ReactJS className Attribute

React.js library is all about splitting the app into several components. Each Component has its own lifecycle. React provides us some in-built methods that we can override at particular stages in the life-cycle of the component.

In class-based components, the className attribute is used to set or return the value of an element’s class attribute. Using this property, the user can change the class of an element to the desired class.

Creating 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
```

Project Structure: It will look like the following.

Example: Now write down the following code in the App.js file. Here, App is our default component where we have written our code.

App.js

import React from 'react'; 

// Defining our App Component 
const App = () => { 

  // Function to get element by its className 

  function getClassNameAttribute() { 

    var element = document.getElementsByClassName('gfg'); 

    // Printing the element 

    console.log(element) 

  } 

  // Returning our JSX code 

  return <> 

    <div> 

      <h1>GeeksforGeeks</h1> 

      <div 

        className='gfg'> 

          ReactJS className Attribute 

      </div> 

      <button onClick={getClassNameAttribute}> 

          click 

      </button> 

    </div> 

  </>; 
} 

// Exporting your Default App Component 

export default App