Conceptual

Master the concepts interviewers actually test. Clear, concise explanations of topics that separate strong candidates from the rest.

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NameDifficultyCompanies

What are the benefits of using hooks in React?New

How does the box model work in CSS?

call( ) vs apply( )

call( ) vs bind( )

Explain the composition pattern in ReactNew

What is the CSS display property and what are examples of its use?New

What is CSS selector specificity and how does it work?New

What is event delegation in JavaScript?

What is event loop?

How to improve website performance?

What are the rules of React hooks?New

this keyword in JavaScript

What happens when the useState setter function is called in React?New

var vs let vs const

Virtual DOM in React

What does preventDefault() do?

What happens when you type a URL into a browser and hit enter?

What is a closure in JavaScript?

What is AB Testing?

What is the event loop in JavaScript?

What is Responsive Design?

Why does React recommend against mutating state?New

What is the use of aria-label, aria-labelledby, and aria-live?

How does positioning work in CSS?

What is dangerouslySetInnerHTML in React?

What is difference between a map object and a plain object in JavaScript?

What are error boundaries in React?New

What are ES2015 classes and how do they differ from ES5 function constructors?New

Describe event capturing in JavaScriptNew

What is forwardRef() in React?New

Garbage Collection

What are iterators and generators in JavaScript?New

key prop in react

What are the differences between Map/Set and WeakMap/WeakSet?New

What is the difference between mouseenter and mouseover?New

Object Comparison Output

What are JavaScript object getters and setters?New

Optimize Rendering Large Datasets

Explain the presentational vs container component patternNew

preventDefault() vs stopPropagation()

What are some common React anti-patterns?New

What are React Fragments used for?New

What is the difference between React Node, React Element, and React Component?New

How do you decide between React state, context, and external state managers?New

What is React Suspense?New

What are render props in React?New

How do you reset a component state in React?New

What are server-sent events?New

translate vs absolute positioning

What is tree shaking?

Arrow functions

What is cookie?

What is hoisting in JavaScript?

What are workers in JavaScript?New

What is an anonymous function and when would you use it?

box-sizing: border-box

Centering Elements in Webpages

What is a static method in a class?

Content Security Policy (CSP)

Cross Origin Resource Sharing (CORS)

Cross-Site Scripting (XSS)

What data structure is used to represent the DOM?

default vs named export

Difference between global scope, function scope, and block scope

How to prevent the UI from blocking during a long running task?

Image Failures in Production

inline vs inline-block vs block

How do you destructure nested objects?

null vs undefined vs undeclared

What are JavaScript object property flags and descriptors?New

Primitive vs Reference

Proxies in JavaScript

What is React Fiber?New

Reference vs Syntax Error

Role of semantic HTML in accessibility

What is semantic HTML?

How would you test a React application?

useEffect vs useLayoutEffect

What are Web Vitals?

What is callback hell?

What is Immutability?

Why is input validation important?

What is the Beacon API?

Critical Rendering Path

What is doctype in HTML?

What is a higher order function?

How do you create a constructor function?

How would you style an SVG?

How would you implement dark mode and light mode?

What is inversion of control?

Reset vs Normalize CSS

What is Test Driven Development?

How to truncate text using CSS only

What does typeof operator do?

What is array destructuring?

What is an async thunk?

What is object destructuring?

What is singleton pattern?

What is TDZ in JavaScript?

What is a thunk?

Where Do We Use Observer Pattern in Frontend Development?

Why do we use polyfills?

Why are functions first-class objects?

Passing function to initial state

How to scope the type of generic?

stopPropagation() vs stopImmediatePropagation()

What is a symbol type?

sync vs async function

Can callbacks be synchronous?

useTransition vs useDeferredValue