Top React Interview Questions Every Fresher Should Know

Top React Interview Questions Every Fresher Should Know

Freshers face predictable React interview questions. Here are the top ones with clear answers.

What is React?

React is a JavaScript library for building user interfaces by describing them as a function of state. It updates the UI efficiently when state changes.

What is JSX?

JSX is a syntax extension for JavaScript that compiles to React.createElement calls. It looks like HTML but is JavaScript, with differences like className.

What is the difference between props and state?

Props are inputs from a parent, read-only in the child. State is internal data the component owns and can change, triggering re-renders.

What is a component?

A component is a reusable, independent piece of UI, usually a function that returns JSX. Components compose to build full UIs.

What are hooks?

Hooks are functions that let functional components use state and effects. useState and useEffect are the most common. They replaced class components for new code.

What does useEffect do?

useEffect runs side effects after render, like fetching and subscriptions. The dependency array controls when it runs.

What is the virtual DOM?

The virtual DOM is React's in-memory description of the UI. React compares the new description to the previous one and updates the real DOM only where they differ, a process called reconciliation.

The Takeaway

Know these fresher questions cold: what React is, JSX, props vs state, components, hooks, useEffect, and the virtual DOM. They form the foundation interviewers test for freshers, and answering them well sets up the rest of the interview.