React Days Between Two Dates

<!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() {
            const [daysRemaining, setDaysRemaining] = useState(null);

useEffect(() => {
                const calculateDaysRemaining = () => {
                    const currentDate = new Date();
                    const examDate = new Date('2025-09-15'); // Replace with your desired exam date
                    const timeDifference = Math.abs(examDate - currentDate);
                    const daysRemaining = Math.ceil(timeDifference / (1000 * 60 * 60 * 24));
                    setDaysRemaining(daysRemaining);
                };

calculateDaysRemaining();
            }, []);

return (
                <div class="container">
                    <h2>React Js Calculate days between two dates</h2>
                    {daysRemaining && <p>Days remaining until Exam Date: {daysRemaining}</p>}
                </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;
        }

.container h2 {
            font-size: 24px;
            font-weight: bold;
            margin-bottom: 10px;
        }

.container p {
            font-size: 18px;
            margin-top: 0;
        }

.container p:first-child {
            margin-top: 10px;
        }
    </style>
</body>

</html>