1.2. Versions of JavaScript

Like any new technology, JavaScript evolved quickly when it was new. Previous editions of this book documented this evolution version by version, explaining exactly which language features were introduced in which version of the language. At the time of this writing, however, the language has stabilized and has been standardized by the European Computer Manufacturer's Association, or ECMA.^[*] Implementations of this standard include the JavaScript 1.5 interpreter from Netscape and the Mozilla Foundation, and the JScript 5.5 interpreter from Microsoft. Any web browser newer than Netscape 4.5 or Internet Explorer 4 supports the latest version of the language. As a practical matter, you are unlikely to encounter a noncompliant interpreter.

^[*] The standard is ECMA-262, version 3 (available at http://www.ecma-international.org/publications/files/ecma-st/ECMA-262.pdf).

Note that the official name of the language, according to the ECMA-262 standard, is ECMAScript. But this awkward name is normally used only when making explicit reference to the standard. Technically, the name "JavaScript" refers only to language implementations from Netscape and the Mozilla Foundation. In practice, however, everyone calls the language JavaScript.