CSSKeyframesRule

Baseline Widely available *

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨August 2016⁩.

* Some parts of this feature may have varying levels of support.

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

Instance properties

Inherits properties from its ancestorCSSRule.

CSSKeyframesRule.name: Represents the name of the keyframes, used by theanimation-name property.
CSSKeyframesRule.cssRulesRead only: Returns aCSSRuleList of the keyframes in the list.
CSSKeyframesRule.lengthRead only: Returns the number of keyframes in the list.

Instance methods

Inherits methods from its ancestorCSSRule.

CSSKeyframesRule.appendRule(): 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, aDOMException with aSYNTAX_ERR is thrown.
CSSKeyframesRule.deleteRule(): 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 between0% and100%.
CSSKeyframesRule.findRule(): 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 between0% and100%. If no such keyframe exists,findRule returnsnull.

Example

Using CSSKeyframesRule

The CSS includes a keyframes at-rule. This will be the firstCSSRule returned bydocument.styleSheets[0].cssRules.myRules[0] returns aCSSKeyframesRule object.

css

@keyframes slide-in {  from {    transform: translateX(0%);  }  to {    transform: translateX(100%);  }}

const myRules = document.styleSheets[0].cssRules;const keyframes = myRules[0]; // a CSSKeyframesRule

Accessing indexes

CSSKeyframesRule can be indexed like an array, and functions similar to itscssRules property.

const keyframes = document.styleSheets[0].cssRules[0];for (let i = 0; i < keyframes.length; i++) {  console.log(keyframes[i].keyText);}// Output:// 0%// 100%