Function serialize

src/common/util.js:34–37

(titles, files)

const isSaved = ({ titles, files, lastTitles, lastFiles }) => {
  const serialize = (titles, files) => JSON.stringify({
    titles,
    files: files.map(({ name, content }) => ({ name, content })),
  });
  return serialize(titles, files) === serialize(lastTitles, lastFiles);
};