Routing
https://dev.to/mrrishimeena/understanding-expressjs-router-nodejs-a-comprehensive-guide-59o8
https://stackoverflow.com/questions/27227650/difference-between-app-use-and-router-use-in-express
It’s just used for sub folder and management, kind of similar to app.use(), lemme see what the actual difference is.
router.use(); mounts middleware for the routes served by the specific router, app.use(); mounts middleware for all routes of the app (or those matching the routes specified if you use app.use('/ANYROUTESHERE', yourMiddleware());).
Example use case could be an app with one router with standard routes and one router that handles api routes, which need a valid user.
You would then mount the authentication middleware for the api router only with router.use(yourAuthMiddleware());.
If you would have an app though that requires a valid user for all routes, mount the middleware for the app with app.use(yourAuthMiddleware());