loadScript.js

(function() {

   var loadScript = function(url){
      var script = document.createElement('script');
      script.src = url;
      script.type = 'text/javascript';

      document.getElementsByTagName("HEAD")[0].appendChild(script);
   };

   //loadScript('http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js');

})();