hyper/lib/selectors.js

import {createSelector} from 'reselect';

const getTermGroups = ({termGroups}) => termGroups.termGroups;
const getRootGroups = createSelector(
  getTermGroups,
  termGroups =>
    Object.keys(termGroups)
      .map(uid => termGroups[uid])
      .filter(({parentUid}) => !parentUid)
);

export default getRootGroups;