If you are using express-session in your express app, you might have wanted to use the res.redirect() function, and you may have faced an unexpected behaviour : changes on session data are not always saved when the client receives the redirect response from the server and makes a new request to the server.

Here is a solution to always save the session before sending a redirect response : create a middleware that overide the redirect function.

app.use((req, res, next) => {
  const oldRedirect = res.redirect;
  res.redirect = function (...args) {
    if (req.session) {
      // redirecting after saving...
      req.session.save(() => Reflect.apply(oldRedirect, this, args))
    } else {
      Reflect.apply(oldRedirect, this, args);
    }
  }
})

As you can see ES6 make it simpler ! 😗