A websocket based multiroom chat with node.js.

websocket.ts

import WebSocket from 'ws'
import mongodb, { ObjectID } from 'mongodb'
import * as querystring from 'querystring'
import {v4 as uuid} from 'uuid'

//Connect to ws://127.0.0.1:8081/thread?name=yourGroupname
//to test the server

interface WsSessionGroup{
  id?: ObjectID
  name?:string
  wsSessions: WebSocket[]
  //Or use a map with uuid
  //wsSessions:Record<string,WebSocket>
}
class WsHub{
  wsSessionGroupMap: Record<string, WsSessionGroup> = {}
  //wsSessionGroupMap:Map<string,WsSessionGroup> = new Map
  addSession(groupName:string,session:WebSocket) {
    if (this.wsSessionGroupMap[groupName]==undefined){
      const sessionGroup = new ThreadSessionGroup
      sessionGroup.name = groupName
      sessionGroup.wsSessions.push(session)
      this.wsSessionGroupMap[groupName] = sessionGroup
      //If you wanna use uuid map
      // const uid = uuid()
      // this.wsSessionGroupMap[groupName].wsSessions[uid]=session
      console.log(`New group "${groupName}" created`)
    }
    else {
      this.wsSessionGroupMap[groupName].wsSessions.push(session)
      console.log(`Old group "${groupName}" connected`)
    }
  }
  deleteSession(groupName:string,session:WebSocket) {
    const sessionList = this.wsSessionGroupMap[groupName].wsSessions
    sessionList.splice(sessionList.indexOf(session), 1)
    console.log(`A member from group "${groupName}" disconnected`)
    if (sessionList.length == 0) {
      delete this.wsSessionGroupMap[groupName]
      console.log(`Delete empty group "${groupName}"`)
    }
  }
  broadcastGroup(groupName:string, message: WebSocket.Data):void {
    const targetGroup = this.wsSessionGroupMap[groupName]
    targetGroup?.wsSessions.forEach((session) => {
      if (session.readyState === WebSocket.OPEN) {
        session.send(message)
      }
    })
    console.log(`"${message}" from "${groupName}"`)
  }
}
class ThreadSessionGroup implements WsSessionGroup{
  id?: ObjectID
  name?:string
  wsSessions: WebSocket[] =[]
}

const threadHub = new WsHub
const threadWs = new WebSocket.Server({
  port: 8081,
  path: "/thread",
})

threadWs.on('connection', (socket, req) => {
  const reParam=req.url?.match(/(?<=\?).+/)
  const urlParam = querystring.decode(reParam![0])
  const sessionNameInURL = urlParam.name?.toString()!
  if ('name' in urlParam) {
    threadHub.addSession(sessionNameInURL,socket)
  }
  else {
    socket.close(4001,"Params aren't correct. ")
  }
  socket.on('message', (message) => {
    threadHub.broadcastGroup(sessionNameInURL,message)
  })
  socket.on('close', () => {
    threadHub.deleteSession(sessionNameInURL, socket)
  })
})