/**
 * @file
 * Javascript behaviors for AJAX.
 */

(function ($, Drupal) {

  'use strict';

  /**
   * Scroll to top ajax command.
   *
   * @param {Drupal.Ajax} [ajax]
   *   A {@link Drupal.ajax} object.
   * @param {object} response
   *   Ajax response.
   * @param {string} response.selector
   *   Selector to use.
   *
   * @see  Drupal.AjaxCommands.prototype.webformScrollTop
   */
  Drupal.AjaxCommands.prototype.webformScrollTop = function (ajax, response) {
    // Scroll to the top of the view. This will allow users
    // to browse newly loaded content after e.g. clicking a pager
    // link.
    var offset = $(response.selector).offset();
    // We can't guarantee that the scrollable object should be
    // the body, as the view could be embedded in something
    // more complex such as a modal popup. Recurse up the DOM
    // and scroll the first element that has a non-zero top.
    var scrollTarget = response.selector;
    while ($(scrollTarget).scrollTop() === 0 && $(scrollTarget).parent()) {
      scrollTarget = $(scrollTarget).parent();
    }
    // Only scroll upward.
    if (offset.top - 10 < $(scrollTarget).scrollTop()) {
      $(scrollTarget).animate({scrollTop: (offset.top - 10)}, 500);
    }
  };

})(jQuery, Drupal);