▸case-01 I'm building an interactive product catalog page in Next.js 15 using App Router. Can you help me structure and write the client and server components for filtering, search, and infinite scrolling product list while keeping it accessible and performant? | fail→fail | 25,927 | 31,269 | +21% | 1 | 1 | 0% | 5,304 | 6,030 | +14% | 0 | 0 | — |
▸case-02 Our React web dashboard experiences severe UI lag whenever users tweak the dynamic data filters. Please analyze our client state structure and provide a refactored component solution that eliminates unnecessary renders and improves accessibility. | fail→fail | 22,572 | 24,983 | +11% | 1 | 1 | 0% | 4,584 | 5,288 | +15% | 0 | 0 | — |
▸case-03 We need to implement a complex user onboarding form with multiple steps in Next.js. Could you design the component hierarchy, set up accessible form controls with proper keyboard navigation, and demonstrate the client-side state flow? | fail→fail | 40,045 | 34,319 | -14% | 1 | 1 | 0% | 7,967 | 7,055 | -11% | 0 | 0 | — |
▸case-04 We are building a social media feed in React 19 where users can click a 'Like' button on a post. We want the UI to update immediately before the server request completes, and revert if the request fails. Explain how to manage this state seamlessly and write the component code using native React 19 hooks rather than third-party libraries. | fail→fail | 20,535 | 24,496 | +19% | 1 | 1 | 0% | 3,106 | 4,232 | +36% | 0 | 0 | — |
▸case-05 In a Next.js 15 App Router blog application, we have an admin portal for editing post content. When an admin submits an updated title, we want to invalidate the cached data for path `/posts/[slug]` on the server so visitors immediately see the new title. How should we write the server action and trigger cache invalidation? | fail→fail | 18,037 | 19,487 | +8% | 1 | 1 | 0% | 2,741 | 3,531 | +29% | 0 | 0 | — |
▸case-06 We are implementing a custom modal dialog component in React without using an external UI component library. When the modal opens, screen readers and keyboard users need proper dialog semantics, focus trapping, and restoration upon closure according to W3C ARIA Authoring Practices. Provide the component implementation. | pass→pass | 28,329 | 33,432 | +18% | 1 | 1 | 0% | 5,088 | 6,792 | +33% | 0 | 0 | — |
▸case-07 Users are reporting lag when typing in an autocomplete search input on our React 19 application. The Interaction to Next Paint (INP) metric is spiking above 300ms because heavy re-indexing runs on every keystroke. How should we decouple the urgent input text update from the non-urgent search results list recalculation using built-in React 19 hooks? | fail→fail | 19,809 | 21,226 | +7% | 1 | 1 | 0% | 2,819 | 3,509 | +24% | 0 | 0 | — |
▸case-08 We are building an e-commerce product detail page at `/products/[id]` in Next.js 15 App Router. We need dynamic Open Graph tags (`og:title`, `og:image`) based on fetched product details for social media link previews. How should we export metadata from the server component page file? | fail→fail | 17,631 | 11,403 | -35% | 1 | 1 | 0% | 2,752 | 2,840 | +3% | 0 | 0 | — |
▸case-09 We need a custom multi-select checkbox group component in React for selecting user interests (e.g. Technology, Sports, Art). It must comply with WCAG 2.1 AA accessibility guidelines for screen reader navigation and field set grouping without using third-party UI libraries. Write the component implementation. | pass→pass | 25,182 | 26,196 | +4% | 1 | 1 | 0% | 4,463 | 5,175 | +16% | 0 | 0 | — |
▸case-10 We are building a Next.js 15 dashboard page where user profile info loads fast (50ms) but analytics charts load slowly (1500ms). We want to stream the slow analytics section progressively without blocking the initial page render. Show the page file architecture and React pattern to achieve progressive loading. | fail→fail | 17,396 | 13,815 | -21% | 1 | 1 | 0% | 3,442 | 3,172 | -8% | 0 | 0 | — |
▸case-11 An internal web tool renders a table of 10,000 log entries in a React 19 application. Rendering all 10,000 DOM nodes simultaneously causes severe browser memory pressure and layout recalculation delays. What DOM rendering technique should we use to only render visible rows in the viewport? | fail→fail | 14,923 | 15,822 | +6% | 1 | 1 | 0% | 1,833 | 2,476 | +35% | 0 | 0 | — |
▸case-12 In Next.js 15 App Router, we have a route `/api/stock-ticker` that defaults to static caching, but we need it to fetch fresh stock data on every request without dynamic render errors. Which route segment config option forces dynamic rendering on every request? | fail→fail | 9,212 | 10,360 | +12% | 1 | 1 | 0% | 799 | 1,439 | +80% | 0 | 0 | — |
▸case-13 We are building an accessible custom dropdown navigation menu component in React. When a keyboard user focuses on the dropdown toggle button, which specific key presses must open the menu and move focus to the first item according to ARIA practices? | fail→fail | 11,790 | 10,509 | -11% | 1 | 1 | 0% | 1,304 | 2,589 | +99% | 0 | 0 | — |
▸case-14 In our React application, we store a large user settings object in a React Context. Whenever a single scalar value like `themeMode` changes, every component consuming the context re-renders, including heavy data grid components that only read `userPermissions`. How should we restructure context or state consumption to avoid re-rendering components that do not read `themeMode`? | fail→fail | 20,511 | 21,196 | +3% | 1 | 1 | 0% | 2,698 | 3,647 | +35% | 0 | 0 | — |
▸case-15 Our Next.js 15 hero banner image at the top of the homepage is causing a high Largest Contentful Paint (LCP) time because the browser lazy-loads it by default. What prop on the Next.js `<Image />` component ensures the hero image is prioritized and preloaded immediately? | fail→fail | 6,356 | 9,694 | +53% | 1 | 1 | 0% | 1,133 | 1,347 | +19% | 0 | 0 | — |
▸case-16 We are building a React component library and want to ensure zero runtime CSS overhead and automatic class scoping. Which styling approach avoids JavaScript bundle runtime overhead while maintaining scoped class names? | fail→fail | 13,792 | 14,599 | +6% | 1 | 1 | 0% | 2,297 | 3,055 | +33% | 0 | 0 | — |
▸case-17 We have an input field for email addresses in a React form. When validation fails, an error message appears below the input. How do we programmatically link the input field to its error message container so screen readers automatically announce the error when the input is focused? | fail→fail | 15,145 | 17,097 | +13% | 1 | 1 | 0% | 2,091 | 2,947 | +41% | 0 | 0 | — |
▸case-18 We are fetching user notifications on a React dashboard. We want the UI to display cached data immediately upon mounting, then silently revalidate in the background and update the screen when new data arrives. What data fetching pattern and strategy achieves this without writing custom `useEffect` caching logic? | fail→fail | 10,631 | 10,760 | +1% | 1 | 1 | 0% | 1,974 | 2,465 | +25% | 0 | 0 | — |
▸case-19 On a news site built with React 19, loading advertisements and dynamic content widgets dynamically causes severe Cumulative Layout Shift (CLS), pushing body text down as elements load. How should we structure the DOM container for dynamically loaded content to stabilize LCP/CLS? | fail→fail | 23,341 | 25,993 | +11% | 1 | 1 | 0% | 4,079 | 4,254 | +4% | 0 | 0 | — |
▸case-20 We are building a tabbed interface component in React for a user profile page with tabs 'Overview', 'Settings', and 'Security'. To conform to WAI-ARIA Tabs pattern, what specific ARIA roles must be assigned to the container list, individual tab buttons, and tab panels? | fail→pass | 8,886 | 16,843 | +90% | 1 | 1 | 0% | 1,877 | 2,902 | +55% | 0 | 0 | — |
▸case-21 We are integrating a custom Google Web Font into a Next.js 15 App Router project. To eliminate layout shifts caused by FOIT/FOUT and eliminate render-blocking external network requests at runtime, how should fonts be loaded using Next.js built-in font utilities? | fail→fail | 17,711 | 15,703 | -11% | 1 | 1 | 0% | 2,487 | 3,041 | +22% | 0 | 0 | — |
▸case-22 In a React 19 application, a third-party widget inside a sidebar component sometimes throws an unhandled JavaScript error, crashing the entire application page. How do we catch runtime errors in that specific component subtree and render a fallback UI without crashing the whole app? | fail→fail | 18,114 | 18,870 | +4% | 1 | 1 | 0% | 2,533 | 4,235 | +67% | 0 | 0 | — |
▸case-23 We are designing a PostgreSQL relational database schema and Node.js Express REST API endpoints for an e-commerce order management system. Provide the SQL table definitions and Express route handlers for processing orders. | pass→pass | 20,718 | 20,768 | +0% | 1 | 1 | 0% | 4,557 | 3,921 | -14% | 0 | 0 | — |
▸case-24 We are building a native iOS application using Swift and SwiftUI for a mobile healthcare app. How should we set up a Swift view model and `@Observable` state for tracking user heart rate trends over time in SwiftUI? | pass→pass | 22,135 | 14,466 | -35% | 1 | 1 | 0% | 4,514 | 2,228 | -51% | 0 | 0 | — |
▸case-25 We need a visual design color palette and typography hierarchy guide for a luxury travel brand's marketing materials in Figma. Please specify the hex color codes, typography scale, and visual design rules for print and digital posters. | pass→fail | 24,920 | 30,494 | +22% | 1 | 1 | 0% | 3,512 | 5,485 | +56% | 0 | 0 | — |