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After 6 months of preparation and 15+ interviews, I landed a frontend engineer role at a big company. Here's exactly how I did it—including what didn't work.
Preparing for frontend engineer interviews—especially at top-tier tech companies—is no small task. The expectations are high, and the range of topics can be surprisingly broad, covering everything from JavaScript internals and browser behavior to system design and communication skills. As someone who now works as a frontend engineer at a FAANG company, I want to share how I approached interview prep: what worked, what didn't, and the tools and resources that helped me most.
This isn't just a list of links or a study plan. It's a walkthrough of the mindset and methodology I used to bridge the gap between being a capable developer and becoming someone who can confidently navigate high-stakes interviews.
Before diving into specifics, here's how I structured my preparation over 12 weeks, dedicating 2-3 hours daily:
Weeks 1-4: Foundation Building
JavaScript fundamentals review (1 hour daily)
Building vanilla JS components (1 hour daily)
Behavioral story preparation (30 minutes, 3x per week)
Weeks 5-8: Framework Deep Dive & Practice
React internals and advanced patterns (1 hour daily)
Frontend system design study (45 minutes daily)
Mock interviews with peers (2 hours, 2x per week)
Weeks 9-12: Interview Simulation & Polish
Daily coding challenges on bfe.dev (1 hour)
System design practice (1 hour daily)
Mock behavioral interviews (1 hour, 3x per week)
Early on, I realized that successful interview prep hinges on direction. It's easy to fall into the trap of endlessly watching tutorials or solving random coding problems without a clear end goal. To avoid this, I structured my preparation using resources like the Front End Interview Handbook and Front End Developer Playbook. These guides helped me understand what topics mattered most—from HTML semantics and CSS layout quirks to advanced JavaScript behavior and performance optimization.
Another standout resource was bfe.dev (BigFrontend.dev). This site offers real-world frontend coding challenges that simulate browser behavior. Think of it as LeetCode—but specifically tailored to frontend engineers. Unlike algorithm-heavy platforms, bfe.dev focuses on DOM manipulation, async JavaScript, event delegation, and related problems that are far more relevant to the daily challenges of a frontend developer.
Resource Breakdown by Experience Level:
For Junior to Mid-Level (0-3 years):
javascript.info for fundamentals
MDN Web Docs for browser APIs
bfe.dev coding challenges (start with easy ones)
For Senior Level (3+ years):
Frontend system design case studies
React internals documentation
Advanced performance optimization techniques
Having this roadmap helped me balance foundational review with advanced topics. It also prevented burnout by keeping me focused on high-impact learning.
Any seasoned frontend engineer knows that deep JavaScript knowledge is non-negotiable. It's not enough to simply understand syntax or ES6 features; you need to internalize how the language works at a low level. That includes understanding the event loop, closures, prototype chains, this binding, and memory management.
To strengthen my fundamentals, I relied heavily on javascript.info. The site provides concise, interactive lessons that helped me grasp and retain key concepts. For example, I reviewed how JavaScript handles asynchronous tasks—critical for understanding how to write performant UI code and debug async bugs in production.
What Actually Worked vs. What Didn't:
❌ What didn't work: Spending hours watching YouTube tutorials about closures and promises. I could explain the concepts but struggled to apply them under pressure.
✅ What worked: Building small features from scratch. I created components like dropdowns, accordions, and form validators without relying on frameworks. This forced me to handle DOM updates manually, understand event bubbling, and respect accessibility best practices.
Real Interview Example: One interviewer asked me to implement a debounced search input. Instead of just writing the debounce function, I had to handle edge cases like clearing previous requests, managing loading states, and ensuring accessibility. Having built similar features during prep, I could discuss trade-offs confidently: "I'm using AbortController here because it's cleaner than boolean flags for canceling requests, and it works well with fetch API."
Many frontend roles—especially at mid to senior levels—expect strong proficiency in a frontend framework, and React is the most common by far. But proficiency goes beyond memorizing the API. It means understanding why React works the way it does, how rendering and reconciliation happen, and how to architect applications for scalability.
I spent considerable time diving into React's internal behavior: how the virtual DOM diffing algorithm works, when re-renders happen, and how to optimize performance using useMemo, useCallback, and React.memo. I also practiced designing features using both Redux and Context API so I could speak confidently about trade-offs.
Another key area was React Hooks. Many interview questions revolve around lifecycle behavior in functional components. For instance: When does useEffect run? What's the difference between useLayoutEffect and useEffect? Understanding these nuances and explaining them clearly was crucial.
Interview Reality Check: I was asked to build a todo app with React, but the follow-up questions were where the real assessment happened: "How would you optimize this if we had 10,000 todos? What if todos could have nested subtodos? How would you handle optimistic updates?" Having studied React's reconciliation process, I could discuss virtualization, memoization strategies, and state normalization confidently.
Frontend system design is often overlooked in interview prep—but it's a critical skill, especially at larger companies. I prepared for this by studying how the browser works under the hood: DNS resolution, rendering pipeline, caching strategies, and how security policies like CORS and CSP affect application architecture.
Key System Design Topics to Master:
Performance Optimization
Code splitting and lazy loading strategies
Caching (browser cache, CDN, service workers)
Critical rendering path optimization
Scalability Concerns
Component architecture for large teams
Micro-frontend strategies
State management at scale
Real-World Constraints
Offline functionality design
Cross-browser compatibility strategies
Mobile performance considerations
Actual System Design Question I Faced: "Design a Google Docs-like collaborative editor." I had to discuss real-time synchronization (WebSockets vs polling), conflict resolution (operational transforms), performance optimization (virtualization for large documents), and offline support (service workers + local storage). The key was breaking down the problem systematically and discussing trade-offs at each step.
Why does it matter? Because interviewers want to know you can make informed decisions under real-world constraints. For example, can you design a frontend application that works offline? Can you explain how lazy-loading images affects performance? Do you know when to use server-side rendering versus client-side rendering?
To build these skills, I practiced by designing common frontend systems—like dashboards with infinite scroll, search interfaces with debounce, or real-time messaging UIs. I paid attention not only to how I built them but why I made specific choices.
Live coding interviews are one of the most intimidating parts of the process. The ability to write clean code under pressure, while thinking aloud and handling unexpected edge cases, takes practice. I simulated this environment using CodeSandbox and other online editors that mimic real-time collaboration tools.
My Simulation Strategy:
Set 45-minute timers for coding challenges
Used unfamiliar online editors to simulate discomfort
Practiced explaining my thought process out loud (felt awkward at first, but crucial)
Recorded myself to identify verbal tics and unclear explanations
The types of tasks I faced typically involved consuming APIs, managing component state, handling loading/error conditions, and building interactive UIs. Some examples: implementing a sortable table, building a custom dropdown, or creating a simple Kanban board with drag-and-drop functionality.
Real Interview Questions I Encountered:
"Build an autocomplete component that fetches suggestions from an API"
"Create a photo gallery with infinite scroll and lazy loading"
"Implement a custom hook for managing form validation"
What helped was not just solving these problems, but revisiting them with new constraints. For instance, could I refactor my solution to use a custom hook? Could I add accessibility features like keyboard navigation or ARIA attributes? These follow-ups helped me think like an interviewer—and made me a more thoughtful engineer in the process.
Technical ability alone won't land you the job. Behavioral interviews assess how you collaborate, handle ambiguity, and reflect on your experiences. I prepared a list of real stories from my career—projects where I took initiative, resolved conflicts, or improved system performance. Using frameworks like STAR (Situation, Task, Action, Result), I practiced delivering these stories concisely and confidently.
My Story Bank (Examples):
Leadership: Led migration from class components to hooks, reducing bundle size by 15%
Conflict Resolution: Resolved disagreement between design and backend teams about API structure
Technical Challenge: Debugged memory leak in React app that was causing crashes on mobile devices
Growth: Failed to meet performance budget on initial feature launch, learned about code splitting, implemented solution
Why does this matter for frontend roles? Because so much of our work involves cross-functional collaboration—with designers, backend engineers, and product managers. Communicating trade-offs and aligning technical decisions with product goals is a skill that interviewers highly value.
Perhaps the most important takeaway from my prep journey is this: clarity matters more than cleverness. Interviews aren't about showing off how much you know—they're about demonstrating how you think. Can you explain your decisions? Do you understand trade-offs? Can you stay calm when something doesn't work?
Before I learned this lesson: "I'll use a custom hook with useReducer and implement memoization with useMemo for optimal performance."
After focusing on clarity: "I'm choosing useReducer here because we have complex state with multiple related values. If performance becomes an issue with re-renders, I can add memoization, but let's start with the clearer solution."
When I focused less on impressing and more on communicating, my interviews improved dramatically. I made sure I could answer questions like: Why did I use useReducer instead of useState? How would I improve the time-to-interactive of a page? What considerations go into building for accessibility?
Mistake #1: Over-preparing on algorithms I spent 2 weeks grinding LeetCode, thinking frontend interviews would be similar to backend ones. Frontend interviews rarely involve complex algorithms—focus on JavaScript fundamentals and browser APIs instead.
Mistake #2: Neglecting the "boring" stuff I initially skipped studying HTML semantics and CSS fundamentals, thinking they were too basic. Multiple interviews included questions about accessibility, form validation, and CSS specificity.
Mistake #3: Not practicing explaining my code I could write code fine but struggled to articulate my decisions clearly. Practice talking through your thought process—it's a learnable skill.
Frontend interview prep can feel overwhelming, especially when it seems like you need to know everything from paint cycles to promise chaining. But with a focused plan, the right resources, and consistent practice, it becomes manageable—and even enjoyable.
Invest time in the fundamentals. Don't just memorize solutions—build real features. Simulate real interview scenarios and take the time to reflect on both your technical and behavioral responses. And most importantly, approach each step with curiosity rather than panic.
If you're about to start your interview prep journey, know this: it's not about cramming every concept. It's about understanding deeply, building with intent, and communicating clearly. That's what interviewers remember—and what truly sets you apart.
Remember, every successful engineer has been where you are now. The difference isn't talent—it's preparation, persistence, and the willingness to learn from both successes and failures. You've got this.
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