Attr.ownerElement

<svg xml:lang="en-US" class="struct" height="1" width="1">Click me</svg>
<label xml:lang="en-US" class="struct"></label>

<button>Click me for &lt;svg&gt;…</button>
<button>Click me for &lt;label&gt;…</button>
<br><br>
Qualified name of the owner element of the attribute <code>xml:lang</code>: <output id="result"><i>None.</i></output>

const elements = document.getElementsByClassName("struct");
const buttons = document.getElementsByTagName("button");
const result  = document.querySelector("#result");

function handleEvent(element) {
  return function(e) {
    attribute = element.attributes[0];
    result.value = attribute.ownerElement.tagName.toLowerCase();
  }
}

let i=0;
for (let button of buttons) {
  button.addEventListener('click', handleEvent(elements[i]));
  i++;
}