setAttributeNodeNS (W3C DOM Core method)

Version Depr. Static
DOM2 No No
Browser support (more…)
IE7 FF1.5+ SA3+ OP9+
None Buggy Full Buggy


var attr = document.createAttributeNS
    ('', 'xml:lang');
attr.nodeValue = 'en-au-tas';


The example above creates an xml:lang attribute in the XML namespace, assigns it the nodeValue en-au-tas, and then adds it to the documentElement.

So if the element in question were this HTML:

<html xmlns="">

Then the operation above would result in this:

<html xmlns="" xml:lang="en-au-tas">


attr (Attr) required

The attribute node to add. The node can subsequently be retrieved using its localName and namespaceURI.


Add a namespaced attribute node to this element.

If an attribute already exists with the specified local name and namespace URI, the existing node is replaced.

The usage and behavior of this method is identical to setAttributeNode except that the local name and namespace URI are both taken into account when determining whether an existing attribute should be replaced, rather than just the name.

Unlike Element nodes, Attr nodes do not inherit a namespace from the element they're attached to — if an attribute does not have an explicitly defined namespace then it simply has no namespace (see Attr for details).

Return value

If the new attribute replaces an existing attribute with the same local name and namespace URI, the previously existing attribute node is returned ; otherwise null is returned.


Internet Explorer Firefox Safari Opera
5.5 6.0 7.0 1.5 2.0 3.0 1.3 2.0 3.0 9.0 9.5
None None None Buggy Buggy Buggy Buggy Buggy Full Buggy Buggy

Internet Explorer doesn't implement this method (it returns undefined).

Opera 9.0 in pure XML (but not XHTML mode1) parses entities when setting the value of an attribute node.

In Safari 1.3 and 2 it's not possible to set the value of a created attribute using the value property (the property is readonly; however using the nodeValue property is supported fine).

An element may contain two attribute nodes which have the same local name but different namespaces (for example, an a element may contain both an href attribute node in no namespace, and an html:href attribute node in the XHTML namespace). Although these are different attribute nodes, Opera will consider the html:href attribute node to be an href attribute node if an existing href attribute node is not already defined (assuming that the html prefix has been declared and assigned to the default namespace). This behavior is not limited to XHTML, but occurs on all XML documents in relation to a prefix declared for the default namespace. This cannot really be considered a bug, because the DOM does not define attribute associations (that job is handled by a DTD); it's more like a convenience feature, though admittedly a very confusing one!

Safari 1.3 and 2 do the same thing as Opera in relation to XHTML (but not XML generally), however they also inherit a namespace from their owning element, therefore they will also overwrite attribute nodes with no explicit namespace if the namespace argument matches the default.

In Firefox and Opera an empty-string namespace is treated the same as a null namespace (ie. it's taken to mean no namespace, when it should be treated as a real namespace URI); only Safari 3 gets this right.

: Behavior in HTML

All supported browsers in HTML mode2 behave exactly the same as they do in XHTML mode.


1 On XHTML pages served as application/xhtml+xml.

2 On XHTML or HTML pages served as text/html.

User-contributed notes

There are no comments yet.

Related Products