React Essentials: Top Interview Questions for 2025 Quiz

Test your knowledge with this easy React quiz based on trending interview questions for 2025. Review core concepts such as components, JSX, props, hooks, and more, to boost your front-end development skills and interview readiness.

1. React's Core Purpose

   What is the main purpose of React in web development?

   1. To compile TypeScript code to JavaScript
   2. To build user interfaces efficiently with reusable components
   3. To enhance CSS styling for web pages
   4. To manage backend databases directly

   Explanation: React is designed to build user interfaces efficiently using a component-based structure. It does not directly manage databases (a backend concern), nor is it focused on CSS, although it can work with styling. Compiling TypeScript is unrelated to React's main purpose.

2. Understanding JSX

   Which statement best describes JSX in React?

   1. A syntax extension that lets you write HTML-like code within JavaScript
   2. A new programming language for web development
   3. A tool for creating advanced CSS stylesheets
   4. A custom database language for React apps

   Explanation: JSX allows developers to write HTML-like code inside JavaScript files, making the component structure clearer. It is not a database language or a styling tool, and it's not a standalone programming language—it's a syntax extension.

3. Functional vs Class Components

   Which is a key difference between functional and class components in React?

   1. Class components are only used in databases
   2. Functional components are written as functions, while class components use ES6 classes
   3. Functional components can access lifecycle methods directly
   4. Class components cannot handle state at all

   Explanation: Functional components are JavaScript functions, whereas class components rely on ES6 class syntax. Class components can handle state and lifecycle methods, while functional ones use hooks. Neither component type is used in databases.

4. The Role of Props

   In React, what are props primarily used for?

   1. Managing the application's global state
   2. Uploading assets to a server
   3. Passing data from parent to child components
   4. Modifying CSS stylesheets

   Explanation: Props enable one-way data flow from parent to child component, making components reusable and dynamic. Application state management generally involves state or context, not props. Asset uploading and CSS styling are unrelated to props.

5. React Hooks Basics

   What is the main use of hooks in modern React functional components?

   1. Applying inline CSS styles
   2. Handling page routing directly
   3. Generating database schemas
   4. Adding state and side effects to functional components

   Explanation: Hooks, like useState and useEffect, bring state and side-effect logic to functional components. They are not for database tasks or routing, and while styling can use hooks, their main role is managing state and side-effects, not CSS.

6. Virtual DOM Advantage

   How does React's virtual DOM enhance app performance?

   1. It minimizes direct updates to the real DOM by batching changes
   2. It encrypts user inputs on forms
   3. It delivers server responses faster
   4. It stores all CSS files in memory

   Explanation: The virtual DOM allows React to make efficient updates by comparing changes and batching real DOM interactions, making updates faster. It does not manage CSS files, server responses, or encryption related to forms.

7. Component Render Example

   Given the function: function Hello() { return u003Ch1u003EHello, world!u003C/h1u003E; }, what type of component is this?

   1. Functional component
   2. Class component
   3. Stateful database
   4. Styled component

   Explanation: This is a functional component because it's a function that returns JSX. Styled components are a different concept related to CSS. Class components use class syntax, and databases are unrelated here.

8. Props Usage Scenario

   If you write u003CGreeting name='Alice' /u003E, how can the Greeting component access 'Alice'?

   1. By using props.name within the component
   2. By using the variable username globally
   3. By calling window.name directly
   4. By accessing document.title

   Explanation: To access the value 'Alice', the Greeting component uses props.name. Accessing window.name or document.title would not yield this data, and no global variable username exists in this context.

9. Component State Introduction

   What does state represent in a React component?

   1. The data that can change over time and influence what is rendered
   2. A static value defined at compile-time
   3. A reserved keyword for styling elements
   4. A fixed configuration for routing

   Explanation: State allows components to store and manage information that can change, triggering re-renders as needed. It is not used for routing, static values, or styling keywords.

10. Component Reusability

    Why is it beneficial to build applications using reusable React components?

    1. It forces all styles to be global only
    2. It removes the need for functions in JavaScript
    3. It requires every component to have a unique state
    4. It allows code to be organized, maintained, and updated easily

    Explanation: Reusable components promote maintainability and code organization, which helps in scaling projects. Global styles, removal of functions, and enforced unique state per component are incorrect or unrelated statements.