React JS Interview Questions
Practice with real React JS interview questions
01
A Full Stack Developer was asked
Asked in 2026
Q. Describe how you would architect a cloud-native React application using microservices for handling different user roles and permissions.
Ans. To architect a cloud-native React application using microservices for managing different user roles and permissions, you can follow these steps:
1. Microservice Architecture: Define microservices for user management, role management, and a service for the main application logic. Each service can be deployed independently on a cloud platform like AWS or Azure.
2. API Gateway: Use an API Gateway to route requests to the corresponding microservices based on user role.
- Example: Using AWS API Gateway or Kong.
3. Authentication and Authorization: Implement a centralized authentication service (e.g., Auth0 or AWS Cognito) to handle user sign-in and issue JWT tokens based on user roles.
4. React Application: Structure your React application to consume these microservices.
- Example of a service call:
5. Deployment: Use Docker containers for each microservice, and orchestrate them with Kubernetes on your cloud provider to ensure scalability and manageability.
This architecture allows for flexible role management, independent service scaling, and improved security through microservices.
Full Stack DeveloperCore Concept
02
A Software Engineer was asked
Asked in 2025
Q. Can you explain the React component lifecycle and the role of the virtual DOM?
Ans. The React component lifecycle refers to the different phases that a component goes through: mounting, updating, and unmounting. Each phase has specific lifecycle methods that can be overridden to execute code at particular times. For instance, during the mounting phase,
componentDidMount is called after the component is inserted into the DOM:
The virtual DOM is a lightweight copy of the actual DOM. When state or props change, React first updates the virtual DOM, then compares it with the actual DOM (a process called reconciliation) to determine the minimal number of updates needed. This optimization leads to improved performance and a smoother user experience.Software EngineerCore Concept
