title: Get sessionID from req object without using express-session
body: <p>I heard somewhere that I can use a property in the req object called <code>sessionID</code> but when I used it, it was undefined. The property is not set. Is there a way to uniquely identify a client without using express's session? Because it would require me to rewrite my whole back-end.</p>
  <pre><code>router.post('/signup', function(req, res) {
      console.log(req)
      var signup = auth.signup(req.body.un, req.body.email, req.body.pw, req.body.pc, req.sessionID);
      if (signup !== 1) {
          res.render(&quot;signup&quot;, { title, err: signup })
      } else {
          res.redirect(&quot;/dashboard&quot;)
      }
  })
  </code></pre>