吐槽/反馈/建议：    

WebSocket.Server is not a constructor

遇到上边错误，直接照着 cjs 写法改成 mjs 形式，但是用不了；

import WebSocket from "ws"
console.log(typeof WebSocket)
console.log(typeof WebSocket.Server)
// function
// undefined

用报错的「WebSocket.Server is not a constructor」作为关键词并没能找到原因；

直到我换了个姿势，直接搜索「import WebSocket from 'ws'」，得到的代码是下边这样子的：

import WebSocket, { WebSocketServer } from 'ws';
console.log(typeof WebSocket)
console.log(typeof WebSocketServer)
// function
// function

然后我去看了 ws 这个库的导出文件；

// cjs
'use strict';

const WebSocket = require('./lib/websocket');

WebSocket.createWebSocketStream = require('./lib/stream');
WebSocket.Server = require('./lib/websocket-server');
WebSocket.Receiver = require('./lib/receiver');
WebSocket.Sender = require('./lib/sender');

WebSocket.WebSocket = WebSocket;
WebSocket.WebSocketServer = WebSocket.Server;

module.exports = WebSocket;

// mjs
import createWebSocketStream from './lib/stream.js';
import Receiver from './lib/receiver.js';
import Sender from './lib/sender.js';
import WebSocket from './lib/websocket.js';
import WebSocketServer from './lib/websocket-server.js';

export { createWebSocketStream, Receiver, Sender, WebSocket, WebSocketServer };
export default WebSocket;

差别不只是有点儿大好么 Orz；