https://greece.fage/modules/contrib/webform/js/webform.scroll.js?tjx8qa

1/**
2 * @file
3 * JavaScript behaviors for webform scroll top.
4 */
5
6(function ($, Drupal) {
7
8  Drupal.webform = Drupal.webform || {};
9  // Allow scrollTopOffset to be custom defined or based on whether there is a
10  // floating toolbar.
11  Drupal.webform.scrollTopOffset = Drupal.webform.scrollTopOffset || ($('#toolbar-administration').length ? 140 : 10);
12
13  /**
14   * Scroll to top ajax command.
15   *
16   * @param {Element} element
17   *   The element to scroll to.
18   * @param {string} target
19   *   Scroll to target. (form or page)
20   */
21  Drupal.webformScrollTop = function (element, target) {
22    if (!target) {
23      return;
24    }
25
26    var $element = $(element);
27
28    // Scroll to the top of the view. This will allow users
29    // to browse newly loaded content after e.g. clicking a pager
30    // link.
31    var offset = $element.offset();
32    // We can't guarantee that the scrollable object should be
33    // the body, as the view could be embedded in something
34    // more complex such as a modal popup. Recurse up the DOM
35    // and scroll the first element that has a non-zero top.
36    var $scrollTarget = $element;
37    while ($scrollTarget.scrollTop() === 0 && $($scrollTarget).parent()) {
38      $scrollTarget = $scrollTarget.parent();
39    }
40
41    if (target === 'page' && $scrollTarget.length && $scrollTarget[0].tagName === 'HTML') {
42      // Scroll to top when scroll target is the entire page.
43      // @see https://stackoverflow.com/questions/123999/how-to-tell-if-a-dom-element-is-visible-in-the-current-viewport
44      var rect = $($scrollTarget)[0].getBoundingClientRect();
45      if (!(rect.top >= 0 && rect.left >= 0 && rect.bottom <= $(window).height() && rect.right <= $(window).width())) {
46        $scrollTarget.animate({scrollTop: 0}, 500);
47      }
48    }
49    else {
50      // Only scroll upward.
51      if (offset.top - Drupal.webform.scrollTopOffset < $scrollTarget.scrollTop()) {
52        $scrollTarget.animate({scrollTop: (offset.top - Drupal.webform.scrollTopOffset)}, 500);
53      }
54    }
55  };
56
57  /**
58   * Scroll element into view.
59   *
60   * @param {jQuery} $element
61   *   An element.
62   */
63  Drupal.webformScrolledIntoView = function ($element) {
64    if (!Drupal.webformIsScrolledIntoView($element)) {
65      $('html, body').animate({scrollTop: $element.offset().top - Drupal.webform.scrollTopOffset}, 500);
66    }
67  };
68
69  /**
70   * Determine if element is visible in the viewport.
71   *
72   * @param {Element} element
73   *   An element.
74   *
75   * @return {boolean}
76   *   TRUE if element is visible in the viewport.
77   *
78   * @see https://stackoverflow.com/questions/487073/check-if-element-is-visible-after-scrolling
79   */
80  Drupal.webformIsScrolledIntoView = function (element) {
81    var docViewTop = $(window).scrollTop();
82    var docViewBottom = docViewTop + $(window).height();
83
84    var elemTop = $(element).offset().top;
85    var elemBottom = elemTop + $(element).height();
86
87    return ((elemBottom <= docViewBottom) && (elemTop >= docViewTop));
88  };
89
90})(jQuery, Drupal);