asynchronously javascript script

asynchronously_javascript.js

//asynchronously javascript script function
function getScript(url){
  var elem = document.createElement('script'),
      script = document.getElementsByTagName('script')[0];
      
      elem.src = url;
      elem.type = 'text/javascript';
      elem.async = true;
      
      script.parentNode.insertBefore(elem, script);
}