Validating route params and query in Express - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are route params in Express?

Route params are dynamic parts of a URL defined with a colon (:) in the route path. They capture values from the URL to be used in the request handler.

beginner

How can you access query parameters in an Express route handler?

Query parameters are accessed via req.query as an object containing key-value pairs from the URL after the question mark.

beginner

Why is it important to validate route params and query parameters?

Validation ensures the data is correct and safe before using it. It prevents errors, security issues, and unexpected behavior in your app.

intermediate

Name a simple way to validate route params and query in Express without external libraries.

You can manually check the values in req.params and req.query using JavaScript conditions like typeof, regex, or number checks.

intermediate

What is a popular library to validate route params and query in Express?

Libraries like Joi or Zod help define schemas and validate route params and query parameters easily and clearly.

How do you define a route param named 'id' in Express?

A /user/:id

B /user/id

C /user/?id

D /user/*id

Route params use a colon before the name, like '/user/:id'.

Where do you find query parameters in an Express request?

A req.body

B req.headers

C req.query

D req.params

Query parameters are in req.query as key-value pairs.

Which of these is NOT a reason to validate route params?

A Prevent security risks

B Improve app performance by caching

C Avoid runtime errors

D Ensure correct data format

Validation helps with security and correctness, not caching or performance directly.

What does this code check? if (!Number.isInteger(+req.params.id))

A If id is an integer number

B If id is missing

C If id is a string

D If id is a boolean

It converts id to a number and checks if it is an integer.

Which library is commonly used for schema validation in Express?

A Express-validator

B React

C Lodash

D Joi

Joi is a popular schema validation library for Express.

Explain how to validate a route parameter and a query parameter in Express without external libraries.

Think about simple JavaScript conditions to check values.

Describe why validating route params and query parameters is important in web applications.

Consider what could happen if you trust user input blindly.