Prevent to open multiple windows from window.open function

function launchApplication(l_url, l_windowName)
{
  if ( typeof launchApplication.winRefs == 'undefined' )
  {
    launchApplication.winRefs = {};
  }
  if ( typeof launchApplication.winrefs[l_windowName] == 'undefined' || launchApplication.winrefs[l_windowName].closed )
  {
    var l_width = screen.availWidth;
    var l_height = screen.availHeight;

    var l_params = 'status=1' +
                   ',resizable=1' +
                   ',scrollbars=1' +
                   ',width=' + l_width +
                   ',height=' + l_height +
                   ',left=0' +
                   ',top=0';

    launchApplication.winrefs[l_windowName] = window.open(l_url, l_windowName, l_params);
    launchApplication.winrefs[l_windowName].moveTo(0,0);
    launchApplication.winrefs[l_windowName].resizeTo(l_width, l_height);
  } else {
    launchApplication.winrefs[l_windowName].focus()
  }
}