What are route parameters

How would you define a route that captures a user ID from the URL in Express?

If you have a route defined as app.get('/posts/:postId/comments/:commentId'), what will req.params contain when a request comes to /posts/12/comments/5?

What happens if you define two routes with overlapping parameters, like '/users/:id' and '/users/profile'?

You added a new route '/orders/:orderId' but requests to '/orders/status' are hitting the wrong handler. How would you debug and fix this?

Explain why using a route parameter for a large numeric ID caused a performance issue in a high‑traffic endpoint, and what alternative you might consider.

When refactoring a set of routes to use a router, how do you preserve access to the original route parameters across middleware?

In a microservices architecture, you need to forward incoming requests with route parameters to downstream services while preserving them. What design considerations and potential pitfalls would you address?

How would you implement validation and sanitization of route parameters in a way that scales across many routes without duplicating code?

If you need to support optional route parameters and also maintain backward compatibility with older URL patterns, how would you design the routing layer?

Your organization is migrating from an Express monolith to a serverless platform. How would you handle existing route parameters to ensure minimal disruption and consistent API contracts?

Discuss the trade‑offs of encoding multiple pieces of data into a single route parameter versus using query strings, especially regarding caching, CDN edge routing, and API versioning.

When designing a shared routing library used across several teams, what conventions and abstractions would you enforce around route parameters to promote maintainability and avoid naming collisions?