title: Flash messages before user is authenticated
body: <p>Using Node.js Express, I am having trouble understanding how flash images work when a user is trying to login and the login fails - I want to send a flash message to the front-end. But the thing is flash data appears to be attached to req.session. What I don't understand is that req.session data should not exist across different requests quite simply because the user is not authenticated.</p>
  
  <p>You can see the structure of req.session, and as you can see for some reason the flash messages are piling up, but I can't read them on the front end (I am using EJS).</p>
  
  <pre><code>  req.session: Session {
        flash: 
         { loginMessage: [ 'No user found.' ],
           error: 
            [ 'No user found.',
              'Invalid username or password.',
              'Invalid username or password.',
              'Invalid username or password.',
              'No user found.',
              'No user found.',
              'No user found.',
              'No user found.',
              'Invalid username or password.',
              'Invalid username or password.',
  </code></pre>
  
  <p>How can I access these flash messages on the front-end (using EJS for templates)?</p>
  
  <p>thanks</p>