Web/API/Element/namespaceURI

The Element.namespaceURI read-only property returns the namespace URI of the element, or null if the element is not in a namespace.

Before DOM4 this API was defined within the Node interface.

Syntax

namespace = element.namespaceURI

Example

In this snippet, an element is being examined for its localName and its namespaceURI. If the namespaceURI returns the XUL namespace and the localName returns "browser", then the node is understood to be a XUL <browser/>.

if (element.localName == "browser" && 
    element.namespaceURI == "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul") {
  // this is a XUL browser 
}

Notes

This is not a computed value that is the result of a namespace lookup based on an examination of the namespace declarations in scope. The namespace URI of a node is frozen at the node creation time.

In Firefox 3.5 and earlier, the namespace URI for HTML elements in HTML documents is null. In later versions, in compliance with HTML5, it is http://www.w3.org/1999/xhtml as in XHTML.

You can create an element with the specified namespaceURI using the DOM Level 2 method document.createElementNS.

The DOM does not handle or enforce namespace validation per se. It is up to the DOM application to do any validation necessary. Also note that the namespace prefix, once it is associated with a particular element, cannot be changed.

Specifications

Specification	Status	Comment
DOMThe definition of 'Element: namespaceURI' in that specification.	Living Standard

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`namespaceURI`	Chrome Full support 31 Notes' Full support 31 Notes' Notes' This API was previously available on the `Node` API.	Edge Full support 17	Firefox Full support 48 Notes' Full support 48 Notes' Notes' This API was previously available on the `Node` API.	IE ?	Opera Full support Yes Notes' Full support Yes Notes' Notes' This API was previously available on the `Node` API.	Safari Full support 10	WebView Android Full support Yes Notes' Full support Yes Notes' Notes' This API was previously available on the `Node` API.	Chrome Android Full support 31 Notes' Full support 31 Notes' Notes' This API was previously available on the `Node` API.	Firefox Android Full support Yes	Opera Android Full support Yes	Safari iOS Full support Yes	Samsung Internet Android Full support 2.0 Notes' Full support 2.0 Notes' Notes' This API was previously available on the `Node` API.

Legend

Full support: Full support
Compatibility unknown: Compatibility unknown
See implementation notes.': See implementation notes.