App.js

import { ref, watch } from 'vue@next';

export default {
 setup() {
    const hasLoaded = ref(false);
    const books = ref([]);

    watch(hasLoaded, (value) => {
      if (value) {
        fetchBooks();
      }
    });

    const fetchBooks = async () => {
      const response = await fetch('https://localhost:3000/books');
      const data = await response.json();
      books.value = data;
    };

    return {
      hasLoaded,
      books,
    };
 },
};