Hook_js (provided module JS)

spaint_cache.module

/**
 * Implements hook_js().
 */
function spaint_cache_js() {
  $items = array();

  require_once DRUPAL_ROOT . '/includes/path.inc';

  $items['user_data'] = array(
    'callback' => 'user_data',
    'bootstrap' => DRUPAL_BOOTSTRAP_SESSION,
    'page arguments' => array(1, 2, 3),
  );

  return $items;
}

//If you need to call js-callback use AJAX and next URL-scheme
// js/{module}/{callback}/{page_arguments}

  $.ajax({
    type: 'GET',
    url: '/js/spaint_cache/user_data/' + language + '/' + uid + '/' + nid,
    success: function (data) {
      Spaint.attachActualData(data, uid, context, settings);
      iambusy.stop();
    },
    dataType: 'json'
  });