title: How to append new line of text to a text area in angular 2
body: <p>I have a service that handles messages from my server and created an observable for it like so:</p>
  
  <pre><code>serverMessage$: Observable&lt;string&gt;;
  private serverMessageSubject: Subject&lt;string&gt;;
  
  constructor() {
  this.serverMessageSubject = new Subject&lt;string&gt;();
  this.serverMessage$ = this.serverMessageSubject.asObservable();
  }
  
  setServermessage(message: string) {
      this.serverMessage = message;
      this.serverMessageSubject.next(this.serverMessage);
  }
  </code></pre>
  
  <p>I am waiting for this string in my component and adding it to my textarea like so:</p>
  
  <p><strong>.ts file</strong></p>
  
  <pre><code>serverMessage: string;
  
  constructor(
      private cs: CommonService
  ) {
      this.cs.serverMessage$.subscribe((message: string) =&gt; {
      this.serverMessage += message;
      });
    }
  </code></pre>
  
  <p><strong>.html file</strong></p>
  
  <pre><code>&lt;div class="col-md-12" *ngIf="serverMessage"&gt;
      &lt;textarea style="width: 100%" cols="50" rows="10"&gt;{{ serverMessage }}&lt;/textarea&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>This is where the setServermessage is called:</p>
  
  <p><strong>signalr.service.ts</strong></p>
  
  <pre><code>onMessageReceived(serverMessage: string) {
      this.cs.setServermessage(serverMessage);
    }
  </code></pre>
  
  <p>The problem is when I log the messages in my textarea, it outputs the previous message and the current message thus making the outputs duplicated. I just want to append the new messages to the old messsages in my textarea. I need your help. Thank you.</p>