setNamedItem (W3C DOM Core method)

Spec
Version Depr. Static
DOM1 No No
Browser support (more…)
IE5.5+ FF1.5+ SA1.3+ OP9+
Buggy Full Full Full
Returns
Node
Throws
WRONG_DOCUMENT_ERR, NO_MODIFICATION_ALLOWED_ERR, INUSE_ATTRIBUTE_ERR

Example

var attrs = document.getElementsByTagName('link').item(0).attributes;
var media = document.createAttribute('media');
media.nodeValue = 'all';

attrs.setNamedItem(media);

The example above saves the attributes collection of an HTML link element, then creates a new attribute node with the name media and the value all, and assigns it to that collection.

If a node with that name already exists in the collection then it will be overwritten with the new value; otherwise a new item will be added, and therefore a new attribute node will apply to the original link element.

Arguments

node (Node) required

The node to add to the map. The node can subsequently be retrieved using its nodeName.

Description

Add a specified node to a NamedNodeMap.

If a node with that name already exists in the map, it will be replaced. For certain kinds of node — where all instances have the same name (such as #text or #comment) — it's not possible to store more than one instance of such a node within a single node map, because the names would clash. The DOM specification considers this preferable to implementing aliases.

Return value

If the new node replaces an existing node, the previously existing node is returned; otherwise null is returned.

Compatibility

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
Buggy Buggy Buggy Full Full Full Full Full Full Full Full

Internet Explorer 5.5 in HTML doesn't implement this method (it returns undefined).

In Internet Explorer 6 and 7 in HTML this method does not always return null when adding to an attributes collection where the specified node didn't previously exist; it returns null, 0, false or an empty string, depending on what type of value IE considers the attribute to have (please see Attr for more information on attribute types in IE).

Internet Explorer in XML returns the newly set value, rather than the previously set value or null.

: More IE weirdness

As an added conundrum, the MSDN documentation for this method says that "an attribute that is set with this method does not have to apply to the element". However in tests, created attributes added to an attributes collection do indeed apply to their owning element, so I have no idea what situation they might be talking about.

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