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Netscape Browsers

Netscape browsers up to and including version 4 are rapidly becoming much less relevant than they once were. Die-hard fans are switching to Mozilla-based browsers, and the number of users with these outdated browsers is rapidly diminishing. The decline of Netscape 4 and earlier will only continue as time goes on, so we only briefly touch on the specifics of this browser in this section.

JavaScript

With a few exceptions, Netscape incorporated JavaScript language improvements into major releases of new browser versions. Netscape refers to its implementation of the language as “JavaScript x” where x identifies the language version number. Table 21-13 shows the correspondence between language and browser versions.

Table 21-13: Correspondence Between JavaScript Language Versions and Netscape Browser Versions

Language Version

Browser Version

JavaScript 1.0

Netscape 2

JavaScript 1.1

Netscape 3

JavaScript 1.2

Netscape 4.0–4.05

JavaScript 1.3

Netscape 4.06–4.7

JavaScript 1.4

None (server-side only)

JavaScript 1.5

Netscape 6.x and 7.x

JavaScript 1.0, the first JavaScript implementation, was included as a part of Netscape 2 and formed the loose basis for ECMAScript, the standard for the core language features of JavaScript. Other versions of Netscape JavaScript correspond to the ECMAScript standard in varying degrees. The correspondence between Netscape JavaScript and ECMAScript is shown in Table 21-14.

Table 21-14: Correspondence Between Language Version and ECMAScript Standards

Netscape Version

Standard Version

Exceptions

JavaScript 1.0–1.2

Very loose conformance to ECMA-262 Edition 1

Many, especially with the Date object, and many extra features

JavaScript 1.3

Strict conformance to ECMA-262 Edition 1

Includes some extra features

JavaScript 1.4

Strict conformance to ECMA-262 Edition 1

Includes some extra features

JavaScript 1.5

Strict conformance to ECMA-262 Edition 3

Includes some extra features

It is sometimes necessary to write JavaScript to accommodate the capabilities of a specific range of browsers. To do so, you need to make sure that you use only language features available in the browsers of interest; for example, you will need to avoid using Number.MAX_VALUE in Netscape 2 because it was introduced in JavaScript 1.1.

Complete documentation of which core ECMAScript features are found in which browser and language version can be found in Appendix B. In addition, there are several Web sites that are very useful for researching compliance and the language standards themselves. For now, Netscape maintains its JavaScript reference in the “Documentation” section of http://devedge.netscape.com, though, with the browser at the end of its life, it may be removed in the relatively near future. References to the ECMAScript standard are included in the JavaScript portion of the Mozilla project at http://www.mozilla.org/js/language/.


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