client.html

<script type="text/javascript" src="https://cdn.jsdelivr.net/npm/@aspnet/signalr@1.1.0/dist/browser/signalr.min.js"></script>
<script type="text/javascript">
    document.addEventListener('DOMContentLoaded', function () {
        var connection = new signalR.HubConnectionBuilder()
            .withUrl('https://func.azurewebsites.net/api')
            .configureLogging(signalR.LogLevel.Information)
            .build();
        // Create a function that the hub can call to broadcast messages.
        connection.on('newFirstLetterData', (name, message) => {
            $("#reportOutput").append(`<div class="entry">${JSON.stringify(message)}</div>`);
        });
        connection.start()
            .then(() => {
                alert("connected");
            })
            .catch((error) => {
                alert("connection failed");
            });
    });
</script>