title: in input onchange event, update array inside the component
body: <p>I'm starting to learn angular right now, and trying to understand the concept of an Observable and how to use them.</p>
  
  <p>I've read all that there is about them in the angular documentation, but I'm either not understanding the concept correctly, or if just not possible.</p>
  
  <p>I'll explain my idea:</p>
  
  <p>I have an input element:</p>
  
  <pre><code>&lt;div class="response" *ngFor="let reply of currentResponse.replies"&gt;
      &lt;input style="word-break: break-all;" type="text" placeholder="Message" value="{{ reply.text }}"/&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>and in the component as a property:</p>
  
  <pre><code>fileData: ResponseModel[];
  // and
  currentResponse: ResponseModel
  </code></pre>
  
  <p>ResponseModel as context:</p>
  
  <pre><code>class ResponseModel {
      constructor(
          public id: string,
          public replies: Array&lt;Reply&gt;,
          public suggestedActions: [],
          public inputHint: string
      ) {}
  }
  </code></pre>
  
  <p>My idea: </p>
  
  <p>could it be possible to attach the <code>onchange</code> event of the input to the <code>fileData</code> array or the <code>currentResponse</code> property, so that when a value changes in the input, the value will change in the array.</p>
  
  <p>And then, when a value changes in the <code>fileData</code> array, update the service that is populating it.</p>
  
  <p>Or If I've misunderstood the use of Observable.</p>
  
  <p>Thanks,
  Nestor</p>