jquery 浮动遮罩

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>jQuery 浮动遮罩</title>
    <style>
        #overlay {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0, 0, 0, 0.5);
            z-index: 999;
        }
    </style>
</head>
<body>
    <button id="showOverlay">显示遮罩</button>
    <div id="overlay"></div>

    <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
    <script>
        $(document).ready(function() {
            $('#showOverlay').click(function() {
                $('#overlay').fadeIn();
            });

            $('#overlay').click(function() {
                $(this).fadeOut();
            });
        });
    </script>
</body>
</html>