Access-Control-Allow-Origin

app.use((req, res, next) => {
  res.header("Access-Control-Allow-Origin", "*"); // "*" for public access and www.example.com for specific uses
  res.header(
    "Access-Control-Allow-Headers",
    "Origin, X-Requested-With, Content-Type, Accept, Authorization"
  );
  if (req.method === 'OPTIONS') {
      res.header('Access-Control-Allow-Methods', 'PUT, POST, PATCH, DELETE, GET');
      return res.status(200).json({});
  }
  next();
});