The Element.getElementsByTagNameNS() method returns a live HTMLCollection of elements with the given tag name belonging to the given namespace. It is similar to Document.getElementsByTagNameNS, except that its search is restricted to descendants of the specified element.
getElementsByTagNameNS(namespaceURI, localName)namespaceURIThe namespace URI of elements to look for (see Element.namespaceURI and Attr.namespaceURI). For example, if you need to look for XHTML elements, use the XHTML namespace URI, http://www.w3.org/1999/xhtml.
localNameEither the local name of elements to look for or the special value "*", which matches all elements (see Element.localName and Attr.localName).
A live HTMLCollection of found elements in the order they appear in the tree.
// Check the alignment on a number of cells in a table in an XHTML document.
const table = document.getElementById("forecast-table");
const cells = table.getElementsByTagNameNS(
"http://www.w3.org/1999/xhtml",
"td",
);
for (const cell of cells) {
const axis = cell.getAttribute("axis");
if (axis === "year") {
// Grab the data
}
}