Javascript 消息上的 iisnode WebSocket.接收到的数据是二进制消息而不是字符串

我已经使用WS模块创建了一个iisnode WebSocket服务器. 我遇到的问题是，尽管客户端将字符串数据发送到服务器，但服务器以二进制消息的形式接收数据.

客户端JS

var socket; 
window.addEventListener('load', function(){ 
    socket = new WebSocket('wss://server/ws/');
    
    socket.addEventListener('open', function (event) {
        console.log('Hello Server!');
        socket.send('Hello Server!');
    });
    
    socket.addEventListener('message', function (event) {
        console.log('Message from server : ', event.data);
    });
    
    socket.onerror = function(event){
        console.log('Error : ', event);
    }; 
    
    socket.onclose = function(event){
        console.log('Close : ', event);
    }; 
}); 

服务器端JS

var express     = require("express"); 
var app         = express(); 
var WebSocket   = require("ws"); 

var server = app.listen(process.env.PORT, function(){
    console.log("listening");
});

var wss = new WebSocket.Server({"server":server}); 
wss.on("connection", function(user){ 
    user.send("connected"); 
    user.on("message", function(message){ 
        wss.clients.forEach(function(client){ 
            if(client.readyState===WebSocket.OPEN){ 
                client.send(typeof(message)); 
                client.send(message); 
            }; 
        }); 
    }); 
}); 

app.get("/ws/", function(req, res) {
    res.send("WebSocket");
});

Web.cofig

<?xml version="1.0" encoding="UTF-8"?>
<configuration> 
    <system.webServer>
        <handlers>
            <add name="iisnode" path="node_app.js" verb="*" modules="iisnode" />
        </handlers>
        <rewrite>
            <rules>
                <rule name="ws" patternSyntax="ECMAScript" stopProcessing="true">
                    <match url="^ws/?$" />
                    <action type="Rewrite" url="\ws\node_app.js" />
                </rule>
            </rules>
        </rewrite>
        <webSocket enabled="false" />
    </system.webServer> 
</configuration>

当我运行代码时，我得到的数据是:

| ↑↓       | Data           | Value                                                            |
| -------- | -------------- | ---------------------------------------------------------------- |
| ↑        | Hello Server!  | Hello Server!                                                    |
| ↓        | connected      | connected                                                        |
| ↓        | object         | object                                                           |
| ↓        | Binary Message | 00000000: 4865 6c6c 6f20 5365 7276 6572 21         Hello Server! |

从我在网上看到的一切来看，我在服务器端收到的数据应该是一个AS字符串"Hello Server！"所以我不确定为什么数据服务器端是对象？