javascript

Chapter 11: DOM Levels 2 and 3
When a node uses a namespace prefix, the nodeName is equivalent to prefix + “ : ” + localName .
Consider the following example:
< html xmlns=”http://www.w3.org/1999/xhtml” >
< head >
< title > Example XHTML page < /title >
< /head >
< body >
< s:svg xmlns:s=”http://www.w3.org/2000/svg” version=”1.1”
viewBox=”0 0 100 100” style=”width:100%; height:100%” >
< s:rect x=”0” y=”0” width=”100” height=”100” style=”fill:red” / >
< /s:svg >
< /body >
< /html >
For the < html > element, the localName and tagName is “ html ” , the namespaceURI is “ http://www
.w3.org/1999/xhtml ” , and the prefix is null . For the < s:svg > element, the localName is “ svg ” , the
tagName is “ s:svg ” , the namespaceURI is “ http://www.w3.org/2000/svg ” , and the prefix is “ s ” .
DOM Level 3 goes one step further and introduces the following methods to work with namespaces:
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isDefaultNamespace( namespaceURI ) — Returns true when the specified namespaceURI is
the default namespace for the node.
lookupNamespaceURI( prefix ) — Returns the namespace URI for the given prefix .
lookupPrefix( namespaceURI ) — Returns the prefix for the given namespaceURI .
In the previous example, the following code can be executed:
alert(document.body.isDefaultNamespace(“http://www.w3.org/1999/xhtml”); //true
//assume svg contains a reference to < s:svg >
alert(svg.lookupPrefix(“http://www.w3.org/2000/svg”)); //”s”
alert(svg.lookupNamespaceURI(“s”)); //”http://www.w3.org/2000/svg”
These methods are primarily useful when you have a reference to a node without knowing its
relationship to the rest of the document.
Changes to Document
The Document type is changed in DOM Level 2 to include the following namespace - specific methods:
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createElementNS( namespaceURI , tagName ) — Creates a new element with the given
tagName as part of the namespace indicated by namespaceURI
createAttributeNS( namespaceURI , attributeName ) — Creates a new attribute node as
part of the namespace indicated by namespaceUR .
getElementsByTagNameNS( namespaceURI , tagName ) — Returns a NodeList of elements
with the given tagName that are also a part of the namespace indicated by namespaceURI
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