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Node: lookupNamespaceURI() method

The lookupNamespaceURI() method of the Node interface takes a prefix as parameter and returns the namespace URI associated with it on the given node if found (and null if not).

Syntax

lookupNamespaceURI(prefix)

Parameters

prefix: The prefix to look for.

Note: This parameter is not optional, but can be set to null.

Return value

A string containing the namespace URI corresponding to the prefix. If the prefix is not found, it returns null. If the requested prefix is null, it returns the default namespace URI.

Example

html

Namespace URL for <code>xlink</code> on &lt;output&gt;:
<output>Not tested</output>.<br />
Namespace URL for <code>xml</code> on &lt;output&gt;:
<output>Not tested</output>.<br />
Namespace URL for <code>html</code> on &lt;output&gt;:
<output>Not tested</output>.<br />
Namespace URL for <code>``</code> on &lt;output&gt;:
<output>Not tested</output>.<br />
Namespace URL for <code>svg</code> on &lt;svg&gt;:
<output>Not tested</output>.<br />
Namespace URL for <code>xlink</code> on &lt;svg&gt;:
<output>Not tested</output>.<br />
Namespace URL for <code>xml</code> on &lt;svg&gt;:
<output>Not tested</output>.<br />
<svg xmlns:svg="http://www.w3.org/2000/svg" height="1"></svg>
<button>Click to see the results</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");
});

Specifications

Specification
DOM Standard # dom-node-lookupnamespaceuri

Browser compatibility