Function tick

animateplus.js:341–393

};

const tick = now => {
  const {all} = rAF;
  all.forEach(object => {
    trackTime(object, now);
    const progress = getProgress(object);
    const {
      element,
      keyframes,
      loop,
      optimize,
      direction,
      change,
      easing,
      duration,
      gaussian,
      end,
      options
    } = object;

    // object is an animation
    if (direction) {
      let curve = progress;
      switch (progress) {
        case 0:
          if (direction == "alternate") reverseKeyframes(keyframes);
          break;
        case 1:
          if (loop)
            resetTime(object);
          else {
            all.delete(object);
            if (optimize && element) accelerate(element);
            if (gaussian) clearBlur(element, gaussian);
          }
          if (end) end(options);
          break;
        default:
          curve = ease(easing, progress);
      }
      if (gaussian) setDeviation(object, curve);
      if (change && end) change(curve);
      if (element) Object.assign(element.style, createStyles(keyframes, curve));
      return;
    }

    // object is a delay
    if (progress < 1) return;
    all.delete(object);
    end(duration);
  });

  if (all.size) requestAnimationFrame(tick);
};

document.addEventListener("visibilitychange", () => {
  const now = performance.now();