difference of async package vs async await. example in https://developer.mozilla.org/en-US/docs/Learn/Server-side/Express_Nodejs/Displaying_data/Author_detail_page

mdnAsyncVsAsyncAwait.js

// Display detail page for a specific Author.
exports.author_detail = async function(req, res) {
  // async.parallel(
  //   {
  //     author: function(callback) {
  //       Author.findById(req.params.id).exec(callback);
  //     },
  //     author_books: function(callback) {
  //       Book.find({ author: req.params.id }, "title summary").exec(callback);
  //     }
  //   },
  //   function(err, results) {
  //     res.render("author_detail", {
  //       title: "Author Detail",
  //       author: results.author,
  //       author_books: results.author_books
  //     });
  //   }
  // );

  // try {
  //   const author = await Author.findById(req.params.id);
  //   const author_books = await Book.find(
  //     { author: req.params.id },
  //     "title summary"
  //   );

  //   res.render("author_detail", {
  //     title: "Author Detail",
  //     author,
  //     author_books
  //   });
  // } catch (error) {
  //   return next(error);
  // }

  Promise.all([
    await Author.findById(req.params.id),
    await Book.find({ author: req.params.id }, "title summary")
  ])
    .then(([author, author_books]) => {
      res.render("author_detail", {
        author,
        author_books
      });
    })
    .catch(err => next(err));
};