index.html

<!DOCTYPE html>
<html>
<head>
    <title>SSE Example</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            text-align: center;
            margin-top: 50px;
        }

        button {
            padding: 10px 20px;
            font-size: 16px;
            background-color: #007BFF;
            color: #FFF;
            border: none;
            cursor: pointer;
            transition: background-color 0.3s;
        }

        button:hover {
            background-color: #0056b3;
        }

        #output {
            margin-top: 20px;
            font-size: 18px;
        }
    </style>
    <script>
        const eventSource = new EventSource('/events');

        eventSource.onmessage = (event) => {
            const output = document.getElementById('output');
            const eventData = event.data;
            output.innerHTML = 'Received: ' + eventData;
        };

        function sendEvent() {
            fetch('/send-event', { method: 'POST' });
        }
    </script>
</head>
<body>
    <button onclick="sendEvent()">Send Event</button>
    <div id="output"></div>
</body>
</html>