getBookDataExample2.js

const getBookData = async (id) => {
  const book = await getBookById(id);

  const [reviews, author, sellers] = await Promise.all([
    getReviewsByBookId(book.id),
    getAuthorById(book.authorId),
    getSellersByBookId(book.id),
  ]);

  return { ...book, reviews, author, sellers };
};