Express, like any good web framework, supports extracting data from URL parts. For example, you can do the following:

app.get('/users/:id', function(req, res, next) {
  console.log(req.params.id);
}

In the preceding example, we will print whatever comes after /users/ in the request URL. This allows an easy way to specify per user routes, or routes that only make sense in the context of a specific user, that is, a profile page only makes sense when you specify a specific user. We will use this kind of routing to implement our profile page. For now, we want to make sure that only the logged-in user can see their own profile page (we can change this functionality later):

app.get('/users/:id', function(req, res, next) {
  if (!req.user || (req.user.id != req.params.id)) {
    return next('Not found'),
  }
  res.render('users/profile', { user: req.user.toJSON() });
});

Here, we check first that the user is signed in and that the requested user's id is the same as the logged-in user's id. If it isn't, then we return an error. If it is, then we render the users/profile.jade template with req.user as the data.

We already looked at models and controllers at length, but our templates have been underwhelming. Finally, we'll show how to write some basic Jade templates. This section will serve as a brief introduction to the Jade templating language, but does not try to be comprehensive. The code for Profile templates is as follows:

html
  body
    h1
      =user.email
    h2
      =user.created_at
    - for (var prop in user.profile)
      if user.profile[prop]
        h4
          =prop + "=" + user.profile[prop]

Notably, because in the controller we passed in the user to the view, we can access the variable user and it refers to the logged-in user! We can execute arbitrary JavaScript to render into the template by prefixing it with = --. In these blocks, we can do anything we would normally do, including string concatenation, method invocation, and so on.

Similarly, we can include JavaScript code that is not intended to be written as HTML by prefixing it with - like we did with the for loop. This basic template prints out the user's e-mail, the created_at timestamp, as well as all of the properties in their profile, if any.