Angular 5 Socket.IO聊天未更新

Question

我正在与Angular 5建立一个实时聊天网站 它适用于用户发送消息，但其他客户端在没有刷新的情况下将无法获取新消息。 后端是NodeJS，它的工作正常，与插座相同 聊天不令人耳目一新是这里的问题。

chat.component.ts：

    import { Component } from '@angular/core';
    import { Socket } from 'ng-socket-io';
    import { ChatService } from '../services/chat.service';

    @Component({
      selector: 'app-chat',
      templateUrl: './chat.component.html',
      styleUrls: ['./chat.component.css'],
      providers : [ChatService]
    })

    export class ChatComponent {

      messages: string[] = [];

      constructor(private socket: Socket, private chatservice: ChatService) {
        this.socket.on('getOldChat', (data) => {
          this.messages.push(data);
        });
      }

      ngOnInit() {
        this.chatservice.onMessage()
        .subscribe((message: string) => {
          console.log('Pushing new msg: '+message);
          this.messages.push(message);
        });
      }

      sendChat(chatmessage) {
        if (!chatmessage) {
          console.log('Blank Message!');
          return;
        }
        console.log('Sending new message: ' + chatmessage);
        this.socket.emit('sendChat', chatmessage);
      }
    }

chat.component.html：
<div *ngFor="let message of messages"><li class="chatmessage">{{ message }}</li></div>

chat.service.ts：

        import { Injectable } from '@angular/core';
        import { Observable } from 'rxjs/Observable';
        import { Observer } from 'rxjs/Observer';
        import { Socket } from 'ng-socket-io';

        @Injectable()
        export class ChatService {

          constructor(private socket: Socket) { }

            public onMessage(): Observable<string> {
                return new Observable<string>(observer => {
                    this.socket.on('getChat', (data: string) => observer.next(data));
                });
            }

        }