talk/plugins/talk-plugin-featured-comments/client/components/Tab.js

import React from 'react';
import {TabCount} from 'plugin-api/beta/client/components/ui';

// TODO: This is just example code, and needs to replaced by an actual implementation.
export default ({active, asset: {featuredCommentCount}}) => (
  <span>
    Featured <TabCount active={active} sub>{featuredCommentCount}</TabCount>
  </span>
);