Route Middleware to Check if a User is Authenticated in Node.js

Introduction

Route middleware is an extremely powerful tool in Node.js and Express. As an example of how powerful Express’s route middleware can be, the awesome Passport.js that handles authentication is a route middleware tool.

Also the other big players you usually use like bodyParser and methodOverride are also considered route middleware.

We’ll be looking at a quick way to make sure your users are authenticated before they visit parts of your application.

Our Route

app.get('/hello', function(req, res) {
    res.send('look at me!');
});

Route Middleware Function

...

function isAuthenticated(req, res, next) {
  // do any checks you want to in here

  // CHECK THE USER STORED IN SESSION FOR A CUSTOM VARIABLE
  // you can do this however you want with whatever variables you set up
  if (req.user.authenticated)
      return next();

  // IF A USER ISN'T LOGGED IN, THEN REDIRECT THEM SOMEWHERE
  res.redirect('/');
}

Implementing the Middleware

Now that we have our function to check if our user is logged in or authenticated, we’ll just apply it to our route.

app.get('/hello', isAuthenticated, function(req, res) {
  res.send('look at me!');
});

Conclsion

While this is a simple example, you can see how you can create any function to do checks to see if your user is authenticated, a certain administrator level, or anything else your app needs.