AnimationEffect and KeyframeEffect are part of the Web Animations API. They allow a developer interactive control over the following parts of their Animation: * the Animation target (i.e. what element is being animated) * the Animation timing properties (duration, delay, etc) We do not intend to ship the composite and iterationComposite members or the getKeyframes/setKeyframes methods at this time.
Explainers: https://www.w3.org/TR/web-animations-1/#the-animationeffect-interface https://www.w3.org/TR/web-animations-1/#the-keyframeeffect-interface