Routing Deep Dive — Chapter Quiz

Question 1

1

Why use express.Router()?

AFor performanceBTo compose self-contained route modules and mount them under a prefixCBecause app is deprecatedDFor TLS support

Routers are mini apps. Compose them into the root app under a URL prefix.

Question 2

2

What does Express 5 do that Express 4 didn't?

AAsync route handlers forward errors to error middleware automaticallyBIt dropped middlewareCIt requires TypeScriptDNothing — same behavior

Express 5 forwards async throws and rejections to the error middleware. Express 4 silently swallowed them (you needed express-async-handler).

Question 3

3

Routes are matched in declaration order. First match wins.

TTrueFFalse

Always declare specific routes BEFORE parameterized ones. /users/me before /users/:id.

Question 4

4

What does Router({ mergeParams: true }) do?

ACombines all middleware into oneBLets the inner router see params from the parent's mount pathCMerges query and bodyDEnables CORS

Without mergeParams, a router mounted at /users/:userId/posts can't see :userId from req.params.

Question 5

5

Why use app.param(name, fn)?

ATo declare a routeBTo run validation/loading whenever a route uses the named paramCFor query string parsingDTo set headers

Run code once per request for every route that has the param. DRY for loadResourceById patterns.

Question 6

6

A 404 catch-all should be mounted AFTER all routes but BEFORE the ___ middleware.

Order: routes → 404 → error middleware. The error middleware must always be last.

Question 7

7

What's a route handler's signature?

A(req, res) or (req, res, next)B(req) onlyC(req, res, next, err)D(ctx) (like Koa)

(req, res, next). next is optional — call it when you want to delegate to the next handler/middleware.

Question 8

8

app.route(path).get(...).post(...) is sugar for…?

ASeveral app.get / app.post calls on the same pathBA WebSocket upgradeCA redirectDSetting headers

Chainable shortcut for grouping methods on one path.

Test what you learned.