javascript

Chapter 11: DOM Levels 2 and 3
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removeNamedItemNS( namespaceURI , localName ) — Removes the item from the namespace
represented by namespaceURI and with a name of localName
setNamedItemNS( node ) — Adds node , which should have namespace information already
applied
These methods are rarely used, because attributes are typically accessed directly from an element.
Other Changes
There are some other minor changes made to various parts of the DOM in DOM Level 2 Core. These
changes don ’ t have to do with XML namespaces and are targeted more toward ensuring the robustness
and completeness of the API.
Changes to DocumentType
The DocumentType type adds three new properties: publicId , systemId , and internalSubset . The
first two of these properties represent data that is readily available in a doctype but were inaccessible
using DOM Level 1. Consider the following HTML doctype:
< !DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01//EN”
“http://www.w3.org/TR/html4/strict.dtd” >
In this doctype, the publicId is “ - //W3C//DTD HTML 4.01//EN ” and the systemId is “ http://www
.w3.org/TR/html4/strict.dtd ” . Browsers that support DOM Level 2 should be able to run the
following JavaScript code:
alert(document.doctype.publicId);
alert(document.doctype.systemId);
Accessing this information is rarely, if ever, needed in web pages.
The internalSubset property accesses any additional definitions that are included in the doctype, as
shown in the following example:
< !DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Strict//EN”
“http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd”
[ < !ELEMENT name (#PCDATA) > ] >
For this code, document.doctype.internalSubset returns “ < !ELEMENT name (#PCDATA) > ” .
Internal subsets are rarely used in HTML and are slightly more common in XML.
Changes to Document
The only new method on Document that is not related to namespaces is importNode() . The purpose of
this method is to take a node from a different document and import it into a new document so that it can
be added into the document structure. Remember, every node has an ownerDocument property that
indicates the document it belongs to. If a method such as appendChild() is called and a node with a
different ownerDocument is passed in, an error will occur. Calling importNode() on a node from
a different document returns a new version of the node that is owned by the appropriate document.
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