Changelog
August 9, 2026
- Added Questions to Ask, a system design guide
- Updated Future-Proof Components, a system design core concept
July 26, 2026
- Added Core Concepts, a system design guide
- Added How to Prepare, a system design guide
- Added External Dependencies, a system design core concept
- Added Design System Library, a system design question
July 25, 2026
- Added AI & LLM Integration, a system design core concept
July 18, 2026
- Added API Design, a system design core concept
- Updated Delivery Framework, a system design guide
July 11, 2026
- Added Future-Proof Components, a system design core concept
July 5, 2026
- Added Performance Budgets, a system design core concept
July 4, 2026
- Added 6 system design core concepts: Choosing a Repo, Microfrontends, Monorepos, Optimistic Updates, Server Sent Events and Styling Approaches
- Added Jira Board, a system design question
June 28, 2026
- Added Delivery Framework, a system design guide
- Added 4 system design core concepts: Broadcast Channels, Microfrontend Perf Problems, Specialized Testing Patterns and State Management Tools
June 27, 2026
- Added Monoliths, a system design core concept
- Added Performance at Scale, a system design core concept
- Added Testing Strategy, a system design core concept
June 21, 2026
- Added 7 user interface questions: Data Table, Heatmap Canvas, Image Gallery, Infinite Canvas, Native Dialog, Spreadsheet UI and Trie Typeahead
- Added Spreadsheet Engine, a JavaScript coding question
- Added Introduction, a system design guide
- Added Real-Time Transports, a system design core concept
- Added Virtualization, a system design core concept
- Added 13 conceptual articles: How do you build an accessible form?, How do you make a custom component keyboard accessible?, What are CSS keyframes?, What are generics in TypeScript?, What are TypeScript utility types?, What is focus management and why does it matter for accessibility?, What is IntersectionObserver?, What is MutationObserver?, What is ResizeObserver?, What is the difference between CSS transitions and animations?, What is the difference between unknown and any in TypeScript?, What is type narrowing in TypeScript? and 1 more
June 20, 2026
- Added 6 user interface questions: File Upload, Markdown Editor, Portfolio Visualizer I, Portfolio Visualizer II, Sliding Puzzle and Streaming Chat
- Added ES5 Extends, a JavaScript coding question
- Added Tree Select, a JavaScript coding question
- Updated What is doctype in HTML?, a conceptual article
June 14, 2026
- Added Connect Four, a user interface question
May 31, 2026
- Added Nested Checkboxes, a user interface question
- Added Random Color Matrix, a user interface question
- Added Temperature Converter, a user interface question
April 26, 2026
- Added Deploy Pipeline Builder, a JavaScript coding question
April 19, 2026
- Added Chainable Add, a JavaScript coding question
- Added Measure Execution Time, a JavaScript coding question
- Added useCountdown, a JavaScript coding question
- Updated Timer Manager, a JavaScript coding question
April 18, 2026
- Added 8 user interface questions: Form Validations, Modal Window I, Modal Window II, Modal Window III, Pagination, Toast I, Toast II and Toast III
- Added 5 JavaScript coding questions: composeAsync, composeAsync II, Implement jQuery css(), Lucky Sevens and Number to Words
- Added HackerRank MCQ, a quiz
April 12, 2026
- Added NxN Tic Tac Toe, a user interface question
April 11, 2026
- Added OTP Input, a user interface question
April 5, 2026
- Added 70 JavaScript coding questions: Animate Elements in Sequence, Camel Case Keys, Check if Called with new, Classnames II, Compact II, Conforms To, CSS Selector Generator, Curry II, Custom instanceof, Cycle, Data Merging, Debounce II and 58 more
- Added 154 conceptual articles: 'this' binding in event handlers, async/await in JavaScript, Attribute vs property in the DOM, Classical vs prototypal inheritance, Common 'this' pitfalls, CommonJS vs ES Modules, Different ways to bind 'this' in JavaScript, Error handling with try...catch, Hoisting pitfalls and how to avoid them, How do floats work in CSS?, How do iframes communicate with the parent page?, How do media queries work for mobile layouts? and 142 more
April 4, 2026
- Added Get Last Task, a JavaScript coding question
- Added Limit Concurrency, a JavaScript coding question
- Added Controlled vs uncontrolled components in React, a conceptual article
- Added What is the difference between debouncing and throttling?, a conceptual article
- Updated 4 conceptual articles: var vs let vs const, What is a closure in JavaScript?, What is semantic HTML and why does it matter for accessibility? and What is the event loop in JavaScript?
March 29, 2026
- Added 4 user interface questions: Like Dislike I, Like Dislike II, Mini Spreadsheet and Tabs (Vanilla JS)
- Added Next.js Interview Prep, a quiz
- Updated Tabs, a user interface question
March 28, 2026
- Added Tooltip, a user interface question
- Updated Calculator, a user interface question
March 22, 2026
- Added Card Deck I, a user interface question
- Added Card Deck II, a user interface question
- Added Card Deck III, a user interface question
- Added Commutative Memoization, a JavaScript coding question
- Added Label Collision Detection, a JavaScript coding question
March 21, 2026
- Updated 4 user interface questions: Tic Tac Toe I, Tic Tac Toe II, Tic Tac Toe III and Todo List
March 15, 2026
- Updated City Search I, a user interface question
- Updated City Search II, a user interface question
- Updated City Search III, a user interface question
March 14, 2026
- Updated Bar Chart I, a user interface question
- Updated Bar Chart II, a user interface question
- Updated Bar Chart III, a user interface question
February 22, 2026
- Added Multi Step Signup, a user interface question
- Added 6 JavaScript coding questions: Get Type, Implement JSON.stringify(), Implement lodash.get(), Implement lodash.set(), Implement setInterval using setTimeout and LRU Cache
- Added 27 conceptual articles: Describe event capturing in JavaScript, Explain the composition pattern in React, Explain the presentational vs container component pattern, How do you decide between React state, context, and external state managers?, How do you reset a component state in React?, What are error boundaries in React?, What are ES2015 classes and how do they differ from ES5 function constructors?, What are iterators and generators in JavaScript?, What are JavaScript object getters and setters?, What are JavaScript object property flags and descriptors?, What are React Fragments used for?, What are render props in React? and 15 more
February 14, 2026
- Added Configurable Text Transformer, a user interface question
- Added Drag and Drop Sortable List, a user interface question
February 8, 2026
- Added 6 user interface questions: Color Swatch, Country Capital Game, Infinite Scroll, Overlapping Circles, Table of Contents and Virtualized List
February 7, 2026
- Added Medical Report Form, a user interface question
- Added Move Array Element, a JavaScript coding question
- Added Throttle Event Handler, a JavaScript coding question
February 1, 2026
January 31, 2026
- Added Browser History, a JavaScript coding question
January 25, 2026
- Added Undo Redo, a user interface question
- Added Deep Remove Falsy, a JavaScript coding question
January 18, 2026
- Added getElementsByTagName, a JavaScript coding question
January 17, 2026
- Added Clock Angle, a JavaScript coding question
January 11, 2026
- Added HEX to RGB, a JavaScript coding question
- Added How would you style an SVG?, a conceptual article
- Added Why is input validation important?, a conceptual article
January 4, 2026
- Added useScrollPosition, a JavaScript coding question
December 28, 2025
- Added Shallow Equality, a JavaScript coding question
December 21, 2025
- Added inRange, a JavaScript coding question
December 14, 2025
- Added Counter Advanced, a JavaScript coding question
- Added Right or wrong?, a JavaScript coding question
December 7, 2025
- Added Chop into Chunks, a JavaScript coding question
- Added mul(a)(b)(c), a JavaScript coding question
November 30, 2025
- Added Kanban Board, a user interface question
- Added Set, a JavaScript coding question
- Added What is an async thunk?, a conceptual article
- Added What is the use of aria-label, aria-labelledby, and aria-live?, a conceptual article
November 23, 2025
- Added Sequential Async, a JavaScript coding question
November 16, 2025
- Added Counter Function, a JavaScript coding question
November 8, 2025
- Added Custom useMemo Hook, a JavaScript coding question
November 2, 2025
- Added promisify, a JavaScript coding question
November 1, 2025
- Added Clamp, a JavaScript coding question
October 26, 2025
- Added Integers Greater Than, a JavaScript coding question
- Added String to Object, a JavaScript coding question
October 25, 2025
- Added Find Security Issue, a JavaScript coding question
October 18, 2025
- Added Polyfill: filter( ), a JavaScript coding question
October 12, 2025
- Added Chaining: Calculator, a JavaScript coding question
October 5, 2025
- Added Event Emitter, a JavaScript coding question
- Added Event Emitter II, a JavaScript coding question
September 28, 2025
- Added 4 JavaScript coding questions: classnames, isNumbersOnly, Retry Promise N Times and useHover
September 27, 2025
- Added pipe, a JavaScript coding question
August 24, 2025
- Added useIdle, a JavaScript coding question
August 23, 2025
- Added Snake to Camel, a JavaScript coding question
August 16, 2025
- Added Parallel Async, a JavaScript coding question
August 9, 2025
- Added getElementsByStyle, a JavaScript coding question
August 3, 2025
- Added Code Review, Debug and Fix, a JavaScript coding question
August 2, 2025
- Added Deep Flatten Object, a JavaScript coding question
- Added How do you destructure nested objects?, a conceptual article
- Added What is object destructuring?, a conceptual article
July 27, 2025
July 26, 2025
- Added City Fetcher API, a JavaScript coding question
July 20, 2025
- Added Cancel Request, a JavaScript coding question
- Added Passing function to initial state, a conceptual article
- Added stopPropagation() vs stopImmediatePropagation(), a conceptual article
- Added useTransition vs useDeferredValue, a conceptual article
July 13, 2025
- Added fetch with cache & expiry, a JavaScript coding question
July 5, 2025
- Added Difference between global scope, function scope, and block scope, a conceptual article
- Added Proxies in JavaScript, a conceptual article
June 22, 2025
- Added Contiguous History, a JavaScript coding question
June 15, 2025
- Added Once, a JavaScript coding question
- Added promise.race( ), a JavaScript coding question
June 1, 2025
- Added Throttle, a JavaScript coding question
May 31, 2025
- Added useIsMounted, a JavaScript coding question
May 25, 2025
- Added Controllable Counter, a JavaScript coding question
May 18, 2025
- Added Immutability Challenge, a JavaScript coding question
- Added Polyfill: call( ), a JavaScript coding question
May 11, 2025
- Added Traverse DOM Tree, a JavaScript coding question
May 3, 2025
- Added Scripts Execution, a JavaScript coding question
April 27, 2025
- Added useOnClickOutside, a JavaScript coding question
April 26, 2025
- Added Paginated Data Ranking, a JavaScript coding question
April 20, 2025
- Added getElementsByClassName, a JavaScript coding question
- Added Polyfill: apply(), a JavaScript coding question
April 19, 2025
- Added Argument Rotator, a JavaScript coding question
April 13, 2025
- Added clearAllTimeouts, a JavaScript coding question
April 12, 2025
- Added Centering Elements in Webpages, a conceptual article
April 6, 2025
- Added Feedback Form, a user interface question
- Added People You May Know, a user interface question
- Added Shallow Merge, a JavaScript coding question
April 5, 2025
- Added Masonry Layout, a user interface question
- Added Zoom Image on Hover, a user interface question
- Added this challenge, a JavaScript coding question
March 30, 2025
- Added Image Carousel, a user interface question
- Added Memoize, a JavaScript coding question
- Added Memoize II, a JavaScript coding question
March 29, 2025
- Added Object Comparison Output, a conceptual article
March 23, 2025
- Added Spinner with CSS, a user interface question
March 22, 2025
- Added usePrevious, a JavaScript coding question
March 16, 2025
- Added Dynamic Table Generator, a user interface question
March 15, 2025
- Added findPattern, a JavaScript coding question
March 9, 2025
- Added HTTP Methods, a conceptual article
March 8, 2025
- Added Accordion, a user interface question
- Added clearAllIntervals, a JavaScript coding question
March 1, 2025
- Added Debounce Without Timer, a JavaScript coding question
- Added useCounter, a JavaScript coding question
- Added Where Do We Use Observer Pattern in Frontend Development?, a conceptual article
February 23, 2025
- Added Roomba, a user interface question
- Added Tabs, a user interface question
- Added Traffic Light, a user interface question
- Added Load CSS Dynamically, a JavaScript coding question
- Added 9 conceptual articles: How to truncate text using CSS only, How would you implement dark mode and light mode?, Image Failures in Production, Optimize Rendering Large Datasets, preventDefault() vs stopPropagation(), What data structure is used to represent the DOM?, What is AB Testing?, What is doctype in HTML? and Why do we use polyfills?
February 22, 2025
- Added How does positioning work in CSS?, a conceptual article
February 16, 2025
- Added sum(a)(b)(c).....(n), a JavaScript coding question
February 15, 2025
- Added Polyfill: concat( ), a JavaScript coding question
February 2, 2025
- Added Roll Call, a JavaScript coding question
- Added Content Security Policy (CSP), a conceptual article
- Added Garbage Collection, a conceptual article
February 1, 2025
- Added Polyfill: reduce( ), a JavaScript coding question
January 26, 2025
- Added Cancellable Timeout, a JavaScript coding question
- Added Queue, a JavaScript coding question
- Added useToggle, a JavaScript coding question
January 19, 2025
- Added Nested Filtering, a JavaScript coding question
- Added How to scope the type of generic?, a conceptual article
January 18, 2025
- Added Promise Output, a JavaScript coding question
January 5, 2025
- Added API: fetch with timeout, a JavaScript coding question
January 4, 2025
- Added promise.allSettled( ), a JavaScript coding question
December 29, 2024
- Added compose, a JavaScript coding question
- Added What is a static method in a class?, a conceptual article
- Added What is a symbol type?, a conceptual article
- Added What is Responsive Design?, a conceptual article
December 28, 2024
- Added 4 conceptual articles: How would you test a React application?, Primitive vs Reference, use strict and What is Immutability?
December 22, 2024
- Added Cancellable Interval, a JavaScript coding question
- Added Unique Elements, a JavaScript coding question
- Added 16 conceptual articles: Code Splitting, Critical Rendering Path, Cross Origin Resource Sharing (CORS), Cross-Site Scripting (XSS), How to improve website performance?, null vs undefined vs undeclared, sync vs async function, useEffect vs useLayoutEffect, Virtual DOM in React, What are Web Vitals?, What is a higher order function?, What is a thunk? and 4 more
December 21, 2024
- Added Transactions Sum, a JavaScript coding question
- Added this keyword in JavaScript, a conceptual article
- Added What is event delegation in JavaScript?, a conceptual article
- Added What is Test Driven Development?, a conceptual article
December 15, 2024
- Added key prop in react, a conceptual article
- Added state vs props, a conceptual article
December 14, 2024
- Added 8 conceptual articles: inline vs inline-block vs block, Reset vs Normalize CSS, What does preventDefault() do?, What is cookie?, What is hoisting in JavaScript?, What is inversion of control?, What is semantic HTML and why does it matter for accessibility? and What is the event loop in JavaScript?
December 7, 2024
- Added translate vs absolute positioning, a conceptual article
- Added var vs let vs const, a conceptual article
December 1, 2024
- Added Reverse Words in a String, a JavaScript coding question
- Added 17 conceptual articles: == vs ===, Arrow functions, async vs defer, box-sizing: border-box, call( ) vs apply( ), call( ) vs bind( ), Can callbacks be synchronous?, CSR vs SSR, default vs named export, Reference vs Syntax Error, What does typeof operator do?, What happens when you type a URL into a browser and hit enter? and 5 more
November 30, 2024
- Added Pub Sub, a JavaScript coding question
November 24, 2024
- Added Compact, a JavaScript coding question
- Added Tennis Score, a JavaScript coding question
November 17, 2024
- Added Click by Domains, a JavaScript coding question
- Added Flexible Curry Function, a JavaScript coding question
November 10, 2024
- Added Analyze Song Data, a JavaScript coding question
- Added Custom Promise, a JavaScript coding question
- Added Polyfill: forEach( ), a JavaScript coding question
November 9, 2024
- Added Tricky Closure, a JavaScript coding question
October 27, 2024
- Added Flatten Array, a JavaScript coding question
October 26, 2024
- Added async filter, a JavaScript coding question
October 13, 2024
- Added groupBy, a JavaScript coding question
- Added multiAdd(1,2)(3)(4,5,6)(), a JavaScript coding question
- Added square( ), a JavaScript coding question
September 29, 2024
- Added Local Storage Expiry, a JavaScript coding question
September 22, 2024
- Added parseNumber, a JavaScript coding question
September 15, 2024
- Added Stopwatch, a user interface question
August 25, 2024
- Added Digital Root, a JavaScript coding question
August 24, 2024
- Added promise.any( ), a JavaScript coding question
August 18, 2024
- Added Object Map, a JavaScript coding question
August 11, 2024
- Added Debounce, a JavaScript coding question
- Added What gets logged?, a JavaScript coding question
August 4, 2024
- Added Toggle, a JavaScript coding question
July 28, 2024
- Added Min Max Stack, a JavaScript coding question
July 21, 2024
- Added Capturing in IIFEs, a JavaScript coding question
July 20, 2024
- Added Stack, a JavaScript coding question
July 13, 2024
- Added sleep( ), a JavaScript coding question
July 7, 2024
- Added Pokemon Rating Display, a JavaScript coding question
- Added Timer Manager, a JavaScript coding question
July 6, 2024
- Added async reject, a JavaScript coding question
June 30, 2024
- Added Filterable Table I, a user interface question
- Added Filterable Table II, a user interface question
June 29, 2024
- Added Custom Assertion Function, a JavaScript coding question
- Added Deep Equality, a JavaScript coding question
June 23, 2024
- Added promise.all( ), a JavaScript coding question
June 1, 2024
- Added Elevator System, a user interface question
- Added Identical DOM Trees, a JavaScript coding question
May 5, 2024
- Added Count by Condition, a JavaScript coding question
April 28, 2024
- Added Deal a Hand, a user interface question
April 14, 2024
- Added Get Number Frequency, a JavaScript coding question
April 13, 2024
- Added Calendar Manager, a JavaScript coding question
- Added Throttle Array, a JavaScript coding question
April 7, 2024
- Added What gets logged 2?, a JavaScript coding question
March 31, 2024
- Added Calculator, a user interface question
- Added Min Height of DOM Tree, a JavaScript coding question
March 24, 2024
- Added Number + String, a JavaScript coding question
March 10, 2024
- Added asyncMap, a JavaScript coding question
March 9, 2024
- Added Polyfill: bind( ), a JavaScript coding question
March 2, 2024
- Added Phone Number Input, a user interface question
- Added Deep Merge, a JavaScript coding question
February 25, 2024
- Added Caps, a JavaScript coding question
- Added Digital Clock, a JavaScript coding question
February 24, 2024
- Added Deep Copy, a JavaScript coding question
February 11, 2024
- Added Polyfill: map( ), a JavaScript coding question
February 4, 2024
- Added Fizz Buzz, a JavaScript coding question
February 3, 2024
- Added Node Unwinder, a user interface question
December 31, 2023
- Added Nested Comments, a user interface question
December 2, 2023
- Added Wordle, a user interface question
October 1, 2023
- Added 4 user interface questions: Transfer List, Tree Navigation I, Tree Navigation II and Tree Navigation III
September 2, 2023
- Added Transaction Filtering I, a user interface question
- Added Transaction Filtering II, a user interface question
July 30, 2023
- Added Todo List, a user interface question
June 3, 2023
- Added 4 user interface questions: Holy Grail Layout, Tic Tac Toe I, Tic Tac Toe II and Tic Tac Toe III
April 30, 2023
- Added Star Widget, a user interface question
April 2, 2023
- Added Progress Bar II, a user interface question
- Added Progress Bar III, a user interface question
April 1, 2023
- Added Progress Bar I, a user interface question
February 26, 2023
- Added Select Menu, a user interface question
February 4, 2023
- Added City Search II, a user interface question
- Added City Search III, a user interface question
January 29, 2023
- Added City Search I, a user interface question
January 15, 2023
- Added How does the box model work in CSS?, a conceptual article
January 1, 2023
- Added Bar Chart I, a user interface question
- Added Bar Chart II, a user interface question
- Added Bar Chart III, a user interface question