Load Scripts asynchronously.

asyncScripts.js

function LoadScriptsAsync (src) {
  if(!src) throw new Error('LoadScriptsAsync : You have to add a script src!');
  
  var script = document.createElement('script'),
      head = document.getElementsByTagName('head')[0];
  
  script.type = "text/javascript";
  script.src  = src;
  script.async = true; // new property in HTML5 : http://davidwalsh.name/html5-async
  
  head.appendChild(script);
  
}