Element.getAttributeNS()
The getAttributeNS()
method of the Element
interface returns the string value of the attribute with the specified namespace and
name. If the named attribute does not exist, the value returned will either be
null
or ""
(the empty string); see Notes for
details.
Syntax
attrVal = element.getAttributeNS(namespace, name)
Parameters
namespace
-
The namespace in which to look for the specified attribute.
name
-
The name of the attribute to look for.
Return value
The string value of the specified attribute. If the attribute doesn't exist, the result
is null
.
Note: Earlier versions of the DOM specification had this method described as returning an empty string for non-existent attributes, but it was not typically implemented this way since null makes more sense. The DOM4 specification now says this method should return null for non-existent attributes.
Examples
The following SVG document reads the value of the foo
attribute in a
custom namespace.
<svg xmlns="http://www.w3.org/2000/svg"
xmlns:test="http://www.example.com/2014/test" width="40" height="40">
<circle id="target" cx="12" cy="12" r="10" stroke="#444"
stroke-width="2" fill="none" test:foo="Hello namespaced attribute!"/>
<script type="text/javascript">
var ns = 'http://www.example.com/2014/test';
var circle = document.getElementById( 'target' );
console.log( 'attribute test:foo: "' + circle.getAttributeNS( ns, 'foo' ) + '"' );
</script>
</svg>
In an HTML5 document the attribute has to be accessed with test:foo
since
namespaces are not supported.
<!DOCTYPE html>
<html>
<body>
<svg xmlns="http://www.w3.org/2000/svg"
xmlns:test="http://www.example.com/2014/test" width="40" height="40">
<circle id="target" cx="12" cy="12" r="10" stroke="#444" stroke-width="2"
fill="none" test:foo="Foo value"/>
</svg>
<script type="text/javascript">
var ns = 'http://www.example.com/2014/test';
var circle = document.getElementById( 'target' );
console.log('Attribute value: ' + circle.getAttribute('test:foo'));
</script>
</body>
</html>
Notes
Namespaces are only supported in XML documents. HTML5 documents have to use
getAttribute()
instead.
getAttributeNS()
differs from getAttribute()
in that it allows you to further specify the requested attribute as
being part of a particular namespace, as in the example above, where the attribute is
part of the fictional "specialspace" namespace on Mozilla.
Prior to the DOM4 specification, this method was specified to return an empty string
rather than null for non-existent attributes. However, most browsers instead returned
null. Starting with DOM4, the specification now says to return null. However, some older
browsers return an empty string. For that reason, you should use
hasAttributeNS()
to check for an attribute's
existence prior to calling getAttributeNS()
if it is possible that the
requested attribute does not exist on the specified element.
DOM methods dealing with element's attributes:
Not namespace-aware, most commonly used methods | Namespace-aware variants (DOM Level 2) | DOM Level 1 methods for dealing with Attr nodes directly (seldom used) |
DOM Level 2 namespace-aware methods for dealing with Attr nodes directly (seldom used) |
---|---|---|---|
setAttribute (DOM 1) |
setAttributeNS |
setAttributeNode |
setAttributeNodeNS |
getAttribute (DOM 1) |
getAttributeNS |
getAttributeNode |
getAttributeNodeNS |
hasAttribute (DOM 2) |
hasAttributeNS |
- | - |
removeAttribute (DOM 1) |
removeAttributeNS |
removeAttributeNode |
- |
Specifications
Specification |
---|
DOM Standard # ref-for-dom-element-getattributensā |
Browser compatibility
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