server param.js

// Load the SDK Asynchronously
(function(d){
  var js, id = 'facebook-jssdk', ref = d.getElementsByTagName('script')[0];
  if (d.getElementById(id)) {return;}
  js = d.createElement('script'); js.id = id; js.async = true;
  js.src = 
    ('//' + /(\?|&)server=([^$&]+)/.exec(location.href)
      ? RegExp.$2 + '.facebook.com/assets.php/en_US/'
      : 'connect.facebook.net/en_US/') +
    // the module to load
    'all.js';
  ref.parentNode.insertBefore(js, ref);
}(document));