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DOM support in Web browsers

When reading about the DOM, you may come across references to DOM Level 0. Note that there is no

standard called DOM Level 0; it is simply a reference point in the history of the DOM (DOM Level 0 is

considered to be the original DHTML supported in Internet Explorer 4.0 and Netscape Navigator 4.0).

Other DOMs

Aside from the DOM Core and DOM HTML interfaces, several other languages have had their own

DOM standards published. The languages are XML-based and each DOM adds methods and interfaces

unique to that language:

Scalable Vector Graphics (SVG) 1.0

Mathematical Markup Language (MathML) 1.0

Synchronized Multimedia Integration Language (SMIL)

Additionally, other languages have developed their own DOM implementations, such as Mozilla’s XML

User Interface Language (XUL). However, only the languages in the preceding list are standard recom-

mendations from W3C.

DOM support in Web browsers

The DOM was already a standard for some time before Web browsers started implementing it. Internet

Explorer took first stab in version 5.0, but it actually didn’t have any realistic DOM support until version

5.5, when it implemented most of DOM Level 1. Internet Explorer hasn’t introduced new DOM function-

ality since that time.

For Netscape, no DOM support existed until Netscape 6 (Mozilla 0.6.0) was introduced. To date, Mozilla

has the best support for the DOM, implementing all of Level 1, nearly all of Level 2, and some parts of

Level 3. (The goal of the Mozilla development team was to build a 100% standards-compliant browser,

and their work paid off.)

Latecomers such as Opera, which didn’t add DOM support until version 7.0, and Safari, which has

implemented most of DOM Level 1, are mostly on par with Internet Explorer 5.5; and in some cases,

they exceed it. However, all the browsers are still a distant second to Mozilla as far as DOM support

goes. The following table shows DOM support for popular browsers:

Browser

DOM Compliance

Netscape Navigator 1.0–4.x

–

Netscape 6.0+ (Mozilla 0.6.0+)

Level 1, Level 2, Level 3 (partial)

Internet Explorer 2.0–4.x

–

Internet Explorer 5.0

Level 1 (minimal)

Internet Explorer 5.5+

Level 1 (almost all)

Opera 1.0–6.0

–

Opera 7.0+

Level 1 (almost all), Level 2 (partial)

Safari 1.0+/Konqueror ~2.0+

Level 1

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