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<!DOCTYPE html>
<html>
<head>
<meta http-equiv="content-type" content="text/html;charset=UTF-8" />
<meta name="description" content="CoffeeScript 中文, Unfancy JavaScript, 翻译">
<title>CoffeeScript 中文</title>
<link rel="canonical" href="http://coffeescript.org" />
<link rel="stylesheet" type="text/css" href="documentation/css/docs.css" />
<link rel="stylesheet" type="text/css" href="documentation/css/tomorrow.css" />
<link rel="shortcut icon" href="documentation/images/favicon.ico" />
</head>
<body>
<div id="fadeout"></div>
<div id="flybar">
<a href="https://github.com/coffee-js/coffee-script">
<img style="position: fixed; top: 0; right: 0; border: 0; z-index: 200;" src="http://coffee-js.qiniudn.com/ribbon.png" alt="Fork me on GitHub">
</a>
<a id="logo" href="#top"><img src="documentation/images/logo.png" width="225" height="39" alt="CoffeeScript" /></a>
<div class="navigation toc">
<div class="button">
目录
</div>
<div class="contents menu">
<a href="#overview">概览</a>
<a href="#installation">安装</a>
<a href="#usage">用法</a>
<a href="#literate">Literate CoffeeScript</a>
<a href="#language">语言手册</a>
<a href="#literals">字面量: 函数, 对象和数组</a>
<a href="#lexical-scope">词法作用域和变量安全</a>
<a href="#conditionals">if, else, unless 和条件赋值</a>
<a href="#splats">变参(splats)...</a>
<a href="#loops">循环和推导式</a>
<a href="#slices">Array Slicing and Splicing</a>
<a href="#expressions">Everything is an Expression</a>
<a href="#operators">Operators and Aliases</a>
<a href="#classes">Classes, Inheritance, and Super</a>
<a href="#destructuring">Destructuring Assignment</a>
<a href="#fat-arrow">Function Binding</a>
<a href="#embedded">Embedded JavaScript</a>
<a href="#switch">Switch and Try/Catch</a>
<a href="#comparisons">Chained Comparisons</a>
<a href="#strings">String Interpolation, Block Strings, and Block Comments</a>
<a href="#regexes">Block Regular Expressions</a>
<a href="#cake">Cake, and Cakefiles</a>
<a href="#source-maps">Source Maps</a>
<a href="#scripts">"text/coffeescript" Script Tags</a>
<a href="#resources">Books, Screencasts, Examples and Resources</a>
<a href="#changelog">Change Log</a>
</div>
</div>
<div class="navigation try">
<div class="button">
试一试 CoffeeScript
<div class="repl_bridge"></div>
</div>
<div class="contents repl_wrapper">
<div class="code">
<div class="screenshadow tl"></div>
<div class="screenshadow tr"></div>
<div class="screenshadow bl"></div>
<div class="screenshadow br"></div>
<div id="repl_source_wrap">
<textarea id="repl_source" rows="100" spellcheck="false">alert "Hello CoffeeScript!"</textarea>
</div>
<div id="repl_results_wrap"><pre id="repl_results"></pre></div>
<div class="minibutton dark run" title="Ctrl-Enter">Run</div>
<a class="minibutton permalink" id="repl_permalink">Link</a>
<br class="clear" />
</div>
</div>
</div>
<div class="navigation annotated">
<div class="button">
代码和注释
</div>
<div class="contents menu">
<a href="documentation/docs/grammar.html">Grammar Rules — src/grammar</a>
<a href="documentation/docs/lexer.html">Lexing Tokens — src/lexer</a>
<a href="documentation/docs/rewriter.html">The Rewriter — src/rewriter</a>
<a href="documentation/docs/nodes.html">The Syntax Tree — src/nodes</a>
<a href="documentation/docs/scope.html">Lexical Scope — src/scope</a>
<a href="documentation/docs/helpers.html">Helpers & Utility Functions — src/helpers</a>
<a href="documentation/docs/coffee-script.html">The CoffeeScript Module — src/coffee-script</a>
<a href="documentation/docs/cake.html">Cake & Cakefiles — src/cake</a>
<a href="documentation/docs/command.html">"coffee" Command-Line Utility — src/command</a>
<a href="documentation/docs/optparse.html">Option Parsing — src/optparse</a>
<a href="documentation/docs/repl.html">Interactive REPL — src/repl</a>
<a href="documentation/docs/sourcemap.html">Source Maps — src/sourcemap</a>
</div>
</div>
<div id="error" style="display:none;"></div>
</div>
<div class="container">
<span class="bookmark" id="top"></span>
<p>
<b>CoffeeScript 是一门编译到 JavaScript 的小巧语言.</b>
在 Java 般笨拙的外表下, JavaScript 其实有着一颗华丽的心脏.
CoffeeScript 尝试用简洁的方式展示 JavaScript 优秀的部分.
</p>
<p>
CoffeeScript 的指导原则是: <b>"她仅仅是 JavaScript"</b>.
代码一一对应地编译到 JS, 不会在编译过程中进行解释.
已有的 JavaScript 类库可以无缝地和 CoffeeScript 搭配使用, 反之亦然.
编译后的代码是可读的, 且经过美化, 能在所有 JavaScript 环境中运行,
并且应该和对应手写的 JavaScript 一样快或者更快.
</p>
<p>
<b>最新版本:</b>
<a href="http://github.com/jashkenas/coffee-script/tarball/1.7.1">1.7.1</a>
</p>
<pre>
sudo npm install -g coffee-script</pre>
<h2>
<span id="overview" class="bookmark"></span>
概览
</h2>
<p>左边是 CoffeeScript, 右边是编译后输出的 JavaScript.</p>
<div class='code'><pre><code><span class="comment"># 赋值:</span>
number = <span class="number">42</span>
opposite = <span class="literal">true</span>
<span class="comment"># 条件:</span>
number = -<span class="number">42</span> <span class="keyword">if</span> opposite
<span class="comment"># 函数:</span>
<span class="function"><span class="title">square</span> = <span class="params">(x)</span> -></span> x * x
<span class="comment"># 数组:</span>
list = [<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="comment"># 对象:</span>
math =
<span class="attribute">root</span>: Math.sqrt
<span class="attribute">square</span>: square
<span class="attribute">cube</span>: <span class="function"><span class="params">(x)</span> -></span> x * square x
<span class="comment"># Splats:</span>
<span class="function"><span class="title">race</span> = <span class="params">(winner, runners...)</span> -></span>
<span class="built_in">print</span> winner, runners
<span class="comment"># 存在性:</span>
alert <span class="string">"I knew it!"</span> <span class="keyword">if</span> elvis?
<span class="comment"># 数组 推导(comprehensions):</span>
cubes = (math.cube num <span class="keyword">for</span> num <span class="keyword">in</span> list)
</code></pre><pre><code><span class="keyword">var</span> cubes, list, math, num, number, opposite, race, square,
__slice = [].slice;
number = <span class="number">42</span>;
opposite = <span class="literal">true</span>;
<span class="keyword">if</span> (opposite) {
number = -<span class="number">42</span>;
}
square = <span class="function"><span class="keyword">function</span><span class="params">(x)</span> {</span>
<span class="keyword">return</span> x * x;
};
list = [<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>];
math = {
root: <span class="built_in">Math</span>.sqrt,
square: square,
cube: <span class="function"><span class="keyword">function</span><span class="params">(x)</span> {</span>
<span class="keyword">return</span> x * square(x);
}
};
race = <span class="function"><span class="keyword">function</span><span class="params">()</span> {</span>
<span class="keyword">var</span> runners, winner;
winner = <span class="built_in">arguments</span>[<span class="number">0</span>], runners = <span class="number">2</span> <= <span class="built_in">arguments</span>.length ? __slice.call(<span class="built_in">arguments</span>, <span class="number">1</span>) : [];
<span class="keyword">return</span> print(winner, runners);
};
<span class="keyword">if</span> (<span class="keyword">typeof</span> elvis !== <span class="string">"undefined"</span> && elvis !== <span class="literal">null</span>) {
alert(<span class="string">"I knew it!"</span>);
}
cubes = (<span class="function"><span class="keyword">function</span><span class="params">()</span> {</span>
<span class="keyword">var</span> _i, _len, _results;
_results = [];
<span class="keyword">for</span> (_i = <span class="number">0</span>, _len = list.length; _i < _len; _i++) {
num = list[_i];
_results.push(math.cube(num));
}
<span class="keyword">return</span> _results;
})();
</code></pre><script>window.example1 = "# 赋值:\nnumber = 42\nopposite = true\n\n# 条件:\nnumber = -42 if opposite\n\n# 函数:\nsquare = (x) -> x * x\n\n# 数组:\nlist = [1, 2, 3, 4, 5]\n\n# 对象:\nmath =\n root: Math.sqrt\n square: square\n cube: (x) -> x * square x\n\n# Splats:\nrace = (winner, runners...) ->\n print winner, runners\n\n# 存在性:\nalert \"I knew it!\" if elvis?\n\n# 数组 推导(comprehensions):\ncubes = (math.cube num for num in list)\n"</script><div class='minibutton ok' onclick='javascript: var cubes, list, math, num, number, opposite, race, square,
__slice = [].slice;
number = 42;
opposite = true;
if (opposite) {
number = -42;
}
square = function(x) {
return x * x;
};
list = [1, 2, 3, 4, 5];
math = {
root: Math.sqrt,
square: square,
cube: function(x) {
return x * square(x);
}
};
race = function() {
var runners, winner;
winner = arguments[0], runners = 2 <= arguments.length ? __slice.call(arguments, 1) : [];
return print(winner, runners);
};
if (typeof elvis !== "undefined" && elvis !== null) {
alert("I knew it!");
}
cubes = (function() {
var _i, _len, _results;
_results = [];
for (_i = 0, _len = list.length; _i < _len; _i++) {
num = list[_i];
_results.push(math.cube(num));
}
return _results;
})();
;alert(cubes);'>run: cubes</div><br class='clear' /></div>
<h2>
<span id="installation" class="bookmark"></span>
安装
</h2>
<p>
CoffeeScript 编译器本身<a href="documentation/docs/grammar.html">是 CoffeeScript 写的</a>,
使用了 <a href="http://jison.org">Jison parser generator</a>.
命令行版本的 <tt>coffee</tt> 是一个实用的 <a href="http://nodejs.org/">Node.js</a> 工具.
不过<a href="extras/coffee-script.js">编译器</a>并不依赖 Node,
而是能运行于任何 JavaScript 执行环境, 比如说在浏览器里(看上边的"试一试 CoffeeScript").
</p>
<p>
安装前你需要最新稳定版 <a href="http://nodejs.org/">Node.js</a>,
和 <a href="http://npmjs.org">npm</a> (Node Package Manager).
借助 npm 可以安装 CoffeeScript:
</p>
<pre>
npm install -g coffee-script</pre>
<p>
(如果不想全局安装可以去掉 <tt>-g</tt> 选项.)
</p>
<p>
如果你希望安装 <b>master</b> 分支上最新的 CoffeeScript,
你可以从<a href="http://github.com/jashkenas/coffee-script">源码仓库</a> 克隆 CoffeeScript,
或直接下载<a href="http://github.com/jashkenas/coffee-script/tarball/master">源码</a>.
还有通过 npm 方式安装 master 分支最新的 CoffeeScript 编译器:
</p>
<pre>
npm install -g http://github.com/jashkenas/coffee-script/tarball/master</pre>
<p>
或者你想将其安装到 <tt>/usr/local</tt>, 而不用 npm 进行管理,
进入 <tt>coffee-script</tt> 目录执行:
</p>
<pre>
sudo bin/cake install</pre>
<h2>
<span id="usage" class="bookmark"></span>
用法
</h2>
<p>
安装之后, 你应该可以运行 <tt>coffee</tt> 命令以执行脚本,
编译 <tt>.coffee</tt> 文件到 <tt>.js</tt> 文件, 和提供一个交互式的 REPL.
<tt>coffee</tt> 命令有下列参数:
</p>
<table>
<tr>
<td><code>-c, --compile</code></td>
<td>
编译一个 <tt>.coffee</tt> 脚本到一个同名的 <tt>.js</tt> 文件.
</td>
</tr>
<tr>
<td><code>-m, --map</code></td>
<td>
随 JavaScript 文件一起生成 source maps. 并且在 JavaScript 里加上 <tt>sourceMappingURL</tt> 指令.
</td>
</tr>
<tr>
<td width="25%"><code>-i, --interactive</code></td>
<td>
启动一个交互式的 CoffeeScript 会话用来尝试一些代码片段.
等同于执行 <tt>coffee</tt> 而不加参数.
</td>
</tr>
<tr>
<td><code>-o, --output [DIR]</code></td>
<td>
将所有编译后的 JavaScript 文件写到指定文件夹.
与 <tt>--compile</tt> 或 <tt>--watch</tt> 搭配使用.
</td>
</tr>
<tr>
<td><code>-j, --join [FILE]</code></td>
<td>
编译之前, 按参数传入顺序连接所有脚本到一起, 编译后写到指定的文件.
对于编译大型项目有用.
</td>
</tr>
<tr>
<td><code>-w, --watch</code></td>
<td>
监视文件改变, 任何文件更新时重新执行命令.
</td>
</tr>
<tr>
<td><code>-p, --print</code></td>
<td>
JavaScript 直接打印到 <b>stdout</b> 而不是写到一个文件.
</td>
</tr>
<tr>
<td><code>-s, --stdio</code></td>
<td>
将 CoffeeScript 传递到 STDIN 后从 STDOUT 获取 JavaScript.
对其他语言写的进程有好处. 比如:<br />
<tt>cat src/cake.coffee | coffee -sc</tt>
</td>
</tr>
<tr>
<td><code>-l, --literate</code></td>
<td>
将代码作为 Literate CoffeeScript 解析.
只会在从 <b>stdio</b> 直接传入代码或者处理某些没有后缀的文件名需要写明这点.
</td>
</tr>
<tr>
<td><code>-e, --eval</code></td>
<td>
直接从命令行编译和打印一小段 CoffeeScript. 比如:<br />
<tt>coffee -e "console.log num for num in [10..1]"</tt>
</td>
</tr>
<tr>
<td><code>-b, --bare</code></td>
<td>
编译到 JavaScript 时去掉<a href="#lexical-scope">顶层函数的包裹</a>.
</td>
</tr>
<tr>
<td><code>-t, --tokens</code></td>
<td>
不对 CoffeeScript 进行解析, 仅仅进行 lex, 打印出 token stream:
<tt>[IDENTIFIER square] [ASSIGN =] [PARAM_START (]</tt> ...
</td>
</tr>
<tr>
<td><code>-n, --nodes</code></td>
<td>
不对 CoffeeScript 进行编译, 仅仅 lex 和解析, 打印 parse tree:
<pre class="no_bar">
Expressions
Assign
Value "square"
Code "x"
Op *
Value "x"
Value "x"</pre>
</td>
</tr>
<tr>
<td><code>--nodejs</code></td>
<td>
<tt>node</tt> 命令有一些实用的参数, 比如<br />
<tt>--debug</tt>, <tt>--debug-brk</tt>, <tt>--max-stack-size</tt>,
和 <tt>--expose-gc</tt>. 用这个参数直接把参数转发到 Node.js.
重复使用 <tt>--nodejs</tt> 来传递多个参数.
</td>
</tr>
</table>
<p>
<b>例子:</b>
</p>
<ul>
<li>
编译一个 <tt>.coffee</tt> 文件的树形目录 <tt>src</tt> 到一个同级
<tt>.js</tt> 文件树形目录 <tt>lib</tt>:<br />
<tt>coffee --compile --output lib/ src/</tt>
</li>
<li>
监视一个文件的改变, 每次文件被保证时重新编译:<br />
<tt>coffee --watch --compile experimental.coffee</tt>
</li>
<li>
合并一组文件到单个脚本:<br />
<tt>coffee --join project.js --compile src/*.coffee</tt>
</li>
<li>
从一个 one-liner 打印编译后的 JS:<br />
<tt>coffee -bpe "alert i for i in [0..10]"</tt>
</li>
<li>
现在全部一起, 在你工作时监视和重复编译整个项目:<br />
<tt>coffee -o lib/ -cw src/</tt>
</li>
<li>
运行 CoffeeScript REPL (<tt>Ctrl-D</tt> 来终止, <tt>Ctrl-V</tt> 激活多行):<br />
<tt>coffee</tt>
</li>
</ul>
<h2>
<span id="literate" class="bookmark"></span>
Literate CoffeeScript
</h2>
<p>
除了被作为一个普通的编程语言, CoffeeScript 也可以在 "literate" 模式下编写。
如果你以 <tt>.litcoffee</tt> 为扩展名命名你的文件, 你可以把它当作 Markdown 文件来编写 —
此文档恰好也是一份可执行的 CoffeeScript 代码, 编译器将会把所有的缩进块 (Markdown 表示源代码的方式) 视为代码, 其他部分则为注释.
</p>
<p>
Just for kicks, a little bit of the compiler is currently implemented in this fashion:
See it
<a href="https://gist.github.com/jashkenas/3fc3c1a8b1009c00d9df">as a document</a>,
<a href="https://raw.github.com/jashkenas/coffee-script/master/src/scope.litcoffee">raw</a>,
and <a href="http://cl.ly/LxEu">properly highlighted in a text editor</a>.
</p>
<p>
I'm fairly excited about this direction for the language, and am looking
forward to writing (and more importantly, reading) more programs in this style.
More information about Literate CoffeeScript, including an
<a href="https://github.com/jashkenas/journo">example program</a>,
are <a href="http://ashkenas.com/literate-coffeescript">available in this blog post</a>.
</p>
<h2>
<span id="language" class="bookmark"></span>
语言手册
</h2>
<p>
<i>
这份手册所设计的结构, 方便从上往下进行阅读. 后边的章节使用前面介绍的语法和手法.
阅读这份手册需要对 JavaScript 比较熟悉.
以下所有的例子, CoffeeScript 源码将在左边显示, 并在右侧直接编译到 JavaScript.
</i>
</p>
<p>
<i>
很多例子可以通过点击右边的 <b>run</b> 按钮直接运行(代码有意义的话),
也可以通过点击左边的 <b>load</b> 按钮载入"试一试 CoffeeScript"的控制台.
</i>
<p>
首先, 一些基础, CoffeeScript 使用显式的空白来区分代码块.
你不需要使用分号 <tt>;</tt> 来关闭表达式,
在一行的结尾换行就可以了(尽管分号依然可以用来把多行的表达式简写到一行里).
不需要再用花括号来
<tt>{ }</tt> 包裹代码快, 在 <a href="#literals">函数</a>,
<a href="#conditionals">if 表达式</a>,
<a href="#switch">switch</a>, 和 <a href="#try">try/catch</a> 当中使用缩进.
</p>
<p>
传入参数的时候, 你不需要再使用圆括号来表明函数被执行.
隐式的函数调用的作用范围一直到行尾或者一个块级表达式.
<br />
<tt>console.log sys.inspect object</tt> → <tt>console.log(sys.inspect(object));</tt>
</p>
<p>
<span id="literals" class="bookmark"></span>
<b class="header">函数</b>
函数通过一组可选的圆括号包裹的参数, 一个箭头, 一个函数体来定义.
一个空的函数像是这样:
<tt>-></tt>
</p>
<div class='code'><pre><code><span class="function"><span class="title">square</span> = <span class="params">(x)</span> -></span> x * x
<span class="function"><span class="title">cube</span> = <span class="params">(x)</span> -></span> square(x) * x
</code></pre><pre><code><span class="keyword">var</span> cube, square;
square = <span class="function"><span class="keyword">function</span><span class="params">(x)</span> {</span>
<span class="keyword">return</span> x * x;
};
cube = <span class="function"><span class="keyword">function</span><span class="params">(x)</span> {</span>
<span class="keyword">return</span> square(x) * x;
};
</code></pre><script>window.example2 = "square = (x) -> x * x\ncube = (x) -> square(x) * x\n"</script><div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><div class='minibutton ok' onclick='javascript: var cube, square;
square = function(x) {
return x * x;
};
cube = function(x) {
return square(x) * x;
};
;alert(cube(5));'>run: cube(5)</div><br class='clear' /></div>
<p>
一些函数函数参数会有默认值, 当传入的参数的不存在 (<tt>null</tt> 或者 <tt>undefined</tt>)
时会被使用.
</p>
<div class='code'><pre><code><span class="function"><span class="title">fill</span> = <span class="params">(container, liquid = <span class="string">"coffee"</span>)</span> -></span>
<span class="string">"Filling the <span class="subst">#{container}</span> with <span class="subst">#{liquid}</span>..."</span>
</code></pre><pre><code><span class="keyword">var</span> fill;
fill = <span class="function"><span class="keyword">function</span><span class="params">(container, liquid)</span> {</span>
<span class="keyword">if</span> (liquid == <span class="literal">null</span>) {
liquid = <span class="string">"coffee"</span>;
}
<span class="keyword">return</span> <span class="string">"Filling the "</span> + container + <span class="string">" with "</span> + liquid + <span class="string">"..."</span>;
};
</code></pre><script>window.example3 = "fill = (container, liquid = \"coffee\") ->\n \"Filling the #{container} with #{liquid}...\"\n\n\n\n\n\n\n"</script><div class='minibutton load' onclick='javascript: loadConsole(example3);'>load</div><div class='minibutton ok' onclick='javascript: var fill;
fill = function(container, liquid) {
if (liquid == null) {
liquid = "coffee";
}
return "Filling the " + container + " with " + liquid + "...";
};
;alert(fill("cup"));'>run: fill("cup")</div><br class='clear' /></div>
<p>
<span id="objects_and_arrays" class="bookmark"></span>
<b class="header">对象和数组</b>
CoffeeScript 中对象和数组的字面量看起来很像在 JavaScript 中的写法.
如果单个属性被写在自己的一行里, 那么逗号是可以省略的.
和 <a href="http://yaml.org">YAML</a> 类似, 对象可以用缩进替代花括号来声明.
</p>
<div class='code'><pre><code>song = [<span class="string">"do"</span>, <span class="string">"re"</span>, <span class="string">"mi"</span>, <span class="string">"fa"</span>, <span class="string">"so"</span>]
singers = {<span class="attribute">Jagger</span>: <span class="string">"Rock"</span>, <span class="attribute">Elvis</span>: <span class="string">"Roll"</span>}
bitlist = [
<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>
]
kids =
<span class="attribute">brother</span>:
<span class="attribute">name</span>: <span class="string">"Max"</span>
<span class="attribute">age</span>: <span class="number">11</span>
<span class="attribute">sister</span>:
<span class="attribute">name</span>: <span class="string">"Ida"</span>
<span class="attribute">age</span>: <span class="number">9</span>
</code></pre><pre><code><span class="keyword">var</span> bitlist, kids, singers, song;
song = [<span class="string">"do"</span>, <span class="string">"re"</span>, <span class="string">"mi"</span>, <span class="string">"fa"</span>, <span class="string">"so"</span>];
singers = {
Jagger: <span class="string">"Rock"</span>,
Elvis: <span class="string">"Roll"</span>
};
bitlist = [<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>];
kids = {
brother: {
name: <span class="string">"Max"</span>,
age: <span class="number">11</span>
},
sister: {
name: <span class="string">"Ida"</span>,
age: <span class="number">9</span>
}
};
</code></pre><script>window.example4 = "song = [\"do\", \"re\", \"mi\", \"fa\", \"so\"]\n\nsingers = {Jagger: \"Rock\", Elvis: \"Roll\"}\n\nbitlist = [\n 1, 0, 1\n 0, 0, 1\n 1, 1, 0\n]\n\nkids =\n brother:\n name: \"Max\"\n age: 11\n sister:\n name: \"Ida\"\n age: 9\n\n\n"</script><div class='minibutton load' onclick='javascript: loadConsole(example4);'>load</div><div class='minibutton ok' onclick='javascript: var bitlist, kids, singers, song;
song = ["do", "re", "mi", "fa", "so"];
singers = {
Jagger: "Rock",
Elvis: "Roll"
};
bitlist = [1, 0, 1, 0, 0, 1, 1, 1, 0];
kids = {
brother: {
name: "Max",
age: 11
},
sister: {
name: "Ida",
age: 9
}
};
;alert(song.join(" ... "));'>run: song.join(" ... ")</div><br class='clear' /></div>
<p>
JavaScript 里, 你不能使用不添加引号的保留字段作为属性名称, 比如 <tt>class</tt>.
CoffeeScript 里作为键出现的保留字会被识别并补上引号,
所以你不用有额外的操心(比如说, 使用 jQuery 的时候).
</p>
<div class='code'><pre><code>$('.account').attr class: 'active'
log object.class
</code></pre><pre><code>$(<span class="string">'.account'</span>).attr({
<span class="string">"class"</span>: <span class="string">'active'</span>
});
log(object[<span class="string">"class"</span>]);
</code></pre><script>window.example5 = "$('.account').attr class: 'active'\n\nlog object.class\n\n\n"</script><div class='minibutton load' onclick='javascript: loadConsole(example5);'>load</div><br class='clear' /></div>
<p>
<span id="lexical-scope" class="bookmark"></span>
<b class="header">词法作用域和变量安全</b>
CoffeeScript 编译器会考虑所有变量, 保证每个变量都在词法域里适当地被定义
— 你永远不需要自己去写 <tt>var</tt>.
</p>
<div class='code'><pre><code>outer = <span class="number">1</span>
<span class="function"><span class="title">changeNumbers</span> = -></span>
inner = -<span class="number">1</span>
outer = <span class="number">10</span>
inner = changeNumbers()</code></pre><pre><code><span class="keyword">var</span> changeNumbers, inner, outer;
outer = <span class="number">1</span>;
changeNumbers = <span class="function"><span class="keyword">function</span><span class="params">()</span> {</span>
<span class="keyword">var</span> inner;
inner = -<span class="number">1</span>;
<span class="keyword">return</span> outer = <span class="number">10</span>;
};
inner = changeNumbers();
</code></pre><script>window.example6 = "outer = 1\nchangeNumbers = ->\n inner = -1\n outer = 10\ninner = changeNumbers()"</script><div class='minibutton load' onclick='javascript: loadConsole(example6);'>load</div><div class='minibutton ok' onclick='javascript: var changeNumbers, inner, outer;
outer = 1;
changeNumbers = function() {
var inner;
inner = -1;
return outer = 10;
};
inner = changeNumbers();
;alert(inner);'>run: inner</div><br class='clear' /></div>
<p>
注意所有变量的定义都被推到相关的顶层作用域, 也就是第一次出现的位置.
<b>outer</b> 在内层的函数里没有被重新定义, 因为它已经存在于作用域当中了.
同时, 内层函数里的 <b>inner</b> 不应该改变外部的同名的变量, 所以在这里有自己的声明.
</p>
<p>
其行为和 Ruby 的局部变量的作用域实际上是一致的.
由于你没有对 <tt>var</tt> 关键字的直接访问, 根据需要隐藏一个外部变量就很容易, 你只能引用它.
所以在写深层的嵌套的函数时, 注意不要意外用到和外部变量相同的名字.
</p>
<p>
尽管要说清楚会受到文档长度限制, 函数的所有 CoffeeScript 结果都被一个匿名函数包裹:
<tt>(function(){ ... })();</tt>
这层安全的封装, 加上自动生成的 <tt>var</tt> 关键字, 使得不小心污染全局命名空间很难发生.
</p>
<p>
如果你希望创建一个其他脚本也能使用的顶层变量, 那么将其作为赋值在 <b>window</b> 上,
或者在 CommonJS 里的 <b>exports</b> 上.
<b>存在操作符(existential operator)</b>可以帮你写出一个可靠的方式找到添加位置;
比如你的目标是同时满足 CommonJS 和浏览器: <tt>exports ? this</tt>
</p>
<p>
<span id="conditionals" class="bookmark"></span>
<b class="header">if, else, unless 和条件赋值</b>
<b>if/else</b> 表达式可以不用圆括号和花括号就写出来.
就像函数和其他块级表达式那样, 多行的条件可以通过缩进来表明.
另外还有一个顺手的后缀形式, 在行尾使用 <tt>if</tt> or <tt>unless</tt>.
</p>
<p>
CoffeeScript 会尝试编译 <b>if</b> 语句到 JavaScript 表达式, 或者一个封装的闭包.
CoffeeScript 里不存在直白的三元表达式.
— 你只要在一行内使用普通的 <b>if</b> 语句.
</p>
<div class='code'><pre><code>mood = greatlyImproved <span class="keyword">if</span> singing
<span class="keyword">if</span> happy <span class="keyword">and</span> knowsIt
clapsHands()
chaChaCha()
<span class="keyword">else</span>
showIt()
date = <span class="keyword">if</span> friday <span class="keyword">then</span> sue <span class="keyword">else</span> jill
</code></pre><pre><code><span class="keyword">var</span> date, mood;
<span class="keyword">if</span> (singing) {
mood = greatlyImproved;
}
<span class="keyword">if</span> (happy && knowsIt) {
clapsHands();
chaChaCha();
} <span class="keyword">else</span> {
showIt();
}
date = friday ? sue : jill;
</code></pre><script>window.example7 = "mood = greatlyImproved if singing\n\nif happy and knowsIt\n clapsHands()\n chaChaCha()\nelse\n showIt()\n\ndate = if friday then sue else jill\n\n\n\n"</script><div class='minibutton load' onclick='javascript: loadConsole(example7);'>load</div><br class='clear' /></div>
<p>
<span id="splats" class="bookmark"></span>
<b class="header">变参(splats)...</b>
使用 JavaScript 的 <b>arguments 对象</b>是一种处理接收不定数量个参数的函数常用办法.
CoffeeScript 在函数定义和调用里提供了变参(splats) <tt>...</tt> 的语法,
让不定个数的参数使用起来更愉悦一些.
</p>
<div class='code'><pre><code>gold = silver = rest = <span class="string">"unknown"</span>
<span class="function"><span class="title">awardMedals</span> = <span class="params">(first, second, others...)</span> -></span>
gold = first
silver = second
rest = others
contenders = [
<span class="string">"Michael Phelps"</span>
<span class="string">"Liu Xiang"</span>
<span class="string">"Yao Ming"</span>
<span class="string">"Allyson Felix"</span>
<span class="string">"Shawn Johnson"</span>
<span class="string">"Roman Sebrle"</span>
<span class="string">"Guo Jingjing"</span>
<span class="string">"Tyson Gay"</span>
<span class="string">"Asafa Powell"</span>
<span class="string">"Usain Bolt"</span>
]
awardMedals contenders...
alert <span class="string">"Gold: "</span> + gold
alert <span class="string">"Silver: "</span> + silver
alert <span class="string">"The Field: "</span> + rest
</code></pre><pre><code><span class="keyword">var</span> awardMedals, contenders, gold, rest, silver,
__slice = [].slice;
gold = silver = rest = <span class="string">"unknown"</span>;
awardMedals = <span class="function"><span class="keyword">function</span><span class="params">()</span> {</span>
<span class="keyword">var</span> first, others, second;
first = <span class="built_in">arguments</span>[<span class="number">0</span>], second = <span class="built_in">arguments</span>[<span class="number">1</span>], others = <span class="number">3</span> <= <span class="built_in">arguments</span>.length ? __slice.call(<span class="built_in">arguments</span>, <span class="number">2</span>) : [];
gold = first;
silver = second;
<span class="keyword">return</span> rest = others;
};
contenders = [<span class="string">"Michael Phelps"</span>, <span class="string">"Liu Xiang"</span>, <span class="string">"Yao Ming"</span>, <span class="string">"Allyson Felix"</span>, <span class="string">"Shawn Johnson"</span>, <span class="string">"Roman Sebrle"</span>, <span class="string">"Guo Jingjing"</span>, <span class="string">"Tyson Gay"</span>, <span class="string">"Asafa Powell"</span>, <span class="string">"Usain Bolt"</span>];
awardMedals.apply(<span class="literal">null</span>, contenders);
alert(<span class="string">"Gold: "</span> + gold);
alert(<span class="string">"Silver: "</span> + silver);
alert(<span class="string">"The Field: "</span> + rest);
</code></pre><script>window.example8 = "gold = silver = rest = \"unknown\"\n\nawardMedals = (first, second, others...) ->\n gold = first\n silver = second\n rest = others\n\ncontenders = [\n \"Michael Phelps\"\n \"Liu Xiang\"\n \"Yao Ming\"\n \"Allyson Felix\"\n \"Shawn Johnson\"\n \"Roman Sebrle\"\n \"Guo Jingjing\"\n \"Tyson Gay\"\n \"Asafa Powell\"\n \"Usain Bolt\"\n]\n\nawardMedals contenders...\n\nalert \"Gold: \" + gold\nalert \"Silver: \" + silver\nalert \"The Field: \" + rest\n\n\n"</script><div class='minibutton load' onclick='javascript: loadConsole(example8);'>load</div><div class='minibutton ok' onclick='javascript: var awardMedals, contenders, gold, rest, silver,
__slice = [].slice;
gold = silver = rest = "unknown";
awardMedals = function() {
var first, others, second;
first = arguments[0], second = arguments[1], others = 3 <= arguments.length ? __slice.call(arguments, 2) : [];
gold = first;
silver = second;
return rest = others;
};
contenders = ["Michael Phelps", "Liu Xiang", "Yao Ming", "Allyson Felix", "Shawn Johnson", "Roman Sebrle", "Guo Jingjing", "Tyson Gay", "Asafa Powell", "Usain Bolt"];
awardMedals.apply(null, contenders);
alert("Gold: " + gold);
alert("Silver: " + silver);
alert("The Field: " + rest);
;'>run</div><br class='clear' /></div>
<p>
<span id="loops" class="bookmark"></span>
<b class="header">循环和推导式</b>
你可以使用CoffeeScript将大多数的循环写成基于数组、对象或范围的推导式(comprehensions)。
推导式替代（编译为）<b>for</b>循环，并且可以使用可选的子句和数组索引值。
不同于<b>for</b>循环，数组的推导式是表达式，可以被返回和赋值。
</p>
<div class='code'><pre><code><span class="comment"># 吃午饭.</span>
eat food <span class="keyword">for</span> food <span class="keyword">in</span> [<span class="string">'toast'</span>, <span class="string">'cheese'</span>, <span class="string">'wine'</span>]
<span class="comment"># 精致的五道菜.</span>
courses = [<span class="string">'greens'</span>, <span class="string">'caviar'</span>, <span class="string">'truffles'</span>, <span class="string">'roast'</span>, <span class="string">'cake'</span>]
menu i + <span class="number">1</span>, dish <span class="keyword">for</span> dish, i <span class="keyword">in</span> courses
<span class="comment"># 注重健康的一餐.</span>
foods = [<span class="string">'broccoli'</span>, <span class="string">'spinach'</span>, <span class="string">'chocolate'</span>]
eat food <span class="keyword">for</span> food <span class="keyword">in</span> foods <span class="keyword">when</span> food <span class="keyword">isnt</span> <span class="string">'chocolate'</span>
</code></pre><pre><code><span class="keyword">var</span> courses, dish, food, foods, i, _i, _j, _k, _len, _len1, _len2, _ref;
_ref = [<span class="string">'toast'</span>, <span class="string">'cheese'</span>, <span class="string">'wine'</span>];
<span class="keyword">for</span> (_i = <span class="number">0</span>, _len = _ref.length; _i < _len; _i++) {
food = _ref[_i];
eat(food);
}
courses = [<span class="string">'greens'</span>, <span class="string">'caviar'</span>, <span class="string">'truffles'</span>, <span class="string">'roast'</span>, <span class="string">'cake'</span>];
<span class="keyword">for</span> (i = _j = <span class="number">0</span>, _len1 = courses.length; _j < _len1; i = ++_j) {
dish = courses[i];
menu(i + <span class="number">1</span>, dish);
}
foods = [<span class="string">'broccoli'</span>, <span class="string">'spinach'</span>, <span class="string">'chocolate'</span>];
<span class="keyword">for</span> (_k = <span class="number">0</span>, _len2 = foods.length; _k < _len2; _k++) {
food = foods[_k];
<span class="keyword">if</span> (food !== <span class="string">'chocolate'</span>) {
eat(food);
}
}
</code></pre><script>window.example9 = "# 吃午饭.\neat food for food in ['toast', 'cheese', 'wine']\n\n# 精致的五道菜.\ncourses = ['greens', 'caviar', 'truffles', 'roast', 'cake']\nmenu i + 1, dish for dish, i in courses\n\n# 注重健康的一餐.\nfoods = ['broccoli', 'spinach', 'chocolate']\neat food for food in foods when food isnt 'chocolate'\n"</script><div class='minibutton load' onclick='javascript: loadConsole(example9);'>load</div><br class='clear' /></div>
<p>
推导式可以适用于其他一些使用循环的地方，例如<b>each</b>/<b>forEach</b>,
<b>map</b>，或者<b>select</b>/<b>filter</b>，例如：
<tt>shortNames = (name for name in list when name.length < 5)</tt><br />
如果你知道循环的开始与结束，或者希望以固定的跨度迭代，你可以在范围推导式中
指定开始与结束。
</p>
<div class='code'><pre><code>countdown = (num <span class="keyword">for</span> num <span class="keyword">in</span> [<span class="number">10.</span><span class="number">.1</span>])
</code></pre><pre><code><span class="keyword">var</span> countdown, num;
countdown = (<span class="function"><span class="keyword">function</span><span class="params">()</span> {</span>
<span class="keyword">var</span> _i, _results;
_results = [];
<span class="keyword">for</span> (num = _i = <span class="number">10</span>; _i >= <span class="number">1</span>; num = --_i) {
_results.push(num);
}
<span class="keyword">return</span> _results;
})();
</code></pre><script>window.example10 = "countdown = (num for num in [10..1])\n\n"</script><div class='minibutton load' onclick='javascript: loadConsole(example10);'>load</div><div class='minibutton ok' onclick='javascript: var countdown, num;
countdown = (function() {
var _i, _results;
_results = [];
for (num = _i = 10; _i >= 1; num = --_i) {
_results.push(num);
}
return _results;
})();
;alert(countdown);'>run: countdown</div><br class='clear' /></div>
<p>
注意：上面的例子中我们展示了如何将推导式赋值给变量，CoffeeScript总是将
每个循环项收集到一个数组中。但是有时候以循环结尾的函数运行的目的就是
它们的副作用(side-effects)。这种情况下要注意不要意外的返回推导式的结果，
而是在函数的结尾增加一些有意义的返回值—例如<tt>true</tt> —
或 <tt>null</tt>。
</p>
<p>
在推导式中使用<tt>by</tt>子句，可以实现以固定跨度迭代范围值：
<tt>evens = (x for x in [0..10] by 2)</tt>
</p>
<p>
推导式也可以用于迭代对象中的key和value。在推导式中使用<tt>of</tt>
来取出对象中的属性，而不是数组中的值。
</p>
<div class='code'><pre><code>yearsOld = <span class="attribute">max</span>: <span class="number">10</span>, <span class="attribute">ida</span>: <span class="number">9</span>, <span class="attribute">tim</span>: <span class="number">11</span>
ages = <span class="keyword">for</span> child, age <span class="keyword">of</span> yearsOld
<span class="string">"<span class="subst">#{child}</span> is <span class="subst">#{age}</span>"</span>
</code></pre><pre><code><span class="keyword">var</span> age, ages, child, yearsOld;
yearsOld = {
max: <span class="number">10</span>,
ida: <span class="number">9</span>,
tim: <span class="number">11</span>
};
ages = (<span class="function"><span class="keyword">function</span><span class="params">()</span> {</span>
<span class="keyword">var</span> _results;
_results = [];
<span class="keyword">for</span> (child <span class="keyword">in</span> yearsOld) {
age = yearsOld[child];
_results.push(<span class="string">""</span> + child + <span class="string">" is "</span> + age);
}
<span class="keyword">return</span> _results;
})();
</code></pre><script>window.example11 = "yearsOld = max: 10, ida: 9, tim: 11\n\nages = for child, age of yearsOld\n \"#{child} is #{age}\"\n"</script><div class='minibutton load' onclick='javascript: loadConsole(example11);'>load</div><div class='minibutton ok' onclick='javascript: var age, ages, child, yearsOld;
yearsOld = {
max: 10,
ida: 9,
tim: 11
};
ages = (function() {
var _results;
_results = [];
for (child in yearsOld) {
age = yearsOld[child];
_results.push("" + child + " is " + age);
}
return _results;
})();
;alert(ages.join(", "));'>run: ages.join(", ")</div><br class='clear' /></div>
<p>
如果你希望仅迭代在当前对象中定义的属性，通过<tt>hasOwnProperty</tt>检查并
避免属性是继承来的，可以这样来写：<br />
<tt>for own key, value of object</tt>
</p>
<p>
CoffeeScript仅提供了一种底层循环，即<b>while</b>循环。与JavaScript中的<b>while</b>
循环的主要区别是，在CoffeeScript中<b>while</b>可以作为表达式来使用，
而且可以返回一个数组，该数组包含每个迭代项的迭代结果。
</p>
<div class='code'><pre><code><span class="comment"># 经济 101</span>
<span class="keyword">if</span> <span class="keyword">this</span>.studyingEconomics
buy() <span class="keyword">while</span> supply > demand
sell() <span class="keyword">until</span> supply > demand
<span class="comment"># 摇篮曲</span>
num = <span class="number">6</span>
lyrics = <span class="keyword">while</span> num -= <span class="number">1</span>
<span class="string">"<span class="subst">#{num}</span> little monkeys, jumping on the bed.
One fell out and bumped his head."</span>
</code></pre><pre><code><span class="keyword">var</span> lyrics, num;
<span class="keyword">if</span> (<span class="keyword">this</span>.studyingEconomics) {
<span class="keyword">while</span> (supply > demand) {
buy();
}
<span class="keyword">while</span> (!(supply > demand)) {
sell();
}
}
num = <span class="number">6</span>;
lyrics = (<span class="function"><span class="keyword">function</span><span class="params">()</span> {</span>
<span class="keyword">var</span> _results;
_results = [];
<span class="keyword">while</span> (num -= <span class="number">1</span>) {
_results.push(<span class="string">""</span> + num + <span class="string">" little monkeys, jumping on the bed. One fell out and bumped his head."</span>);
}
<span class="keyword">return</span> _results;
})();
</code></pre><script>window.example12 = "# 经济 101\nif this.studyingEconomics\n buy() while supply > demand\n sell() until supply > demand\n\n# 摇篮曲\nnum = 6\nlyrics = while num -= 1\n \"#{num} little monkeys, jumping on the bed.\n One fell out and bumped his head.\"\n"</script><div class='minibutton load' onclick='javascript: loadConsole(example12);'>load</div><div class='minibutton ok' onclick='javascript: var lyrics, num;
if (this.studyingEconomics) {
while (supply > demand) {
buy();
}
while (!(supply > demand)) {
sell();
}
}
num = 6;