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Roblox·Frontend Engineer·Take-home Assignment·Intermediate

IntermediatePrefer not to say
May 2026

Summary

Took a take-home for a frontend role at Roblox. The prompt was to build an image feed and they gave you the API plus pretty detailed specs, so it wasn't one of those vague 'build whatever' situations. The real meat was in infinite scrolling, offline support, and how well you tested the thing.

Questions Asked (1)

Q1

Build an image feed with infinite scrolling, offline support, and solid test coverage. An API and detailed requirements were provided.

System DesignTechnical Trade-offsAPI & Integrations
Author's notes

The spec was detailed enough that you couldn't really complain about ambiguity, which is kind of a double-edged thing.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints, then outline a high-level architecture that separates concerns: data fetching, caching, UI rendering, and testing. Walk through the design decisions for infinite scrolling, offline support, and test coverage, explaining trade-offs and how you would validate the solution.

Pro tip: Emphasize how you would simulate offline scenarios and edge cases in tests, and discuss how you would measure performance metrics like time-to-interactive and scroll jank to ensure a smooth user experience.

1. Clarify Requirements and Constraints

Ask questions to understand the API capabilities, expected data volume, offline expectations, and performance targets. Confirm the scope of test coverage and any platform-specific constraints.

2. Design the Data Layer

Outline how to fetch, cache, and synchronize data. Discuss using a service worker for offline support, IndexedDB for persistent storage, and strategies for pagination and prefetching.

3. Design the UI and Infinite Scrolling

Explain how to implement infinite scrolling efficiently, using intersection observers or virtualization to avoid performance issues. Describe how to handle loading states, errors, and offline indicators.

4. Plan for Test Coverage

Describe the testing strategy: unit tests for components and utilities, integration tests for data flow, and end-to-end tests for critical user journeys. Include how to mock network conditions and test offline behavior.

5. Discuss Trade-offs and Scalability

Highlight key trade-offs such as cache invalidation strategies, memory usage vs. performance, and complexity of offline sync. Explain how the design scales with growing data and user base.

Key Points to Mention

  • Service workers for offline caching and background sync
  • IndexedDB or similar for persistent storage of feed data
  • Intersection Observer API for efficient infinite scrolling
  • Virtualized lists to handle large datasets and maintain performance
  • Testing strategies: unit, integration, and E2E with network mocking
  • Cache invalidation and data freshness strategies (e.g., stale-while-revalidate)

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.