The abort/cleanup part is where I spent most of my time.
Start by clarifying requirements and choosing a framework, then outline the component architecture with state for items, loading, and error. Emphasize the stale response prevention using AbortController and a request ID or cancellation flag, and demonstrate handling of mount, manual refresh, and unmount scenarios.
Pro tip: Use AbortController to cancel in-flight requests on unmount or new requests, and combine it with a request ID to ignore responses from outdated requests. This shows you understand both network-level and state-level race condition prevention.
Ask about API details, expected error handling, and whether the component should support pagination or filtering. Choose React, Vue, or Angular based on your expertise and the company's stack.
Define state for items, loading, error, and a request identifier. Plan useEffect (React) or equivalent lifecycle hooks to fetch on mount and expose a refresh function.
Use AbortController to cancel previous requests and a request ID or timestamp to ignore responses that don't match the latest request. Ensure cleanup on unmount to avoid setting state on unmounted component.
Show a loading indicator during fetch, display error messages with retry option, and ensure UI updates correctly when requests are cancelled or fail.
Mention testing overlapping requests, rapid refresh clicks, and unmount during fetch. Discuss trade-offs between AbortController and request ID, and between different state management approaches.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
Start by clarifying the requirements and constraints, then outline a component-based solution using stable keys and immutable state updates. Explain the swap logic and disabled states for boundary items, and discuss trade-offs like performance and accessibility. Conclude with testing and edge cases.
Pro tip: Mention that using array index as key breaks identity when reordering, so stable IDs are crucial; also note that disabling buttons should be accompanied by aria-disabled for accessibility.
Confirm the expected behavior: swapping with neighbor, disabled states for first/last, and any constraints like performance or accessibility.
Propose a list component that renders items with up/down buttons, passing handlers and disabled flags based on index.
Use immutable array operations to swap items, ensuring stable keys (e.g., item.id) are used to preserve identity across renders.
Disable buttons appropriately, add aria-labels, and ensure keyboard navigation works; consider visual feedback for disabled states.
Talk about performance implications (e.g., re-rendering only affected items), and how to test the component (unit tests for swap logic, integration tests for UI).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
Wrote tests for the empty state, the disabled controls at list boundaries, and mocked the fetch to test loading/error/success flows.
Start by clarifying the component's API and expected behaviors, then outline a layered testing strategy: unit tests for pure logic, component tests for rendering and interactions, and integration tests for data fetching. Prioritize edge cases like empty state and boundary items, and explain how you'd mock dependencies and assert reordering outcomes.
Pro tip: Emphasize testing user-visible behavior over implementation details, and use data-driven tests for boundary conditions to keep coverage high without brittle assertions.
Ask about the component's props, state, and expected behaviors (e.g., what triggers reordering, data fetching patterns). Confirm the testing tools and environment (Jest, React Testing Library, MSW).
Decide which tests belong at unit level (pure functions, reducers) vs component level (rendering, user events) vs integration level (data fetching with mocked API). Map each requirement to a test type.
Test initial render with loading and success states, mock API calls to verify data fetching and error handling, and assert that the UI updates correctly when data arrives.
Simulate drag-and-drop or button-based reordering, assert the new order and any side effects (e.g., API calls). Cover empty state, single item, and boundary items (first/last) to ensure no crashes or incorrect behavior.
Ensure tests are readable, avoid over-mocking, and use helpers for repetitive setup. Discuss trade-offs like test speed vs realism and how to handle flaky async tests.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
Split into a container component handling fetch state and a purely presentational list.
Start by clarifying the app's requirements and constraints, then propose a layered architecture that separates data fetching (e.g., custom hooks, services) from presentational components. Explain how you would implement accessibility (keyboard navigation, ARIA labels, focus management) and responsiveness (CSS Grid/Flexbox, media queries) with concrete examples and trade-offs.
Pro tip: Emphasize that accessibility and responsiveness are not afterthoughts but should be baked into the component design from the start, and mention how you would test them (e.g., axe, Lighthouse, manual keyboard testing).
Ask questions to understand the app's scale, data sources, target devices, and accessibility standards (e.g., WCAG 2.1 AA). This ensures your design meets the actual needs.
Propose a clear separation: use custom hooks (e.g., useQuery) or services to handle data fetching, caching, and state management, keeping components pure and presentational.
Create reusable, accessible UI components that receive data via props. Ensure they are keyboard navigable, have proper ARIA labels, and manage focus appropriately.
Use CSS Grid/Flexbox, relative units, and media queries to make the layout adapt to different screen sizes. Consider mobile-first approach.
Explain trade-offs (e.g., performance vs. simplicity) and how you would test accessibility (axe, Lighthouse) and responsiveness (device emulation, real devices).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.