Node Js Online Test

1. In Express.js, how is error-handling middleware different from regular middleware?

Error-handling middleware does not take any arguments. Error-handling middleware is defined using app.error. Error-handling middleware has an additional first parameter (usually named err) to capture errors. Error-handling middleware is executed before regular middleware.

2. What is a writable stream in Node.js?

A stream that can only be read from A stream that can only be written to A stream that can be both read from and written to A stream that is never used for I/O operations

3. What type of applications are well-suited for Node.js development?

Scientific simulations Real-time applications, such as chat applications and online gaming 3D modeling and animation Batch processing applications

4. What is "callback hell" in the context of Node.js development, and how can it be mitigated?

A coding style that involves nested callbacks, making the code hard to read and maintain A design pattern for asynchronous code A debugging technique A method for optimizing database queries

5. Which Yarn command is used to install project dependencies based on the information in the "yarn.lock" file?

yarn build yarn install yarn create yarn add

6. What is a JSON Web Token (JWT) in the context of authentication in Node.js?

A token used for accessing hardware devices A token used for database connections A compact, URL-safe means of representing claims to be transferred between two parties A session ID

7. Who is the original author of Node.js?

Tim Berners-Lee Mark Zuckerberg Ryan Dahl Larry Page

8. What is the role of a "Docker container" in the context of Node.js application deployment?

To execute code on the client-side To simulate a physical server To package the application and its dependencies in an isolated environment To manage database migrations

9. What is the purpose of the WebSocket.on('message') event in Node.js WebSocket communication?

To log errors To close the WebSocket connection To handle incoming messages from the WebSocket clients To establish a secure connection

10. What is the primary trigger for AWS Lambda functions in serverless applications?

Database queries HTTP requests Manual execution Network monitoring

11. What is "watch mode" in debugging tools like nodemon or ts-node-dev for Node.js?

A mode for executing code without any debugging A mode for monitoring code changes and automatically restarting the application during development A mode for profiling code performance A mode for handling HTTP requests

12. What is the WebSocket protocol identifier in a URL, often used for WebSocket connections in Node.js?

http:// ws:// tcp:// udp://

13. In Node.js, what is the "Poll" phase responsible for?

Executing timer callbacks Handling incoming network requests Cleaning up memory resources Blocking the event loop

14. What is Node.js primarily used for?

Front-end development Back-end development Mobile app development Game development

15. Which HTTP status code should be returned when a requested resource is not found in a Node.js web application?

200 OK 201 Created 404 Not Found 500 Internal Server Error

16. What is the purpose of the app.use() method in Express.js?

To define API routes To create HTML templates To specify middleware functions that should be executed for incoming requests To manage database connections

17. What is the purpose of a reverse proxy server like Nginx when deploying a Node.js application?

To add complexity to the server setup To make the application slower To improve security and performance by handling incoming requests and load balancing To optimize database queries

18. Which Node.js module is commonly used for handling command-line arguments and options in CLI applications?

http fs yargs express

19. In Node.js, what command is commonly used to launch a script in debug mode from the command line?

npm start node inspect node run npm debug

20. What is asynchronous programming in Node.js?

A programming style that uses only synchronous functions A programming style that avoids using functions altogether A programming style that allows non-blocking execution of tasks, often involving callbacks or promises A programming style that focuses on single-threaded execution