let app = require('express')();let http = require('http').Server(app);let io = require('socket.io')(http);io.on('connection', (socket) => { console.log('user connected');  socket.on('disconnect', function(){  console.log('user disconnected'); });  socket.on('add-message', (message) => {  io.emit('message', {type:'new-message', text: message});   });});http.listen(5000, () => { console.log('started on port 5000');});

import { Subject } from 'rxjs/Subject';import { Observable } from 'rxjs/Observable';import * as io from 'socket.io-client';export class ChatService { private url = 'http://localhost:5000';  private socket;  sendMessage(message){  this.socket.emit('add-message', message);   }  getMessages() {  let observable = new Observable(observer => {   this.socket = io(this.url);   this.socket.on('message', (data) => {    observer.next(data);     });   return () => {    this.socket.disconnect();   };   })     return observable; } }

import { Component, OnInit, OnDestroy } from '@angular/core';import { Control }      from '@angular/common';import { ChatService }    from './chat.service';@Component({ moduleId: module.id, selector: 'chat', template: `<div *ngFor="let message of messages">           {{message.text}}          </div>          <input [(ngModel)]="message" /><button (click)="sendMessage()">Send</button>`, providers: [ChatService]})export class ChatComponent implements OnInit, OnDestroy { messages = []; connection; message;  constructor(private chatService:ChatService) {} sendMessage(){  this.chatService.sendMessage(this.message);  this.message = ''; } ngOnInit() {  this.connection = this.chatService.getMessages().subscribe(message => {   this.messages.push(message);  }) }  ngOnDestroy() {  this.connection.unsubscribe(); }}