Angular不订阅SignalR消息

npm install @aspnet/signalr

import { Component, OnInit } from '@angular/core';
import * as signalR from '@aspnet/signalr';

@Component({
  selector: 'app-my-component',
  templateUrl: './my-component.component.html',
  styleUrls: ['./my-component.component.css']
})
export class MyComponent implements OnInit {
  private hubConnection: signalR.HubConnection;

  ngOnInit() {
    this.hubConnection = new signalR.HubConnectionBuilder()
      .withUrl('http://example.com/signalr')
      .build();

    this.hubConnection.start()
      .then(() => {
        console.log('SignalR connection started');
        this.hubConnection.on('ReceiveMessage', (message) => {
          console.log('Received message: ' + message);
        });
      })
      .catch(err => console.error(err));
  }
}

import 'zone.js/dist/webapis-shadydom';
import 'zone.js/dist/zone';