files/en-us/web/api/namednodemap/setnameditemns/index.md
{{APIRef("DOM")}}
The setNamedItemNS() method of the {{domxref("NamedNodeMap")}} interface
puts the {{domxref("Attr")}} identified by its name in the map.
If there was already an {{domxref("Attr")}} with the same name in the map,
it is replaced.
[!NOTE] This method is an alias of
setNamedItem()you can use them interchangeably.
setNamedItemNS(attr)
attr
Returns the old attribute if replaced, or null if the attribute is new.
InUseAttributeError {{domxref("DOMException")}}
<span ob:one="one"></span>
<pre></pre>
const parser = new DOMParser();
// ob:one in <span> is not in a namespace, while ob:one in <warning>, is.
const xmlString =
'<warning ob:one="test" xmlns:ob="http://www.example.com/ob">Beware!</warning>';
const doc = parser.parseFromString(xmlString, "application/xml");
const span = document.querySelector("span");
const pre = document.querySelector("pre");
const warning = doc.querySelector("warning");
const attrMap = span.attributes;
let result = `The '<span>' element initially contains ${attrMap.length} attribute.\n\n`;
result += "We remove `one` from '<span>' and adds it to '<pre>'.\n";
const one = warning.attributes.removeNamedItemNS(
"http://www.example.com/ob",
"one",
);
attrMap.setNamedItemNS(one);
result += `The '<span>' element now contains ${span.attributes.length} attributes:\n\n`;
result += "Prefix\tLocal name\tQualified name\n";
result += "=========================================\n";
for (const attr of attrMap) {
result += `${attr.prefix}\t${attr.localName}\t\t${attr.name}\n`;
}
pre.textContent = result;
{{EmbedLiveSample("Example", "100%", 200)}}
{{Specifications}}
{{Compat}}