javascript

Chapter 11: DOM Levels 2 and 3
Here, the namespace for XHTML is defined with a prefix of xhtml , requiring all XHTML elements to
begin with that prefix. Attributes may also be namespaced to avoid confusion between languages, as
shown in the following example:
< xhtml:html xmlns:xhtml=”http://www.w3.org/1999/xhtml” >
< xhtml:head >
< xhtml:title > Example XHTML page < /xhtml:title >
< /xhtml:head >
< xhtml:body xhtml:class=”home” >
Hello world!
< /xhtml:body >
< /xhtml:html >
The class attribute in this example is prefixed with xhtml . Namespacing isn ’ t really necessary when
only one XML - based language is being used in a document; it is, however, very useful when mixing two
languages together. Consider the following document containing both XHTML and SVG:
< html xmlns=”http://www.w3.org/1999/xhtml” >
< head >
< title > Example XHTML page < /title >
< /head >
< body >
< svg xmlns=”http://www.w3.org/2000/svg” version=”1.1”
viewBox=”0 0 100 100” style=”width:100%; height:100%” >
< rect x=”0” y=”0” width=”100” height=”100” style=”fill:red” / >
< /svg >
< /body >
< /html >
In this example, the < svg > element is indicated as foreign to the containing document by setting its own
namespace. All children of the < svg > element, as well as all attributes of the elements, are considered to
be in the http://www.w3.org/2000/svg namespace. Even though the document is technically an
XHTML document, the SVG code is considered valid because of the use of namespaces.
The interesting problem with a document such as this is what happens when a method is called on the
document to interact with nodes in the document. When a new element is created, which namespace
does it belong to? When querying for a specific tag name, what namespaces should be included in the
results? DOM Level 2 Core answers these questions by providing namespace - specific versions of most
DOM Level 1 methods.
Changes to Node
The Node type evolves in DOM Level 2 to include the following namespace - specific properties:
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localName — The node name without the namespace prefix
namespaceURI — The namespace URI of the node or null if not specified
prefix — The namespace prefix or null if not specified
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