Why limit router nesting to one level?
Deep nesting (e.g., /users/:userId/posts/:postId/comments/:commentId) makes URLs long, rigid, and hard to refactor. Use a separate top-level router with a filter (?post=postId) for deeper resources. Keeps URLs clean.
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More FAQs in Express Router Mounting and Nesting Explained
app.use('/path', router). The router's paths are then relative to /path. For example, router.get('/:id') mounted at /users responds to /users/:id. Mount in app.js to keep it thin.
Yes. Mount one router inside another: router.use('/:userId/posts', postsRouter). Now /users/:userId/posts/... hits postsRouter. Limit nesting to one level; for deeper resources, use a separate top-level router with a filter.
router.use(middleware) at the top of the router file applies the middleware to every route in the router. Useful for auth and role checks across a feature without repeating per route.
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