Recently, I developed a web application that integrated a React frontend with a Node.js backend. My role involved designing the database schema using MongoDB, implementing RESTful APIs, and ensuring responsive UI components. I also collaborated with the design team to ensure the frontend matched the wireframes and optimized the application for performance. This project required me to manage both the client-side and server-side logic, ensuring seamless data flow and user experience.

I use a combination of browser developer tools, logging frameworks, and debugging tools like Chrome DevTools and Postman. For frontend issues, I inspect the DOM, check network requests, and use breakpoints in the code. On the backend, I rely on detailed logging and error tracking tools like Sentry to identify and resolve issues. I also follow a systematic approach, starting with isolating the problem, identifying the root cause, and then applying the appropriate fix.

I prioritize security by implementing best practices such as input validation, using secure authentication mechanisms like OAuth, and encrypting sensitive data. I also ensure that all dependencies are up-to-date and free from known vulnerabilities. Regular code reviews and penetration testing are part of my workflow to identify and mitigate potential security risks. Additionally, I educate the team on security practices to foster a culture of security awareness.

In SPAs, I manage state using libraries like Redux or React Context API, depending on the complexity of the application. For simpler applications, React's built-in state management is sufficient. I structure the state to be modular and easy to update, ensuring that components receive only the data they need. I also use middleware like Redux Thunk or Saga for handling asynchronous actions, ensuring a consistent and predictable state management approach.

I start by profiling the application to identify bottlenecks, using tools like Lighthouse for frontend and New Relic for backend. For frontend, I optimize by reducing the number of HTTP requests, using lazy loading, and compressing assets. On the backend, I focus on optimizing database queries, caching frequently accessed data, and scaling horizontally. I also ensure that the application is responsive by implementing efficient algorithms and minimizing blocking operations.