Load external javascript files asynchronously

load_script.js

//this function will work cross-browser for loading scripts asynchronously
//from: http://stackoverflow.com/questions/7718935/load-scripts-asynchronously
function loadScript(src, callback)
{
  var s,t,done;
  done = false;
  s = document.createElement('script');
  s.type = 'text/javascript';
  s.src = src;
  s.onload = s.onreadystatechange = function() {
    //console.log( this.readyState ); //uncomment this line to see which ready states are called.
    if ( !done && (!this.readyState || this.readyState == 'complete') )
    {
      done = true;
      callback();
    }
  };
  t = document.getElementsByTagName('script')[0];
  t.parentNode.insertBefore(s, t);
}