Ravikesh Yadav

If I’m testing your React knowledge in a Frontend interview, I’m definitely going to ask 1–2 questions out of these 50+ problems (collected over my 12+ years of exp.) These cover everything : → Component design and reusability → State management and hooks → Handling user interactions and events → Accessibility and ARIA roles → Optimizing rendering and performance → Working with external data and APIs ➥UI/Component Building - Memory Game - Image Carousel - Image Carousel II (smooth transitions) - Digital Clock - Analog Clock - Whack-A-Mole - Tic-tac-toe - Tic-tac-toe II (N x N, variable win condition) - Connect Four - Modal Dialog - Modal Dialog II (ARIA roles, semi-accessible) - Modal Dialog III (common close methods, moderately accessible) - Accordion II (accessible, ARIA support) - Accordion III (full keyboard support, ARIA) - Tabs - Tabs II (semi-accessible) - Tabs III (keyboard/ARIA spec) - Star Rating - Like Button - Progress Bars III (multiple concurrent, pause/resume) - Progress Bars II (sequential fill, one at a time) - Grid Lights - Traffic Light - Data Table - Data Table II (sorting) - Data Table III (pagination, sorting) - Data Table IV (pagination, sorting, filtering) - Nested Checkboxes (parent-child selection logic) - File Explorer - File Explorer II (ARIA roles, semi-accessible) - File Explorer III (flat DOM) - Table of Contents (HTML parsing, tree) - Selectable Cells (drag-select grid) - Auth Code Input (6-digit entry) - Modal Dialog IV (fully accessible, keyboard support) - Undoable Counter (undo/redo) - Pixel Art (drawing grid) - Todo List ➥Logic/Algorithmic & Data Handling - Birth Year Histogram (API + plotting) - Job Board (API data + rendering) - Transfer List - Transfer List II (bulk select, add, transfer) - Users Database (CRUD) - Dice Roller - Backbone Model (custom object store) - Data Selection (filtering) - getElementsByTagNameHierarchy (DOM queries) - Curry III (JS currying logic) - Classnames II (join/dedupe classnames) - Heap (implement data structure) - Heap Operations - End of Array Reachable (jump game) - Find the Longest Palindromic Substring - Find Words in Grid - Find Word in Grid (existence check) - Shortest Substring Containing Characters - Disjoint Intervals (remove overlaps) - Minimum Meeting Rooms Needed - Graph Clone (deep copy graph) - Binary Tree Serialization and Deserialization - Binary Tree Maximum Total Path - Binary Tree Rebuilding from Preorder/Inorder - Graph Count Connected Components - Number Stream Median - Linked Lists Combine K Sorted ➥Custom Hooks - useDebounce - useEventListener - useHover - useInterval - useKeyPress - useMap - useObject - useSet - useStep - useThrottle - useTimeout - useWindowSize - useIdle - useInputControl - useMediaQuery - useMediatedState - useQuery - useArray - useBreakpoint - useClickOutside - useCountdown If you can build, debug, and explain at least half of these, you’re already ahead of 90% of candidates.

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Prepare these React interview questions before your next SDE interview (topic-wise list) → Here’s a list of the 30 most commonly asked Interview concepts and questions. 𝗩𝗶𝗿𝘁𝘂𝗮𝗹 𝗗𝗢𝗠 𝗮𝗻𝗱 𝗥𝗲𝗻𝗱𝗲𝗿𝗶𝗻𝗴 1. What is the Virtual DOM, and how does it work 2. Why is the Virtual DOM faster than the real DOM 3. What is reconciliation in React, and how does it optimize performance 4. How does React decide when to re-render a component 5. What are key props in React, and why are they important 6. How can you prevent unnecessary re-renders in React 7. What is React.memo, and how does it optimize performance 8. What is the difference between PureComponent and React.memo 𝗖𝗼𝗺𝗽𝗼𝗻𝗲𝗻𝘁 𝗟𝗶𝗳𝗲𝗰𝘆𝗰𝗹𝗲 9. What are the different phases of the React component lifecycle 10. What is the difference between mounting, updating, and unmounting in React 11. What lifecycle methods are available in class components 12. What is the difference between componentDidMount, componentDidUpdate, and componentWillUnmount 13. How do lifecycle methods compare to useEffect in functional components 14. How does React handle cleanup when a component unmounts 15. What is the role of shouldComponentUpdate in class components 16. What are the side effects in React, and how should they be managed 𝗥𝗲𝗮𝗰𝘁 𝗛𝗼𝗼𝗸𝘀 17. What are React Hooks, and why were they introduced 18. What is useState, and how does it work 19. What is useEffect, and what are its common use cases 20. What is the difference between useEffect and lifecycle methods in class components 21. What is useRef, and how does it help manage DOM elements 22. What is useMemo, and how does it optimize performance 23. What is useCallback, and how does it prevent unnecessary re-renders 24. What is useContext, and how does it simplify prop drilling 𝗦𝘁𝗮𝘁𝗲 𝗠𝗮𝗻𝗮𝗴𝗲𝗺𝗲𝗻𝘁 𝗶𝗻 𝗥𝗲𝗮𝗰𝘁 25. What is the difference between controlled and uncontrolled components 26. How does state management work in React without external libraries 27. What is Context API, and how does it help manage global state 28. What are the advantages and limitations of using Context API 29. What is the difference between Redux and Context API 30. What is Recoil, and how does it compare to Redux Try to solve these React questions, and if you’re in need of guidance from top industry experts, I’d suggest checking out Bosscoder Academy. Check them out here: https://bit.ly/4kKOoxL They’ve helped over 2200+ engineers successfully transition to top product-based companies, even in challenging markets. Here’s what they offer: 💡 Structured curriculum for DSA, System Design, and Full Stack Development 💡 1:1 mentorship from industry experts. 💡 24/7 doubt support and live interactive classes. 💡 Real-world project building and 100% job switch support.

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Top 50 Angular Interview Questions You Must Know! Here are some essential Angular interview questions to help you prepare: 1. What is the main purpose of Angular? 2. What are directives in Angular and how many types of directives exist? 3. Explain data bindings and the different types. 4. What are the basic components involved in Angular? 5. What’s the difference between AngularJS and Angular? 6. What are components and modules in Angular? 7. What are decorators in Angular? 8. What is metadata or annotations in Angular? 9. What are templates in Angular? 10. What is SPA and how do you implement it in Angular? 11. Explain the importance of routing in Angular & how to implement it. 12. What is lazy loading in Angular? 13. How do you implement lazy loading in Angular? 14. What is Node.js? 15. What is NPM? 16. Why is the node_modules folder important? 17. What is package.json? 18. What is TypeScript? 19. What is the need for Angular CLI? 20. What are services in Angular? 21. When would you use content projection? 22. Explain content projection slots in Angular. 23. Why do we need ViewChild and ViewChildren in Angular? 24. What is a template reference variable? 25. Explain ContentChild and ContentChildren. 26. Differentiate between ViewChild, ViewChildren, ContentChild, and ContentChildren. 27. What is { static: true } in ViewChild? 28. What is the importance of Angular component hooks/life cycles? 29. Explain Angular life cycle hooks in detail. 30. Differentiate between constructor and ngOnInit(). 31. How do you implement lazy loading in Angular? 32. How do you implement HTTP in Angular? 33. How do you pass data between components? 34. What are pipes in Angular? 35. Can you give examples of inbuilt Angular pipes? 36. How do you write a custom pipe? 37. What is RxJs and why is it needed? 38. What are observables and observers? 39. What is a stream in RxJs? 40. What is the use of subscribe in RxJs? 41. How do you unsubscribe from a stream? 42. What are operators in RxJs? 43. Where have you used RxJs in Angular? 44. Differentiate between RxJs and Promises. 45. How do you install RxJs? 46. Why is RxJs called push/reactive and not pull/imperative? 47. Name some RxJs operators. 48. What are interceptors in Angular? 49. How do you implement interceptors? 50. What are some uses of interceptors, and can we provide multi-interceptors? Follow Alpna P. for more related content! Prepare with these questions and ace your next Angular interview! 🌟 🤔 Having Doubts in technical journey? 🚀 Book 1:1 session with me : https://lnkd.in/gQfXYuQm 🚀 Get Complete React JS Interview Q&A Here: https://lnkd.in/d5Y2ku23 🚀 Get Complete JavaScript Interview Q&A Here: https://lnkd.in/d8umA-53 🚀 Support the NGO : https://lnkd.in/du4hTPgT 🚀 Subscribe and stay up to date: https://lnkd.in/dGE5gxTy #angular #typescript #javascript #framework

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50 Fundamental #React Questions You Will Be Asked in #Interviews 1. What is React and why is it popular? 2. What are the limitations of React? 3. Key advantages of using React in large-scale apps? 4. Explain Strict Mode in React,when do you use it? 5. Can React Hooks replace Redux in all scenarios? 6. Difference between useState() and useReducer(). 7. How does useEffect() work? List real use cases. 8. How do you prevent unnecessary re-renders in React? 9. What’s the Virtual DOM and why does it matter? 10. Controlled vs uncontrolled components,when to use each? 11. Handling forms and form validation in React. 12. How do refs work? When should you use them? 13. Error boundaries,how and why to use them? 14. React context API,how does it help with prop drilling? 15. useCallback() vs useMemo(),when and why? 16. SSR vs CSR,benefits and trade-offs in React. 17. What is lazy loading in React? Give practical examples. 18. Code splitting in React,how do you implement it? 19. How do you manage global state in React apps? 20. Redux vs Context API,when to choose what? 21. What’s the purpose of keys in lists? Why are they needed? 22. Fragment vs div,how and when to use each? 23. Portals in React,what are they, and why would you use one? 24. useRef(),how does it differ from createRef()? 25. useLayoutEffect() vs useEffect(). 26. Best practices for side effects in React apps. 27. Debouncing and throttling in React,where and how? 28. How do you handle component communication (parent-child, siblings)? 29. Prop drilling,problems and solutions. 30. React Router,how do you manage navigation and params? 31. Dynamic routing,how do you set it up? 32. How do you test React components? (unit, integration, e2e) 33. How does React handle events? Custom vs native events. 34. How do you optimize React performance in large apps? 35. What is reconciliation? How does React diff trees? 36. Mounting, updating, and unmounting phases,what happens when? 37. How do you fetch data on mount? (show code) 38. When should you use class components over function components (if ever)? 39. HOCs vs render props,differences, use cases, gotchas. 40. Lifting state up,what is it and when do you do it? 41. Memoization,how do you actually use React.memo()? 42. How to handle browser resize or scroll events in React. 43. How to secure a React app? (common vulnerabilities) 44. Integrating third-party libraries in React (charts, maps, etc.) 45. Common pitfalls with useEffect() and how to avoid them. 46. How do you handle authentication in React? 47. Accessibility in React,what do you do for a11y? 48. How do you manage environment variables in a React app? 49. Deployment strategies for React apps (static, server-side, etc.) 50. Debugging tools and techniques for React developers. #javascript #interview #reactjs #freshers #learn #linkedin #webdevelopment #frontend

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Top JavaScript Topics Interviewers Focus on in Frontend Interviews 𝟭. 𝗩𝗮𝗿, 𝗟𝗲𝘁 𝗮𝗻𝗱 𝗖𝗼𝗻𝘀𝘁 - Differences in scope (global, function, block) - Hoisting behavior - Redeclaration and reassignment rules - Temporal dead zone 𝟮. 𝗠𝗮𝗽, 𝗙𝗶𝗹𝘁𝗲𝗿 𝗮𝗻𝗱 𝗥𝗲𝗱𝘂𝗰𝗲 - Output based Questions - Polyfills 𝟯. 𝗙𝘂𝗻𝗰𝘁𝗶𝗼𝗻𝘀 - Function declarations vs expressions - Arrow functions and lexical this - Default parameters - Rest and spread operators 𝟰. 𝗖𝗹𝗼𝘀𝘂𝗿𝗲𝘀 - Definition and how closures work in JS - Practical use cases (data privacy, function factories) - Closure pitfalls and memory considerations 𝟱. 𝗖𝘂𝗿𝗿𝘆𝗶𝗻𝗴 - currying functions - Benefits of partial application - Writing curried functions in JS 𝟲. 𝗢𝗯𝗷𝗲𝗰𝘁𝘀 - Object literals and property shorthand - Dynamic property keys - Object destructuring - Object methods and this context 𝟳. ‘𝘁𝗵𝗶𝘀’ 𝗞𝗲𝘆𝘄𝗼𝗿𝗱 (𝗜𝗺𝗽𝗹𝗶𝗰𝗶𝘁 𝗕𝗶𝗻𝗱𝗶𝗻𝗴) - How this is determined in different invocation contexts - Implicit binding rules - Common mistakes and how to avoid them 𝟴. 𝗖𝗮𝗹𝗹, 𝗕𝗶𝗻𝗱 𝗮𝗻𝗱 𝗔𝗽𝗽𝗹𝘆 (𝗘𝘅𝗽𝗹𝗶𝗰𝗶𝘁 𝗕𝗶𝗻𝗱𝗶𝗻𝗴) - Using .call(), .apply() and .bind() - Differences between these methods - Use cases in event handlers and functional programming 𝟵. 𝗣𝗿𝗼𝗺𝗶𝘀𝗲𝘀 - Promise lifecycle and states - Creating and chaining promises - Error handling with .catch() - Promise.all and async/await 𝟭𝟬. 𝗗𝗲𝗯𝗼𝘂𝗻𝗰𝗶𝗻𝗴 𝗮𝗻𝗱 𝗧𝗵𝗿𝗼𝘁𝘁𝗹𝗶𝗻𝗴 - Definition and difference between debounce and throttle - When to use each for performance optimization - Implementing debounce and throttle functions 𝟭𝟭. 𝗘𝘃𝗲𝗻𝘁 𝗣𝗿𝗼𝗽𝗮𝗴𝗮𝘁𝗶𝗼𝗻 - Event capturing and bubbling phases - Event delegation pattern - Stopping propagation and preventing default behavior 𝟭𝟮. 𝗖𝗼𝗺𝗽𝗼𝘀𝗲 𝗮𝗻𝗱 𝗣𝗶𝗽𝗲 - Functional composition concepts - Writing compose and pipe functions - Practical use in data transformation pipelines 𝟭𝟯. 𝗣𝗿𝗼𝘁𝗼𝘁𝘆𝗽𝗲𝘀 - Prototype chain and inheritance - Prototype vs instance properties - Using Object.create and setting prototypes 𝟭𝟰. 𝗖𝗹𝗮𝘀𝘀 𝗮𝗻𝗱 𝗖𝗼𝗻𝘀𝘁𝗿𝘂𝗰𝘁𝗼𝗿𝘀 - ES6 class syntax vs constructor functions - Class methods and static methods - Inheritance with extends and super 𝟭𝟱. 𝗘𝘃𝗲𝗻𝘁 𝗟𝗼𝗼𝗽 - Call stack, task queue, microtask queue explained - How JS handles asynchronous operations - Examples with setTimeout, promises, async/await If you want to crack your frontend interview, mastering these JavaScript topics is essential. This series breaks down each topic with videos covering all important concepts you need to know. Here’s the Complete Interview Prep - https://lnkd.in/gWMcsPiH

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🚀 Top 30 Front-End Interview Questions You MUST Know Nail your next interview with these core concepts every serious frontend dev should master 👇 --- ✅ 1. HTML & Semantics • What are semantic tags and why do they matter? • Difference between <div> and <section> • Role of alt, aria-*, and accessibility best practices --- ✅ 2. CSS Mastery • Flexbox vs Grid – When to use what? • How to make a design responsive (media queries, units)? • What is specificity? How does the cascade work? --- ✅ 3. JavaScript Essentials • What are closures and lexical scope? • How does async/await work internally? • Explain this, hoisting, call stack, event loop • Array methods: map, filter, reduce, find • Debouncing vs Throttling --- ✅ 4. Framework Knowledge (React/Vue/Angular) • Lifecycle methods vs hooks (React) • State vs props vs context • Virtual DOM – what is it and how does it work? • Conditional rendering and controlled forms --- ✅ 5. Performance & Testing • How do you improve performance in large apps? • Core Web Vitals & Lighthouse audits • Lazy loading, code splitting • Writing tests with Jest or React Testing Library --- 🔥 Final Takeaway ✔ Cover the full front-end spectrum ✔ Go beyond surface-level answers—give examples ✔ Interviews love candidates who show both depth and practical thinking Cradit - Asif Ali Quraishy ♞ --- 💡 Save & Share 👍 Like if you learned something 🔁 Repost to help your job-hunting friends 🔖 Bookmark this for last-minute revision 💬 Drop your toughest frontend topic below! Follow Anurag Shukla for more tech breakdowns! #FrontendInterview #WebDevelopment #JavaScript #CSS #ReactJS #VueJS #Angular #CodingInterview #FrontendDev #DevCommunity #Linkedin #LinkedinCommunity #Connections #viral #fyp #w3schools #expressjs #frontend #backend #developers #nextjs #roadmap #mern #mean #nodejs #postgresql #sql #guide #useful #notes

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🚀 Top 30 Front-End Interview Questions You MUST Know Nail your next interview with these core concepts every serious frontend dev should master 👇 --- ✅ 1. HTML & Semantics • What are semantic tags and why do they matter? • Difference between <div> and <section> • Role of alt, aria-*, and accessibility best practices --- ✅ 2. CSS Mastery • Flexbox vs Grid – When to use what? • How to make a design responsive (media queries, units)? • What is specificity? How does the cascade work? --- ✅ 3. JavaScript Essentials • What are closures and lexical scope? • How does async/await work internally? • Explain this, hoisting, call stack, event loop • Array methods: map, filter, reduce, find • Debouncing vs Throttling --- ✅ 4. Framework Knowledge (React/Vue/Angular) • Lifecycle methods vs hooks (React) • State vs props vs context • Virtual DOM – what is it and how does it work? • Conditional rendering and controlled forms --- ✅ 5. Performance & Testing • How do you improve performance in large apps? • Core Web Vitals & Lighthouse audits • Lazy loading, code splitting • Writing tests with Jest or React Testing Library --- 🔥 Final Takeaway ✔ Cover the full front-end spectrum ✔ Go beyond surface-level answers—give examples ✔ Interviews love candidates who show both depth and practical thinking Cradit - Asif Ali Quraishy ♞ --- 💡 Save & Share 👍 Like if you learned something 🔁 Repost to help your job-hunting friends 🔖 Bookmark this for last-minute revision 💬 Drop your toughest frontend topic below! Follow Dharmendra kumar for more tech breakdowns! #FrontendInterview #WebDevelopment #JavaScript #CSS #ReactJS #VueJS #Angular #CodingInterview #FrontendDev #DevCommunity #dharamgfx

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🧠 What to Prepare for SDE-1 Frontend Interviews (JavaScript Focus) 📌 Core JavaScript 👉 Understand scoping, hoisting, closures, and the this keyword 👉 Learn how call, apply, and bind work 👉 Master promises, async/await, and the event loop 👉 Know ES6+ features like arrow functions, destructuring, spread/rest 🧩 DSA (Data Structures & Algorithms) 👉 Practice arrays, strings, and object manipulations 👉 Get comfortable with recursion and loop patterns 👉 Understand hash maps, sets, stacks, queues, and basic tree traversal 👉 Use LeetCode, InterviewBit, or CodeStudio to practice daily 🌐 Browser & Web APIs 👉 Understand event bubbling, delegation, and capturing 👉 Learn debounce vs throttle 👉 Know localStorage vs sessionStorage 👉 Understand CORS, cookies, HTTP methods, and browser caching 👉 Practice basic DOM manipulation without libraries ⚛️ React Fundamentals 👉 Use useState, useEffect, and understand lifecycle in functional components 👉 Differentiate between props and state 👉 Build forms with controlled and uncontrolled components 👉 Learn component structure and composition 👉 Use React Router for basic client-side routing ⚙️ Tooling & Ecosystem 👉 Use npm/yarn and understand package.json 👉 Practice version control with Git and GitHub 👉 Use ESLint and Prettier for consistent code formatting 👉 Know the basics of Webpack and Babel (just enough to debug) 🚀 Projects & Portfolio 👉 Build 1–2 projects (e.g., task manager, blog, movie app) 👉 Host projects using Netlify or Vercel 👉 Keep UI clean, responsive, and mobile-friendly 👉 Add GitHub links to your resume or LinkedIn 💬 Communication & Behavioral Rounds 👉 Practice explaining your project decisions clearly 👉 Be ready for questions like "Why frontend?" or "What challenge did you face?" 👉 Communicate your thought process in coding rounds 👉 Highlight teamwork and collaboration experiences 🧠 (Bonus) Frontend System Design 👉 Organize folders and components logically 👉 Learn lazy loading and code splitting basics 👉 Keep performance and accessibility in mind from the start ✨ Final Tip: Frameworks and libraries come and go, but strong JavaScript fundamentals will always stand out. 👇 Book an appointment with me if you would like any personal guidance from me. #frontend #javascript #reactjs #interviewprep #webdevelopment #sde1 #techinterview #codinglife

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Frontend Interview Questions You Actually Need to Prepare For From core JavaScript to real-world challenges, here’s what MNC's really ask. JavaScript Fundamentals ➤ Closures: Build a createCounter() using closure — a favorite in interviews. ➤ Memoization: Create a memoize() function to speed up expensive calls. ➤ Polyfills: Recreate Array.prototype.map, reduce, and Function.prototype.bind from scratch. ➤ Async Handling: Write a fetchWithRetry() to handle flaky APIs with retry logic. ➤ Custom Promise.all: Rebuild promiseAll() to understand how Promise coordination works. ➤ Debounce: Implement a debounce() function — key for optimizing user inputs. ➤ Event Loop Insight: Predict the output of tricky async JS questions and explain the why. Arrays ➤ Rotate by K: Shift an array to the left/right by k positions. ➤ Max Subarray (Kadane’s): Solve for the highest sum in a contiguous subarray. ➤ Two-Pointer Technique: Find all pairs that sum up to a target — time-efficient and clean. ➤ Sort 0s, 1s, 2s: Use Dutch National Flag algorithm — no extra space. ➤ Sliding Window: Longest substring without repeating characters? This one’s a classic. ➤ Fixed Window Sum: Max sum of any subarray of length k. Strings ➤ Anagram Check: Validate if two strings are anagrams. ➤ First Unique Character: Find the first non-repeating character in a string. ➤ Longest Palindrome: Extract the longest palindromic substring. ➤ Rearranged Palindrome: Can the given string be shuffled into a palindrome? Objects ➤ Deep Clone: Write a recursive deep clone function - no JSON.parse(JSON.stringify) allowed. ➤ Flatten Object: Convert deeply nested objects into flat key-value pairs. ➤ Frequency Counters: Count character or element frequencies - the go-to tool for many problems. Real-World Problems ➤ Pagination Logic: Split an array based on page number and size. ➤ Debounce in UI: Optimize search bars or auto-suggest inputs with debounce(). ➤ Throttle API Calls: Limit rapid-fire API calls with a throttle() function. Advanced/Systems Thinking ➤ DOM Tree Serialization: Turn a DOM structure into JSON — and rebuild it back. ➤ Event Delegation: Efficiently handle events on dynamically generated DOM nodes. ➤ LRU Cache: Implement Least Recently Used cache using Map. ➤ Custom Promise Class: Build your own version of Promise with then, catch, and resolve. ➤ Dependency Graph: Simulate how bundlers resolve JS module dependencies. Interview Tips That Actually Work: 1. Don’t rush - talk through your thought process before jumping into code. 2. Think in terms of edge cases and time/space trade-offs. 3. Write clean, modular code - that’s what interviewers remember. You've got this - preparation > luck. 💪 Tag someone prepping for frontend interviews or save this list for your own roadmap 𝐅𝐨𝐫 𝐌𝐨𝐫𝐞 𝐃𝐞𝐯 𝐈𝐧𝐬𝐢𝐠𝐡𝐭𝐬 𝐉𝐨𝐢𝐧 𝐌𝐲 𝐂𝐨𝐦𝐦𝐮𝐧𝐢𝐭𝐲 : Telegram - https://lnkd.in/d_PjD86B Whatsapp - https://lnkd.in/dvk8prj5 Happy learning !

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JavaScript Array Methods Cheatsheet From filtering data to transforming UI — arrays are everything in JS. Master these methods to write cleaner, faster, smarter code. 1️⃣ Iteration Methods forEach() – Run a function on each element arr.forEach((item, i) => console.log(i, item)); map() – Transform each element and return a new array const doubled = arr.map(num => num * 2); filter() – Return only elements that meet a condition const even = arr.filter(num => num % 2 === 0); reduce() – Accumulate values into one (sum, avg, etc.) const total = arr.reduce((acc, curr) => acc + curr, 0); some() – Check if any element matches condition arr.some(x => x > 10); every() – Check if all elements match condition arr.every(x => x < 100); find() – Return the first match arr.find(x => x > 50); findIndex() – Return the index of the first match arr.findIndex(x => x === 42); 2️⃣ Modifying Arrays push() / pop() – Add/remove at end arr.push(5); arr.pop(); unshift() / shift() – Add/remove at start arr.unshift(1); arr.shift(); splice(start, deleteCount, ...items) – Add/remove at any index arr.splice(2, 1, 'newItem'); fill() – Replace all/part of array with value arr.fill(0, 1, 3); // fill 0 from index 1 to 2 copyWithin() – Copy elements inside array arr.copyWithin(2, 0, 2); 3️⃣ Sorting & Reversing sort() – Sort in place (custom comparator needed) arr.sort((a, b) => a - b); reverse() – Reverse the array in place arr.reverse(); 4️⃣ Creating Arrays Array.from() – From iterable/array-like Array.from('hello'); // ['h', 'e', 'l', 'l', 'o'] Array.of() – Creates array from args Array.of(1, 2, 3); Spread [...] – Clone or combine arrays const copy = [...arr]; const merged = [...a, ...b]; 5️⃣ Checking & Info includes() – Check if value exists arr.includes(42); indexOf() / lastIndexOf() – Find position arr.indexOf('apple'); isArray() – Check if a value is an array Array.isArray(arr); 6️⃣ Joining & Slicing join() – Combine to string arr.join(', '); slice(start, end) – Extract portion without changing original arr.slice(1, 4); concat() – Merge arrays arr.concat(otherArray); 7️⃣ New ES2023+ Goodies toSorted() – Non-mutating sort arr.toSorted((a, b) => b - a); toSpliced() – Non-mutating splice arr.toSpliced(1, 1, 'insert'); with() – Non-mutating value update arr.with(2, 'changed'); 🔥 Pro Tips: map() and filter() are chainable Use reduce() for advanced logic like grouping or flattening Prefer non-mutating methods (slice, map, etc.) for safer code Follow Suraj Dubey for daily JS nuggets, roadmaps & frontend prep 🔖 Save this for your next interview or side project 💬 Want this as a PDF, Notion template, or interactive playground? Just say the word! 📝 Credits: Coding with JD

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Practice these 5 important Interview questions on RxJS operator for Angular developer Interviews. 1. Interviewer: What's the difference between 𝘀𝘄𝗶𝘁𝗰𝗵𝗠𝗮𝗽 & 𝗺𝗲𝗿𝗴𝗲𝗠𝗮𝗽? Candidate: switchMap stops previous requests and only processes the newest one if it gets new input. mergeMap handles multiple requests simultaneously without cancelling any. 2. Interviewer: What does 𝗱𝗲𝗯𝗼𝘂𝗻𝗰𝗲𝗧𝗶𝗺𝗲 achieve? Candidate: debounceTime waits until the user stops actions (like typing) for a set time before processing input. 3. Interviewer: How do 𝗰𝗼𝗻𝗰𝗮𝘁𝗠𝗮𝗽 and 𝗲𝘅𝗵𝗮𝘂𝘀𝘁𝗠𝗮𝗽 differ? Candidate: concatMap waits for each request to complete before starting the next. exhaustMap ignores new requests if one is already running. 4. Interviewer: How can you handle observable errors? Candidate: 𝗰𝗮𝘁𝗰𝗵𝗘𝗿𝗿𝗼𝗿 lets you manage errors by returning fallback results. 𝗿𝗲𝘁𝗿𝘆 automatically tries the request again when errors occur. 5. Interviewer: When to use 𝗳𝗼𝗿𝗸𝗝𝗼𝗶𝗻 𝘃𝘀. 𝗰𝗼𝗺𝗯𝗶𝗻𝗲𝗟𝗮𝘁𝗲𝘀𝘁? Candidate: forkJoin waits until all requests finish and gives you one combined final result. combineLatest emits only after each observable has emitted at least one value, then keeps giving updated results whenever any input changes. Be ready for your next angular interviews. This is one of very commonly asked interview questions. I have written a detailed medium article on RxJS where you can practice with easy example. https://lnkd.in/gYf9pfEy #angular #interview #rxjs #learnwithbittu

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#React Performance Interview Questions 👇 1. What is React.memo() and when should you use it? Hint: Prevents unnecessary re-renders by memoizing component props 2. Explain useMemo() and useCallback() hooks Hint: useMemo for expensive calculations, useCallback for function references 3. What causes unnecessary re-renders in React? Hint: State changes, prop changes, parent re-renders, and context updates 4. How does React's Virtual DOM improve performance? Hint: Batches DOM updates and compares virtual trees for minimal real DOM changes 5. What is code splitting and how to implement it? Hint: Use React.lazy() and Suspense for dynamic imports 6. Explain the difference between controlled and uncontrolled components Hint: Controlled uses state, uncontrolled uses refs - affects form performance 7. What are React keys and why are they important? Hint: Help React identify which items have changed in lists for efficient updates 8. How to optimize React Context performance? Hint: Split contexts, use multiple providers, and memoize context values 9. What is the React Profiler and how to use it? Hint: DevTools feature to identify performance bottlenecks and render times 10. Explain debouncing and throttling in React Hint: Debouncing delays execution, throttling limits frequency - both reduce API calls 11. How to handle large lists efficiently? Hint: Use virtualization libraries like react-window or react-virtualized 12. What is lazy loading and how to implement it? Hint: Load components/images only when needed using Intersection Observer 13. How to optimize bundle size in React? Hint: Tree shaking, code splitting, webpack-bundle-analyzer, and unused code removal 14. What are React Fragments and their performance benefits? Hint: Avoid extra DOM nodes by grouping elements without wrapper divs 15. Explain React's reconciliation process Hint: Algorithm that compares virtual DOM trees to determine minimal changes Key Areas to Focus On: • Component memoization (React.memo, useMemo, useCallback) • Virtual DOM and reconciliation • Code splitting and lazy loading • Context optimization • Bundle size reduction Pro Tips: ✅ Always measure before optimizing ✅ Use React DevTools Profiler ✅ Implement virtualization for large lists ✅ Debounce user inputs ✅ Split your code strategically #React #JavaScript #WebDevelopment #Performance #Interview #Frontend #ReactJS #Optimization #TechInterview #WebPerformance

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Recall the JavaScript Console Interview Questions!! console.log(typeof null); ➤ Output: "object" ➤ Legacy bug in JavaScript, but still present. console.log(+'dude'); ➤ Output: NaN ➤ Unary + tries to convert string to number. console.log([] + []); ➤ Output: "" ➤ Empty arrays convert to empty strings in addition. console.log([] + {}); ➤ Output: "[object Object]" ➤ Array becomes string; object gets stringified. console.log({} + []); ➤ Output: 0 ➤ {} is parsed as block, +[] = 0. console.log([] == false); ➤ Output: true ➤ Loose comparison with coercion. console.log([] === false); ➤ Output: false ➤ Strict comparison fails due to type mismatch. console.log(null == undefined); ➤ Output: true ➤ They’re loosely equal in JS. console.log(null === undefined); ➤ Output: false ➤ Strict comparison considers type. console.log(typeof NaN); ➤ Output: "number" ➤ NaN is of number type. console.log(0.1 + 0.2 === 0.3); ➤ Output: false ➤ Floating-point precision issue. console.log(!!'false'); ➤ Output: true ➤ Non-empty strings are truthy. console.log(typeof typeof 1); ➤ Output: "string" ➤ typeof 1 is "number", and typeof "number" is "string". console.log(1 < 2 < 3); ➤ Output: true ➤ Evaluates as (1 < 2) → true → true < 3 → 1 < 3. console.log(3 > 2 > 1); ➤ Output: false ➤ 3 > 2 is true, then true > 1 → 1 > 1 → false. console.log([1,2,3] == [1,2,3]); ➤ Output: false ➤ Different references, not the same object. console.log('5' - 3); ➤ Output: 2 ➤ String gets coerced to number in subtraction. console.log('5' + 3); ➤ Output: "53" ➤ + with string triggers concatenation. console.log(true + true); ➤ Output: 2 ➤ true coerced to 1. console.log(null + 1); ➤ Output: 1 ➤ null coerces to 0. console.log(undefined + 1); ➤ Output: NaN ➤ undefined can't convert to number. console.log([] == ![]); ➤ Output: true ➤ Weird coercion: [] is truthy, ![] is false, so [] == false. console.log(typeof []); ➤ Output: "object" ➤ Arrays are technically objects. console.log(typeof {}); ➤ Output: "object" ➤ Plain object. console.log(typeof function(){}); ➤ Output: "function" ➤ Only type that returns "function". console.log(0 == '0'); ➤ Output: true ➤ Loose equality coercion. console.log(0 === '0'); ➤ Output: false ➤ Different types. console.log(false == ''); ➤ Output: true ➤ Both are falsy. console.log([] == 0); ➤ Output: true ➤ Array becomes "", which becomes 0. console.log([null] == ''); ➤ Output: true ➤ Array with null stringifies to empty string. For more insightful content checkout below: 🟦 𝑳𝒊𝒏𝒌𝒆𝒅𝑰𝒏 - https://lnkd.in/dwi3tV83 ⬛ 𝑮𝒊𝒕𝑯𝒖𝒃 - https://lnkd.in/dkW958Tj 🟥 𝒀𝒐𝒖𝑻𝒖𝒃𝒆 - https://lnkd.in/dDig2j75 or Priya Frontend Vlogz 🔷 𝐓𝐰𝐢𝐭𝐭𝐞𝐫 - https://lnkd.in/dyfEuJNt   #frontend #javascript #react #reactjs #html #css #typescript #es6 #interviewquestions #interview #interviewpreparation #ReactJS #FrontendDevelopment

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How to Find Read/Write Access on Firebase Database : Step-by-Step Misconfigured Firebase rules can leak sensitive user data. Here’s how to test for read/write access systematically: 1. Get the Firebase URL: Find the database URL in app source code or network traffic, e.g., https://<project-id>.firebaseio.com/. 2. Check read access: Open your browser or use curl to check if you have read access: curl https://<project-id>.firebaseio.com/.json If data returns without authentication, it’s publicly readable. 3. Test write access: Try to write data: curl -X PUT -d '{"test": "vulnerability"}' https://<project-id>.https://lnkd.in/dTWwX_6t If successful, the database allows public write. Delete test data afterward if permitted. Use tools: Automate checks with tools like Nuclei or custom scripts for large targets. Report responsibly: Document your findings with proof and report per responsible disclosure guidelines.  TIP: Public read access isn't just about what you see at first glance, dig deeper to look for secrets, tokens, or sensitive configs. If write access is allowed and escalation testing is permitted, carefully try escalation vectors to increase impact responsibly. Want to hunt, and level-up your bug bounty skills with us? Timings: 9–10 PM IST, Wednesday & Thursday Join: https://lnkd.in/d9S8vyi4 #bugbounty #firebase #securitytesting #websecurity #pentesting #infosec #ethicalhacking #automation #cybersecurity #bughunting

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Many beginners think that setState() is enough to handle complete Flutter projects, but that's absolutely incorrect. setState() is only good for understanding basic state management and building very simple applications. For complex applications like e-commerce, you must use a standard state management solution such as Bloc, Riverpod, or GetX. Face your next interview with at least one of these state management skills to increase your chances of getting hired. #theparthee #flutter #dart #statemanagement #bloc #riverpod #getx

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🚀 Top React Design Patterns (2025) 🎯 🔹 1. Higher-Order Components (HOC) – Reuse component logic (withAuth(Component)). 🔹 2. Render Props – Share logic via function props (<DataProvider render={(data) => <Component data={data} />}) 🔹 3. Compound Components – Flexible UI (<Accordion><Item /></Accordion>) 🔹 4. Context API – Manage global state without prop drilling. 🔹 5. Hooks Pattern – Use custom hooks for reusable logic (useFetch(), useAuth()). 🔹 6. Controlled vs. Uncontrolled Components – Form handling efficiently. 🔹 7. Provider Pattern – Wrap components with state (<ThemeProvider> <App /> </ThemeProvider>). 🔹 8. Container-Presenter Pattern – Separate logic (Container handles state, Presenter handles UI). 🚀 Master these patterns for scalable React apps! #React #DesignPatterns #WebDevelopment

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Must-Know JavaScript & React Concepts for Frontend Interviews! 🚀 If you're preparing for frontend interviews, mastering these JavaScript & React concepts will give you a strong edge 📌 JavaScript Fundamentals 📌 ⚡ Call Stack & Execution Context ⚡ Closures & High-Order Functions ⚡ Spread & Rest Operators ⚡ Promises & Async Await ⚡ IIFE Immediately Invoked Function Expressions ⚡ Primitive vs Reference Types ⚡ Key Array Methods like Map Reduce Filter ⚡ Scopes Function Scope Block Scope Lexical Scope ⚡ Event Loop Callback Queue Microtask Queue ⚡ setTimeout setInterval requestAnimationFrame ⚡ ES6 Classes & Factory Functions ⚡ Comparison Checks == vs === ⚡ this keyword call apply bind functions ⚡ new keyword Constructor Prototype Instances ⚡ Prototype Inheritance & Prototype Chain ⚡ Object create & Object assign ⚡ Functional Programming Currying Composition Partial Applications ⚡ Polyfills for JavaScript functions 📌 React Fundamentals 📌 ⚡ React Reconciliation & Fiber ⚡ Virtual DOM vs Real DOM ⚡ State Management Context Redux Zustand ⚡ Custom Hooks & Performance Optimization ⚡ Server Side Rendering SSR vs Client Side Rendering CSR ⚡ React Concurrent Mode & Suspense ⚡ Error Boundaries & React Profiler ⚡ Machine Coding Problems #Frontend #JavaScript #React #MachineCoding #Polyfills #InterviewPreparation #WebDevelopment

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