connection.closed 不是函数 SignalR

Question

我对SignalR. 显然，有什么称呼它如一些争论onClosed()，closed()等等。

在SignalR客户端的侦听器中，我正在尝试实现此事件，但不断收到错误消息，指出它不是函数。我试过onClosed()和closed()。同样的错误。如何检测客户端的关闭事件？

const signalRListener = () => {

   connection.on('new_message', message => {

      // Handle incoming message.
      // This is working fine.
   })

   connection.closed(e => {

       // Try to restart connection but I never get here to due error I'm receiving
   })

}

我究竟做错了什么？

这是我开始连接的方式：

export const signalRStart = (token) => {

    connection = new signalR.HubConnectionBuilder()
        .withUrl("/chat?access_token=" + token)
        .configureLogging(signalR.LogLevel.Information)
        .build();

    // Set connection time out
    connection.serverTimeoutInMilliseconds = 30000;

    // Start connection
    connection.start();

    // Invoke listener
    signalRListener();
}

Answer 1

作为最佳实践，请connection.start在connection.on收到任何消息之前调用，以便您的处理程序注册。

export const signalRStart = (token) => {

    const connection = new signalR.HubConnectionBuilder()
        .withUrl("/chat?access_token=" + token)
        .configureLogging(signalR.LogLevel.Information)
        .build();

    // Set connection time out
    connection.serverTimeoutInMilliseconds = 30000;

    //register listeners

    //Registers a handler that will be invoked when the hub method with the specified method name is invoked.
    connection.on('new_message', message => {    
        // Handle incoming message.
        // This is working fine.
    });

    //Registers a handler that will be invoked when the connection is closed.
    connection.onclose(e => {
        // ...
    });

    // Start connection
    connection.start();

};

参考ASP.NET Core SignalR JavaScript 客户端

参考SignalR JavaScript API - HubConnection 类