何时使用来自浏览器的SignalR关闭连接

我正在与SignalR 2.0进行一些聊天应用程序(就像每个人一样).

我有一个win8.1应用程序,当应用程序关闭时,集线器接收OnDisconnected事件并从集线器上的列表中删除用户.集线器向每个客户端发送用户已离开聊天的内容,因此我们可以看到用户已离开.

但是当我在网页中使用SignalR和Javascript并且页面关闭时,集线器不会收到选项卡/浏览器关闭的通知...

任何人都知道如何关闭连接？

我编码的内容:

启动中心

[assembly: OwinStartup(typeof(ChatServer.Startup))]

namespace ChatServer
{
public class Startup
{
    public void Configuration(IAppBuilder app)
    {
        // Map all hubs to "/signalr"
        app.MapSignalR();
    }
}
}

毂

[HubName("ChatHub")]
public class ChatHub : Hub
{
    private static List Users = new List();
    public void Send(string name, string message)
    {
        // Call the broadcastMessage method to update clients.
        Clients.All.broadcastMessage(name, message, DateTime.Now);
    }

    public void UserConnected(string name)
    {
        Clients.Caller.connected(JsonConvert.SerializeObject(Users));
        User user = new User() { Name = name, ConnectionID = Context.ConnectionId };
        Clients.Others.userConnected(JsonConvert.SerializeObject(user));
        Users.Add(user);
    }

    public void UserLeft()
    {
        if(Users.Any(x=>x.ConnectionID == Context.ConnectionId))
        {
            User user = Users.First(x => x.ConnectionID == Context.ConnectionId);
            Users.Remove(user);
            Clients.Others.userLeft(JsonConvert.SerializeObject(user), Context.ConnectionId);
        }
    }

    public override System.Threading.Tasks.Task OnDisconnected()
    {
        // Only called when win8.1 app closes
        // Not called when browsers closes page
        UserLeft();
        return base.OnDisconnected();
    }
}

HTML - Javascript:

使用Javascript:

chat = new function () {

var ChatHub;
// Connecting to the hub
this.attachEvents = function () {
    if ($.connection != null) {
        ChatHub = $.connection.ChatHub;
       $.connection.hub.start({ transport: 'auto' }, function () {
            // Register client on hub
            ChatHub.server.userConnected("web name");
        });
    }

    this.send = function (name,message) {
        if ($.connection != null) {
                //Send chat message
                ChatHub.server.send(name, message).fail(function (e) {
                    alert(e);
                });
        }
    }
  }
};

 window.onbeforeunload = function (e) {
    //This is called when we close the page
    $.connection.hub.stop();
    return "You killed me! :'(";
};

Win8.1客户端

    internal async void ConnectToHub(string userName)
    {
        try
        {
            HubConnection hubConnection = new HubConnection(SERVER_PROXY);
            chat = hubConnection.CreateHubProxy("ChatHub");
            Context = SynchronizationContext.Current;

            MakeHubFunctionsAvailableOnClient();

            await hubConnection.Start();
            // Register client on hub
            await chat.Invoke("UserConnected", userName);
        }
        catch (Exception)
        {
            throw;
        }
    }

    private void MakeHubFunctionsAvailableOnClient()
    {
        //Receive chat messages
        chat.On("broadcastMessage",
                (name, message, date) => Context.Post(
                    delegate {
                        Messages.Add(new UserMessage() { Message = message, User = name, Date = date }); 
                    }, null
                )
        );

        //Receive all online users
        chat.On("connected",
                (users) => Context.Post(
                    delegate
                    {
                        List userList = JsonConvert.DeserializeObject>(users);
                        foreach (User user in userList)
                        {
                            Users.Add(user);
                        }
                        Messages.Add(new UserMessage() { Message = "CONNECTED", User = "System", Date = DateTime.Now }); 
                    }, null
                )
        );

        //New user connected
        chat.On("userConnected",
                (user) => Context.Post(
                    delegate
                    {
                        User newUser = JsonConvert.DeserializeObject(user);
                        Users.Add(newUser);
                        Messages.Add(new UserMessage() { Message = newUser.Name + " CONNECTED", User = "System", Date = DateTime.Now }); 
                    }, null
                )
        );

        //User left, remove user from list on client
        chat.On("userLeft",
                (user) => Context.Post(
                    delegate
                    {
                        User newUser = JsonConvert.DeserializeObject(user);
                        User y = Users.First(x=>x.ConnectionID == newUser.ConnectionID);
                        bool ux  = Users.Remove(y);
                        Messages.Add(new UserMessage() { Message = newUser.Name + " left the conversation", User = "System", Date = DateTime.Now });
                    }, null
                )
        );
    }

当我关闭标签/浏览器/导航到其他网站时,我的集线器不会触发OnDisconnected该网站是一个单页网站(暂时)

我用的是什么浏览器？
Chrome:版本32.0.1700.68 beta-m
Internet Explorer 11