最近遊んでいるAngular2でnode.js側にパラメータを投げてonやemitする値を動的に変えてconnectするものを作ってみようと思って遊んでみたのでメモ
（component単位でconnectするとかあるかのかなぁと妄想して）

node.js側

$ mkdir web-socket
$ cd web-socket
$ npm init
$ npm install socket.io --save
$ npm install express --save
$ touch web-socket.js

web-socket.js


let app           = require(　'express'　)();
let http          = require(　'http'　).Server(　app　);
let socket_io     = require(　'socket.io'　)(　http　);

socket_io.on( 'connection', ( socket ) => {
  let query       = socket.handshake.query;
  let hoge        = query.hoge;

  socket.on( 'disconnect', function(){} );

  socket.on( 'on_name', ( data ) => {
    socket_io.emit( 'emit_name', { data: data } );
  } );

} );

http.listen( 5000, () => { } );

Angular側

$ npm install socket.io-client --save
$ npm install @types/socket.io-client --save-dev

Service


import { Injectable } from '@angular/core';

import * as io from 'socket.io-client';

import { Observable } from 'rxjs/Observable';

@Injectable()
export class WebSocketService {

  constructor(){}

  private url     = 'http://localhost:5000';
  private socket;

  connect( queryString: string ){
    this.socket   = io( this.url, { query: queryString } );
  }

  emit( emitName: string, data? ){
    this.socket.emit( emitName, data );
  }

  on( onName: string ){
    let observable = new Observable( observer => {
      this.socket.on( onName, ( data ) => {
        observer.next( data );
      });

      return () => { this.socket.disconnect(); };
    } );
    return observable;
  }

}

Component

import { Component, OnInit, OnDestroy } from '@angular/core';
import { WebSocketService }       from './web-socket.service';

@Component({
  providers: [WebSocketService],
  selector: 'app-web-socket',
  templateUrl: './web-socket.component.html',
  styleUrls: ['./web-socket.component.scss'],
})
export class WebSocketComponent implements OnInit, OnDestroy {

  connection;
  data;

  constructor( private webSocketService: WebSocketService ){}

  onClick(){
    this.webSocketService.emit( 'on_name', this.data );
    this.data = '';
  }

  ngOnInit() {
    this.webSocketService.connect( 'hoge=hoge' )
    this.connection = this.webSocketService.on( 'emit_name' ).subscribe( data => {
      this.data = data;
    } )
  }

  ngOnDestroy() {
    this.connection.unsubscribe();
  }

}

あとは
web-socket.component.htmlに onClickのボタンを置いて　ng serve と node web-socket.jsをして別々に起動

補足

下記の部分でクエリを受け取っているので、ここで条件分岐等でonやemitの値を動的にセットしてあげれば目的達成

  let query       = socket.handshake.query;
  let hoge        = query.hoge;