TOP 360 react interview questions for candidate screening in 2025

Why React Interview Questions Matter More Than You Think

As a hiring manager, you've probably noticed how React developers are in incredibly high demand right now. And honestly, it makes perfect sense. When you're trying to fill a frontend position, having the right react interview questions can be the difference between hiring someone who truly gets React's ecosystem and someone who just knows the buzzwords. I've seen too many hiring decisions go wrong because the interview process didn't dig deep enough into a candidate's actual React knowledge.

The React Revolution is Real

Let's talk numbers for a second. React was first deployed on Facebook's news feed in 2011 and on Instagram in 2012, but it wasn't until Facebook open-sourced it in 2013 that it really took off. Today, companies like Netflix, Airbnb, Instagram, and WhatsApp rely heavily on React for their user interfaces. React Native was released in 2015, extending React's reach into mobile development, which means your React developer might also be able to contribute to mobile projects.

The technical evolution has been impressive too. React 16.8 introduced Hooks, completely changing how developers write components. Error boundaries were introduced in React version 16, and React 18 brought concurrent rendering and automatic batching. These aren't just technical details - they represent fundamental shifts in how modern React applications are built, and your candidates should understand them.

What Makes React Special for Your Team

Here's what you need to know: React uses virtual DOM instead of real DOM because real DOM manipulations are expensive. This makes applications significantly faster. React follows unidirectional data flow, which makes debugging easier and applications more predictable. Companies leveraging modern stacks like React report a 50% reduction in development time compared to traditional approaches.

ReactJS is a component-based JavaScript library used to build dynamic and interactive user interfaces. It supports all popular browsers including Internet Explorer 9 and above, and there are React DevTools available for Chrome and Firefox to help with development and debugging. The library continues to dominate the front-end development landscape, making React skills essential for any serious frontend team.

Now that you understand why React expertise is crucial for your team's success, let's dive into the 360 best practice react interview questions for 2024 that will help you identify truly skilled React developers who can contribute from day one.

Because you're reading this article, you might be interested in the following article as well: One Way Video Interview: Basics and Features.

🏆 The list of TOP 360 react interview questions in 2025

What is React?

A good candidate should be able to explain that React is a front-end, open-source JavaScript library used for building user interfaces, especially for single-page applications (SPAs). It’s widely used in both mobile and web development.

A solid answer should highlight that React:

• Uses a component-based architecture, allowing developers to build reusable UI components.
• Helps create dynamic and interactive user experiences.
• Is maintained by Meta (formerly Facebook) and has a large community support.

Comment:

Look for candidates who don’t just say "React is a JavaScript library" but also understand its purpose and benefit — like its use in building complex, reusable UI components. Best practice is screening for both technical knowledge and the practical application of React in real-world projects.

What are the advantages of using React?

React offers several valuable benefits that make it a popular choice for developing modern web applications. If you're hiring for front-end or full-stack roles, this is an important question to ask to gauge how well a candidate understands core UI technologies.

Here are key points to look for in a strong response:

• Virtual DOM for speed: Candidates should mention how React uses a Virtual DOM to improve performance. This means faster updates and smoother user experiences.
• Reusable components: The modular structure of React allows developers to build components that can be reused throughout the application, saving time and ensuring consistency.
• Gentle learning curve: A good sign is when a candidate notes that React is relatively easy to pick up, especially for those already familiar with JavaScript.
• SEO-friendly: Look for an understanding of how React, with tools like Next.js, supports server-side rendering to improve SEO performance.
• Vast ecosystem & community: Strong answers will mention the wide range of third-party libraries and community support available, making it easier to build feature-rich apps quickly.

Best practice: Ask follow-up questions to dig into their hands-on experience with these features. For example, how they've optimized components using the Virtual DOM or leveraged reusable components in a past project.

What are the limitations of React?

React is a powerful and popular JavaScript library, especially for building user interfaces. However, like any tool, it has its share of limitations.

• Not a Complete Framework: One of the most important things to remember is that React is just a library, not a full-fledged framework. It focuses only on the UI layer of your application. That means developers often need to bring in additional libraries to handle things like routing, state management, or form validation. For hiring managers, this means a candidate’s ability to integrate React with other tools is crucial.

• Steep Learning Curve for Beginners: React uses JSX, a syntax that mixes HTML with JavaScript. While powerful, it can be confusing to developers who are just starting out. Inline templating and complex state handling can also be tough. Ask candidates about how they learned React and how they managed the initial learning phase. It helps gauge their problem-solving mindset and ability to learn.

• Boilerplate and Configuration Overhead: Building a large-scale React application often involves a lot of setup with tools like Webpack, Babel, or Next.js. This can be overwhelming unless the candidate is experienced with front-end workflows. A good follow-up here is to ask candidates if they've set up a React project from scratch or mainly worked on existing codebases.

• Performance with Large Applications: React can face performance issues in very large and dynamic applications, especially if not managed well. That’s why understanding optimization techniques like memoization or virtualization is important. You can ask: “How have you optimized React performance in your previous projects?”

Best Practice Tip: During interviews, don't just look for familiarity with React. Ask situation-based questions that uncover a candidate's ability to navigate its limitations. Understanding where React falls short tells you how adaptable and experienced the developer is.

What is useState() in React?

useState() is a built-in Hook in React that lets you add state to functional components. In simpler terms, it allows your component to remember values between function calls.

It returns an array with two elements:

• The current state value
• A function to update that value

Example:

const [count, setCount] = useState(0);

Here, `count` is the value stored in state, and `setCount` is the function used to update it.

Common use cases for useState():

• Handling form inputs
• Toggling elements on and off
• Tracking user interactions

Best practice tip: Always use the setter function (like `setCount`) to update the state instead of directly modifying the variable. This ensures React knows the state has changed and will re-render the component as needed.

Comment:

The useState() Hook is a foundational concept in React. It lets your functional components "remember" things—like what a user typed into an input or whether a dropdown is open. It should be used anytime a part of the page changes based on something the user does or something that updates over time.

What are keys in React?

A key in React is a special string attribute used when rendering lists of elements. It helps React identify which items in the list have changed, been added, or removed, making the rendering process more efficient.

React uses these keys to optimize updates and avoid unnecessary re-renders. Without keys, React would re-render every item in a list each time the component changes, leading to slower performance.

Keys should be unique among siblings and are most commonly extracted from a unique id (like a user ID or database key).

Best practice:

• Use a unique and stable value as a key (avoid using indexes if the list order can change).
• Don’t use random values or array indexes as keys unless you are sure the list won’t re-order or change.

Good example:

{users.map(user => (
  <li key={user.id}>{user.name}</li>
))}

Use this question to test if candidates:

• Understand React’s rendering behavior.
• Can explain why using keys is important.
• Know best practices around choosing unique keys.

Avoid candidates who just say “keys help React render lists” without depth—they might be memorizing, not understanding. Look for real-world examples in their explanations.

What is JSX?

JSX stands for JavaScript XML. It allows developers to write HTML-like syntax directly within JavaScript code. This syntax makes it easier to create user interfaces, especially when using libraries like React. Instead of calling functions like `createElement()` or modifying the DOM manually, JSX helps you write components more intuitively—like you're writing regular HTML.

Comment:

Look for a candidate who not only knows the definition of JSX but also understands why it's used—to simplify UI building in React and improve code readability. The best responses should show familiarity with React.createElement(), DOM manipulation alternatives, and how JSX compiles under the hood. Strong candidates might also touch on JSX's need for a transpiler like Babel.

What are the differences between functional and class components?

Functional and class components are two main ways to create components in React, and they differ in how they are written and how they manage state and lifecycle methods.

Here’s what sets them apart:

• Syntax:
• Functional components are simple JavaScript functions.
• Class components use the `class` keyword and extend `React.Component`.

• State Management:
• Initially, functional components didn’t manage state.
• Now, with Hooks like `useState`, functional components can manage state just like class components.
• Class components use `this.state` and `this.setState` for managing state.

• Lifecycle Methods:
• Class components use methods like `componentDidMount`, `componentDidUpdate`, and `componentWillUnmount`.
• Functional components now use `useEffect` to handle lifecycle events.

• Handling Props:
• Both handle props similarly, but functional components use props directly as a function argument.
• Class components access props with `this.props`.

Best practice today? Use functional components. They're shorter, cleaner, easier to test, and the current standard in modern React development. Class components are still valid but are considered more verbose and are less common in new codebases.

---

Comment:

Before the introduction of Hooks in React, functional components were called stateless components and were behind class components on a feature basis. After the introduction of Hooks, functional components are equivalent to class components. They differ in declaration, handling props, and handling state.

What is the virtual DOM? How does React use the virtual DOM to render the UI?

This question helps identify a candidate’s understanding of how React manages UI updates efficiently. It’s great for frontend developer roles.

What to look for in a strong answer:

A good candidate should explain that the virtual DOM is an in-memory representation of the real DOM. It exists so that changes can be calculated quickly before updating the real DOM, which is a performance-heavy operation.

React uses this concept by keeping two virtual DOMs:

• One for the previous state
• One for the current state

When a change occurs, React compares the new virtual DOM with the previous one through a process called "diffing". Then, it updates only the elements that actually changed in the actual DOM. This makes React highly efficient for updating interfaces.

Best practice: Top candidates will mention performance benefits and React’s diffing algorithm. If they can explain it in simple terms, even better—it shows they truly understand the concepts, not just buzzwords.

What are the differences between controlled and uncontrolled components?

When interviewing a frontend developer or React candidate, asking about controlled and uncontrolled components helps gauge their understanding of form handling and state management in React.

Controlled Component: A controlled component is an input form element whose value is controlled by React using state. In simple terms, the component’s state reflects the input’s current value, and changes are managed through event handlers like `onChange`.

• React keeps the data in its state
• Value updates on each keystroke
• Easy to validate and manipulate
• Great choice for dynamic forms

Uncontrolled Component: An uncontrolled component, on the other hand, handles its own state internally through the DOM. We access the value using refs, not by binding it to the React state.

• DOM handles input data
• Less code but harder to test
• Used where state management isn’t needed

Comment:

This question helps reveal how deep the candidate understands React’s approach to form data. Look for answers that mention:

• State control in controlled components
• Refs usage in uncontrolled components
• Advantages and disadvantages of each

A strong candidate will also mention when to use one over the other, which shows real-world experience. Best practice is to use controlled components for anything interactive or requiring validation.

What are props in React?

Props in React are short for “properties”. They act like function arguments and are used to pass data from one component to another, especially from a parent to a child component. Props make React components more dynamic and reusable, helping developers build flexible UI blocks.

They are read-only—meaning a component should never change the props it receives. Instead, it can use them to render dynamic content, trigger functional changes, or determine component behavior.

Example scenario: Imagine you have a Button component. Instead of hard-coding the button text, you use props to set it dynamically so you can reuse the component:

<Button text="Submit" />
<Button text="Cancel" />

Here, the Button component receives a different `text` prop each time, making it reusable.

---

Comment

When screening candidates with this question, look for answers that mention:

• Props are used to pass data between components
• They are immutable inside the receiving component
• Common use includes dynamic rendering of content
• Syntax: props are passed like HTML attributes

A strong candidate might even mention accessing props via `this.props` in class components or directly in function components via destructuring.

Best practice tip: Ask for a code example. It helps show the candidate truly understands real-world use.

Explain React state and props

When screening candidates for frontend roles, especially React developers, it's key to test their understanding of core React concepts like state and props. Ask them:

"Can you explain the difference between React state and props, and how each is used?"

A strong candidate should clearly explain:

• State: It's a built-in object used to hold values that may change over the component's lifecycle. It helps React handle dynamic data.
• Props: Short for "properties", they are read-only inputs passed down from a parent component. Props let components talk to each other.

They might add that state changes are handled internally via `useState` or class methods, and that props are passed via JSX attributes and shouldn't be modified inside the component receiving them.

Comment:

React State: Every component in React has a built-in state object, which contains all the property values that belong to that component. The state object controls the behavior of the component. It’s what makes your component interactive and dynamic.

React Props: Every React component accepts a single object argument called props. These props are used to send data from parent to child components and can be passed using HTML-like attributes. Props are read-only and help keep your components reusable and predictable.

This is a basic but crucial question. If they mix up state and props or struggle to explain the difference, you may want to dig deeper into their React experience. Always look for candidates who offer specific examples of when to use each, showing more than just a textbook definition.

Explain about types of side effects in React component

Side effects in React components are operations that affect something outside the scope of the component, like interacting with the browser or performing asynchronous tasks. These are handled using the `useEffect` hook in functional components.

There are two main types of side effects you need to be aware of:

• Effects without Cleanup

These are tasks that do not require any kind of memory cleanup after they're executed. Examples include:

• Fetching data from an API
• Logging values to the console
• Updating local storage
• Manually updating the DOM (though this is rare in React)

These effects typically run once after the component mounts or when specified dependencies change.

• Effects with Cleanup

These effects need cleanup to avoid memory leaks, especially when components unmount or before the effect re-runs. Common examples include:

• Setting up subscriptions (like WebSocket or API listeners)
• Adding event listeners (like scroll or resize)
• Starting timers (e.g., `setInterval` or `setTimeout`)

Cleanup is done by returning a function inside the `useEffect` hook that will be called during the unmount phase or before the effect re-executes.

Best practice: Always identify whether your side effect needs cleanup. If it does, provide a cleanup function inside `useEffect`. This keeps your React app running efficiently and prevents bugs due to lingering subscriptions or event listeners.

By understanding these two types of side effects, you can write safer and more predictable React components.

What is prop drilling in React?

Prop drilling in React refers to the process of passing data from a parent component to a deeply nested child component through multiple layers of intermediate components. This happens when the data needed in a deep child component is only available in a top-level parent, so it has to be passed down as props step-by-step through each level of the component tree.

Comment:

This technical question helps assess if a candidate understands one of the common architectural challenges in React. Candidates who can clearly explain why prop drilling can become a problem—and how to solve it (for example, using context API or state management tools like Redux)—show a stronger grasp of React’s design patterns.

Best practice tip: Look for answers that not only define prop drilling but also acknowledge alternative solutions. That shows practical knowledge beyond theory.

What are error boundaries?

Error boundaries are special components in React that catch JavaScript errors in the component tree during rendering, in lifecycle methods, and in constructors of the whole tree below them. They prevent the entire application from crashing by catching the error in a single part of the UI and rendering a fallback user interface instead.

They work using specific lifecycle methods like `getDerivedStateFromError` and `componentDidCatch`, making any component with these methods an error boundary.

Comment:

Error boundaries help keep your app stable by catching UI-related errors before they break the whole page. If your app has shared layouts or dynamic components, placing error boundaries around them is a best practice. It improves the user experience and makes debugging easier. Use them to isolate specific components that are more prone to errors, so they don't affect other parts of your app.

What is React Hooks?

React Hooks are built-in functions introduced in React 16.8 that let you use state and lifecycle methods in functional components. Before Hooks, these features were only available in class components. Hooks simplify code, reduce boilerplate, and encourage cleaner component structure.

Popular hooks include:

• useState – for managing state within a component
• useEffect – for handling side effects like data fetching or manual DOM manipulation
• useContext – to use global data without prop drilling
• useRef – for accessing DOM elements or keeping mutable values
• useReducer, useMemo, useCallback – for advanced state and performance optimization

Comment:

When a candidate answers this question, look for more than just the definition. Strong candidates will mention common hooks like useState, useEffect, and how these help eliminate the need for class components. The best answers give a quick example or explain how Hooks improve code readability or maintainability. It's a good sign if they also talk about the rules of Hooks (like only calling them at the top level and inside functions), which shows real-world experience.

Explain React Hooks.

React Hooks are special functions that let you use state and other React features without writing a class. They were introduced in React 16.8 and made functional components much more powerful. Common hooks include useState, useEffect, and useContext.

Hooks allow you to reuse logic across components and keep your code clean and organized. Instead of dealing with `this` or binding methods, you can just use functions. Here's a simple example with `useState`:

import { useState } from 'react';

function Counter() {
  const [count, setCount] = useState(0);

  return (
    <button onClick={() => setCount(count + 1)}>
      Clicked {count} times
    </button>
  );
}

This approach makes functional components easier to read and maintain. Hooks also promote better separation of concerns by letting you split component logic into smaller, reusable pieces.

Comment:

Hooks are functions that let us 'hook into' React state and lifecycle features from a functional component. React Hooks cannot be used in class components. They let us write components without class.

Best practice tip: Always call hooks at the top level of a component and never inside loops, conditions, or nested functions. This keeps the hook calls in the same order and ensures reliable behavior.

What are the rules that must be followed while using React Hooks?

React Hooks are a powerful feature in React, but they come with a specific set of rules that candidates must follow to use them correctly. Asking this question during the screening process can help you quickly evaluate a candidate’s understanding of core React concepts and coding discipline.

Comment:

React Hooks must be called only at the top level. This means you should never call Hooks inside:

• Loops
• Conditional blocks
• Nested functions

Doing so can break the order in which Hooks are called, making the component state unpredictable.

Also, Hooks can only be called from React function components or from custom Hooks (functions that start with "use" and follow the same rules).

A strong candidate will not only know these rules but also be able to explain why they exist — to preserve the integrity of the React rendering process. Best practice is to follow React's official Hook rules and use ESLint plugins like `eslint-plugin-react-hooks` to enforce them automatically.

What is the use of useEffect React Hooks?

The `useEffect` React Hook is used to handle side effects in functional components—like fetching data, updating the DOM, or starting a timer. It's a built-in Hook introduced in React 16.8, and it helps replace lifecycle methods in class components such as `componentDidMount`, `componentDidUpdate`, and `componentWillUnmount`.

The structure of useEffect:

useEffect(() => {
  // side effect logic
}, [dependencies]);

• The first argument is a callback function that runs the effect.
• The second argument is an optional array of dependencies. It determines when the effect should re-run.

If this array is empty `[]`, the effect runs only once after the first render—best practice for tasks like fetching data on page load.

If there are values inside it, the effect runs every time any value in the array changes.

Best practice tip: Always clean up your side effects (like subscriptions or timers) to avoid memory leaks. This is done by returning a function inside the effect.

Comment:

This is a key question for screening React developers. A good candidate should not only describe what `useEffect` does but also explain how it replaces lifecycle methods and handles dependencies. Look for examples like fetching data or setting event listeners. Top candidates will also mention the cleanup function and dependency management, which helps avoid bugs.

Why do React Hooks make use of refs?

React Hooks use refs to access and interact with DOM elements directly. This is especially useful when you need to perform certain imperative actions that can't be easily handled using React's declarative style alone.

Here’s when refs come in handy:

• Managing focus: Like setting focus on an input field when a component mounts.
• Controlling media playback: Play, pause, or control video/audio elements dynamically.
• Text selection: Programmatically select or manipulate text inside an input or textarea.
• Integrating with third-party DOM libraries: Refs help bridge React with libraries that aren’t built using it (e.g., jQuery plugins).
• Triggering animations: Useful for starting animations that require direct access to DOM elements.

Best practice: Use refs sparingly. They should not replace the React data flow. Use them primarily when you need direct DOM access. Always prefer state and props unless you specifically need a ref to accomplish a task.

What are Custom Hooks?

A Custom Hook is a function in JavaScript—specifically in React—that starts with the word `'use'` and lets you reuse logic that involves other hooks. Instead of copying the same useEffect or useState logic in different components, you wrap that logic in a custom hook and call it wherever you need.

Why ask this during candidate screening?

This is a smart screening question for front-end or React developers. It helps identify whether the candidate has hands-on experience writing modular, reusable code—something that's common in real-world React development.

What to look for in a good answer

• They start by explaining a custom hook as a reusable function that encapsulates hook-based logic.
• They mention that it allows for code abstraction without affecting how components are structured.
• Candidates who also explain a real-world use case (like fetching data or form handling) show practical understanding.

Red flags in answers

• They confuse custom hooks with basic functions or general hooks.
• They fail to start their examples or custom hooks with `'use'`.
• No mention of how it's used in development or real projects.

Best practice:

Strong candidates not only define custom hooks but also clarify how it helps maintain cleaner, more manageable code in large React apps.

Use this question to find developers who value code reusability and understand the deeper component logic in React.

How to perform automatic redirect after login?

To perform an automatic redirect after login in a React application, you can use the React Router library. The core idea is to check if the user has successfully logged in and then programmatically navigate them to the desired page, such as a dashboard or home page.

Here’s a basic approach using `react-router-dom`:

import { useNavigate } from 'react-router-dom';
import { useEffect } from 'react';

const LoginPage = () => {
  const navigate = useNavigate();

  useEffect(() => {
    // Assuming you store an auth token or flag on login success
    const isLoggedIn = localStorage.getItem('authToken');

    if (isLoggedIn) {
      navigate('/dashboard'); // Redirect to dashboard after successful login
    }
  }, []);

  return (
    <div>
      {/* Your login form goes here */}
    </div>
  );
};

Best Practice:

• Use `useNavigate` from `react-router-dom@6` for cleaner redirect logic.
• Always verify login status securely, not just from localStorage.
• After submitting the login form successfully, trigger the `navigate()` function.

Comment:

When using React Router v6 or later, use `useNavigate` instead of ``, as `` was used in earlier versions. Rendering a `` component used to send users to a new route, but in the newer approach, handling redirection programmatically is clearer and more flexible for login flows.

How to pass data between sibling components using React Router?

Passing data between sibling components in React can be done using React Router by leveraging features like `history.push` and `match.params`. Here's how it works:

When one sibling component needs to send data to another (and they don’t share a direct parent-child relationship), a common approach is to:

• Use React Router's `history.push()` to navigate and send data
• Use URL parameters (`match.params`) or location state to pass data
• The receiving component reads that data using `props.match.params` or `props.location.state`

Best practice tip: Instead of relying solely on URL parameters for complex objects, use `location.state`. This prevents sensitive or large data from being exposed in the URL.

Example approach:

// Sender Component
props.history.push({
  pathname: '/sibling',
  state: { userId: 123, userName: 'Jane' }
})

// Receiver Component
const { userId, userName } = props.location.state;

Pro Tip: For clean and maintainable code, keep your shared state in a context or a global state manager like Redux if multiple components need access to the same data. Use router-based data passing only when navigating between routes.

How to re-render the view when the browser is resized?

When hiring for front-end or full-stack roles, it's important to check a candidate’s understanding of browser behavior and component life cycles. A great way to test this is by asking:

"How would you re-render the view when the browser is resized?"

This question helps you gauge if the candidate understands how to listen to browser events and update component state accordingly.

What to listen for in the answer:

A strong candidate should mention using the `resize` event listener in the `componentDidMount()` method to watch for window size changes. They should also emphasize the importance of cleaning up by removing the listener in `componentWillUnmount()` to avoid memory leaks — a best practice.

Look for mentions of:

• `window.addEventListener('resize', this.handleResize)`
• Updating component state with current width/height
• Removing the event listener with `window.removeEventListener` in `componentWillUnmount`

Bonus points if they mention using modern hooks like `useEffect` and `useState` in functional components, which shows up-to-date React knowledge.

This question helps filter candidates who not only understand React but write clean and maintainable code.

How to create a switching component for displaying different pages?

Creating a switching component is key when building applications with multiple views or pages. It allows you to dynamically switch between different components based on a condition, typically a route or a state.

Best practice: Use a mapping object to associate specific prop values with the components you want to render. This approach keeps your logic clean and scalable.

Here's a basic way to create a switching component:

const Page1 = () => <div>Welcome to Page 1</div>;
const Page2 = () => <div>Welcome to Page 2</div>;
const Page3 = () => <div>Welcome to Page 3</div>;

const pageMap = {
  page1: Page1,
  page2: Page2,
  page3: Page3
};

const PageSwitcher = ({ currentPage }) => {
  const Component = pageMap[currentPage] || (() => <div>Page not found</div>);
  return <Component />;
};

Why this works well:

• It's simple and avoids messy `if` or `switch` statements.
• Easy to expand—just add a new key-value pair to `pageMap`.
• Promotes separation of concerns.

When screening developers, ask them how they would structure dynamic rendering for pages or views. Look for answers that:

• Show understanding of component mapping
• Use clean, maintainable code
• Avoid deeply nested conditional logic

This shows they're thinking ahead and understand how to structure scalable React apps.

How to Create a Simple React Hooks Example Program

Creating a simple React application using Hooks is a great way to understand how modern React works. Hooks, especially `useState`, let you manage state in functional components without writing a class. Here's a basic step-by-step guide:

---

1. Set Up Your React App

The easiest way to start is by using Create React App, which sets up everything for you.

npx create-react-app react-hooks-demo
cd react-hooks-demo
npm start

Best Practice: Always start with a clean boilerplate to avoid configuration issues. npx ensures you use the latest version without installing globally.

---

2. Create a Functional Component Using JSX

In your `src` folder, replace the code in `App.js` with a functional component. This is where we'll use JSX (JavaScript XML) to return elements.

function App() {
  return (
    <div>
      <h1>Hello React Hooks</h1>
    </div>
  );
}

Tip: Functional components are simple functions that return UI. No need for `render()` or lifecycle methods like old class components.

---

3. Use the useState Hook to Manage State

Let’s add interactivity by using the `useState` hook to manage a counter.

import React, { useState } from 'react';

function App() {
  const [count, setCount] = useState(0);

  return (
    <div>
      <h1>You clicked {count} times</h1>
      <button onClick={() => setCount(count + 1)}>
        Click Me
      </button>
    </div>
  );
}

• `useState(0)` sets the initial state to 0.
• `count` is the current state value.
• `setCount` is the function to update it.

Best Practice: Always name your state variables clearly. It helps future developers (and you) understand their purpose.

---

Comment:

Use `npx create-react-app` to quickly set up a skeleton React application. Write your components as functions that return JSX for clear, concise code. Use the `useState` hook to manage state in functional components—it's the simplest and most effective way to make UI interactive without converting to class syntax. Keep your components small and focused on doing one thing well.

Explain conditional rendering in React

Conditional rendering in React refers to the ability of a component to render different UI elements or components based on certain conditions. It's a way of dynamically showing content depending on what's happening in your app — for example, whether a user is logged in or if data is loading.

Developers often use different JavaScript techniques for this, such as:

• `if-else` statements – when the logic is more complex
• Ternary operators (`condition ? true : false`) – for shorter, in-line conditions
• Logical AND (`&&`) operator – great for rendering something only if a single condition is true
• Element variables – where components are stored in a variable before rendering

Using the right method depends on the context. Ternary operators are commonly used because they keep the code clean, but for more complex scenarios, using separate functions or `if-else` blocks makes it more readable.

---

Comment:

This question helps you understand how comfortable the candidate is with React's core concepts. A strong answer should explain what conditional rendering is, mention common techniques like ternary operators, `if-else`, and logical `&&`, and ideally give a simple example. Look for clarity in their explanation and whether they mention best practices, like keeping code readable and concise.

Can React Hook replace Redux?

React Hooks, especially `useReducer` and `useContext`, can manage local and shared state within components quite effectively. They’re great for simple to medium complexity applications where prop drilling is minimal, and the app structure is relatively flat.

However, in large, complex applications where you need to manage a global state across multiple deeply nested components, React Hooks alone often fall short. This is where Redux comes in—it provides a clear, predictable pattern for state updates and powerful tools like middleware, devtools, and time-travel debugging.

Best Practice: Use built-in React Hooks for local component state and small shared state needs. But when your application grows and you face challenges like multiple data sources, asynchronous updates, and state shared across many components—stick with Redux or hybrid solutions that include Redux Toolkit.

• React Hooks: Great for simple state logic
• Redux: Better for managing complex global state
• Conclusion: React Hooks complement but do not replace Redux in larger apps. Use the right tool for the job.

What is React Router?

React Router is the standard library for handling routing in React applications. It lets developers create single-page apps with seamless navigation, meaning users can move between different views or components without the page reloading. This results in a smoother and faster user experience.

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Screening for React knowledge? This is a great foundational question. A technically sound candidate should explain that React Router allows for client-side routing in single-page applications (SPAs). Look for responses that mention how it helps without reloading the page, improving user experience. Best practice answer includes mention of components like ``, ``, and ``. If a candidate names these and explains their role, it’s a strong signal they’ve worked with it in real projects.

Do Hooks cover all the functionalities provided by the classes?

React Hooks are powerful and have changed the way developers write components. But no, they don’t cover all class-based functionalities yet.

Specifically, Hooks don’t currently provide built-in equivalents for these class lifecycle methods:

• `getSnapshotBeforeUpdate()`
• `getDerivedStateFromError()`
• `componentDidCatch()`

These methods handle some edge-case behaviors and advanced error handling that Hooks haven’t fully replicated. While you can manage most component logic using Hooks like `useEffect()`, `useState()`, and `useContext()`, you'll still need class components if your app relies heavily on the methods above.

Best practice tip: Don’t convert class components to function components blindly. If your component uses these specific lifecycle methods, evaluate whether it's worth switching or if a class-based structure is still the better fit for that logic.

When screening candidates, ask follow-up questions like:

• "How would you handle error boundaries in a functional component?"
• "What are the limitations of Hooks compared to class components?"

These follow-ups help you learn how deep their React knowledge goes and whether they understand the trade-offs.

How does the performance of using Hooks differ in comparison with Classes?

React Hooks are designed to simplify your components and improve performance. Unlike class components, Hooks avoid several overheads:

• No need to create class instances
• No event binding required
• Cleaner, more readable code

Hooks reduce the size of your component tree by cutting out unnecessary layers that come with higher-order components (HOCs) and render props patterns. This leads to better render performance and simpler component management.

Best practice: When screening a React developer, ask this question to check whether they understand not just syntax, but also how Hooks optimize performance. A good candidate should mention:

• Avoidance of boilerplate in class components
• Reduced memory footprint
• More predictable and readable lifecycle with `useEffect`, `useState`, etc.

Look for responses that show they’ve used both approaches and understand why Hooks handle performance better, not just how.

💡 Remaining 330 questions...

The online article only includes the first 30 questions to keep it digestible, but we’ve put together an ebook for you with all the questions we gathered through our extensive research.

Download E-Book here 👉

Real-World Success Stories: How Top Companies Use React Interview Questions

The story of React is pretty fascinating when you think about it. Jordan Walke, a software engineer at Facebook (now Meta), created this game-changing framework that's now powering some of the biggest applications we use daily. What started as an internal Facebook project in 2011 has become the fastest-growing JavaScript framework globally.

Major tech giants like Facebook, PayPal, Instagram, Uber, Netflix, and Discord have built their user interfaces using React. This widespread adoption means that knowing the right react interview questions has become crucial for both recruiters and candidates. When companies like Airbnb, WhatsApp, Khan Academy, and Dropbox are all looking for React talent, the competition gets pretty intense.

Indian IT service companies like Infosys, TCS, and Wipro have also jumped on the React bandwagon, making React skills a must-have for front-end developers. This shift has created a ripple effect across the entire tech recruitment landscape.

Braintrust, a leading talent platform, reports they can match companies with five highly-qualified React developers within minutes. This speed comes from having a solid understanding of what react interview questions actually matter in real-world scenarios.

Mafuzur Rahman from Esap AI shared some interesting insights based on his experience with junior frontend role screenings. He noted that the questions being asked have evolved significantly over the past few years. Meanwhile, Barry Michael Doyle from SecuritEase raised an important point about balancing theoretical knowledge with practical React experience - something many recruiters struggle with.

The challenge isn't just knowing React; it's knowing how to identify candidates who can actually use React effectively in production environments. That's where the right screening approach becomes critical.

Hiring React developers? Pair this guide with JavaScript interview questions and common interview questions to balance core JS fundamentals with role-specific depth.

Why Video Screening Software Is Revolutionizing React Recruitment

The recruitment game has changed dramatically, and here's why video screening software is becoming the go-to solution for hiring React developers:

Time efficiency is everything in today's competitive market. Instead of scheduling dozens of phone screens just to eliminate obvious mismatches, recruiters can now review video responses to react interview questions at their own pace. This means better candidates get faster responses, and hiring managers can focus their time on the most promising prospects.

Consistency across interviews has always been a challenge. With video screening, every candidate gets asked the same core react interview questions, making it much easier to compare skills objectively. No more wondering if one interviewer was having a bad day or if another was too lenient.

Remote-first hiring isn't going anywhere. Video screening allows companies to tap into global React talent without the logistics nightmare of coordinating live interviews across time zones. A developer in India can showcase their skills to a company in San Francisco without anyone losing sleep.

Better candidate experience matters more than ever. Candidates can take their time, think through their answers, and present their best selves. This is especially valuable for React developers who might be brilliant coders but get nervous in traditional interview settings.

The numbers don't lie - companies using video screening report 40% faster time-to-hire and 60% better candidate satisfaction scores. When you're competing for top React talent, these advantages can make or break your hiring success.

Ready to transform your React hiring process? Discover how our video screening platform can help you identify the best React developers faster and more efficiently than traditional methods. Stop letting great candidates slip away due to scheduling conflicts and inconsistent interviews.