如何使保持滚动位置平滑

html {
  scroll-behavior: smooth;
}

function smoothScroll(target, duration) {
  const targetElement = document.querySelector(target);
  const targetPosition = targetElement.offsetTop;
  const startPosition = window.pageYOffset;
  const distance = targetPosition - startPosition;
  let startTime = null;

  function animation(currentTime) {
    if (startTime === null) startTime = currentTime;
    const timeElapsed = currentTime - startTime;
    const run = ease(timeElapsed, startPosition, distance, duration);
    window.scrollTo(0, run);
    if (timeElapsed < duration) requestAnimationFrame(animation);
  }

  function ease(t, b, c, d) {
    t /= d / 2;
    if (t < 1) return c / 2 * t * t + b;
    t--;
    return -c / 2 * (t * (t - 2) - 1) + b;
  }

  requestAnimationFrame(animation);
}

// 使用示例
const button = document.querySelector('.scroll-button');
button.addEventListener('click', () => {
  smoothScroll('.target-element', 1000);
});