Question

When I create a sample Express application using the express binary, the bootstrap code has these lines:

...

var app = express();
...
app.use(app.router);

I didn’t find much about app.router. I thought that this is the middleware that handles the routing (app.get(), app.post() etc.) rules, but these rules also get executed when I remove the app.use(app.router); line.

So what is the exact purpuse of this middleware?

Answer 1

This is from the Express 2.x guide http://expressjs.com/2x/guide.html

“Note the use of app.router, which can (optionally) be used to mount
the application routes, otherwise the first call to app.get(),
app.post(), etc will mount the routes.”

I suspect this applies to Express 3.x too.