Chapter 1. Introduction to JavaScript
2009-02-19 22:00
JavaScript is an interpreted programming language with object-oriented (OO) capabilities. Syntactically, the core JavaScript language resembles C, C++, and Java, with programming constructs such as the if statement, the while loop, and the && operator. The similarity ends with this syntactic resemblance, however. JavaScript is a loosely typed language, which means that variables do not need to have a type specified. Objects in JavaScript map property names to arbitrary property values. In this way, they are more like hash tables or associative arrays (in Perl) than they are like structs (in C) or objects (in C++ or Java). The OO inheritance mechanism of JavaScript is prototype-based like that of the little-known language Self. This is quite different from inheritance in C++ and Java. Like Perl, JavaScript is an interpreted language, and it draws inspiration from Perl in a number of areas, such as its regular-expression and array-handling features.
JavaScript 是一种具有面向对象能力的并且非常有意思的编程语言。依据造句法，核心 JavaScript 语言类似于 C, C++,和Java ，编程构造如 if 语句, while 循环 还有 && 操作符. [还有一些其他东西相似],可是,JavaScript 是一种动态语言,它意味着变量不需要特定的类型。[对象在JavaScript 属性名任意对应属性值]。这样非常像哈希表或者Perl语言中的联合数组,像C中的结构或C++和Java的对象。[JavaScript OO 以prototype为基础继承机制].这点完全不同于C++和Java的继承.像Perl. JavaScript 是一种解释型语言,许多部分从Perl上得到启示.例如正则表达式和数组的操作。
The core JavaScript language supports numbers, strings, and Boolean values as primitive datatypes. It also includes built-in support for array, date, and regular-expression objects.
核心JavaScript 语言支持数字,字符串和布尔值作为简单类型。同时也包含了内置支持像数组，日期，正则表达式对象。
JavaScript is most commonly used in web browsers, and, in that context, the general-purpose core is extended with objects that allow scripts to interact with the user, control the web browser, and alter the document content that appears within the web browser window. This embedded version of JavaScript runs scripts embedded within HTML web pages. It is commonly called client-side JavaScript to emphasize that scripts are run by the client computer rather than the web server.
JavaScript是WEB游览器种最通用的语言，并且，在这种背景之下，[对象是扩展的核心，它允许脚本与用户、控制游览器相结合，并且改变游览器窗体文档中的内容].JavaScript脚本运行在HTML web页中。通常成为客户端脚本。客户端脚本在客户端计算机中'速度'胜于服务端。
The core JavaScript language and its built-in datatypes are the subject of international standards, and compatibility across implementations is very good. Parts of client-side JavaScript are formally standardized, other parts are de facto standards, and other parts are browser-specific extensions. Cross-browser compatibility is often an important concern for client-side JavaScript programmers.
核心JavaScript与语言和内置类型建立在国际标准上，[有非常好的兼容性],[部分客户端JavaScript是形式上的标准],其他一部分是事实上的标准,还有其他一部分是对特定游览器的扩展.[客户端JavaScript编程跨游览器的能力是很重要的]。
This chapter is a high-level overview of JavaScript; it provides the background information you need before embarking on a study of the language. As motivation and introduction, it includes some simple examples of client-side JavaScript code.
这一章是对JavaScript的高度概括。给学习这门语言提供了背景信息。与动机和导言一样，它包含的许多简单的客户端JavaScript代码。
end 2009-02-18 22:39