AJAX - The Complete Reference

554 Part IV: Appendixes

NNOT EOTE Inclusion of less common JavaScript versions supported in modern versions of Firefox requires

different type settings for the <script> tag. For example, <script type="application/

javascript;version=1.7"> or <script type="application/javascript;

version=1.8"> would be used to signify JavaScript 1.7 or 1.8, respectively.

Microsoft’s JScript is more ubiquitous, given Internet Explorer’s market share and

compatibility with this browser family, and its object model is often a goal for developers.

Table A-3 details the evolution of JavaScript support within these browsers.

NNOT EOTE JScript.NET also exists and has more features, but it is not currently browser based.

JavaScript Inclusion Methods

While not formally part of the language itself, the methods used to include JavaScript

within Web pages are quite important. Table A-4 details each method.

Including JavaScript in a document does not guarantee it will be understood or run by

the fetching user agent. To address such concerns, JavaScript developers should use the

<noscript> tag to present an alternative path for non-JavaScript-aware browsers.

<noscript>

<h1 class="jsError">Error: This Web application requires JavaScript</h1>

<a href="errors/jsoff.html">More information about required technology</a>

</noscript>

JScript

Language

Version

Approximate

JavaScript

Equivalence ECMA Conformance

Browser

Version Notes

JScript 1.0 1.0 Loose ECMA-262

Edition 1

Internet

Explorer 3.0

Similar features to the

Netscape 2 implementation of

JavaScript.

JScript 3.0 1.3 ECMA-262 Edition 1 Internet

Explorer 4.0

DHTML generation object model

with document.all and

full style sheet manipulation.

Some basic W3C DOM ideas

introduced.

JScript 5.0 1.5 ECMA-262 Edition 1 Internet

Explorer 5.0

ActiveX based XHRs introduced.

JScript 5.5 1.5 ECMA-262 Edition 3 Internet

Explorer 5.5

Partial W3C DOM conformance.

JScript 5.6 1.5 ECMA-262 Edition 3 Internet

Explorer 6.0

Improved but partial W3C DOM

conformance.

JScript 5.7 1.5 ECMA-262 Edition 3 Internet

Explorer 7.0

Native XHRs added.

TABLE A-3 Internet Explorer JScript/JavaScript Version History