Node: isDefaultNamespace() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

See full compatibility

The isDefaultNamespace() method of the Node interface accepts a namespace URI as an argument. It returns a boolean value that is true if the namespace is the default namespace on the given node and false if not. The default namespace can be retrieved with Node.lookupNamespaceURI() by passing null as the argument.

Syntax

isDefaultNamespace(namespaceURI)

Parameters

namespaceURI: A string representing the namespace against which the element will be checked. The empty string is equivalent to null.

Note: namespaceURI is not an optional parameter, but can be null.

Return value

A boolean value that holds the return value true or false, indicating if the parameter is the default namespace, or not. It is equivalent to node.lookupNamespaceURI(null) === namespaceURI.

Example

Note: This example runs in an HTML document, where xmlns: attributes are ignored (except xmlns:xlink). Firefox sets all elements' namespace URI to null, while Chrome and Safari appropriately set HTML, SVG, and MathML elements' default namespace URIs. If you want to conduct more meaningful tests, you can open a standalone SVG document and execute scripts in its context.

html

<div class="hidden">
  <div>Test HTML element</div>
  <svg>
    <text>Test SVG element</text>
  </svg>
  <svg xmlns:xlink="http://www.w3.org/1999/xlink" id="with-xlink">
    <text>Test SVG element with xlink</text>
  </svg>
  <math>Test MathML element</math>
</div>

<table>
  <thead>
    <tr>
      <th><code>namespaceURI</code></th>
      <th><code>&lt;div&gt;</code></th>
      <th><code>&lt;svg&gt;</code></th>
      <th><code>&lt;svg xmlns:xlink&gt;</code></th>
      <th><code>&lt;math&gt;</code></th>
    </tr>
  </thead>
  <tbody></tbody>
</table>

.hidden {
  display: none;
}

const htmlElt = document.querySelector("div");
const svgElt = document.querySelector("svg");
const svgEltXLink = document.querySelector("#with-xlink");
const mathElt = document.querySelector("math");

const tbody = document.querySelector("tbody");

for (const uri of [
  "http://www.w3.org/2000/xmlns/",
  "http://www.w3.org/XML/1998/namespace",
  "http://www.w3.org/1999/xhtml",
  "http://www.w3.org/2000/svg",
  "http://www.w3.org/1999/xlink",
  "http://www.w3.org/1998/Math/MathML",
  "",
  null,
]) {
  const row = document.createElement("tr");
  tbody.appendChild(row);
  row.appendChild(document.createElement("td")).textContent =
    JSON.stringify(uri);
  for (const el of [htmlElt, svgElt, svgEltXLink, mathElt]) {
    console.log(el, uri, el.isDefaultNamespace(uri));
    row.appendChild(document.createElement("td")).textContent = String(
      el.isDefaultNamespace(uri),
    );
  }
}

Specifications

Specification
DOM # dom-node-isdefaultnamespace

Browser compatibility

	desktop					mobile
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on iOS	Samsung Internet	WebView Android	WebView on iOS
`isDefaultNamespace`	Chrome – Full support Chrome 1 (Release date: 2008-12-11) footnote Full support	Edge – Full support Edge 12 (Release date: 2015-07-29) footnote Full support	Firefox – Full support Firefox 1 (Release date: 2004-11-09) footnote Full support	Opera – Full support Opera 12.1 (Release date: 2012-11-20) footnote Full support	Safari – Full support Safari 3 (Release date: 2007-10-26) footnote Full support	Chrome Android – Full support Chrome Android 18 (Release date: 2012-06-27) footnote Full support	Firefox for Android – Full support Firefox for Android 4 (Release date: 2011-03-29) footnote Full support	Opera Android – Full support Opera Android 12.1 (Release date: 2012-10-09) footnote Full support	Safari on iOS – Full support Safari on iOS 1 (Release date: 2007-06-29) footnote Full support	Samsung Internet – Full support Samsung Internet 1 (Release date: 2013-04-27) footnote Full support	WebView Android – Full support WebView Android 4.4 (Release date: 2013-12-09) footnote Full support	WebView on iOS – Full support WebView on iOS 1 (Release date: 2007-06-29) footnote Full support

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Full support: Full support