React Js Array findIndex() Method

<!DOCTYPE html>
<html>

<body>
    <div id="app"></div>
    <script type="text/babel">
        const { useState } = React;

function App() {
            const myArray = [10, 20, 30, 40, 50];
            const [index, setIndex] = useState(null);

const findIndex = () => {
                // Finding the index of the first element greater than 30
                const foundIndex = myArray.findIndex(element => element > 30);
                setIndex(foundIndex);
            };

return (
                <div className='container'>
                    <h3>React js Array findIndex() Method</h3>
                    <p className="array">Array: {myArray.join(', ')}</p>
                    <button onClick={findIndex}>Find Index</button>
                    {index !== null && (
                        <p className={index !== -1 ? 'yes' : 'no'}>
                            Index: {index !== -1 ? index : 'Not found'}
                        </p>
                    )}
                </div>
            );
        }

ReactDOM.render(<App />, document.getElementById('app'));
    </script>
    <style>
        .container {
            width: 400px;
            margin: 0 auto;
            box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.12), 0 2px 4px 0 rgba(0, 0, 0, 0.24);
            padding: 20px;
        }

.title {
            color: #333;
            font-size: 24px;
            margin-bottom: 10px;
        }

.array {
            color: #666;
            font-size: 16px;
            margin-bottom: 5px;
            font-weight: bold;
        }

.yes {
            color: green;
        }

.no {
            color: red;
        }
    </style>
</body>

</html>