Top Front-End Development Interview Questions Commonly Asked by Mid-Sized Companies and FAANG

Preparing for a front-end development interview can be both exciting and nerve-wracking, especially when you're aiming for mid-sized companies or tech giants like FAANG (Facebook, Amazon, Apple, Netflix, Google). These companies often look for candidates who not only have a strong grasp of fundamental concepts but also possess problem-solving skills and the ability to write clean, efficient code. To help you prepare, here’s a list of commonly asked front-end development interview questions:

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1. HTML & CSS Fundamentals

• What is the difference between display: none, visibility: hidden, and opacity: 0?
• Explain the box model in CSS. How does box-sizing: border-box differ from content-box?
• What are semantic HTML elements, and why are they important?
• How do you center a div horizontally and vertically?
• What are CSS pseudo-elements and pseudo-classes? Can you give examples?

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2. JavaScript Core Concepts

• What is the difference between let, const, and var?
• Explain event delegation in JavaScript.
• What are closures, and how do they work? Can you provide an example?
• What is the difference between == and ===?
• How does the this keyword work in JavaScript?
• What are promises, and how do they differ from async/await?

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3. DOM Manipulation

• How would you add or remove a class from an element using JavaScript?
• What is the difference between innerHTML and textContent?
• How do you handle events in JavaScript?
• Explain the concept of event bubbling and capturing.

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4. Responsive Design

• What is the difference between responsive design and adaptive design?
• How do media queries work in CSS?
• What are some best practices for making a website responsive?
• Explain the concept of mobile-first design.

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5. Performance Optimization

• How do you optimize the performance of a web application?
• What is lazy loading, and how does it improve performance?
• Explain the critical rendering path and how to optimize it.
• What are some ways to reduce page load time?

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6. Frameworks and Libraries

• What are the key differences between React, Angular, and Vue?
• Explain the virtual DOM and how it improves performance in React.
• What are React hooks, and how do they differ from class components?
• What is two-way data binding, and how does it work in Angular?
• How do you manage state in a React application?

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7. Web APIs and Browser Storage

• What is the difference between localStorage, sessionStorage, and cookies?
• How do you make an API call in JavaScript?
• What is CORS, and how do you handle it?
• Explain the Fetch API and how it differs from XMLHttpRequest.

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8. Debugging and Testing

• How do you debug JavaScript code in the browser?
• What are some common tools for testing front-end code?
• Explain the difference between unit testing and integration testing.

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9. System Design and Architecture

• How would you design a responsive navigation bar?
• Explain how you would structure a large-scale React application.
• What are some best practices for organizing CSS in a large project?

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10. Behavioral and Problem-Solving Questions

• Describe a challenging project you worked on and how you overcame the challenges.
• How do you stay updated with the latest front-end technologies?
• Explain a time when you had to optimize a slow-performing website.

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Tips for Acing the Interview

1. Practice Coding Problems: Use platforms like LeetCode, HackerRank, or CodeSignal to practice coding challenges.
2. Build Projects: Showcase your skills by building real-world projects and hosting them on GitHub.
3. Understand the Basics: Ensure you have a strong understanding of core concepts before diving into advanced topics.
4. Mock Interviews: Practice mock interviews with peers or use platforms like Pramp or Interviewing.io.
5. Ask Questions: At the end of the interview, ask thoughtful questions about the company’s tech stack, team structure, or challenges they’re facing.

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Final Thoughts

Front-end development interviews can be challenging, but with the right preparation, you can confidently tackle any question thrown your way. Focus on understanding the underlying concepts, practice coding problems, and be ready to explain your thought process clearly. Good luck, and happy coding!