@itwin/itwinui-react/esm/utils/hooks/useIntersection.js

A react component library for iTwinUI

import * as React from 'react';
import { getWindow } from '../functions/dom.js';
export const useIntersection = (onIntersect, options = {}, once = true) => {
  let { root, rootMargin, threshold } = options;
  let cleanupRef = React.useRef(() => {});
  let setRef = React.useCallback(
    (node) => {
      cleanupRef.current?.();
      cleanupRef.current = () => {};
      if (!node || !getWindow()?.IntersectionObserver) return;
      let observer = new IntersectionObserver(
        ([entry], obs) => {
          if (entry.isIntersecting) {
            if (once) obs.disconnect();
            onIntersect();
          }
        },
        {
          root,
          rootMargin,
          threshold,
        },
      );
      observer.observe(node);
      cleanupRef.current = () => observer.disconnect();
    },
    [onIntersect, once, root, rootMargin, threshold],
  );
  return setRef;
};