title: Google Maps V3 API setMap
body: <p>Let's say I have the following objects:</p>
  
  <pre><code>var map = new google.maps.Map(...)
  var marker = new google.maps.Marker(...);
  </code></pre>
  
  <p>I can add <code>marker</code> to <code>map</code> with:</p>
  
  <pre><code>marker.setMap(map);
  </code></pre>
  
  <p>If the marker already exists on the map, and I call <code>marker.setMap(map)</code> again, does the API actually redraw the marker? Or does it know the marker already exists on the map, so it doesn't take any further actions?</p>
  
  <p>I am listening for events and need to either add or remove markers from the map when those events occur. I'm wondering if I can simply keep calling <code>setMap(map)</code> even if the marker already exists without performance suffering significantly, or do I need to be smarter and not call <code>setMap</code> in the first place if the marker is already on the map.</p>
  
  <p>If you don't know the answer, do you have any idea how I could figure this out?</p>