hooks/usePosts.js

import {useEffect, useState, useCallback} from 'react';
import {getNewerPosts, getOlderPosts, getPosts, PAGE_SIZE} from '../lib/posts';

export default function usePosts(userId) {
  (...)

  const onRefresh = useCallback(async () => {
    if (!posts || posts.length === 0 || refreshing) {
      return;
    }
    const firstPost = posts[0];
    setRefreshing(true);
    const newerPosts = await getNewerPosts(firstPost.id, userId);
    setRefreshing(false);
    if (newerPosts.length === 0) {
      return;
    }
    setPosts(newerPosts.concat(posts));
  }, [posts, userId, refreshing]);

(...)