> Web Browser Guide

Browser Compatibility Chart

The following chart outlines support for key features across all major browsers.

Notes

By default, Java Runtime Environment 1.1.4 (JRE 1.1.4) is installed with IE 5.5. You can quickly upgrade to Java Development Kit 1.3 (JDK 1.3) with Sun's plug-in.

Most browsers do not understand THEAD, TBODY, and TFOOT which is unfortunate given the power these tags can have for printing and viewing long tables.

IE 5.5 uses JScript which is basically ECMA-compliant in recent versions. JScript maps relatively cleanly to the JavaScript versions used by Netscape and Opera. IE 5.5 uses JScript 5.5 which is compatible with ECMA-262 and (for the most part) supports JavaScript 1.5 features.

There are a few problems with CSS1 although CSS1 is pretty well supported. CSS2 is weak, even for XML support and positioning. Watch for IE 6.0 to fix up much of the CSS2 and CSS Positioning (CSS-P) support.

DOM2 is not well supported in IE 5.5 and proprietary extensions are still frequently used when manipulating the IE document (e.g. innerHTML) even though these features are not yet approved by W3C.

XML 1.0 is partly supported, and XHTML 1.0 is pretty well supported. IE 5.5 has included an XSLT engine via MSXML (unlike Netscape's CSS/XML solution). A new MSXML release (3.0) includes an upgraded XSL engine that is much improved—look for it in IE 6.0. CSS/XML integration in IE 5.5 is minimal.

Netscape 6 comes with JRE 1.3 but only a specific Sun version of the JRE (J2SE 1.30_01) is supported at present.

Netscape has provided good JavaScript 1.5/ECMA-262 support in their new browser. However, they have made a very significant (and unfortunate) decision to rule out some of their noncompliant JavaScript additions that were introduced with NN 4.x contrary to specifications. Consequently, some of your JavaScript may have to test for NN 4.x, IE 4/5 and NN 6.x now, as document.layers , document.embeds , and so on are now missing. Even more surprising, Netscape now supports some of IE 5.x's proprietary features like innerHTML.

CSS1 is well supported in NN 6, thanks to the new Gecko rendering engine. CSS2 is partially implemented, and excellent integration for XML/DOM support is provided.

DOM1 is well supported, and DOM2 partial support (e.g. events) are also integrated into the browser. The DOM Model now complies with the W3C standard, but as mentioned in note 9, Netscape has chosen to forego its noncompliant additions introduced in NN 4.x, meaning that some of your code may still detect NN 6 as non-IE, yet break due to the lack of support for legacy DOM interface elements.

I-Frames are now supported in NN 6, but don't look for layers anymore! As already discussed above (note 9) Netscape has tossed many of its noncompliant features.

XML is well supported, as is XHTML 1.0. Netscape has also provided support for RDF metadata definition. Unlike IE 5.x, Netscape has not integrated XSLT capability into the rendering engine, forcing you to rely on simpler CSS/XML capabilities instead.

JRE 1.3 is provided, but as an optional download configuration and installation option.

Realize that frames can be turned off, so frames behavior is not guaranteed.

JavaScript 1.3/ECMA are partially supported in Opera. Not only are some features missing, but many have been broken since the latest 3.x release. They are working hard to fix this up. Also, realize that Opera can spoof NN or IE, meaning that your browser detection script may not detect Opera properly. Check out Netscape's "Ultimate Sniffer Script" for pretty reliable detection.

CSS1 and CSS2 are both partially supported in Opera. Unfortunately, there are bugs and missing features that make CSS rendering in Opera a bit uncertain for some code that validates and displays properly in IE 5.x and NN 6.

By default, these were disabled in my installation. You can turn this feature on from the preferences.

A good portion of DOM1 is supported in IE 5 for the Mac (chunks of DOM1 core are missing). However, the DOM support in Mac and Windows IE 5 is not consistent. This code is not cross-platform, and the Macintosh engine, while perhaps better at implementing DOM 1.0, is not consistent with IE 5 for Windows in all areas.

Mac IE 5 has partial XML 1.0 support.

Our tests indicate that CSS1 is exceptionally well supported in Macintosh IE 5, but that CSS2 is quite partial.

IE 5 lets you upgrade your JRE independent of your browser, as it leverages the MRJ provided from Apple. Tests and reports indicate that MRJ 2.2.3 (compatible with JDK 1.1.8) is relatively stable with IE 5 on the Mac, but earlier versions of MRJ may not be nearly as stable or predictable.