4 Overview(概览)

This section contains a non-normative overview of the ECMAScript language.

本节包含ECMAScript语言的非规范性概述。

ECMAScript is an object-oriented programming language for performing computations and manipulating computational objects within a host environment. ECMAScript as defined here is not intended to be computationally self-sufficient; indeed, there are no provisions in this specification for input of external data or output of computed results. Instead, it is expected that the computational environment of an ECMAScript program will provide not only the objects and other facilities described in this specification but also certain environment-specific objects, whose description and behaviour are beyond the scope of this specification except to indicate that they may provide certain properties that can be accessed and certain functions that can be called from an ECMAScript program.

ECMAScript是一个在宿主环境中用来执行计算和操作计算对象的面向对象的编程语言。在这里定义的ECMAScript并不打算计算性自足；事实上，本规范没有任何针对输入外部数据或输出计算结果的条文。相反，我们期望 ECMAScript 程序的计算环境可提供本规范中描述的对象和其它设施之外的、某些特定环境下的 宿主 (host) 对象，除了说明宿主对象应该提供可被 ECMAScript 程序访问的某些属性，调用的某些方法外，关于它的其他描述和行为超出了本规范涉及的范围。

ECMAScript was originally designed to be used as a scripting language, but has become widely used as a general-purpose programming language. Ascripting languageis a programming language that is used to manipulate, customize, and automate the facilities of an existing system. In such systems, useful functionality is already available through a user interface, and the scripting language is a mechanism for exposing that functionality to program control. In this way, the existing system is said to provide a host environment of objects and facilities, which completes the capabilities of the scripting language. A scripting language is intended for use by both professional and non-professional programmers.

ECMAScript最初是作为一种脚本语言来设计的，但是已经广泛的被作为一种通用编程语言在使用。脚本语言是一种用来在现有系统中操作、自定义和自动化实施的编程语言。在这种系统中，可用的功能已经可以通过一个用户接口来使用，该脚本语言是用来暴露这些功能给程序控制的一种机制。通过这种方法，已经存在的系统被称作提供了一个对象和工具的宿主环境来完成脚本语言的能力。脚本语言倾向于可以同时被专业和非专业的程序员使用。

ECMAScript was originally designed to be aWeb scripting language, providing a mechanism to enliven Web pages in browsers and to perform server computation as part of a Web-based client-server architecture. ECMAScript is now used to provide core scripting capabilities for a variety of host environments. Therefore the core language is specified in this document apart from any particular host environment.

ECMAScript 最初被设计为 Web 脚本语言 ，提供了一种机制，使浏览器里的网页更加活跃，成为基于 Web 的客户 - 服务器架构的一部分执行服务器计算。ECMAScript 可以为各种宿主环境提供核心的脚本功能，因此本文档为不依赖特定宿主环境的核心脚本语言作出规范。

ECMAScript usage has moved beyond simple scripting and it is now used for the full spectrum of programming tasks in many different environments and scales. As the usage of ECMAScript has expanded, so has the features and facilities it provides. ECMAScript is now a fully featured general-purpose programming language.

ECMAScript的用已经超越了简单的脚本语言范围，它可用于多种不同的环境和各类的编程任务中。由于ECMAScript的用途被扩大了，所以它提供了这些特性和工具。ECMAScript现在功能完善的通用编程语言。

Some of the facilities of ECMAScript are similar to those used in other programming languages; in particular C, Java™, Self, and Scheme as described in:

部分ECMAScript的功能和那些已经存在的编程语言类似，特别是下文中描述的C, Java™, Self, 和 Scheme ：

ISO/IEC 9899:1996,Programming Languages – C.

Gosling, James, Bill Joy and Guy Steele.The Java™Language Specification. Addison Wesley Publishing Co., 1996.

Ungar, David, and Smith, Randall B. Self: The Power of Simplicity.OOPSLA '87 Conference Proceedings, pp. 227-241, Orlando, FL, October 1987.

IEEE Standard for the Scheme Programming Language. IEEE Std 1178-1990.