OnInitializedAsync

index.razor

protected override async Task OnInitializedAsync()
{
    hubConnection = new HubConnectionBuilder()
        .WithUrl(NavigationManager.ToAbsoluteUri("/clienthub"))
        .Build();

    hubConnection.On<string, string, string>("ReceiveMessage", (connectionId, x, y) =>
    {
        JSRuntime.InvokeVoidAsync("nextjs.updateCursor", connectionId, x, y);
        StateHasChanged();
    });

    hubConnection.On<string, int>("UserConnected", (connectionId, connectedUserIdsCount) =>
    {
        connectedUsersCount = connectedUserIdsCount;
        JSRuntime.InvokeVoidAsync("nextjs.onUserConnected", connectionId);

        StateHasChanged();
    });

    hubConnection.On<string, int>("UserDisconnected", (connectionId, connectedUserIdsCount) =>
    {
        connectedUsersCount = connectedUserIdsCount;
        JSRuntime.InvokeVoidAsync("nextjs.onUserDisconnected", connectionId);

        StateHasChanged();
    });

    hubConnection.On<List<string>>("LoadAllConnectedUsers", (connectedUserIds) =>
    {
        connectedUsersCount = connectedUserIds.Count;
        JSRuntime.InvokeVoidAsync("nextjs.loadAllConnectedUsers", connectedUserIds);

        StateHasChanged();
    });

    func = new Func<Cursor, Task>((cursor) => SendMouseEvents(cursor));

    await hubConnection.StartAsync();

    await JSRuntime.InvokeVoidAsync("nextjs.addMouseEventListener");
}