How to create Class Component in React?

JavaScript syntax extension permits HTML-like code within JavaScript files, commonly used in React for defining component structure. It simplifies DOM element manipulation by closely resembling HTML syntax. JSX facilitates the creation of reusable UI building blocks, defined as JavaScript functions or classes in React.

Prerequisites:

• Node or NPM
• React
• JSX

Steps to Create React Application And Installing Module:

Step 1: Create a React application using the following command:

npx create-react-app foldername

Step 2: After creating your project folder i.e. foldername, move to it using the following command:

cd foldername

Step 3: After setting up React environment on your system, we can start by creating an App.js file and create a directory by the name of components in which we will write our desired function.

Project Structure:

The updated dependencies in package.json file will look like.

"dependencies": {
    "react": "^18.2.0",
    "react-dom": "^18.2.0",
    "react-scripts": "5.0.1",
    "web-vitals": "^2.1.4",
}

Example 1: In this example, we will demonstrate how to add a class component in our application.

Javascript

//App.js
import GeeksforGeeks
    from "./components/geeksforgeeks";
import "./styles.css";

export default function App() {
    return (
        <div className="App">
            {
                /* Creating custom JSX tag
                to return the component */
            }
            <GeeksforGeeks />
        </div>
    );
}

Javascript

//GeeksforGeeks.js
import React from "react";

/* This is the class component that will be
added to the application */
class GeeksforGeeks
    extends React.Component {
    render() {
        return (
            <div>
                <h2>GeeksforGeeks</h2>
                <p>
                    A computer science
                    portal for GeeksforGeeks
                </p>
            </div>
        );
    }
}

export default GeeksforGeeks;

Step to run the app:

npm start

Output:

Example 2: In this example, we will demonstrate how to add a class component in our application with a custom input by changing the contents of the header in the App.js file.

Javascript

//App.js
import GeeksforGeeks
    from "./components/geeksforgeeks";
import "./styles.css";

export default function App() {
    return (
        <div className="App">
            {
                /* Creating custom JSX
                tags with different inputs */
            }
            <GeeksforGeeks data="GeeksforGeeks" />
            <GeeksforGeeks data="A computer science portal" />
            <GeeksforGeeks data="for geeks" />
        </div>
    );
}

Javascript

//GeeksforGeeks.js
import React from "react";

/* This is the class component that will be
added to the application with custom inputs */
class GeeksforGeeks
    extends React.Component {
    render() {
        return (
            <div>
                <p>{this.props.data}</p>
            </div>
        );
    }
}

export default GeeksforGeeks;

Step to run the app:

npm start

Output: