title: Check if window is already open window.open
body: <p>I have a html page. In the body of the page I am calling <code>onload</code> event which calls javascript function to open a pop up window. here is the code: </p>
  
  <pre><code>var newWindow = null;
  function launchApplication()
  {
      if ((newWindow == null) || (newWindow.closed))
      {
          newWindow = window.open('abc.html','','height=960px,width=940px');
      }
  }
  </code></pre>
  
  <p>when I move to another page, and come back to that page again, popup reopens, although it is already opened. Please guide me to proper direction so that if pop up is already open then it should not open again. I tried <code>document.referred</code> but it requires the site online, currently I am working offline.</p>