The CSSKeyframesRule interface describes an object representing a complete set of keyframes for a CSS animation. It corresponds to the contents of a whole @keyframes at-rule.

CSSRule CSSKeyframesRule

Instance properties

Inherits properties from its ancestor CSSRule.


Represents the name of the keyframes, used by the animation-name property.

CSSKeyframesRule.cssRules Read only

Returns a CSSRuleList of the keyframes in the list.

Instance methods

Inherits methods from its ancestor CSSRule.


Inserts a new keyframe rule into the current CSSKeyframesRule. The parameter is a string containing a keyframe in the same format as an entry of a @keyframes at-rule. If it contains more than one keyframe rule, a DOMException with a SYNTAX_ERR is thrown.


Deletes a keyframe rule from the current CSSKeyframesRule. The parameter is the index of the keyframe to be deleted, expressed as a string resolving as a number between 0% and 100%.


Returns a keyframe rule corresponding to the given key. The key is a string containing an index of the keyframe to be returned, resolving to a percentage between 0% and 100%. If no such keyframe exists, findRule returns null.


The CSS includes a keyframes at-rule. This will be the first CSSRule returned by document.styleSheets[0].cssRules. myRules[0] returns a CSSKeyframesRule object.

@keyframes slidein {
  from {
    transform: translateX(0%);

  to {
    transform: translateX(100%);
let myRules = document.styleSheets[0].cssRules;
let keyframes = myRules[0]; // a CSSKeyframesRule


CSS Animations Level 1
# interface-csskeyframesrule

Browser compatibility

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See also