JavaScript：世界上误解最深的语言

JavaScript:

The World's Most Misunderstood Programming Language

Douglas Crockford

www.crockford.com

翻译：袁晓辉（http://blog.csdn.net/uoyevoli/）

JavaScript, aka Mocha, aka LiveScript, aka JScript, aka ECMAScript, is one of the world's most popular programming languages. Virtually every personal computer in the world has at least one JavaScript interpreter installed on it and in active use. JavaScript's popularity is due entirely to its role as the scripting language of the WWW.

JavaScript，或者叫 Mocha，或者叫 LiveScript，或者叫 JScript，又或者叫 ECMAScript，是世界上最流行的编程语言之一。事实上世界上的每一台个人电脑都安装并在频繁使用至少一个JavaScript解释器。JavaScript的流行完全是由于他在WWW脚本语言领域中的地位决定的。

Despite its popularity, few know that JavaScript is a very nice dynamic object-oriented general-purpose programming language. How can this be a secret? Why is this language so misunderstood?

尽管它很流行，但是很少有人知道JavaScript是一个非常棒的动态面向对象通用编程语言。这居然能成为一个秘密！这门语言为什么被误解如此之深？

The Name

名字

The Java- prefix suggests that JavaScript is somehow related to Java, that it is a subset or less capable version of Java. It seems that the name was intentionally selected to create confusion, and from confusion comes misunderstanding. JavaScript is not interpreted Java. Java is interpreted Java. JavaScript is a different language.

Java- 前缀很容易使人联想到Java，并认为它是Java的子集或简化版的Java。看起来最初给它选这个名字是别有用心的，是故意混淆概念、故意制造"误解"的。JavaScript不是解释执行的Java。Java是解释执行的Java。JavaScript是另外一种语言。

JavaScript has a syntactic similarity to Java, much as Java has to C. But it is no more a subset of Java than Java is a subset of C. It is better than Java in the applications that Java (fka Oak) was originally intended for.

JavaScript的语法和Java有相似之处，这就像Java的语法和C很相像一样。但是它不是Java的子集，就像Java不是C的子集一样。它在Java（Oak）最初打算进军的领域中比Java更好。

JavaScript was not developed at Sun Microsystems, the home of Java. JavaScript was developed at Netscape. It was originally called LiveScript, but that name wasn't confusing enough.

JavaScript不是Sun Microsystems的产品，Sun是Java的家。JavaScript是在Netscape被开发出来的。它最初叫LiveScript，嗯……还是这个名字好。

The -Script suffix suggests that it is not a real programming language, that a scripting language is less than a programming language. But it is really a matter of specialization. Compared to C, JavaScript trades performance for expressive power and dynamism.

-Script后缀让人认为他不是一门真正的编程语言，和一门"编程语言"还有相当的差距。但是这只是应用领域的问题。和C相比，JavaScript是牺牲了性能但换来了丰富的表现力和灵活的形态。

Lisp in C's Clothing

披着C皮的Lisp

JavaScript's C-like syntax, including curly braces and the clunky for statement, makes it appear to be an ordinary procedural language. This is misleading because JavaScript has more in common with functional languages like Lisp or Scheme than with C or Java. It has arrays instead of lists and objects instead of property lists. Functions are first class. It has closures. You get lambdas without having to balance all those parens.

JavaScript的类C语法，包括大括号和语句的形式，让它看起来像普通的面向过程编程语言。这是一种误解，因为JavaScript和函数式语言，比如 Lisp 或 Scheme，有更多的相似之处，而不是和C或Java。它使用数组而不是列表，使用对象而不是属性列表。函数是第一位的，它有闭包（closures），另外你还可以使用lambda表达式。

Typecasting

类型转换

JavaScript was designed to run in Netscape Navigator. Its success there led to it becoming standard equipment in virtually all web browsers. This has resulted in typecasting. JavaScript is the George Reeves of programming languages. JavaScript is well suited to a large class of non-Web-related applications

JavaScript最初被设计成在Netscape Navigator中运行，它在Navigator中的成功引领它成为事实上所有web浏览器的标准装备。这就造就了"类型转换"。JavaScript是编程语言中的 George Reeves（超人），是大量非web程序的称职之选。

Moving Target

移动靶

The first versions of JavaScript were quite weak. They lacked exception handling, inner functions, and inheritance. In its present form, it is now a complete object-oriented programming language. But many opinions of the language are based on its immature forms.

JavaScript的最初几版非常弱，没有异常处理，没有内部函数和继承。现如今，它已经成为完全面向对象的编程语言。但是这门语言的许多思想是基于它不成熟的形式的。

The ECMA committee that has stewardship over the language is developing extensions which, while well intentioned, will aggravate one of the language's biggest problems: There are already too many versions. This creates confusion.

ECMA委员会，这门语言的管家，正在对它进行扩展，也在蓄意恶化它最大的问题：有太多的版本。这是混乱的根源。

Design Errors

设计上的错误

No programming language is perfect. JavaScript has its share of design errors, such as the overloading of + to mean both addition and concatenation with type coercion, and the error-prone with statement should be avoided. The reserved word policies are much too strict. Semicolon insertion was a huge mistake, as was the notation for literal regular expressions. These mistakes have led to programming errors, and called the design of the language as a whole into question. Fortunately, many of these problems can be mitigated with a good lint program.

没有什么编程语言是完美的。JavaScript也有它设计上的错误，比如重载的+号随着类型的不同既表示"相加"又表示"连接"，和本该避免的有错误倾向的 with 语句。它的保留字策略过于严格。分号的插入是一个巨大的错误，比如作为字面正则表达式的符号时。这些失误已直接导致编程中的错误，也使这门语言的整体设计遭人质疑。还好，这些问题中有许多都可以在良好的 lint 程序中得以缓解。

The design of the language on the whole is quite sound. Surprisingly, the ECMAScript committee does not appear to be interested in correcting these problems. Perhaps they are more interested in making new ones.

这门语言的整体设计（上的问题）是相当明显的。奇怪的是ECMAScript委员会并没有对修正其中存在的问题表现出太大的兴趣，也许他们更热衷于制造新的问题。

Lousy Implementations

糟糕的实现

Some of the earlier implementations of JavaScript were quite buggy. This reflected badly on the language. Compounding that, those implementations were embedded in horribly buggy web browsers.

JavaScript的一些早期实现有许多bug，这反过来对语言本身产生了很坏的影响。更糟糕的是这些满是bug的实现是嵌入在满是bug的web浏览器中的。

Bad Books

糟糕的书

Nearly all of the books about JavaScript are quite awful. They contain errors, poor examples, and promote bad practices. Important features of the language are often explained poorly, or left out entirely. I have reviewed dozens of JavaScript books, and I can only recommend one: JavaScript: The Definitive Guide (4th Edition) by David Flanagan. (Attention authors: If you have written a good one, please send me a review copy.)

几乎所有的JavaScript书都是相当可怕的。它们包含错误，包含不好的例子，并鼓励不好的做法。JavaScript语言的一些重要特性它们要么没有解释清楚，要么根本就没有提及。我看过很多JavaScript的书，但我只能推荐一本：David Flanagan著的 JavaScript: The Definitive Guide (4th Edition) （《JavaScript权威指南第四版》）。（作者们请注意：如果你们写出了好书请发给我一份副本，我给你们校对。）

Substandard Standard

“准标准”的标准

The official specification for the language is published by ECMA. The specification is of extremely poor quality. It is difficult to read and very difficult to understand. This has been a contributor to the Bad Book problem because authors have been unable to use the standard document to improve their own understanding of the language. ECMA and the TC39 committee should be deeply embarrassed.

ECMA公布的官方语言规范的质量极其的差。不仅难读而且极其难懂。它可为那些"糟糕的书"做出了不小的贡献，因为那些作者无法通过这个标准文档来更深地理解这门语言。ECMA和TC39应该为此感到非常尴尬。

Amateurs

业余者

Most of the people writing in JavaScript are not programmers. They lack the training and discipline to write good programs. JavaScript has so much expressive power that they are able to do useful things in it, anyway. This has given JavaScript a reputation of being strictly for the amateurs, that it is not suitable for professional programming. This is simply not the case.

使用JavaScript的人大多不是程序员，他们缺少写良好程序的培训和训练。JavaScript有非常强大的表现力，不管怎样他们也能使用它做有用的事情。这给了JavaScript一个”全然适合业余爱好者而不适合专业程序员“的名声。这很明显是一个错误。

Object-Oriented

面向对象

Is JavaScript object-oriented? It has objects which can contain data and methods that act upon that data. Objects can contain other objects. It does not have classes, but it does have constructors which do what classes do, including acting as containers for class variables and methods. It does not have class-oriented inheritance, but it does have prototype-oriented inheritance.

JavaScript是面向对象的吗？它有对象，它的对象可以包含数据以及对数据进行操作的方法，对象也可以包含其他的对象。它没有类，但是它有构造函数来做类的事情，包括声明类的变量和方法。它没有面向类的继承，但是他有面向原型的继承。

The two main ways of building up object systems are by inheritance (is-a) and by aggregation (has-a). JavaScript does both, but its dynamic nature allows it to excel at aggregation.

构建对象系统的两大主要方法是继承（is-a）和聚合（has-a）。这两者JavaScript都有，但是它的动态天性允许有比聚合更好的实现方式。

Some argue that JavaScript is not truly object oriented because it does not provide information hiding. That is, objects cannot have private variables and private methods: All members are public.

一些关于JavaScript不是真的面向对象的争论其理由是它没有提供信息隐藏。也就是说JavaScript的对象没有私有变量和私有方法：它的所有成员都是公开的。

But it turns out that JavaScript objects can have private variables and private methods. (Click here now to find out how.) Of course, few understand this because JavaScript is the world's most misunderstood programming language.

但是事实是JavaScript 的对象可以有私有变量和私有方法（点击这里来看如何实现）。当然，之所以很少有人知道这个是因为JavaScript是世界上误解最深的语言嘛。

Some argue that JavaScript is not truly object oriented because it does not provide inheritance. But it turns out that JavaScript supports not only classical inheritance, but other code reuse patterns as well.

另一些关于JavaScript不是真的面向对象的争论其理由是它没有提供继承。但是事实是JavaScript不但支持经典的继承，而且支持其他一些代码重用的模式。

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原文链接：http://www.crockford.com/javascript/javascript.html