how to restrict Admin Page node.js

Hey guys im trying to make my admin page off limits to all the users except the one i have named john. What i have in my app.js file is

 app.get('/admin',requireLogin, function(req, res){



  res.render('admin', {
    title: 'Admin'});
});

function requireLogin (req, res, next) {
  if (req.user.username ==='john') {
    next();
  } else {

    res.redirect('/login');
  }
};