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

Components are the building blocks of React applications, encapsulating UI logic and presentation into reusable, independent pieces.

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

Functional components are simpler JavaScript functions. With hooks, they have the same capabilities as class components, which is why they are now preferred.

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

Props (properties) flow down from parent to child components, allowing parents to pass data and callbacks to customize child behavior.

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

JSX combines HTML-like syntax with JavaScript, making it easy to write UI code that describes what the rendered output should look like.

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

React keeps a virtual copy of the DOM in memory. When state changes, it compares the virtual DOM to the real DOM and updates only what changed (reconciliation).

React Practice Test

React Practice Test

React Components