Pure JS animated scrollTop using requestAnimationFrame

scroll.ts

export function animateScrollTop(element: HTMLElement, value: number, timing: number) {
  let start: number = null;
  let animationToken: number;
  const valueSign = value >= 0 ? 1 : -1;
  const currentScroll = element.scrollTop;

  const step = (timestamp: number) => {
      if (!start) {
        start = timestamp;
      }

      const progress = timestamp - start;
      const stepValue = Math.min(Math.abs((progress / timing) * value), Math.abs(value));
      element.scrollTop = currentScroll + (valueSign * stepValue);

      if (progress < timing) {
          window.requestAnimationFrame(step);
      } else {
          window.cancelAnimationFrame(animationToken);
      }
  };

  animationToken = window.requestAnimationFrame(step);
}