This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for the proper prefixes to use in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the spec changes.

The CSSNamespaceRule interface describes an object representing a single CSS @namespace at-rule. It implements the CSSRule interface, with a type value of 10 (CSSRule.NAMESPACE_RULE).


The syntax is described using the WebIDL format.

interface CSSNamespaceRule : CSSRule {
    readonly attribute DOMString namespaceURI;
    readonly attribute DOMString? prefix;


As a CSSRule, CSSNamespaceRule also implements the properties of that interface. It has some specific properties:

Returns a DOMString containing the text of the URI of the given namespace.
Returns a DOMString with the name of the prefix associated to this namespace. If there is no such prefix, returns  null.


As a CSSRule, CSSNamespaceRule also implements the methods of that interface. It has no specific methods:


Specification Status Comment
CSS Object Model (CSSOM)
The definition of 'CSSNamespaceRule' in that specification.
Working Draft Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 47 (Yes) 9 ? ?
Feature Android Android Webview Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile Chrome for Android
Basic support Not supported 47 (Yes) ? ? ? 47

Document Tags and Contributors

 Contributors to this page: jpmedley, fscholz, teoli, kscarfone, Sheppy
 Last updated by: jpmedley,