React Beginner Quiz
JSX, props, state and events — the basics, checked by reading real components rather than reciting definitions.
Start the quizSample questions from this quiz
A preview of the style and depth. Try each one, then reveal the answer — or skip straight to the timed quiz.
1. What renders?
function Greeting() {
const name = 'Sam'
return <h1>Hello, {name}!</h1>
}- An error
- Hello, {name}!
- Hello, !
- Hello, Sam!
Show answer
Answer: Hello, Sam!. Curly braces embed a JavaScript expression in JSX, so `{name}` is evaluated rather than printed literally. Anything that produces a value works there — a variable, a function call, a ternary — but statements like `if` do not.
2. This fails to compile. Which line is wrong?
1 function Card() {
2 return (
3 <h2>Title</h2>
4 <p>Body</p>
5 )
6 }- Line 2 — the parentheses are invalid
- Lines 3-4 — a component must return a single root element
- Line 4 — <p> cannot follow <h2>
- Line 1 — the component needs props
Show answer
Answer: Lines 3-4 — a component must return a single root element. JSX compiles to a single expression, so sibling elements need a wrapper. Use a `<div>`, or a Fragment (`<>...</>`) when you do not want an extra DOM node — inside a table or a flex container an extra div would break the layout.
3. What does the child render?
function App() {
return <Hello name="Ali" age={30} />
}
function Hello({ name, age }) {
return <p>{name} is {age}</p>
}- Ali is 30
- name is age
- Ali is {30}
- An error — props must be strings
Show answer
Answer: Ali is 30. Props pass data from parent to child. Strings use quotes; anything else — numbers, booleans, arrays, functions — goes in braces. Destructuring in the parameter list is the usual way to read them.
Frequently asked questions
How many questions are in this React quiz?+
30 questions, with a 30-minute time limit. Every question includes a written explanation of the correct answer.
Is this React quiz free?+
Yes. Every quiz on CodexQuizz is free and needs no account. You only enter a name if you choose to post your score to the leaderboard.
What level is the beginner quiz aimed at?+
JSX, props, state and events — the basics, checked by reading real components rather than reciting definitions.
Can I use this to prepare for a React interview?+
Yes. The questions cover the topics that come up in React technical screens, and the explanations are written so that a wrong answer still teaches you the underlying concept.
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