title: How to push to Observable of Array in Angular 4? RxJS
body: <p>I have a property on my service class as so:</p>
  
  <pre><code>articles: Observable&lt;Article[]&gt;;
  </code></pre>
  
  <p>It is populated by a getArticles() function using the standard <code>http.get().map()</code> solution. </p>
  
  <p><strong>How can I manually push a new article in to this array; One that is not yet persisted and so not part of the http get?</strong></p>
  
  <p>My scenario is, you create a new Article, and before it is saved I would like the Article[] array to have this new one pushed to it so it shows up in my list of articles.</p>
  
  <p>Further more, This service is shared between 2 components, If component A consumes the service using ng <code>OnInit()</code> and binds the result to a repeating section <code>*ngFor</code>, <strong>will updating the service array from component B simultaneously update the results in components A's <code>ngFor</code> section?</strong> Or must I update the view manually?</p>
  
  <p>Many Thanks,
  Simon</p>