Redirecting to previous page after authentication in node.js using passport.js

Take a look at connect-ensure-login, which works along side Passport to do exactly what you want!

In your ensureAuthenticated method save the return url in the session like this:

...
req.session.returnTo = req.originalUrl; 
res.redirect('/login');
...

Then you can update your passport.authenticate route to something like:

app.get('/auth/google/return', passport.authenticate('google'), function(req, res) {
    res.redirect(req.session.returnTo || '/');
    delete req.session.returnTo;
}); 

I don't know about passport, but here's how I do it:

I have a middleware I use with app.get('/account', auth.restrict, routes.account) that sets redirectTo in the session...then I redirect to /login

auth.restrict = function(req, res, next){
    if (!req.session.userid) {
        req.session.redirectTo = '/account';
        res.redirect('/login');
    } else {
        next();
    }
};

Then in routes.login.post I do the following:

var redirectTo = req.session.redirectTo || '/';
delete req.session.redirectTo;
// is authenticated ?
res.redirect(redirectTo);