如果用户向下滚动，如何在x秒后自动转到顶部

// 获取滚动条位置
function getScrollTop() {
  return (document.documentElement && document.documentElement.scrollTop) || document.body.scrollTop;
}

// 设置滚动条位置
function setScrollTop(position) {
  if (document.documentElement) {
    document.documentElement.scrollTop = position;
  }
  document.body.scrollTop = position;
}

// 滚动到顶部
function scrollToTop() {
  var currentPosition = getScrollTop();
  if (currentPosition > 0) {
    window.requestAnimationFrame(scrollToTop);
    setScrollTop(currentPosition - currentPosition / 8);
  }
}

// 监听滚动事件
window.addEventListener('scroll', function() {
  var scrollPosition = getScrollTop();
  var windowHeight = window.innerHeight;
  var scrollHeight = document.body.scrollHeight;
  
  // 当滚动到页面底部时，延迟x秒后自动转到顶部
  if (scrollPosition + windowHeight === scrollHeight) {
    setTimeout(scrollToTop, x * 1000);
  }
});