conditional load script helper function with jQuery

jQuery.loadScript

jQuery.loadScript = function (url, arg1, arg2) {
  var cache = false, callback = null;
  //arg1 and arg2 can be interchangable as either the callback function or the cache bool
  if ($.isFunction(arg1)){
    callback = arg1;
    cache = arg2 || cache;
  } else {
    cache = arg1 || cache;
    callback = arg2 || callback;
  }
               
  var load = true;
  //check all existing script tags in the page for the url we are trying to load
  jQuery('script[type="text/javascript"]').each(function () { return load = (url != $(this).attr('src')); });
  if (load){
    //didn't find it in the page, so load it
    //equivalent to a jQuery.getScript but with control over cacheing
    jQuery.ajax({
      type: 'GET',
      url: url,
      success: callback,
      dataType: 'script',
      cache: cache
    });
  } else {
    //already loaded so just call the callback
    if (jQuery.isFunction(callback)) {
      callback.call(this);
    };
  };
};