为什么Client方法在siganlR中调用了4次？

Question

我是signalR核心的初学者，我正在尝试学习它。我逐步遵循了video，除了 Client方法在siganlR中调用了4次之外，其他所有工作都正常吗？

结果：

枢纽：

using Microsoft.AspNetCore.SignalR;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace signalR
{
    public class Chat:Hub
    {
        public async  Task SendMessage(string user,string message)
        {
            await Clients.All.SendAsync("ForwardToClients", user,message);
        }
    }
}

Javascript：

var connection = new signalR.HubConnectionBuilder().withUrl("/chat").configureLogging(signalR.LogLevel.Information).build();
connection.on("ForwardToClients", (user, message) => {
    const encoding = user + "Says:" + message;
    const li = document.createElement("li");
    li.textContent = encoding;
    document.getElementById("messagesList").appendChild(li);
});

connection.start().catch(er => console.log(er.toString()));
document.getElementById("sendMessage").addEventListener("click", event => {
    const user = document.getElementById("userInput").value;
    const message = document.getElementById("messageInput").value;
    connection.invoke("SendMessage", user, message).catch(er => console.log(er.toString()));    
});

请问有人可以帮我吗？ ！