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先说JavaScript

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JavaScript让人又爱又恨，因为它独特，卓越，而且不可或缺。尽管如此，要说JavaScript很美，恐怕也有些勉强。 JavaScript现在如日中天，未来发展更是不可小觑。但毕竟它的设计非常仓促¹, 有些陷阱², 有些晦涩³; 要不为啥Douglas Crockford的书名字叫《The Good Parts of JavaScript》呢? (题外话: 中文翻译叫\"JavaScript语言精粹\", 这实在是春秋笔法, 为圣者讳:D)\r\n
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所以, 要是中肯的评价JavaScript: “就是不美”.\r\n

JavaScript为什么不美

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我觉得amix讲的很清楚⁴:\r\n

JavaScript是函数式语言;

是基于prototype实现的面向对象语言;

是动态语言, 更像Lisp而非C/Java; 但却使用了C/Java的语法;

名字里面叫Java, 其实和Java根本不搭边;

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结论就是JavaScript的诞生是个悲剧. 它是函数式+动态语言的优秀内核, 却硬被绑上了C/Java的语法; 如同高分屏贴膜, 又如同剑宗人士非摆出气宗架势; 带有这种语法的JavaScript就如同包裹石头的璞玉⁵, 外壳和内涵大不相称.\r\n
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所以最大的别扭, 就在语法上.\r\n

CoffeeScript为什么美

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语法从Lisp系重生

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CoffeeScript打蛇打到七寸了. 它的最大功绩, 就是将JavaScript硬绑的C/Java语法抛弃了; 改为采用类似Ruby/Python的语法. Ruby/Python本来就是深受Lisp影响的, 和JavaScript算是同门师兄, 他们的语法经过了实践考验, 是更适合函数式+动态语言内核的.\r\n

Good Parts

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CoffeeScript只使用了JavaScript的\"Good Parts(精粹)\", 抛弃了原来JavaScript晦涩的,容易出问题的那部分东西. 比如, 全局变量声明, with 啥的.\r\n

语法糖和ECMAScript

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CoffeeScript提供了很多语法糖, 让代码更优雅可读. 去主页仔细看看CoffeeScript的语法清单, 就会发现边边角角到处是创新. 这让编程语言真的成了开发者的朋友, 而不是机器的朋友.\r\n
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CoffeeScript还提供了一个机会, 让你现在就可以使用ECMAScript⁶里面的特性. 将来有个更多新特性, CoffeeScript也有机会在浏览器支持之前实现它们. 程序员面对的是CoffeeScript的优雅接口, 它是程序员和JavaScript之间的中间层, 脏活累活它都干了.\r\n

八卦一下未来

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CoffeeScript构建在JavaScript上层, 这让人联想起.Net和C#/F#/VB… , 以及JVM和Java/JRuby/Scala…\r\n
在JavaScript上层做事情的, 不只CoffeeScript, 还有很多其他的. 比如lua就有通过LLVM转换成JavaScript的实现. 前段时间的JavaScript PC模拟器⁷也证明了这种思路的威力.\r\n
也许JavaScript就是下一个JVM, 上面会有最适用于各种场景的各种语言. 很多人盼望JavaScript成为为未来的唯一语言, 看起来这是不切实际的幻想了.\r\n

CoffeeScript首页的一段展示代码

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# Assignment:\r\n
number   = 42\r\n
opposite = true\r\n
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# Conditions:\r\n
number = -42 if opposite\r\n
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# Functions:\r\n
square = (x) -> x * x\r\n
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# Arrays:\r\n
list = [1, 2, 3, 4, 5]\r\n
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# Objects:\r\n
math =\r\n
  root:   Math.sqrt\r\n
  square: square\r\n
  cube:   (x) -> x * square x\r\n
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# Splats:\r\n
race = (winner, runners...) ->\r\n
  print winner, runners\r\n
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# Existence:\r\n
alert \"I knew it!\" if elvis?\r\n
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# Array comprehensions:\r\n
cubes = (math.cube num for num in list)

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1: Javascript诞生记\r\n
2: Javascript的10个设计缺陷\r\n
3: JavaScript: 世界上最被误解的语言\r\n
4: CoffeeScript: The beautiful way to write JavaScript\r\n
5: JavaScript: 死或新生(4)\r\n
6: ECMAScript – WikiPedia\r\n
7: JavaScript PC emulator\r\n
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我的blog: http://www.dulao5.com/ ; 原文 ; 在Twitter上推它 ;","title","为什么CoffeeScript这么美?","last_reply_at","2013-05-27 10:49:21.084","good","top",19,"visit_count",27223,"2011-07-28 09:36:16","author",{"_13":54,"_22":55},"duzhigang","http://www.gravatar.com/avatar/864eaff251427ff19791105794ba59cc?s=48"]