Add Drupal.arg() for parsing urls in Drupal

drupal.arg.js

/**
 * Adds method arg to the Drupal object for grabbing url args
 *
 * @author Aaron Klump, In the Loft Studios, LLC
 * @see http://www.intheloftstudios.com
 * @see http://gist.github.com/3078482
 *
 * For use in a theme or module add the following to your .info file
 * @code
 * scripts[] = [path to js dir]/drupal.arg.js
 * @endcode
 *
 * @author Aaron Klump, In the Loft Studios, LLC
 * @see http://www.intheloftstudios.com
 * @see http://gist.github.com/3078482
 */

/**
 * JS equivalent of arg()
 *
 * @param index
 * @param path
 *
 * @return array, string or false
 */
var Drupal = Drupal || { 'settings': {}, 'behaviors': {}, 'locale': {} };

Drupal.arg = Drupal.arg || function (index, path) {
  if (path === null) {
    path = window.location.pathname;
  }
  if (path.substr(0, 1) === '/') {
    path = path.substr(1);
  }
  path = path.split('?');
  var args = path[0].split('/');
  if (index === null) {
    return args;
  }
  if (args[index]) {
    return args[index];
  }
  return false;
};