// ...other instantiation logic...

var userID = getIDFromPageURI();
var user = null;

var loadUser = function (id) {
    // GET the latest state of the user from the backend
    $.get("/api/user" + id)
       .done(function (response) {
           if (!user) {
               // if the user variable is NOT defined yet, create a new instance of a UserModel.
               user = new UserModel(response);
           } else {
               // If the user variable IS defined, fill in missing data
               UserModel.fill(user, response);
           }
       });
}

var subscribeToNotifications = function(id) {
    // only subscribe to notifications if we have a web socket open
    if (notifications.isConnected()) {
        
        notifications.subscribe("users."+id, onNotification)
            .done(function () {
                loadUser(id);
            });
    }
}

var onNotification = function (data) {
    if (!user) {
      // If the user variable is NOT defined, create a new instance of the user model.
      user = new UserModel(data);
    } else {
      // If the user variable IS defined, merge the new data into the existing model
      UserModel.merge(user, data);
    }

}

// Now that the page is defined, load the data from the backend and subscribe to notifications
loadUser(userID);
subscribeToNotifications(userID);

// ...other instantiation logic...