React Components

Question 1

What is a React component?

Accepted Answer

A reusable piece of UI that can accept inputs (props) and return JSX describing what should appear on screen

Answer

A CSS class

Answer

A database table

Answer

A server endpoint

Question 2

What is the difference between a functional and class component?

Accepted Answer

Functional components are functions that return JSX; class components extend React.Component with a render method

Answer

There is no difference

Answer

Functional components cannot have state

Answer

Class components are faster

Question 3

What are props in React?

Accepted Answer

Read-only inputs passed from parent to child components to configure their behavior and display

Answer

CSS properties

Answer

Mutable state values

Answer

API endpoints

Question 4

What is JSX?

Accepted Answer

A syntax extension that looks like HTML but is actually JavaScript, used to describe UI structure in React

Answer

A JavaScript library

Answer

A CSS framework

Answer

A testing tool

Question 5

What is the virtual DOM?

Accepted Answer

A lightweight JavaScript representation of the real DOM that React uses to efficiently determine what needs to change

Answer

A real DOM in a virtual machine

Answer

A hidden webpage

Answer

A testing environment

Question 6

What is component composition in React?

Accepted Answer

Building complex UIs by combining simpler components together, passing children and props

Answer

Mixing chemicals

Answer

Writing CSS

Answer

Compiling code