title: Javascript | Check if a windows with specific URL already is opened
body: <p>This functions show a /ticket.html popup window.</p>
  
  <p>I need to check before if the window is already opened. If it is, cancel the new openning.</p>
  
  <p>How could this be done?</p>
  
  <pre><code>function popitup() {
             newwindow=window.open("ticket.html","_blank","toolbar=yes,scrollbars=yes, resizable=yes, top=500, left=500, width=730, height=700");
             newwindow.moveTo(350,150);
         if (window.focus) 
                {
                   newwindow.focus()
                }
        }
  </code></pre>
  
  <p>Regards,</p>