js置顶代码

.sticky-element {
  position: fixed;
  top: 0;
  width: 100%;
}

window.addEventListener('scroll', function() {
  var element = document.getElementById('stickyElement');
  if (window.pageYOffset > 100) { // 假设滚动超过100px时置顶
    element.classList.add('sticky-element');
  } else {
    element.classList.remove('sticky-element');
  }
});

window.addEventListener('scroll', function() {
  var element = document.getElementById('stickyElement');
  if (window.pageYOffset > 100) { // 假设滚动超过100px时置顶
    element.style.position = 'fixed';
    element.style.top = '0';
  } else {
    element.style.position = '';
    element.style.top = '';
  }
});