High order function in Express.js

JavaScript
#1

I am having difficulty conceptualizing what goes on here. Is my commentary valid or is it acting in a different way?

app.post('/auth/signin', function(req, res, next) {
	passport.authenticate('local', null,function(error, user, info) {
		if (error) { return next(error) }
		if (user === false) { return res.json({ message : 'Invalid user'}); }
		req.logIn(user, function(error) {
			if (error) { return next(error); }
			return res.json({ userInfo : user })
		});
	})(req, res, next) // there is a returned inner function that requires these 3 inputs.
		// I guess authenticate() returns a route handler function
});

In this example, note that authenticate() is called from within the route handler, rather than being used as route middleware. This gives the callback access to the req and res objects through closure.

I remember a closure as being an inner function for holding state, so I’m thinking what’s happening is: the outer function passes its arguments to the closure to be processed in the callback function. Is that right?

#2