React interview questions

React Introduction is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem react introduction solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

function LessonList() {
  const topics = ["React Introduction", "practice", "quiz"];
  return <ul>{topics.map((item) => <li key={item}>{item}</li>)}</ul>;
}

JSX is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem jsx solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Components is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem components solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Props is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem props solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

function StatCard({ label, value }) {
  return <section><strong>{value}</strong><span>{label}</span></section>;
}

export default function Dashboard() {
  return <StatCard label="Paid orders" value={24} />;
}

State is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem state solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Events is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem events solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Lists is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem lists solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

function LessonList() {
  const topics = ["Lists", "practice", "quiz"];
  return <ul>{topics.map((item) => <li key={item}>{item}</li>)}</ul>;
}

Conditional Rendering is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem conditional rendering solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Forms is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem forms solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

useEffect is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem useeffect solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

import { useEffect, useState } from "react";

export function OrdersPanel() {
  const [orders, setOrders] = useState([]);
  useEffect(() => { fetch("/api/orders").then((res) => res.json()).then(setOrders); }, []);
  return <p>{orders.length} orders loaded</p>;
}

useRef is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem useref solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Custom Hooks is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem custom hooks solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Context API is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem context api solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

import { useEffect, useState } from "react";

export function OrdersPanel() {
  const [orders, setOrders] = useState([]);
  useEffect(() => { fetch("/api/orders").then((res) => res.json()).then(setOrders); }, []);
  return <p>{orders.length} orders loaded</p>;
}

Routing is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem routing solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Performance Optimization is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem performance optimization solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Memoization is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem memoization solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

function LessonList() {
  const topics = ["Memoization", "practice", "quiz"];
  return <ul>{topics.map((item) => <li key={item}>{item}</li>)}</ul>;
}

API Calls is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem api calls solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Error Boundaries is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem error boundaries solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

React Query is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem react query solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

function LessonList() {
  const topics = ["React Query", "practice", "quiz"];
  return <ul>{topics.map((item) => <li key={item}>{item}</li>)}</ul>;
}

Authentication UI is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem authentication ui solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Dashboard Project is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem dashboard project solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Composition is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem composition solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

function LessonList() {
  const topics = ["Composition", "practice", "quiz"];
  return <ul>{topics.map((item) => <li key={item}>{item}</li>)}</ul>;
}

Children Props is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem children props solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Controlled Inputs is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem controlled inputs solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Reducer Pattern is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem reducer pattern solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

function LessonList() {
  const topics = ["Reducer Pattern", "practice", "quiz"];
  return <ul>{topics.map((item) => <li key={item}>{item}</li>)}</ul>;
}

Accessibility is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem accessibility solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Testing Basics is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem testing basics solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

Deployment is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem deployment solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

function LessonList() {
  const topics = ["Deployment", "practice", "quiz"];
  return <ul>{topics.map((item) => <li key={item}>{item}</li>)}</ul>;
}

TypeScript with React is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem typescript with react solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.

React Review is best explained with its purpose, a small example, and one common mistake.

Start by naming the problem react review solves in React. Then show a short example, discuss the tradeoff, and mention how you would test it in a real codebase.