title: How to get the status of angular $interval - check if the interval has been cancelled or not
body: <p>I am new to Angular (and JS) and just a little confused.</p>
  
  <p>I start a timer with :</p>
  
  <pre><code>var getOverviewMapTimer = $interval($scope.UpdateOverviewMap, UPDATE_FREQUENCY); 
  </code></pre>
  
  <p>and, if I understand it, <code>getOverviewMapTimer</code> is a "promise".</p>
  
  <p>I want to be able to check if the timer is running &amp; had excepted that if I ever<br>
  <code>$interval.cancel(getOverviewMapTimer);</code> then <code>getOverviewMapTimer</code> would be <code>null</code> and I could check for that.</p>
  
  <p>This seems not to be the case.</p>
  
  <p>Do I have to explicitly destroy the promise (what goo is a promise to timer that has been cancelled?).? If so, how &amp; would I then have to explicitly set it to <code>null</code>? </p>
  
  <p>I <em>think</em> that I should use <code>cancel(getOverviewMapTimer);</code>, but am not 100% sure as <code>getOverviewMapTimer</code> is still non-null afterwards.</p>
  
  <p>Thanks for your help</p>