2–5 years · Mid — React · JavaScript / TypeScript · State management · CSS · Performance · Accessibility
Analyzes existing components for reusability; plans a new component structure to minimise props drilling; uses React.lazy for code splitting; applies memoization to prevent unnecessary renders; collaborates with the product manager to clarify performance metrics.
After implementing the component, performance still isn't meeting expectations. What additional steps do you take to troubleshoot and enhance performance?
Outlines the feature's purpose and scope; details the specific challenges encountered during development; explains decisions made regarding architecture and technology; describes the testing and feedback process; reflects on the impact of the feature post-launch.
If you could revisit that project, what would you change?
Identifies the component's props and state to find unnecessary updates; checks if shouldComponentUpdate or React.memo can be applied; considers using useCallback or useMemo to memoise functions/values; profiles the component using React DevTools to confirm the cause of re-renders.
What additional measures can you implement if the problem persists after memoising?
Analyses the CSS file for unused styles with tools like PurgeCSS; considers splitting CSS into smaller, component-specific styles; implements code splitting for critical CSS; evaluates the use of CSS-in-JS for dynamic styling.
How do you handle CSS specificity to avoid styling conflicts in this approach?
Identifies the conflicting state variables and logic; checks compatibility of the new library with existing state management; isolates the feature in a separate branch; begins to refactor state logic to accommodate the new library; considers using context or reducers for efficient state handling.
The conflicts persist even after refactoring. What measures do you take to evaluate whether to stick with the new library or revert to the old state management solution?
Implements windowing or virtualisation techniques (e.g., react-window or react-virtualized); checks for unnecessary re-renders by profiling the component; breaks the list into smaller components; considers lazy loading data or components as needed.
If rendering time is still excessive, what further optimisations could you explore?
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