(PHP 5, PHP 7, PHP 8)
DOMNamedNodeMap::getNamedItem — Retrieves a node specified by name
   Retrieves a node specified by its nodeName.
  
qualifiedName
       The nodeName of the node to retrieve.
      
   A node (of any type) with the specified nodeName, or 
   null if no node is found.
  
Example #1 Getting an attribute on a node
<?php
$doc = new DOMDocument;
$doc->load('examples/book.xml');
$id = $doc->firstChild->nextSibling->nextSibling->firstChild->nextSibling->attributes->getNamedItem('id');
?>Example #2 Accessing attribute with array syntax
<?php
$doc = new DOMDocument;
$doc->load('examples/book.xml');
$id = $doc->firstChild->nextSibling->nextSibling->firstChild->nextSibling->attributes['id'];
?>