span>).bind(<span class="String"><span class="String">'</span>click<span class="String">'</span></span>, (<span class="Storage">function</span>(__this) {
|
|
<span class="Storage">var</span> <span class="FunctionName">__func</span> = <span class="Storage">function</span>(<span class="FunctionArgument">event</span>) {
|
|
<span class="Keyword">return</span> <span class="Variable">this</span>.customer.purchase(<span class="Variable">this</span>.cart);
|
|
};
|
|
<span class="Keyword">return</span> (<span class="Storage">function</span>() {
|
|
<span class="Keyword">return</span> __func.<span class="LibraryFunction">apply</span>(__this, arguments);
|
|
});
|
|
})(<span class="Variable">this</span>));
|
|
};
|
|
</pre><br class='clear' /></div>
|
|
|
|
<p id="embedded">
|
|
<b class="header">Embedded JavaScript</b>
|
|
Hopefully, you'll never need to use it, but if you ever need to intersperse
|
|
snippets of JavaScript within your CoffeeScript, you can
|
|
use backticks to pass it straight through.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">hi</span><span class="Keyword">:</span> <span class="String"><span class="String">`</span>function() {</span>
|
|
<span class="String"> return [document.title, "Hello JavaScript"].join(": ");</span>
|
|
<span class="String">}<span class="String">`</span></span>
|
|
|
|
|
|
</pre><pre class="idle"><span class="Storage">var</span> hi;
|
|
<span class="FunctionName">hi</span> = <span class="Storage">function</span>() {
|
|
<span class="Keyword">return</span> [<span class="LibraryClassType">document</span>.<span class="LibraryConstant">title</span>, <span class="String"><span class="String">"</span>Hello JavaScript<span class="String">"</span></span>].<span class="LibraryFunction">join</span>(<span class="String"><span class="String">"</span>: <span class="String">"</span></span>);
|
|
};
|
|
</pre><button onclick='javascript: var hi;
|
|
hi = function() {
|
|
return [document.title, "Hello JavaScript"].join(": ");
|
|
};
|
|
;alert(hi());'>run: hi()</button><br class='clear' /></div>
|
|
|
|
<p id="switch">
|
|
<b class="header">Switch/When/Else</b>
|
|
<b>Switch</b> statements in JavaScript are rather broken. You can only
|
|
do comparisons based on string equality, and need to remember to <b>break</b> at the end of
|
|
every <b>case</b> statement to avoid accidentally falling through to
|
|
the default case. CoffeeScript compiles <b>switch</b> statements into JavaScript if-else chains, allowing you to
|
|
compare any object (via <b>===</b>), preventing fall-through, and resulting
|
|
in a returnable, assignable expression. The format is: <tt>switch</tt> condition,
|
|
<tt>when</tt> clauses, <tt>else</tt> the default case.
|
|
</p>
|
|
<p>
|
|
As in Ruby, <b>switch</b> statements in CoffeeScript can take multiple
|
|
values for each <b>when</b> clause. If any of the values match, the clause
|
|
runs.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="Keyword">switch</span> day
|
|
<span class="Keyword">when</span> <span class="String"><span class="String">"</span>Mon<span class="String">"</span></span> <span class="Keyword">then</span> go_to_work()
|
|
<span class="Keyword">when</span> <span class="String"><span class="String">"</span>Tue<span class="String">"</span></span> <span class="Keyword">then</span> go_to_the_park()
|
|
<span class="Keyword">when</span> <span class="String"><span class="String">"</span>Thu<span class="String">"</span></span> <span class="Keyword">then</span> go_ice_fishing()
|
|
<span class="Keyword">when</span> <span class="String"><span class="String">"</span>Fri<span class="String">"</span></span>, <span class="String"><span class="String">"</span>Sat<span class="String">"</span></span>
|
|
<span class="Keyword">if</span> day <span class="Keyword">is</span> bingo_day
|
|
go_to_bingo()
|
|
go_dancing()
|
|
<span class="Keyword">when</span> <span class="String"><span class="String">"</span>Sun<span class="String">"</span></span> <span class="Keyword">then</span> go_to_church()
|
|
<span class="Keyword">else</span> go_to_work()
|
|
</pre><pre class="idle"><span class="Keyword">if</span> (day <span class="Keyword">===</span> <span class="String"><span class="String">"</span>Mon<span class="String">"</span></span>) {
|
|
go_to_work();
|
|
} <span class="Keyword">else</span> <span class="Keyword">if</span> (day <span class="Keyword">===</span> <span class="String"><span class="String">"</span>Tue<span class="String">"</span></span>) {
|
|
go_to_the_park();
|
|
} <span class="Keyword">else</span> <span class="Keyword">if</span> (day <span class="Keyword">===</span> <span class="String"><span class="String">"</span>Thu<span class="String">"</span></span>) {
|
|
go_ice_fishing();
|
|
} <span class="Keyword">else</span> <span class="Keyword">if</span> (day <span class="Keyword">===</span> <span class="String"><span class="String">"</span>Fri<span class="String">"</span></span> <span class="Keyword">||</span> day <span class="Keyword">===</span> <span class="String"><span class="String">"</span>Sat<span class="String">"</span></span>) {
|
|
<span class="Keyword">if</span> (day <span class="Keyword">===</span> bingo_day) {
|
|
go_to_bingo();
|
|
go_dancing();
|
|
}
|
|
} <span class="Keyword">else</span> <span class="Keyword">if</span> (day <span class="Keyword">===</span> <span class="String"><span class="String">"</span>Sun<span class="String">"</span></span>) {
|
|
go_to_church();
|
|
} <span class="Keyword">else</span> {
|
|
go_to_work();
|
|
}
|
|
</pre><br class='clear' /></div>
|
|
|
|
<p id="try">
|
|
<b class="header">Try/Catch/Finally</b>
|
|
Try/catch statements are just about the same as JavaScript (although
|
|
they work as expressions).
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="Keyword">try</span>
|
|
all_hell_breaks_loose()
|
|
cats_and_dogs_living_together()
|
|
<span class="Keyword">catch</span> error
|
|
print error
|
|
<span class="Keyword">finally</span>
|
|
clean_up()
|
|
</pre><pre class="idle"><span class="Keyword">try</span> {
|
|
all_hell_breaks_loose();
|
|
cats_and_dogs_living_together();
|
|
} <span class="Keyword">catch</span> (error) {
|
|
<span class="LibraryFunction">print</span>(error);
|
|
} <span class="Keyword">finally</span> {
|
|
clean_up();
|
|
}
|
|
</pre><br class='clear' /></div>
|
|
|
|
<p id="comparisons">
|
|
<b class="header">Chained Comparisons</b>
|
|
CoffeeScript borrows
|
|
<a href="http://docs.python.org/reference/expressions.html#notin">chained comparisons</a>
|
|
from Python — making it easy to test if a value falls within a
|
|
certain range.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">cholesterol</span><span class="Keyword">:</span> <span class="Number">127</span>
|
|
|
|
<span class="FunctionName">healthy</span><span class="Keyword">:</span> <span class="Number">200</span> <span class="Keyword">></span> cholesterol <span class="Keyword">></span> <span class="Number">60</span>
|
|
|
|
|
|
</pre><pre class="idle"><span class="Storage">var</span> cholesterol, healthy;
|
|
cholesterol <span class="Keyword">=</span> <span class="Number">127</span>;
|
|
healthy <span class="Keyword">=</span> (<span class="Number">200</span> <span class="Keyword">></span> cholesterol) <span class="Keyword">&</span><span class="Keyword">&</span> (cholesterol <span class="Keyword">></span> <span class="Number">60</span>);
|
|
</pre><button onclick='javascript: var cholesterol, healthy;
|
|
cholesterol = 127;
|
|
healthy = (200 > cholesterol) && (cholesterol > 60);
|
|
;alert(healthy);'>run: healthy</button><br class='clear' /></div>
|
|
|
|
<p id="strings">
|
|
<b class="header">Multiline Strings and Heredocs</b>
|
|
Multiline strings are allowed in CoffeeScript.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">moby_dick</span><span class="Keyword">:</span> <span class="String"><span class="String">"</span>Call me Ishmael. Some years ago --</span>
|
|
<span class="String">never mind how long precisely -- having little</span>
|
|
<span class="String">or no money in my purse, and nothing particular</span>
|
|
<span class="String">to interest me on shore, I thought I would sail</span>
|
|
<span class="String">about a little and see the watery part of the</span>
|
|
<span class="String">world...<span class="String">"</span></span>
|
|
|
|
|
|
</pre><pre class="idle"><span class="Storage">var</span> moby_dick;
|
|
moby_dick <span class="Keyword">=</span> <span class="String"><span class="String">"</span>Call me Ishmael. Some years ago -- \</span>
|
|
<span class="String">never mind how long precisely -- having little \</span>
|
|
<span class="String">or no money in my purse, and nothing particular \</span>
|
|
<span class="String">to interest me on shore, I thought I would sail \</span>
|
|
<span class="String">about a little and see the watery part of the \</span>
|
|
<span class="String">world...<span class="String">"</span></span>;
|
|
</pre><button onclick='javascript: var moby_dick;
|
|
moby_dick = "Call me Ishmael. Some years ago -- \
|
|
never mind how long precisely -- having little \
|
|
or no money in my purse, and nothing particular \
|
|
to interest me on shore, I thought I would sail \
|
|
about a little and see the watery part of the \
|
|
world...";
|
|
;alert(moby_dick);'>run: moby_dick</button><br class='clear' /></div>
|
|
<p>
|
|
Heredocs can be used to hold formatted or indentation-sensitive text
|
|
(or, if you just don't feel like escaping quotes and apostrophes). The
|
|
indentation level that begins the heredoc is maintained throughout, so
|
|
you can keep it all aligned with the body of your code.
|
|
</p>
|
|
<div class='code'><pre class="idle"><span class="FunctionName">html</span><span class="Keyword">:</span> <span class="String"><span class="String">'''</span></span>
|
|
<span class="String"> <strong></span>
|
|
<span class="String"> cup of coffeescript</span>
|
|
<span class="String"> </strong></span>
|
|
<span class="String"> <span class="String">'''</span></span>
|
|
</pre><pre class="idle"><span class="Storage">var</span> html;
|
|
html <span class="Keyword">=</span> <span class="String"><span class="String">"</span><strong><span class="UserDefinedConstant">\n</span> cup of coffeescript<span class="UserDefinedConstant">\n</span></strong><span class="String">"</span></span>;
|
|
</pre><br class='clear' /></div>
|
|
|
|
<h2 id="resources">Resources</h2>
|
|
|
|
<ul>
|
|
<li>
|
|
<a href="http://github.com/jashkenas/coffee-script/">Source Code</a><br />
|
|
Use <tt>bin/coffee</tt> to test your changes,
|
|
<tt>rake test</tt> to run the test suite,
|
|
<tt>rake build:parser</tt> to regenerate the Racc parser if you're
|
|
working on the grammar,
|
|
and <tt>rake gem:install</tt> to
|
|
create and install a custom version of the gem.
|
|
</li>
|
|
<li>
|
|
<a href="http://github.com/jashkenas/coffee-script/issues">CoffeeScript Issues</a><br />
|
|
Bugs reports, feature requests, and general discussion all belong here.
|
|
</li>
|
|
<li>
|
|
If you'd like to chat, stop by <tt>#coffeescript</tt> on Freenode.
|
|
</li>
|
|
<li>
|
|
<a href="http://github.com/mattly/rack-coffee">rack-coffee</a><br />
|
|
Rack middleware for serving CoffeeScripts as JavaScript directly to
|
|
the browser, without having to compile them first. From
|
|
<a href="http://github.com/mattly">Matt Lyon</a>.
|
|
</li>
|
|
<li>
|
|
<a href="http://github.com/jnicklas/bistro_car">BistroCar</a><br />
|
|
A Rails plugin by
|
|
<a href="http://github.com/jnicklas">Jonas Nicklas</a>
|
|
that includes CoffeeScript helpers,
|
|
bundling and minification.
|
|
</li>
|
|
<li>
|
|
<a href="http://github.com/inem/coffee-haml-filter">coffee-haml-filter</a><br />
|
|
A custom <a href="http://haml-lang.com/">HAML</a> filter, by
|
|
<a href="http://github.com/inem">Ivan Nemytchenko</a>, that embeds
|
|
snippets of CoffeeScript within your HAML templates.
|
|
</li>
|
|
</ul>
|
|
|
|
<h2 id="change_log">Change Log</h2>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.3.2</b>
|
|
<tt>@property</tt> is now a shorthand for <tt>this.property</tt>.<br />
|
|
Switched the default JavaScript engine from Narwhal to Node.js. Pass
|
|
the <tt>--narwhal</tt> flag if you'd like to continue using it.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.3.0</b>
|
|
CoffeeScript 0.3 includes major syntax changes:
|
|
<br />
|
|
The function symbol was changed to
|
|
<tt>-></tt>, and the bound function symbol is now <tt>=></tt>.
|
|
<br />
|
|
Parameter lists in function definitions must now be wrapped in parentheses.
|
|
<br />
|
|
Added property soaking, with the <tt>?.</tt> operator.
|
|
<br />
|
|
Made parentheses optional, when invoking functions with arguments.
|
|
<br />
|
|
Removed the obsolete block literal syntax.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.2.6</b>
|
|
Added Python-style chained comparisons, the conditional existence
|
|
operator <tt>?=</tt>, and some examples from <i>Beautiful Code</i>.
|
|
Bugfixes relating to statement-to-expression conversion, arguments-to-array
|
|
conversion, and the TextMate syntax highlighter.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.2.5</b>
|
|
The conditions in switch statements can now take multiple values at once —
|
|
If any of them are true, the case will run. Added the long arrow <tt>==></tt>,
|
|
which defines and immediately binds a function to <tt>this</tt>. While loops can
|
|
now be used as expressions, in the same way that comprehensions can. Splats
|
|
can be used within pattern matches to soak up the rest of an array.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.2.4</b>
|
|
Added ECMAScript Harmony style destructuring assignment, for dealing with
|
|
extracting values from nested arrays and objects. Added indentation-sensitive
|
|
heredocs for nicely formatted strings or chunks of code.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.2.3</b>
|
|
Axed the unsatisfactory <tt>ino</tt> keyword, replacing it with <tt>of</tt> for
|
|
object comprehensions. They now look like: <tt>for prop, value of object</tt>.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.2.2</b>
|
|
When performing a comprehension over an object, use <tt>ino</tt>, instead
|
|
of <tt>in</tt>, which helps us generate smaller, more efficient code at
|
|
compile time.
|
|
<br />
|
|
Added <tt>::</tt> as a shorthand for saying <tt>.prototype.</tt>
|
|
<br />
|
|
The "splat" symbol has been changed from a prefix asterisk <tt>*</tt>, to
|
|
a postfix ellipsis <tt>...</tt>
|
|
<br />
|
|
Added JavaScript's <tt>in</tt> operator,
|
|
empty <tt>return</tt> statements, and empty <tt>while</tt> loops.
|
|
<br />
|
|
Constructor functions that start with capital letters now include a
|
|
safety check to make sure that the new instance of the object is returned.
|
|
<br />
|
|
The <tt>extends</tt> keyword now functions identically to <tt>goog.inherits</tt>
|
|
in Google's Closure Library.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.2.1</b>
|
|
Arguments objects are now converted into real arrays when referenced.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.2.0</b>
|
|
Major release. Significant whitespace. Better statement-to-expression
|
|
conversion. Splats. Splice literals. Object comprehensions. Blocks.
|
|
The existential operator. Many thanks to all the folks who posted issues,
|
|
with special thanks to
|
|
<a href="http://github.com/kamatsu">Liam O'Connor-Davis</a> for whitespace
|
|
and expression help.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.1.6</b>
|
|
Bugfix for running <tt>coffee --interactive</tt> and <tt>--run</tt>
|
|
from outside of the CoffeeScript directory. Bugfix for nested
|
|
function/if-statements.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.1.5</b>
|
|
Array slice literals and array comprehensions can now both take Ruby-style
|
|
ranges to specify the start and end. JavaScript variable declaration is
|
|
now pushed up to the top of the scope, making all assignment statements into
|
|
expressions. You can use <tt>\</tt> to escape newlines.
|
|
The <tt>coffee-script</tt> command is now called <tt>coffee</tt>.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.1.4</b>
|
|
The official CoffeeScript extension is now <tt>.coffee</tt> instead of
|
|
<tt>.cs</tt>, which properly belongs to
|
|
<a href="http://en.wikipedia.org/wiki/C_Sharp_(programming_language)">C#</a>.
|
|
Due to popular demand, you can now also use <tt>=</tt> to assign. Unlike
|
|
JavaScript, <tt>=</tt> can also be used within object literals, interchangeably
|
|
with <tt>:</tt>. Made a grammatical fix for chained function calls
|
|
like <tt>func(1)(2)(3)(4)</tt>. Inheritance and super no longer use
|
|
<tt>__proto__</tt>, so they should be IE-compatible now.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.1.3</b>
|
|
The <tt>coffee</tt> command now includes <tt>--interactive</tt>,
|
|
which launches an interactive CoffeeScript session, and <tt>--run</tt>,
|
|
which directly compiles and executes a script. Both options depend on a
|
|
working installation of Narwhal.
|
|
The <tt>aint</tt> keyword has been replaced by <tt>isnt</tt>, which goes
|
|
together a little smoother with <tt>is</tt>.
|
|
Quoted strings are now allowed as identifiers within object literals: eg.
|
|
<tt>{"5+5": 10}</tt>.
|
|
All assignment operators now use a colon: <tt>+:</tt>, <tt>-:</tt>,
|
|
<tt>*:</tt>, etc.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.1.2</b>
|
|
Fixed a bug with calling <tt>super()</tt> through more than one level of
|
|
inheritance, with the re-addition of the <tt>extends</tt> keyword.
|
|
Added experimental <a href="http://narwhaljs.org/">Narwhal</a>
|
|
support (as a Tusk package), contributed by
|
|
<a href="http://tlrobinson.net/">Tom Robinson</a>, including
|
|
<b>bin/cs</b> as a CoffeeScript REPL and interpreter.
|
|
New <tt>--no-wrap</tt> option to suppress the safety function
|
|
wrapper.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.1.1</b>
|
|
Added <tt>instanceof</tt> and <tt>typeof</tt> as operators.
|
|
</p>
|
|
|
|
<p>
|
|
<b class="header" style="margin-top: 20px;">0.1.0</b>
|
|
Initial CoffeeScript release.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<script type="text/javascript" src="lib/rewriter.js"></script>
|
|
<script type="text/javascript" src="lib/lexer.js"></script>
|
|
<script type="text/javascript" src="lib/parser.js"></script>
|
|
<script type="text/javascript" src="lib/scope.js"></script>
|
|
<script type="text/javascript" src="lib/nodes.js"></script>
|
|
<script type="text/javascript" src="lib/coffee-script.js"></script>
|
|
|
|
<script type="text/javascript">
|
|
window.repl_compile = function() {
|
|
var source = document.getElementById('repl_source').value;
|
|
var js = '';
|
|
try {
|
|
js = compile(source, {no_wrap: true});
|
|
} catch(error) {
|
|
alert(error);
|
|
}
|
|
document.getElementById('repl_results').innerHTML = js;
|
|
}
|
|
</script>
|
|
|
|
</body>
|
|
</html>
|