GitLab Frontend Engineer Interview: Rounds, Questions and Preparation

What the job involves

Frontend engineers at global tech companies build and maintain user-facing web applications, often working in distributed teams with a strong focus on code quality, performance, and accessibility. Day to day, they write JavaScript/TypeScript, collaborate on design systems, review merge requests, and ship features behind feature flags. In remote-first companies, clear written communication and async collaboration are as important as coding skills.

Role and technical knowledge

1. 1

   Explain the difference between `let`, `const`, and `var` in JavaScript.

   Cover block scoping, hoisting, temporal dead zone, and why `const` prevents reassignment but not mutation of objects.

2. 2

   How does the virtual DOM work in React, and when does it help performance?

   Describe reconciliation, diffing, and batching. Mention that it avoids direct DOM manipulation but is not always faster than optimal manual updates.

3. 3

   What are Core Web Vitals and how would you improve them?

   Name LCP, FID/INP, and CLS. Give concrete tactics like image optimization, code splitting, lazy loading, and reducing main-thread work.

4. 4

   How do you ensure a web app is accessible to screen reader users?

   Mention semantic HTML, ARIA roles only when needed, keyboard navigation, focus management, and testing with tools like axe or screen readers.

Practical scenarios

1. 5

   You need to add a new feature to a large React codebase you have never seen. How do you start?

   Talk about reading documentation, exploring folder structure, finding similar components, running tests, and asking questions in the right channel.

2. 6

   A page is loading slowly in production but fast locally. How do you debug it?

   Compare environments, check network throttling, bundle size, API latency, and use Lighthouse or performance profiling. Suggest feature flags for safe rollout.

3. 7

   You disagree with a design decision in a merge request. How do you handle it?

   Emphasize respectful, written feedback with reasoning, offering alternatives, and deferring to data or user impact. Avoid blocking without discussion.

4. 8

   How would you implement a dark mode toggle that persists across sessions?

   Cover CSS custom properties, localStorage or cookies, system preference via `prefers-color-scheme`, and avoiding flash of incorrect theme.

Behavioural and remote work

1. 9

   Tell me about a time you had to learn a new technology quickly for a project.

   Use STAR format. Highlight how you found resources, built a small prototype, and applied it under a deadline.

2. 10

   Describe a situation where you received critical feedback on your code.

   Show you can separate ego from work, ask clarifying questions, and make concrete changes. Mention what you learned.

3. 11

   How do you stay productive and communicate when working remotely or asynchronously?

   Mention written updates, over-communication in issues, setting clear statuses, and respecting time zones. Give a specific example.

4. 12

   Tell me about a time you had to explain a technical concept to a non-technical person.

   Focus on simplifying without jargon, using analogies, and checking for understanding. Relate it to design or product conversations.

HR and motivation

1. 13

   Why do you want to work as a frontend engineer at a global remote-first company?

   Connect personal interest in user experience with the company's mission and remote culture. Avoid generic praise; mention specific products or values.

2. 14

   Where do you see yourself in three years?

   Show ambition to grow technically and in scope, like leading a feature area or mentoring. Align with the company's engineering ladder without overpromising.

3. 15

   How do you handle working across time zones with teammates?

   Emphasize flexibility, clear documentation, and using async tools. Mention a personal habit like overlapping hours for critical discussions.

4. 16

   What are your salary expectations for this role?

   Research market rates for freshers in global tech. Give a range based on location and total compensation, and show openness to discussion.