req.params for route parameters in Express - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is req.params in Express?

req.params is an object in Express that holds route parameters from the URL. It lets you access dynamic parts of the route.

beginner

How do you define a route parameter in Express?

You define a route parameter by adding a colon : before a name in the route path, like /user/:id. This means id is a variable part of the URL.

beginner

Example: What does req.params.id contain if the route is /user/:id and the URL is /user/42?

req.params.id will contain the string "42". It captures the part of the URL that matches the :id parameter.

intermediate

Can req.params hold multiple parameters? How?

Yes. You can define multiple parameters in the route like /user/:userId/book/:bookId. Then req.params will have both userId and bookId as keys.

beginner

What type of data does req.params store for each parameter?

All route parameters in req.params are stored as strings, even if they look like numbers.

How do you access the value of a route parameter named id in Express?

A req.route.id

B req.query.id

C req.params.id

D req.body.id

req.params.id accesses the route parameter named id. req.query is for query strings, and req.body is for POST data.

What symbol is used to define a route parameter in Express routes?

A :

B #

C $

D @

The colon : is used before a name to define a route parameter, like /user/:id.

If the route is /product/:productId/review/:reviewId, how do you get the review ID?

A req.params.reviewId

B req.query.reviewId

C req.params.productId

D req.body.reviewId

req.params.reviewId holds the value of the :reviewId parameter from the URL.

What data type are route parameters in req.params?

A Number

B Object

C Boolean

D String

Route parameters are always strings in req.params, even if they look like numbers.

Which of these URLs matches the route /user/:id?

A /user

B /user/123

C /user/123/profile

D /user?id=123

The URL /user/123 matches the route and sets req.params.id to "123". The others do not match exactly.

Explain how to use req.params to get dynamic values from a URL in Express.

Think about how URLs can have parts that change and how Express lets you capture those.

Describe how multiple route parameters work in Express and how to access them.

Imagine a URL with two dynamic parts, like user and book IDs.