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.

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.

Instance properties

Inherits properties from its ancestor CSSRule.

CSSKeyframesRule.name: 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.
CSSKeyframesRule.length Read only: Returns the number of keyframes in the list.

Instance methods

Inherits methods from its ancestor CSSRule.

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, a DOMException with a SYNTAX_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 between 0% and 100%.
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 between 0% and 100%. If no such keyframe exists, findRule returns null.

Example

Using CSSKeyframesRule

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.

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 its cssRules property.

const keyframes = document.styleSheets[0].cssRules[0];

for (let i = 0; i < keyframes.length; i++) {
  console.log(keyframes[i].keyText);
}

// Output:
// 0%
// 100%

Specifications

Specification
CSS Animations Level 1 # interface-csskeyframesrule