select uid, name, is_app_user from user where uid in (select uid2 from friend where uid1=me()) and is_app_user=1

/fql?q=

/fql?q=select%20uid%2C%20name%2C%20is_app_user%20from%20user%20where%20uid%20in%20(select%20uid2%20from%20friend%20where%20uid1%3Dme())%20and%20is_app_user%3D1&access_token={YOUR_USER_ACCESS_TOKEN}

FB.api('/fql?q=select%20uid%2C%20name%2C%20is_app_user%20from%20user%20where%20uid%20in%20(select%20uid2%20from%20friend%20where%20uid1%3Dme())%20and%20is_app_user%3D1&access_token={YOUR_USER_ACCESS_TOKEN}', function(response) {
  console.log(response);
});

FB.api("/fql?q="+encodeURIComponent('{your-query}'), function(response) {
  if (!response || response.error) {
     console.log('Error occurred: '+response.error.message);
  } else {
     console.log(response);
  }
});