WhatsApp Web Creating a tailored list of 25 questions and answers specifically for Web interviews involves blending technical knowledge about web development, an understanding of WhatsApp features and architecture, and possibly some insights into general interview questions that could be relevant. Let’s dive into a mix that covers these bases:

WhatsApp Web for Interviews: 25 Questions and Answers.

1. What is WhatsApp Web?

  • WhatsApp is the browser-based PC client of WhatsApp Messenger that allows users to send and receive messages through a web browser, syncing with their mobile device.

2. How does WhatsApp synchronise messages with the mobile app?

  • It uses WebSocket technology for a persistent, real-time connection with the mobile device, ensuring messages are synchronised instantly between the Web and mobile.

3. What are WebSockets, and why are they crucial for WhatsApp Web?

  • WebSockets provide a full-duplex communication channel over a single TCP connection, allowing for real-time data transfer between a client and a server, which is essential for instant messaging.

4. Describe the security measures implemented in WhatsApp Web.

  • WhatsApp uses end-to-end encryption for all messages, QR code scanning for secure login, and HTTPS for secure communication between the browser and the server.

5. How does QR code scanning work for WhatsApp Web?

  • The QR code contains a token that the WhatsApp mobile app scans to authenticate the web session, establishing a secure and encrypted connection.

6. Can WhatsApp Web work independently without the mobile app?

  • No, it must be connected to the mobile app to synchronise messages.

7. What is local storage, and how does Whats App Web use it?

  • Local storage allows web applications to store data persistently in the browser. It is used to store app states and preferences.

WhatsApp for Interview.

8. Explain the role of service workers in WhatsApp Web.

  • Service workers act as a proxy between the web application and the network, allowing offline support, background syncing, and push notifications.

9. What technologies are used to build WhatsApp Web?

  • Technologies include HTML, CSS, JavaScript, React (or similar libraries and frameworks), WebSockets, and encryption algorithms for security.

10. How does WhatsApp Web ensure message delivery when the internet connection is unstable?

  • It uses service workers for background syncing and a local cache to store unsent messages, attempting to resend them once the connection is stable.

11. Describe how WhatsApp handles push notifications.

  • It uses the Push API and service workers to receive and display notifications for new messages, even when the browser is closed.

12. How does end-to-end encryption work on the WhatsApp Web?

  • Messages are encrypted on the sender’s device and can only be decrypted by the recipient’s device, ensuring no third party, including WhatsApp, can read them.

13. What challenges might you face when developing an application like WhatsApp Web, and how would you address them?

  • Challenges include handling real-time data, ensuring message security, and optimising for various browsers. Solutions involve using WebSockets, implementing end-to-end encryption, and extensive cross-browser testing.

14. How do you ensure cross-browser compatibility for an app like WhatsApp Web?

  • Use progressive enhancement, polyfills for unsupported features, and extensive testing across browsers.

15. What is a WebSocket handshake, and why is it essential for WhatsApp Web?

  • The initial upgrade request from HTTP to the WebSocket protocol is crucial for establishing a full-duplex communication channel.


16. Explain the concept of session management in WhatsApp Web.

  • Session management involves maintaining a user’s state (e.g., logged-in status) across web requests using cookies, local storage, or session storage.

17. What role do cookies play on the WhatsApp Web?

  • Cookies store session information to keep users logged in and track web usage to improve the user experience.

18. How does WhatsApp Web manage media files such as images and videos?

  • Media files are temporarily cached in the browser and loaded from the server on demand to manage memory and performance efficiently.

19. Explain how QR codes are generated and validated on the WhatsApp Web.

  • The server generates a unique QR code linked to a session ID. The mobile app scans the QR code, validates the session ID, and establishes a connection.

20. How does WhatsApp Web handle video calls?

  • Video calls are not natively supported in WhatsApp due to the complexities of real-time video streaming and device hardware access; they require using the mobile app.

21. What is the significance of the “Keep me signed in” feature in WhatsApp Web?

  • It allows users to remain logged into WhatsApp Web without scanning the QR code again at each visit, using cookies to maintain the session.

22. How can developers debug and test applications like WhatsApp Web?

  • Developers can use browser developer tools for debugging, automated testing frameworks for testing functionality, and

Interview: 25 Questions and Answers.

23. Discuss the impact of network latency on WhatsApp and potential mitigation strategies.

  • Network latency can delay message delivery and synchronisation with the mobile app. Mitigation strategies include optimising server response times, using content delivery networks (CDNs) for static assets, and implementing efficient data transmission protocols like WebSockets.

24. How does the Web handle large groups and chats without performance degradation?

  • It employs lazy loading for messages and media, only fetching and displaying what’s needed. Efficient data structures and algorithms are used to quickly manage and search through large volumes of chat data.

25. What are some potential future improvements or features for the Web?

  • Possible improvements include native support for voice and video calls, better integration with desktop operating systems for file sharing and notifications, and enhanced privacy features like self-destructing messages.

These questions cover a broad spectrum of WhatsApp-related knowledge areas, including technical aspects, security measures, and potential interview questions about system design and problem-solving. Preparing detailed answers to these questions would equip you with a solid understanding of the challenges and solutions in developing and maintaining a web application like WhatsApp.

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