需要将socket.io类更改为单例

使socket.io成为单例的最佳方法是什么？这里我有三个文件，我需要在user.mjs

socket.mjs

class socketBusiness extends baseBusiness {
  //io = null;
  //connectedUsers = {}
  constructor(io) {
    super(io);
    this.io = io;
    this.connectedUsers = {};
    this.addUserRef= {}; 
    this.bindEvents();
  }

  unBindEvents() {
    this.io.off("connection", this.onConnection);
  }

  onConnection(socket) {
    let _io = this.io;
    let socketId = socket.id;
    let transport = socket.conn.transport.name;
    let address = socket.handshake.address;

    logHelper.logInfo(
      `a user connected with transport: ${transport}, ip: ${address}`
    );

    //socket.broadcast.emit('hi');

    socket.on("disconnect", reason => {
    });

    socket.on("chat message", function(msg) {
    });
  }
 addUserRef(userId, cstId) {

      let arr = this.addUserRef[cstId] || [];
      if (arr.indexOf(cstId) < 0) {
        arr.push(cstId);
      }
      this.addUserRef[userId] = arr; 
  }
}
export default socketBusiness;

user.mjs

const socket = require("socket.mjs)
export async function addCst(req, res) {
socket.addUserRef(req.id,req.cstId)
}

我如何访问socket.io方法？任何帮助将不胜感激

www.mjs

import socket from '../socket.mjs';


var server = createServer(app);
var io = new SocketServer(server, {})
var sb = new socketBusiness(io);

导出实例：

 export default new socketBusiness;