use_actions.ts

import { Action, calculateActions, arrayContentsEqual } from './actions';

export const useActions = (): Action[] => {
  const [actions, setActions] = React.useState(calculateActions());

  React.useEffect(() => {
    function callback() {
      const newActions = calculateActions();
      if (!arrayContentsEqual(newActions, actions)) {
        setActions(newActions);
      }
    }

    const observer = new MutationObserver(callback);
    observer.observe(document.body, { childList: true, subtree: true });

    return () => observer.disconnect();
  });

  return actions;
};