🚀 React Interview Experience (August 2025): L & T(Part -2)

Overview

This document outlines a candidate's interview experience for a React Developer position at L & T in August 2025. The interview process focused on evaluating the candidate's knowledge of React, frontend development best practices, and general software engineering principles. The questions spanned various domains, including API design, security, testing, and deployment strategies.

Interview Rounds

The interview included questions on the following topics:

• API Concepts: The candidate was asked to explain what an API is and how it facilitates communication between applications. The response detailed the role of an API as a messenger, abstracting internal system complexities.
• Authentication and Authorization: The interviewer probed the candidate's understanding of authentication and authorization mechanisms. The candidate described a JWT token-based authentication flow, emphasizing secure token storage in HttpOnly cookies or localStorage, protected routes, and API request handling with token authorization.
• Handling Large Datasets: The candidate was questioned on strategies for managing API responses with large datasets. Techniques discussed included filtering, projection, pagination, lazy loading, server-side filtering and sorting, compression, caching, and streaming responses.
• Security Measures: The discussion covered essential security measures to consider in application development. The candidate mentioned authentication & authorization, input validation & sanitization, HTTPS, CSRF protection, rate limiting, Content Security Policy (CSP), secure headers, dependency updates, parameterized queries, password hashing, and CORS rules.
• API Testing: The candidate outlined approaches to API testing, including unit tests, integration tests, and the use of tools like Postman/Newman/Swagger. Automated testing with Jest, Mocha, or Supertest was also mentioned, along with testing for happy paths, edge cases, and error handling.
• Postman and Swagger: The candidate confirmed experience with Postman for manual API testing and Swagger/OpenAPI for API documentation and interactive testing.
• Unit Testing Implementation: The candidate detailed their use of Jest with React Testing Library, adhering to the Arrange-Act-Assert (AAA) pattern. The approach included testing component rendering, user interactions, and state changes, mocking API calls, simulating user behavior, and ensuring good coverage.
• Docker: The candidate provided a definition of Docker as a containerization platform that packages applications and dependencies, ensuring consistent execution and simplifying deployment.
• Project Methodologies: The candidate stated their use of Agile/Scrum methodologies for iterative development, incorporating sprint planning, daily standups, and retrospectives. The response also included DevOps practices for automation and continuous delivery, with CI/CD pipelines and tools like Jira and Trello for task tracking.

Key Takeaways

• A strong understanding of fundamental frontend concepts, including React, JavaScript, and API interactions, is crucial.
• Knowledge of security best practices, such as authentication, authorization, input validation, and secure communication, is essential.
• Experience with testing methodologies, including unit, integration, and API testing, is highly valued.
• Familiarity with DevOps practices and tools for automation and continuous delivery is beneficial.
• The ability to articulate problem-solving approaches and design considerations is critical for success in frontend interviews.