Load Facebook Like Box Asynchronously

gistfile1.txt

<?php
function fb_js() {
  if(self::$script_loaded == 1) return;
  self::$script_loaded = 1;
  echo '
    <script>(function(d, s, id) {
      var js, fjs = d.getElementsByTagName(s)[0]; 
      if (d.getElementById(id)) return; 
      js = d.createElement(s); js.id = id; 
      js.async = true; 
      js.src = "//connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.4"; 
      fjs.parentNode.insertBefore(js, fjs); 
    }
    (document, "script", "facebook-jssdk"));</script> 
  '; 
}
?>