index.md

title	short-title	slug	page-type	browser-compat
Node: lookupNamespaceURI() method	lookupNamespaceURI()	Web/API/Node/lookupNamespaceURI	web-api-instance-method	api.Node.lookupNamespaceURI

{{APIRef("DOM")}}

The lookupNamespaceURI() method of the {{domxref("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

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");
});

{{ EmbedLiveSample('Example','100%',190) }}

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{domxref("Node.lookupPrefix")}}
• {{domxref("Node.isDefaultNameSpace")}}