While walking through this tutorial, I came across a problem wherein the router methods would not work. Using
var router = express.Router();
var app = express();
app.use(express.static(__dirname + '/api/'));
A router has to be connected to your express app in order to be part of your server.
Or, more commonly with a path that isolates that router's effect to just URLs that start with a specific path and the router's own URLs are relative to this path:
Without this, it's just a declared and configured router that isn't attached to any server.
Express documentation examples here.
The tutorial you reference does not appear to show this part of using a router.