code: function (src, success, error) {
  		var s = document.createElement('script');
  		s.src = src;
  		s.async = true;
  		s.onload = function() {
  			document.body.removeChild(s);
  			success && success();
  		};
  		s.onerror = function() {
  			document.body.removeChild(s);
  			error && error();
  		};
  		document.body.appendChild(s);
  	}
docs: Lazy loads an external script
  @param {string} src
  @param {function=} success
  @param {function=} error