index.html

<script src="https://login.persona.org/include.js"></script>

index.js

navigator.id.watch({
  onlogin: function(assertion) {
   $.post('/user/login', { assertion: assertion}).done(loggedIn);
  },
  onlogout: function() {
    $.post('/user/logout').done(loggedOut);
  }
});

$('#login').click(function() {
  navigator.id.request();
});

server.js

app.post('/user/login', function(req, res) {
  request.post('https://verifier.login.persona.org/verify', { json: {
    assertion: req.body.assertion, audience: 'example.com'
  }}, function(err, r, body) {
    if (body.status === 'okay') {
      res.json({ email: body.email });
    } else {
      res.send(401, 'Unauthorized');
    }
  })
});