title: Perform API call in background if Angular HTTP observable does not give response in n seconds
body: <p>I am using Angular with RxJS observables for HTTP API calls in an Ionic/Angular application.</p>
  
  <pre><code>this.http
      .post('https://API URL', data, {
          headers: headers
      }).map(response =&gt; response.json()).subscribe(
          (res) =&gt; {},
          (err) =&gt; {}
      );
  </code></pre>
  
  <p>Requirement is that if the API request takes too much time say 10-12s to give success or error i.e 200 or 500, etc. response then I want to trigger some other modal popUp or ui element and keep the processing, the API request as it is, happening in the background and notifying on completion.</p>