web/packages/util/modules/dom/scroll.js

/**
 * 判断元素是否在滚动区域内
 * element: 目标元素dom
 * scrollContainer: 滚动区域
 */
export function isElementInScrollArea(element, scrollContainer) {
  const elementRect = element.getBoundingClientRect()
  const containerRect = scrollContainer.getBoundingClientRect()

  // 判断元素的上边界和下边界是否在滚动容器的上边界和下边界之间
  const isElementAboveContainer = elementRect.bottom < containerRect.top
  const isElementBelowContainer = elementRect.top > containerRect.bottom

  // 如果元素在滚动容器的上下边界之间，则认为它在滚动区域内
  return !(isElementAboveContainer || isElementBelowContainer)
}