An object implementing the CSSRule
DOM interface represents a single CSS at-rule. References to a CSSRule
-implementing object may be obtained by looking at a CSS style sheet's cssRules
list.
There are several kinds of rules. 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.
Syntax
The syntax is described using the WebIDL format.
interface CSSRule { const unsigned short STYLE_RULE = 1; const unsigned short CHARSET_RULE = 2; // Obsolete const unsigned short IMPORT_RULE = 3; const unsigned short MEDIA_RULE = 4; const unsigned short FONT_FACE_RULE = 5; const unsigned short PAGE_RULE = 6; const unsigned short KEYFRAMES_RULE = 7; const unsigned short KEYFRAME_RULE = 8; const unsigned short NAMESPACE_RULE = 10; const unsigned short COUNTER_STYLE_RULE = 11; const unsigned short SUPPORTS_RULE = 12; const unsigned short DOCUMENT_RULE = 13; const unsigned short FONT_FEATURE_VALUES_RULE = 14; const unsigned short VIEWPORT_RULE = 15; const unsigned short REGION_STYLE_RULE = 16; readonly attribute unsigned short type; attribute DOMString cssText; readonly attribute CSSRule? parentRule; readonly attribute CSSStyleSheet? parentStyleSheet; };
Properties common to all CSSRule instances
CSSRule.cssText
- Represents the textual representation of the rule, e.g.
"h1,h2 { font-size: 16pt }"
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 thatCSSMediaRule
. 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 |
---|---|---|
CSSRule.STYLE_RULE |
1 |
CSSStyleRule |
CSSRule.MEDIA_RULE |
4 |
CSSMediaRule |
CSSRule.FONT_FACE_RULE |
5 |
CSSFontFaceRule |
CSSRule.PAGE_RULE |
6 |
CSSPageRule |
CSSRule.IMPORT_RULE |
3 |
CSSImportRule : IDL: nsIDOMCSSImportRule |
CSSRule.CHARSET_RULE |
2 |
CSSCharsetRule [Removed in most browsers] |
CSSRule.UNKNOWN_RULE |
0 |
CSSUnknownRule |
CSSRule.KEYFRAMES_RULE |
7 |
CSSKeyframesRule [1] |
CSSRule.KEYFRAME_RULE |
8 |
CSSKeyframeRule [1] |
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 |
An up-to-date informal list of constants can be found on the CSSWG Wiki.
[1] 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.
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
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | 9 | (Yes) | (Yes) |
CSSCharsetRule |
Not supported [1] | Not supported [3] | ? | Not supported | ? |
CSSUnknownRule |
Not supported [2] | ? | ? | ? | ? |
Feature | Android | Android Webview | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|
Basic support | ? | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
CSSCharsetRule |
? | Not supported [1] | Not supported [3] | ? | Not supported | ? | Not supported [1] |
CSSUnknownRule |
? | Not supported [2] | ? | ? | ? | ? | Not supported [2] |
[1] Removed in Chrome version 41.0.
[2] Removed in Chrome version 45.0.
[3] Removed in Gecko version 40.