Students, freshers, interns, frontend developers, and MERN Stack learners9 min read

React Interview Questions and Answers for Freshers

A practical React interview questions and answers guide for students, freshers, frontend developers, and MERN Stack learners. Learn React concepts like components, props, state, hooks, useEffect, routing, conditional rendering, lists, forms, and API integration.

Question 1: What Is React

Best answer: React is a JavaScript library used to build user interfaces. It helps developers create reusable UI components and manage dynamic data efficiently. React is commonly used for single-page applications, dashboards, portals, admin panels, and interactive websites. Senior interviewer advice: Do not call React a full framework. It is mainly a UI library.

Question 2: What Are Components in React

Best answer: Components are reusable building blocks of a React application. A component can represent a button, navbar, card, form, page section, or complete page. Components help divide UI into smaller manageable parts, making code cleaner and reusable. Example: A job portal can have JobCard, Navbar, FilterSidebar, ApplicationForm, and Dashboard components. Senior interviewer advice: Give a project-based example. It shows practical thinking.

Question 3: Difference Between Props and State

Best answer: Props are used to pass data from a parent component to a child component. Props are read-only. State is used to manage data inside a component that can change over time. Example: A JobCard component may receive job title and company as props. A form component may use state to store input values. Senior interviewer advice: Mention that props are external data and state is internal component data.

Question 4: What Is useState

Best answer: useState is a React hook used to manage state in functional components. It returns the current state value and a function to update that value. Example: const [count, setCount] = useState(0); In real projects, useState is used for form inputs, modal open or close status, filters, selected tabs, and loading states. Senior interviewer advice: Always explain where you used it in a project.

Question 5: What Is useEffect

Best answer: useEffect is a React hook used to handle side effects such as API calls, subscriptions, timers, or updating something after the component renders. Example use cases: Fetching job listings from an API Updating document title Running code when a component loads Reacting to dependency changes Senior interviewer advice: Mention dependency array. It is important for a complete answer.

Question 6: What Is Conditional Rendering

Best answer: Conditional rendering means showing different UI based on a condition. Example: If a user is logged in, show dashboard. If not, show login page. In React, conditional rendering can be done using if statements, ternary operators, logical AND operator, or separate components. Senior interviewer advice: Connect this with authentication, loading states, and error messages.

Question 7: How Do You Fetch API Data in React

Best answer: API data is usually fetched using fetch or axios inside useEffect. The data is stored in state and then displayed in the UI. Basic flow: Create state for data Call API inside useEffect Store response in state Show loading and error states Render data using map Senior interviewer advice: Mention loading and error handling. That shows real project maturity.

Quick checklist

React definition is clear

Components are understood

Props vs state is revised

useState is practiced

useEffect is practiced

Conditional rendering is clear

List rendering is practiced

Forms are revised

API fetching is practiced

Project examples are prepared