React Interview Questions

Q:- What is React.js?

React js is an open-source JavaScript library created by Facebook for building complex and interactive UI in web and mobile applications.

Q:- What are the features of React.js?

Major features of React are listed below:

1. Virtual DOM: It uses the Virtual DOM instead of the real DOM.
2. Server-Side Rendering: It uses Server-side rendering (SSR).
3. Uni-Directional: It follows Uni-directional data flow or data binding.
4. Components: It uses reusable UI components.

Q:- How to Install React.js using Create React App?

Step-1: First, install react app creator.

For Windows:

npm install -g create-react-app

For Linux and Mac:

sudo npm install -g create-react-app

Step-2: Now, create a your project using react app.

create-react-app myFirstReactProject

Step-3: Now, go to the project folder & start the your app/project.

cd myFirstReactProject
npm start

Q:- What are props in React?

props are immutable passed into react components.

Q:- What is state in React?

State of a component is an object that holds some information that may change over the lifetime of the component.

Changing the state Object:

use this.setState() method to change the state.
Whenever you will change the state, the component will be re-render.

Important Tips:

Never use this.setState() method inside the render.
If you will use this.setState() inside componentWillUnmount(), component will not be re-render.

Q:- What are Components?

Components let you split the UI into independent, reusable pieces, and think about each piece in isolation.

There are mainly two types of Components:

1. Functional Component (Stateless Component) - Only props, no state
2. Class Component (Stateful Component) - Both props and state.

Q:- What is Reconciliation?

Reconciliation is the process through which React updates the DOM.

Read the Complete Article React.js Interview Questions & Answers