General Frontend Interview Questions
I’ve recently been asked to go into the office for an interview which hasn’t happened in a few years. Outside of feeling some nervousness, I’m really excited to actually be in person talking to potential coworkers. As expected it will be a behavioral interview and a frontend design architecture — I’ve never had a frontend design architecture interview.
I joined my startup as a Junior Developer and after three years — I failed to realize that as I matured in my career so would the interview questions. So I’ve curated some potential questions (with answers) for the frontend design architecture portion. I hope it helps other developer in my position!
General Frontend Architecture Questions
What are the key principles of frontend architecture?
Modularity — designing the application in small, independent modules to enhance reusability and manageability.
Reusability — creating components that can be reused across different parts of the application
Separation of Concerns — Dividing the application logic into distinct sections, each handling a specific aspect like UI, business logic, and data management.
Maintainability — Ensuring code is easy to maintain and update by following consistent coding practices and documentation.
2. How do you approach structuring a large-scale frontend application?
Folder Structure — Organize files by feature or function, using directories like ‘components’, ‘services’, ‘views’, and ‘assets’.
Component Hierarchies — Design components to be as independent as possible, using a tree-like hierarchy where parent components manage state and child components handle presentation.
State Management — Implement a state management solution like Redux and Context API to manage application-wide state, ensuring state consistency and ease of debugging.
3. What are the pros and cons of using a component based architecture in frontend development?
Pros
a. Reusability — Components can be reused across different parts of the application
b. Maintainability — Easier to update and manage individual components
c. Testability — Components can be tested in isolation
Cons
a. Complexity — Can be complex with deeply nested components
b. Overhead — Initial setup and learning curve can be higher
4. What are the difference between React, Angular, and Vue.js in terms of architecture and use cases?
React
Architecture — Library focused on building UI components, with virtual DOM performance optimization
Use Cases — Suitable for single page applications where a high degree of customization and performance is required.
Angular
Architecture — Full-fledged framework with a strong opinion on how to structure applications, includes features like a two-way data binding and dependency injection.
Use Cases — Ideal for enterprise applications requiring a robust framework with many built-in features.
Vue
Architecture — Progressive framework that can be incrementally adopted, combining the best features of React and Angular.
Use Cases — Great for both small and large applications, with a gentle learning curve and flexibility.
5. How do you decide which framework or library to use for a new project?
Project Requirements — Consider the complexity, scale, and needs of the project.
Team Expertise — Choose a framework or library that the team is comfortable with or can quickly learn.
Scalability — Assess how well the framework/library scales with the application’s growth.
Community Support — Prefer frameworks/libraries with strong community support and frequent updates.
6. Explain the concept of a virtual DOM and its significance in modern frontend frameworks.
Virtual DOM: a lightweight, in-memory representation of the actual DOM. Changes are first applied to the virtual DOM, which then efficiently updates the real DOM.
Significance: Improves performance by minimizing direct DOM manipulations and batching updates, leading to smoother and faster UI rendering.
State Management
7. What are the different state management solutions available in frontend development, and how do you choose among them?
Redux — Suitable for large applications with complex state logic and strict state management requirements.
MobX — Ideal for applications requiring reactive state management with less boilerplate.
Context API — Best for simpler state management needs within React applications.
8. How do you manage state in a React application?
Local State — Managed within individual components using useState hook.
Lifting State Up — Move state to a common ancestor to share it between components
Context API — Use createContext and useContext for sharing state across the component tree.
Third Party — Redux or MobX
9. What techniques do you use to optimize the performance of a frontend application?
Code Splitting — Break the applicaition into smaller chunks that can be loaded on demand.
Lazy Loading — Load components or modules only when needed.
Memoization — use Memo to prevent unnecessary re-renders.
10. How do you measure and monitor the performance of a frontend application?
Lighthouse — a tool for auditing web page performance
Web Vitals — a set of metrics for measuring essential aspects of user experience
Browser Developer Tools: Built-in tools in browsers like Chrome DevTools for profiling and analyzing performance
11. How do you approach testing in frontend development?
Unit Testing — Test individual components and functions using tools like Jest or Mocha.
Integration Testing — Test interactions between components or modules.
End-to-end testing — Test the entire application flow using tools like Cypress or Selenium.
12. What are some common debugging techniques and tools for frontend applications?
Browser Developer Tools — Elements panel, Console, Network panel, and Performance Panel.
Logging — console.log for simple debugging
Debugging Extensions — React Developer Tools, Redux DevTools
13. What are some common security concerns in frontend development, and how do you mitigate them?
XSS (Cross-Site Scripting) — Sanitize user inputs, use Content Security Policy (CSP), and escape HTML.
CSRF (Cross-Site Request Forgery) — Implement anti-CSRF tokens and use same-site cookies
CORS (Cross-Origin Resource Sharing) — Configure CORS headers correctly on the server.
Secure Authentication/Authorization — use secure methods for storing tokens, like HttpOnly cookies, and implement proper access controls.
14. What is a Progressive Web App (PWA), and what are its key characteristics?
A progressive web app is an app thats built using web platform technologies but provides a user experience like that of a platform specific app.
Offline Capabilities — work offline or with poor network connections using service workers.
App-like Experience — Provides a native app-like user experience.
Performance — Fast loading and smooth interactions.
Engagement — Push notifications and home screen installation.
15. What build tools and task runners do you commonly use in frontend development?
Webpack: powerful bundler for JavaScript apps, capable of handling CSS, images, and more.
Babel: a compiler for writing next-generation JavaScript and ensuring compatibility with older browsers.
16. What practices do you follow to ensure code quality and maintainability in a frontend project?
Code Reviews: Implement regular code reviews to ensure code quality and knowledge sharing.
Linting: Use tools like ESLint to enforce coding standards.
Documentation: Maintain comprehensive documentation for the codebase and development processes.
Automated Testing: Ensure high test coverage with automated tests for critical parts of the application.
