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ReactJS className Attribute

  • Last Updated : 25 May, 2021
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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

Step to Run Application: Run the application using the following command from the root directory of the project:

npm start

Output: Now open your browser and go to http://localhost:3000/, you will see the following output:

Reference:https://reactjs.org/docs/dom-elements.html#classname

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