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1How does async/await work in JavaScript?2Why use hooks in React?3Explain the CSS box model 4call() vs apply()5call() vs bind()6Client-side rendering vs server-side rendering 7How does the composition pattern work in React?8Controlled vs uncontrolled components 9How does CSRF work?10How does the CSS display property work?11How does CSS selector specificity work?12Debouncing vs throttling — what's the difference?13How does event delegation work in JS?14Explain the JavaScript event loop 15Techniques for improving website performance 16Promises vs callbacks 17How does prototypal inheritance work?18When does React trigger a re-render?19Rules of React hooks 20sessionStorage vs localStorage vs cookies 21Shallow copy vs deep copy 22How does the 'this' keyword behave in JavaScript?23Unit vs integration vs E2E testing 24How does useCallback work in React?25How does the useEffect dependency array work?26How does useMemo work in React?27Purpose of the useRef hook in React 28What happens when you call a useState setter?29var vs let vs const 30How does the Virtual DOM work in React?31What does preventDefault() do?32What happens after you type a URL and press enter?33Explain closures in JavaScript 34How does A/B testing work?35Explain responsive design 36Why shouldn't you mutate state in React?37How does AbortController work?38How do aria-label, aria-labelledby, and aria-live work?39Why are array indices bad keys in React?40Patterns for async data loading in React 41async vs defer 42How does caching improve performance?43Explain callback functions in JavaScript 44Classical vs prototypal inheritance 45Closures for creating private variables 46How does code splitting work?47Common data fetching pitfalls in React 48Common pitfalls with 'this'49CommonJS vs ES Modules 50How does CSS positioning work?51What does dangerouslySetInnerHTML do in React?52Map object vs plain object in JavaScript 53Techniques for optimizing DOM manipulation 54Explain the DOM tree structure 55== vs ===56How do error boundaries work in React?57Error handling with try...catch 58Handling errors in async operations 59ES2015 classes vs ES5 function constructors 60How does event capturing work?61Flexbox vs Grid — when to use which?62How does forwardRef() work in React?63How does garbage collection work in JavaScript?64Hoisting pitfalls and how to avoid them 65How do iterators and generators work in JavaScript?66JavaScript data types 67How do JavaScript modules work?68How does JSX work under the hood?69Purpose of the key prop in React 70How does lazy loading improve performance?71Explain lexical scoping in JavaScript 72load vs DOMContentLoaded event 73Map/Set vs WeakMap/WeakSet — what's different?74How does the microtask queue work?75Mocks vs stubs in testing 76mouseenter vs mouseover — what's the difference?77How does object comparison work in JavaScript?78How do getters and setters work in JavaScript?79Explain one-way data flow in React 80Rendering large datasets efficiently 81Optimizing React context performance 82Presentational vs container component pattern 83preventDefault() vs stopPropagation()84Explain the prototype chain 85How do pseudo-elements work in CSS?86Common React anti-patterns to avoid 87Pitfalls of React context 88Why use React Fragments?89How does React hydration work?90React Node vs React Element vs React Component 91When to use state, context, or external state managers in React?92How does React Suspense work?93Explain reflows and repaints in the browser 94How do render props work in React?95Ways to reset component state in React 96Rest parameters in JavaScript 97How does the same-origin policy work?98Implementing secure authentication and authorization 99How do server-sent events work?100Explain server-side rendering in React 101Spread operator in JavaScript 102How does static generation work?103Ways to bind 'this' in JavaScript 104How 'this' behaves in event handlers 105translate vs absolute positioning 106How does tree shaking work?107How does useReducer work in React?108Visually hiding content while keeping it accessible 109Arrow functions 110How do cookies work?111Explain hoisting in JavaScript 112How do Web Workers work?113Best practices for writing unit tests 114XMLHttpRequest vs fetch API 115How do z-index and stacking contexts work?116Adding, removing, and modifying DOM elements 117How does AJAX work?118Anonymous functions and their use cases 119Testing asynchronous code 120Attribute vs property in the DOM 121Explain Block Formatting Context in CSS 122box-sizing: border-box 123Ways to center elements in CSS 124How to check a variable's data type 125How to reliably check if an object is empty 126Ways to check if an object has a property 127Static methods in classes 128How does clickjacking work and how to prevent it?129Explain code coverage in testing 130How does Content Security Policy (CSP) work?131How does CORS work?132How does Cross-Site Scripting (XSS) work?133How to use CSS Grid 134Optimal placement of CSS and JS in HTML 135Explain currying in JavaScript 136Currying vs partial application 137How do data attributes work in HTML?138What data structure represents the DOM?139Debugging React applications 140Explain the decorator pattern 141How do default parameters work?142default vs named exports 143What are design patterns and why use them?144Global scope vs function scope vs block scope 145Dot notation vs bracket notation 146How does error propagation work in JavaScript?147Explain the factory pattern 148How do CSS floats work?149Preventing UI blocking during long-running tasks 150HTTP Methods 151Handling image failures in production 152inline vs inline-block vs block 153innerHTML vs textContent 154Different ways to iterate over arrays 155Ways to iterate over object properties 156Manipulating CSS with JavaScript 157How do media queries work for responsive layouts?158Explain mobile-first design 159Why use a module bundler?160Explain the module pattern 161Destructuring nested objects 162Strategies for optimizing network requests 163What does the new keyword do?164null vs undefined vs undeclared 165Object.freeze vs Object.seal vs Object.preventExtensions 166Property flags and descriptors in JavaScript 167Identifying performance bottlenecks 168Tools for measuring web performance 169Primitive vs Reference types 170How does progressive rendering work?171Explain Progressive Web Apps (PWAs)172How do Proxies work in JavaScript?173querySelector vs getElementById 174How does React Fiber work?175How do React Portals work?176What does React strict mode do?177How does recursion work in JavaScript?178ReferenceError vs SyntaxError 179Responsive vs adaptive design 180How do security headers work?181Why does semantic HTML matter for accessibility?182Best practices for handling sensitive data 183Why use the callback form of setState?184How do SPAs impact SEO?185SQL injection — how it works and how to prevent it 186Explain the strategy pattern 187How do template literals work?188Approaches to testing a React application 189Types of errors in JavaScript 190useEffect vs useLayoutEffect 191How does the useId hook work in React?192Ways to create objects in JavaScript 193Explain Web Vitals and their metrics 194Explain callback hell and how to avoid it 195Explain immutability in JavaScript 196Why is input validation important for security?197How does the window.history API work?198Window object vs Document object 199How does the Beacon API work?200How do break and continue work?201Handling cross-browser styling issues 202CSS clearing techniques 203Organizing code in a JavaScript project 204Explain the command pattern 205How does the Constraint Validation API work?206Explain the critical rendering path 207CSS frameworks you've worked with 208Pros and cons of CSS preprocessors 209What does doctype do in HTML?210CSS efficiency pitfalls to watch for 211How does feature detection work?212Explain the Flux pattern 213Extracting query string values in JavaScript 214Explain higher-order functions 215How do constructor functions work?216Ways to style an SVG 217Core building blocks of HTML5 218How do iframes communicate with the parent page?219Implementing dark mode and light mode 220Explain inversion of control 221When is the load event used?222Localizing a React application 223Module metadata fields in package.json 224Concerns when building a multilingual site 225Parameter vs argument — what's the difference?226Explain the prototype pattern 227Redirecting to a new page in JavaScript 228Reset CSS vs Normalize CSS 229Serving retina-ready graphics 230Tools for finding security vulnerabilities 231Serving pages for feature-limited browsers 232Converting a Set to an Array 233How does the srcset attribute work?234state vs props in React 235Converting strings to numbers in JavaScript 236How does the switch statement work?237How do tagged templates work?238How does the ternary operator work?239Explain Test Driven Development (TDD)240Testing tools and frameworks you use 241Truncating text with CSS only 242How does the typeof operator work?243What does 'use strict' do?244How does array destructuring work?245Explain async thunks 246How does object destructuring work?247Explain the singleton pattern 248Explain the Temporal Dead Zone (TDZ)249What is a thunk in JavaScript?250Observer pattern in frontend development 251What are polyfills and why use them?252Pros and cons of compiling to JavaScript 253How do CSS sprites work?254Detecting if JavaScript is disabled 255Why is document.write() bad practice?256Why are functions first-class objects in JavaScript?257How does JSONP work?258@media types beyond screen 259Passing a function as initial state in useState 260Constraining generic types in TypeScript 261stopPropagation() vs stopImmediatePropagation()262How does the Symbol type work?263Synchronous vs asynchronous functions 264Can callbacks be synchronous?265useTransition vs useDeferredValue

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