Node: lookupNamespaceURI() メソッド

lookupNamespaceURI(prefix)

Namespace URL for <code>xlink</code> on &lt;output&gt;:
<output>未検査</output>.<br />
Namespace URL for <code>xml</code> on &lt;output&gt;:
<output>未検査</output>.<br />
Namespace URL for <code>html</code> on &lt;output&gt;:
<output>未検査</output>.<br />
Namespace URL for <code>``</code> on &lt;output&gt;:
<output>未検査</output>.<br />
Namespace URL for <code>svg</code> on &lt;svg&gt;:
<output>未検査</output>.<br />
Namespace URL for <code>xlink</code> on &lt;svg&gt;:
<output>未検査</output>.<br />
Namespace URL for <code>xml</code> on &lt;svg&gt;:
<output>未検査</output>.<br />
<svg xmlns:svg="https://www.w3.org/2000/svg" height="1"></svg>
<button>ここをクリックして結果を確認</button>

const button = document.querySelector("button");
button.addEventListener("click", () => {
  const aHtmlElt = document.querySelector("output");
  const aSvgElt = document.querySelector("svg");
  const result = document.getElementsByTagName("output");
  result[0].value = aHtmlElt.lookupNamespaceURI("xlink");
  result[1].value = aHtmlElt.lookupNamespaceURI("xml");
  result[2].value = aHtmlElt.lookupNamespaceURI("html");
  result[3].value = aHtmlElt.lookupNamespaceURI("");
  result[4].value = aSvgElt.lookupNamespaceURI("svg");
  result[5].value = aSvgElt.lookupNamespaceURI("xlink");
  result[6].value = aSvgElt.lookupNamespaceURI("xml");
});