ladybird/Libraries/LibWeb/Animations/AnimationEffect.idl

// https://www.w3.org/TR/web-animations-1/#the-effecttiming-dictionaries
dictionary EffectTiming {
    double delay = 0;
    double endDelay = 0;
    FillMode fill = "auto";
    double iterationStart = 0.0;
    unrestricted double iterations = 1.0;
    (unrestricted double or DOMString) duration = "auto";
    PlaybackDirection direction = "normal";
    DOMString easing = "linear";
};

// https://www.w3.org/TR/web-animations-1/#dictdef-optionaleffecttiming
dictionary OptionalEffectTiming {
    double delay;
    double endDelay;
    FillMode fill;
    double iterationStart;
    unrestricted double iterations;
    (unrestricted double or DOMString) duration;
    PlaybackDirection direction;
    DOMString easing;
};

// https://www.w3.org/TR/web-animations-1/#the-fillmode-enumeration
enum FillMode { "none", "forwards", "backwards", "both", "auto" };

// https://www.w3.org/TR/web-animations-1/#the-playbackdirection-enumeration
enum PlaybackDirection { "normal", "reverse", "alternate", "alternate-reverse" };

// https://www.w3.org/TR/web-animations-1/#the-computedeffecttiming-dictionary
dictionary ComputedEffectTiming : EffectTiming {
    [GenerateAsRequired] unrestricted double endTime;
    [GenerateAsRequired] unrestricted double activeDuration;
    double? localTime;
    double? progress;
    unrestricted double? currentIteration;
};

// https://www.w3.org/TR/web-animations-1/#the-animationeffect-interface
[Exposed=Window]
interface AnimationEffect {
    EffectTiming getTiming();
    ComputedEffectTiming getComputedTiming();
    undefined updateTiming(optional OptionalEffectTiming timing = {});
};