@base-ui/react/esm/utils/scrollable.js

Base UI is a library of headless ('unstyled') React components and low-level hooks. You gain complete control over your app's CSS and accessibility features.

import { getComputedStyle, isHTMLElement } from '@floating-ui/utils/dom';
export function isScrollable(element, axis) {
  const style = getComputedStyle(element);
  if (axis === 'vertical') {
    const overflowY = style.overflowY;
    return (overflowY === 'auto' || overflowY === 'scroll') && element.scrollHeight > element.clientHeight;
  }
  const overflowX = style.overflowX;
  return (overflowX === 'auto' || overflowX === 'scroll') && element.scrollWidth > element.clientWidth;
}
export function hasScrollableAncestor(target, root, axes) {
  let node = target;
  while (node && node !== root) {
    for (const axis of axes) {
      if (isScrollable(node, axis)) {
        return true;
      }
    }
    node = node.parentElement;
  }
  return false;
}
export function findScrollableTouchTarget(target, root, axis = 'vertical') {
  let node = isHTMLElement(target) ? target : null;
  while (node && node !== root) {
    if (isScrollable(node, axis)) {
      return node;
    }
    node = node.parentElement;
  }
  return isScrollable(root, axis) ? root : null;
}