Build a driving-log replay viewer with an AI assistantCodingIn two to three hours, with an AI coding assistant, build a web app that loads recorded autonomous-vehicle logs from cloud storage and plays them back as an interactive…
Last asked Oct 2026
#frontend
React social feed with voting, re-sorting and pinned postsCodingBuild a feed page in React. Each post can be upvoted or downvoted, and after every vote the feed re-sorts by score, highest first. A post can be pinned, and pinned posts stay at…Last asked Sep 2026
Design a real-time comment feed with optimistic updatesSystem designDesign the front end of a comment section where other people's comments arrive live and the viewer can post their own. The focus is optimistic posting: a submitted comment shows…Last asked Sep 2026- Credit card form with validation and linked fieldsCodingBuild a card-details form in the browser (React is fine): cardholder name, card number, expiry date and security code. Validate each field as the user types and on submit, and…Last asked Sep 2026
React typeahead with async suggestions and keyboard navigationCodingBuild a typeahead in React: a search input with a dropdown of suggestions that come from an asynchronous source while the user types. The user can pick a suggestion with the mouse…Last asked Sep 2026- Render nested JSON in a code-style viewerCodingBuild a React component that displays a given JSON object the way a code editor would: indentation, braces and brackets, keys and values styled by type, and nested objects and…Last asked Sep 2026
- React list loaded with useEffectCodingWrite a React component that loads a list from an endpoint with useEffect and displays it. Handle loading and error states, keys for list items, and cleanup so a late response…Last asked Sep 2026
Filter an n-ary tree by substring and render it indentedCodingEach node of an n-ary tree has a string value and a list of children. 1. Given a search string, return the filtered tree: keep every node whose value contains the substring, plus…Last asked Sep 2026- Autocomplete search bar with a hand-written debounceCodingBuild an autocomplete search bar: as the user types, show suggestions for the current text, fetched from a suggestion service. Calls must be debounced, so the service is called…Last asked Sep 2026
Autocomplete product search boxCodingBuild a front-end search box that suggests products as the user types. Debounce the requests so typing doesn't send one per keystroke, and make the component accessible, including…Last asked Aug 2026- Accessible popovers that load dataCodingBuild popovers for several buttons on a page: each button opens its own popover, which loads its data when opened. Make them accessible and handle the loading state.Last asked Aug 2026
- JavaScript let versus varCodingPredict what short JavaScript snippets print and explain the difference between let and var: scope, hoisting, and how each behaves in loops and closures.Last asked Aug 2026
Arrow-key controlled kanban board in ReactCodingBuild a kanban board in React with columns of cards. A card can be selected, and the arrow keys move the selection or the selected card between positions and columns. Keep the…Last asked Aug 2026- Design calendar front-end state for recurring eventsSystem designDesign the client-side state for a calendar app that supports recurring events. Cover how recurrence rules are stored versus expanded into visible occurrences, how a single…Last asked Aug 2026
Virtualized spreadsheet grid in React with cell formulasCodingBuild a spreadsheet in React. The grid is large, so render only the rows and columns in view and keep scrolling smooth. Cells can hold plain values or formulas that refer to other…Last asked Jul 2026
Diagnose a slow cold load and a huge table in a web appCodingA web app is slow on its first load, and one page renders a table with a very large number of rows that makes the page sluggish. Explain how you would find the causes (profiling…Last asked Jul 2026- JavaScript scope, closures, timers and the event loopCodingA frontend fundamentals round: predict what short JavaScript snippets print and explain why. Expect scope (var versus let, hoisting), closures (including the classic loop with…Last asked Jul 2026
- Accessible expand-and-collapse tree in ReactCodingBuild a React component that renders nested data as a tree where each node can be expanded or collapsed, to any depth. Render it recursively, keep the expanded state sensibly, and…Last asked Jul 2026
Build a React interface against an undocumented APICodingWith an AI coding assistant available, build a React interface on top of an API that has no documentation. Work out the endpoints and the shape of their data by exploring them…Last asked Jun 2026- Debug an Angular UI from user reportsCodingYou get an Angular application and a handful of user bug reports. Reproduce each problem, find the cause in the code and fix it, explaining how you narrowed it down.Last asked May 2026
Parking lot manager in ReactCodingBuild a small React app that manages a parking lot: show the spots and whether each is free, let vehicles park and leave, and keep everything on screen in sync. The round focuses…Last asked May 2026
Build a chat input that renders a streamed AI replyCodingBuild a minimal ChatGPT-like page: a text box and a submit button, and below them the model's reply, rendered as it streams back from the API rather than all at once. Handle the…Last asked Apr 2026
Design an embeddable streaming chat interfaceAI system designFor a frontend role: design the interface for a chat agent that other products can embed. Cover the component's API, streaming the agent's replies as they are generated, how…Last asked Apr 2026- Render more than 100 million points on a mapSystem designFor a frontend role: design a web map that shows more than a hundred million data points. Cover what the server sends at each zoom level (tiles, clustering, aggregation), how the…Last asked Apr 2026
Infinite-scroll news feed in TypeScriptCodingUsing supplied mock data and fetch helpers, build a feed page of article cards in TypeScript that loads more as the reader scrolls. Show clean component structure, pagination…Last asked Apr 2026
Autocomplete data fetching with debounce, retry and cachingCodingThe UI of an autocomplete box is already built; you write only the data-fetching logic behind it. Debounce requests while the user types, retry requests that fail, show only the…Last asked Apr 2026- Technical recruiter screen: duplicate requests and a streaming chat UISystem designThe first recruiter call is more technical than most. After the background questions (how much of the last year you spent writing code, whether you lean frontend, backend or full…Last asked Apr 2026
- React Battleship boardCodingIn React, build the board for the game Battleship (just the board, no opponent logic). Each cell can be clicked to change its state (empty, hit, miss), and the board shows which…Last asked Apr 2026
- React fundamentals and error handlingCodingExplain core React concepts: components and props, state and re-renders, hooks and their rules, effects and cleanup, keys in lists. Then explain how you handle errors in a React…Last asked Feb 2026
- Responsive grid of fixed-size boxesCodingBuild a web page that lays out fixed-size boxes in a grid that reflows as the window gets wider or narrower: as many boxes per row as fit, wrapping to new rows. Explain the CSS…Last asked Jan 2026
- React class components, lifecycle methods and hooksCodingExplain how React class components work and the order of their lifecycle methods (mount, update, unmount), then how the same behavior is written with hooks: useState, useEffect…Last asked Jan 2026
- Implement an event emitterCodingImplement an event emitter class: on(event, handler), off(event, handler), once(event, handler) and emit(event, ...args). Handlers run in the order they were added. Handle a…Last asked Jan 2026
- Reusable dialog componentCodingBuild a reusable dialog component for a web page. It takes a background color, a title, a close button and a list of action buttons from the caller. Make it reusable across pages…Last asked Oct 2025
React hook for API data and UI changes in a starter appCodingIn a starter React app with API and UI code already written: write a hook that fetches data from the API and converts it to the shape the UI needs, then change the UI as asked…Last asked Sep 2025- Searchable transaction list that highlights the largestCodingBuild a small interface in three steps: 1. Render a list of transactions given as {name: string, amount: number}. 2. Highlight the name of the transaction with the largest amount…Last asked Sep 2025
Design the front end of a desktop AI chat appSystem designDesign the client side of a desktop chat app for an AI assistant: the conversation list, the chat view and the model's replies as they stream in. This is a front-end system design…Last asked Sep 2025- Debounce and throttle in JavaScriptCodingImplement debounce(fn, wait) and throttle(fn, wait) in JavaScript. Keep this and the arguments of the latest call, support cancelling, and discuss options to fire on the leading…Last asked Sep 2025
- Passport number form with per-country formatsCodingYou get a map from country to passport number format, for example {USA: "LLDDDD", Canada: "AALLDDDD"}, where L must be a letter, D a digit and A either one. 1. Build the layout: a…Last asked Aug 2025
Build a booking widget with live pricingCodingBuild a small reservation widget for a listing, front end and a simple back end. Pick check-in and check-out dates and the number of adults and children; show the total price…Last asked Aug 2025
Paginated, sortable React tableCodingBuild a React table component that takes its column definitions as data, sorts by a column when its header is clicked and pages through rows. Keep the component split and the…Last asked Aug 2025- Find bugs and slow renders in a React appCodingYou get a small React codebase with several bugs and performance problems. Find and fix them: unnecessary re-renders, event listeners that are never cleaned up, and similar…Last asked Aug 2025
Collapsible JSON viewer in ReactCodingIn an hour of React, pretty-print a JSON value (objects, arrays, strings, numbers) with indentation, and give every nested object and array a toggle that collapses it to a…Last asked Jul 2025