Beginner React Questions

Definition

A collection of the most common entry-level React interview questions.

Explain Like I'm New

These questions test if you actually know what React is, how it differs from vanilla JavaScript, and if you understand the absolute basics of JSX, state, and props.

Real World Example

If you are applying for a Junior React Developer role, expect 80% of your technical questions to come from this list.

Common Use Cases

•Junior Developer Interviews
•Basic technical screening

Interactive Example

// Typical beginner question: "Write a simple Counter component"
import { useState } from 'react';

export default function Counter() {
  const [count, setCount] = useState(0);
  return (
    <button onClick={() => setCount(c => c + 1)}>
      Count: {count}
    </button>
  );
}

Interview Questions

basic

What is React and why did you choose it over Angular or Vue?

intermediate

What is the Virtual DOM and how does it work?

advanced

What is JSX and how does the browser read it?

Flash Cards

Question

What is React?

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Answer

React is an open-source JavaScript library developed by Facebook for building user interfaces. It is declarative, component-based, and uses a Virtual DOM to optimize rendering performance.

Question

What is the Virtual DOM?

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Answer

The Virtual DOM is a lightweight JavaScript object representation of the real DOM. When state changes, React updates the Virtual DOM, compares it to the previous version (Diffing), and calculates the minimum number of changes needed to update the real DOM (Reconciliation).

Question

What is JSX?

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Answer

JSX stands for JavaScript XML. It is a syntax extension for React that allows you to write HTML-like code inside JavaScript files. Browsers cannot read JSX, so it must be compiled into standard `React.createElement` calls using a tool like Babel.