React Js Get Element by ClassName

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8" />
</head>
<body>
    <div id="app"></div>
    <script src="https://unpkg.com/react@17.0.2/umd/react.development.js"></script>
    <script src="https://unpkg.com/react-dom@17.0.2/umd/react-dom.development.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/babel-standalone/6.26.0/babel.min.js"></script>

function App() {
            useEffect(() => {
                const elements = document.querySelectorAll('.my-class');
                elements.forEach((element) => {
                    element.style.color = 'green';
                    // Do something with each element
                    console.log(element);
                });
            }, []);

return (
                <div className='container'>
                    <h3>React Js Get Element by Class Name</h3>
                    <div className="my-class">Element 1</div>
                    <div className="my-class">Element 2</div>
                    <div className="my-class">Element 3</div>
                </div>
            );
        }

ReactDOM.render(<App />, document.getElementById("app"));
    </script>

.container {
            margin: 0 auto;
            width: 500px;
            text-align: center;
            box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.12), 0 2px 4px 0 rgba(0, 0, 0, 0.24);
            padding: 20px;
        }
    </style>
</body>

</html>

 
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8" />
</head>
<body>
    <div id="app"></div>
    <script src="https://unpkg.com/react@17.0.2/umd/react.development.js"></script>
    <script src="https://unpkg.com/react-dom@17.0.2/umd/react-dom.development.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/babel-standalone/6.26.0/babel.min.js"></script>
​
    <script type="text/babel">
        const { useState, useEffect } = React;
​
        function App() {
            useEffect(() => {
                const elements = document.querySelectorAll('.my-class');
                elements.forEach((element) => {
                    element.style.color = 'green';
                    // Do something with each element
                    console.log(element);
                });
            }, []);
​
            return (
                <div className='container'>
                    <h3>React Js Get Element by Class Name</h3>
                    <div className="my-class">Element 1</div>
                    <div className="my-class">Element 2</div>
                    <div className="my-class">Element 3</div>
                </div>
            );
        }
​
        ReactDOM.render(<App />, document.getElementById("app"));
    </script>
​
    <style>
        * {
            box-sizing: border-box;
        }
​
        .container {
            margin: 0 auto;
            width: 500px;
            text-align: center;
            box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.12), 0 2px 4px 0 rgba(0, 0, 0, 0.24);
            padding: 20px;
        }
    </style>
</body>
​
</html>