title: How to iterate markers on a Google maps (API 3)
body: <p>I have the following map:</p>
  
  <p>var map = new google.maps.Map(document.getElementById('map'), myOptions);</p>
  
  <p>and a couple of markers created calling to new google.maps.Marker()</p>
  
  <p>Now I need to hide all the markers of a certain group when a checkbox is clicked but can't find a way to iterate through all the markers on the map.</p>