CSSRule

The CSSRule interface represents a single CSS rule. There are several types of rules, listed in the Type constants section below.

The CSSRule interface specifies the properties common to all rules, while properties unique to specific rule types are specified in the more specialized interfaces for those rules' respective types.

References to a CSSRule may be obtained by looking at a CSSStyleSheet's cssRules list.

Properties common to all CSSRule instances

CSSRule.cssText

Represents the textual representation of the rule, e.g. "h1,h2 { font-size: 16pt }" or "@import 'url'". To access or modify parts of the rule (e.g. the value of "font-size" in the example) use the properties on the specialized interface for the rule's type.

CSSRule.parentRule Read only

Returns the containing rule, otherwise null. E.g. if this rule is a style rule inside an @media block, the parent rule would be that CSSMediaRule.

CSSRule.parentStyleSheet Read only

Returns the CSSStyleSheet object for the style sheet that contains this rule

CSSRule.type Read only

One of the Type constants indicating the type of CSS rule.

Constants

Type constants

The CSSRule interface specifies integer constants that can be used in conjunction with a CSSRule's type property to discern the rule type (and therefore, which specialized interface it implements). The relationships between these constants and the interfaces are:

Type	Value	Rule-specific interface	Comments and examples
CSSRule.STYLE_RULE	1	CSSStyleRule	The most common kind of rule: selector { prop1: val1; prop2: val2; }
CSSRule.IMPORT_RULE	3	CSSImportRule	An @import rule. (Until the documentation is completed, see the interface definition in the Mozilla source code: nsIDOMCSSImportRule.)
CSSRule.MEDIA_RULE	4	CSSMediaRule
CSSRule.FONT_FACE_RULE	5	CSSFontFaceRule
CSSRule.PAGE_RULE	6	CSSPageRule
CSSRule.KEYFRAMES_RULE	7	CSSKeyframesRule
CSSRule.KEYFRAME_RULE	8	CSSKeyframeRule
Reserved for future use	9		Should be used to define color profiles in the future
CSSRule.NAMESPACE_RULE	10	CSSNamespaceRule
CSSRule.COUNTER_STYLE_RULE	11	CSSCounterStyleRule
CSSRule.SUPPORTS_RULE	12	CSSSupportsRule
CSSRule.DOCUMENT_RULE	13	CSSDocumentRule
CSSRule.FONT_FEATURE_VALUES_RULE	14	CSSFontFeatureValuesRule
CSSRule.VIEWPORT_RULE	15	CSSViewportRule
CSSRule.REGION_STYLE_RULE	16	CSSRegionStyleRule
CSSRule.UNKNOWN_RULE	0	CSSUnknownRule
CSSRule.CHARSET_RULE	2	CSSCharsetRule	(Removed in most browsers.)

An up-to-date informal list of constants can be found on the CSSWG Wiki.

Specifications

Specification	Status	Comment
CSS Object Model (CSSOM) The definition of 'CSSRule' in that specification.	Working Draft	Obsoleted values CHARSET_RULE and UNKNOWN_RULE. Added value NAMESPACE_RULE.
CSS Animations The definition of 'CSSRule' in that specification.	Working Draft	Added values KEYFRAMES_RULE and KEYFRAME_RULE.
CSS Fonts Module Level 3 The definition of 'CSSRule' in that specification.	Candidate Recommendation	Added value FONT_FEATURE_VALUES_RULE.
CSS Counter Styles Level 3 The definition of 'CSSRule' in that specification.	Candidate Recommendation	Added value COUNTER_STYLE_RULE.
CSS Conditional Rules Module Level 3 The definition of 'CSSRule' in that specification.	Candidate Recommendation	Added value SUPPORTS_RULE. (DOCUMENT_RULE has been pushed to CSS Conditional Rules Level 4)
Document Object Model (DOM) Level 2 Style Specification The definition of 'CSSRule' in that specification.	Recommendation	Initial definition.

Browser compatibility

[1] CSSCharsetRule was removed in Chrome version 41.0.

[2] CSSUnknownRule was removed in Chrome version 45.0.

[3] CSSCharsetRule was removed in Gecko version 40.

[4] On Gecko, before Firefox 19, the keyframe-related constants existed only in their prefixed version: CSSRule.MOZ_KEYFRAMES_RULE and CSSRule.MOZ_KEYFRAME_RULE. From Firefox 20 onwards, both versions are available. The prefixed version will be removed in the future.

See also

• Using dynamic styling information