Synchronize Shared Data Across Two Lists

Quick Overview

This question evaluates state management, data synchronization across multiple views, handling of asynchronous data fetching with loading and error states, and maintaining a single source of truth for shared items in a mobile UI.

Synchronize Shared Data Across Two Lists

Company: Whatnot

Role: Software Engineer

Category: Software Engineering Fundamentals

Difficulty: medium

Interview Round: Technical Screen

Build a small mobile app with two list screens that fetch and display data. Some items may appear in both lists. Each item has at least: - `id` - `title` - `status` - `updatedAt` Requirements: - Fetch initial data for both list screens from a mock API or repository. - Render both lists independently. - Allow the user to update an item from either list screen, such as changing its `status` or `title`. - If the same item appears in both lists, an update made in one list must be reflected in the other list without requiring a full app restart. - Handle loading and error states. - Avoid maintaining two inconsistent copies of the same item. - Be prepared to explain your state-management approach and how you would allocate time during a 45-minute implementation interview.

Quick Answer: This question evaluates state management, data synchronization across multiple views, handling of asynchronous data fetching with loading and error states, and maintaining a single source of truth for shared items in a mobile UI.

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Whatnot
Jan 24, 2026, 12:00 AM
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Build a small mobile app with two list screens that fetch and display data. Some items may appear in both lists.

Each item has at least:

  • id
  • title
  • status
  • updatedAt

Requirements:

  • Fetch initial data for both list screens from a mock API or repository.
  • Render both lists independently.
  • Allow the user to update an item from either list screen, such as changing its status or title .
  • If the same item appears in both lists, an update made in one list must be reflected in the other list without requiring a full app restart.
  • Handle loading and error states.
  • Avoid maintaining two inconsistent copies of the same item.
  • Be prepared to explain your state-management approach and how you would allocate time during a 45-minute implementation interview.
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