Issue #2531700 by dmsmidt, alexrayu, cboyden, finne, tameeshb, kattekrab, andrewmacpherson, hass, droplet, drpal, dsnopek, nod_: Fragment links to children elements in closed grouping elements don't work

core/misc/collapse.es6.js

@@ -137,6 +137,28 @@
     },
   };
 
+  /**
+   * Open parent details elements of a targeted page fragment.
+   *
+   * Opens all (nested) details element on a hash change or fragment link click
+   * when the target is a child element, in order to make sure the targeted
+   * element is visible. Aria attributes on the summary
+   * are set by triggering the click event listener in details-aria.js.
+   *
+   * @param {jQuery.Event} e
+   *   The event triggered.
+   * @param {jQuery} $target
+   *   The targeted node as a jQuery object.
+   */
+  const handleFragmentLinkClickOrHashChange = (e, $target) => {
+    $target.parents('details').not('[open]').find('> summary').trigger('click');
+  };
+
+  /**
+   * Binds a listener to handle fragment link clicks and URL hash changes.
+   */
+  $('body').on('formFragmentLinkClickOrHashChange.details', handleFragmentLinkClickOrHashChange);
+
   // Expose constructor in the public space.
   Drupal.CollapsibleDetails = CollapsibleDetails;
 }(jQuery, Modernizr, Drupal));

core/misc/collapse.js

@@ -77,5 +77,11 @@
     }
   };
 
+  var handleFragmentLinkClickOrHashChange = function handleFragmentLinkClickOrHashChange(e, $target) {
+    $target.parents('details').not('[open]').find('> summary').trigger('click');
+  };
+
+  $('body').on('formFragmentLinkClickOrHashChange.details', handleFragmentLinkClickOrHashChange);
+
   Drupal.CollapsibleDetails = CollapsibleDetails;
 })(jQuery, Modernizr, Drupal);

core/misc/form.es6.js

@@ -12,6 +12,16 @@
  * @event formUpdated
  */
 
+/**
+ * Triggers when a click on a page fragment link or hash change is detected.
+ *
+ * The event triggers when the fragment in the URL changes (a hash change) and
+ * when a link containing a fragment identifier is clicked. In case the hash
+ * changes due to a click this event will only be triggered once.
+ *
+ * @event formFragmentLinkClickOrHashChange
+ */
+
 (function ($, Drupal, debounce) {
   /**
    * Retrieves the summary for the first element.
@@ -245,4 +255,45 @@
       });
     },
   };
+
+  /**
+   * Sends a fragment interaction event on a hash change or fragment link click.
+   *
+   * @param {jQuery.Event} e
+   *   The event triggered.
+   *
+   * @fires event:formFragmentLinkClickOrHashChange
+   */
+  const handleFragmentLinkClickOrHashChange = (e) => {
+    let $target;
+
+    if (e.type === 'click') {
+      $target = e.currentTarget.location ? $(e.currentTarget.location.hash) : $(e.currentTarget.hash);
+    }
+    else {
+      $target = $(`#${location.hash.substr(1)}`);
+    }
+
+    $('body').trigger('formFragmentLinkClickOrHashChange', [$target]);
+
+    /**
+     * Clicking a fragment link or a hash change should focus the target
+     * element, but event timing issues in multiple browsers require a timeout.
+     */
+    setTimeout(() => {
+      $target.focus();
+    }, 300, $target);
+  };
+
+  // Binds a listener to handle URL fragment changes.
+  $(window).on('hashchange.form-fragment', debounce(handleFragmentLinkClickOrHashChange, 300, true));
+
+  /**
+   * Binds a listener to handle clicks on fragment links and absolute URL links
+   * containing a fragment, this is needed next to the hash change listener
+   * because clicking such links doesn't trigger a hash change when the fragment
+   * is already in the URL.
+   */
+  $(document).on('click.form-fragment', 'a[href*="#"]', debounce(handleFragmentLinkClickOrHashChange, 300, true));
+
 }(jQuery, Drupal, Drupal.debounce));

core/misc/form.js

@@ -124,4 +124,24 @@
       });
     }
   };
+
+  var handleFragmentLinkClickOrHashChange = function handleFragmentLinkClickOrHashChange(e) {
+    var $target = void 0;
+
+    if (e.type === 'click') {
+      $target = e.currentTarget.location ? $(e.currentTarget.location.hash) : $(e.currentTarget.hash);
+    } else {
+      $target = $('#' + location.hash.substr(1));
+    }
+
+    $('body').trigger('formFragmentLinkClickOrHashChange', [$target]);
+
+    setTimeout(function () {
+      $target.focus();
+    }, 300, $target);
+  };
+
+  $(window).on('hashchange.form-fragment', debounce(handleFragmentLinkClickOrHashChange, 300, true));
+
+  $(document).on('click.form-fragment', 'a[href*="#"]', debounce(handleFragmentLinkClickOrHashChange, 300, true));
 })(jQuery, Drupal, Drupal.debounce);

core/misc/vertical-tabs.es6.js

@@ -13,6 +13,23 @@
  */
 
 (function ($, Drupal, drupalSettings) {
+  /**
+   * Show the parent vertical tab pane of a targeted page fragment.
+   *
+   * In order to make sure a targeted element inside a vertical tab pane is
+   * visible on a hash change or fragment link click, show all parent panes.
+   *
+   * @param {jQuery.Event} e
+   *   The event triggered.
+   * @param {jQuery} $target
+   *   The targeted node as a jQuery object.
+   */
+  const handleFragmentLinkClickOrHashChange = (e, $target) => {
+    $target.parents('.vertical-tabs__pane').each((index, pane) => {
+      $(pane).data('verticalTab').focus();
+    });
+  };
+
   /**
    * This script transforms a set of details into a stack of vertical tabs.
    *
@@ -36,6 +53,11 @@
         return;
       }
 
+      /**
+       * Binds a listener to handle fragment link clicks and URL hash changes.
+       */
+      $('body').once('vertical-tabs-fragments').on('formFragmentLinkClickOrHashChange.verticalTabs', handleFragmentLinkClickOrHashChange);
+
       $(context).find('[data-vertical-tabs-panes]').once('vertical-tabs').each(function () {
         const $this = $(this).addClass('vertical-tabs__panes');
         const focusID = $this.find(':hidden.vertical-tabs__active-tab').val();

core/misc/vertical-tabs.js

@@ -6,6 +6,12 @@
 **/
 
 (function ($, Drupal, drupalSettings) {
+  var handleFragmentLinkClickOrHashChange = function handleFragmentLinkClickOrHashChange(e, $target) {
+    $target.parents('.vertical-tabs__pane').each(function (index, pane) {
+      $(pane).data('verticalTab').focus();
+    });
+  };
+
   Drupal.behaviors.verticalTabs = {
     attach: function attach(context) {
       var width = drupalSettings.widthBreakpoint || 640;
@@ -15,6 +21,8 @@
         return;
       }
 
+      $('body').once('vertical-tabs-fragments').on('formFragmentLinkClickOrHashChange.verticalTabs', handleFragmentLinkClickOrHashChange);
+
       $(context).find('[data-vertical-tabs-panes]').once('vertical-tabs').each(function () {
         var $this = $(this).addClass('vertical-tabs__panes');
         var focusID = $this.find(':hidden.vertical-tabs__active-tab').val();

core/tests/Drupal/FunctionalJavascriptTests/Core/Form/FormGroupingElementsTest.php

@@ -0,0 +1,133 @@
+<?php
+
+namespace Drupal\FunctionalJavascriptTests\Core\Form;
+
+use Drupal\FunctionalJavascriptTests\JavascriptTestBase;
+
+/**
+ * Tests for form grouping elements.
+ *
+ * @group form
+ */
+class FormGroupingElementsTest extends JavascriptTestBase {
+
+  /**
+   * Required modules.
+   *
+   * @var array
+   */
+  public static $modules = ['form_test'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    $account = $this->drupalCreateUser();
+    $this->drupalLogin($account);
+  }
+
+  /**
+   * Tests that vertical tab children become visible.
+   *
+   * Makes sure that a child element of a vertical tab that is not visible,
+   * becomes visible when the tab is clicked, a fragment link to the child is
+   * clicked or when the URI fragment pointing to that child changes.
+   */
+  public function testVerticalTabChildVisibility() {
+    $session = $this->getSession();
+    $web_assert = $this->assertSession();
+
+    // Request the group vertical tabs testing page with a fragment identifier
+    // to the second element.
+    $this->drupalGet('form-test/group-vertical-tabs', ['fragment' => 'edit-element-2']);
+
+    $page = $session->getPage();
+
+    $tab_link_1 = $page->find('css', '.vertical-tabs__menu-item > a');
+
+    $child_1_selector = '#edit-element';
+    $child_1 = $page->find('css', $child_1_selector);
+
+    $child_2_selector = '#edit-element-2';
+    $child_2 = $page->find('css', $child_2_selector);
+
+    // Assert that the child in the second vertical tab becomes visible.
+    // It should be visible after initial load due to the fragment in the URI.
+    $this->assertTrue($child_2->isVisible(), 'Child 2 is visible due to a URI fragment');
+
+    // Click on a fragment link pointing to an invisible child inside an
+    // inactive vertical tab.
+    $session->executeScript("jQuery('<a href=\"$child_1_selector\"></a>').insertAfter('h1')[0].click()");
+
+    // Assert that the child in the first vertical tab becomes visible.
+    $web_assert->waitForElementVisible('css', $child_1_selector, 50);
+
+    // Trigger a URI fragment change (hashchange) to show the second vertical
+    // tab again.
+    $session->executeScript("location.replace('$child_2_selector')");
+
+    // Assert that the child in the second vertical tab becomes visible again.
+    $web_assert->waitForElementVisible('css', $child_2_selector, 50);
+
+    $tab_link_1->click();
+
+    // Assert that the child in the first vertical tab is visible again after
+    // a click on the first tab.
+    $this->assertTrue($child_1->isVisible(), 'Child 1 is visible after clicking the parent tab');
+  }
+
+  /**
+   * Tests that details element children become visible.
+   *
+   * Makes sure that a child element of a details element that is not visible,
+   * becomes visible when a fragment link to the child is clicked or when the
+   * URI fragment pointing to that child changes.
+   */
+  public function testDetailsChildVisibility() {
+    $session = $this->getSession();
+    $web_assert = $this->assertSession();
+
+    // Store reusable JavaScript code to remove the current URI fragment and
+    // close all details.
+    $reset_js = "location.replace('#'); jQuery('details').removeAttr('open')";
+
+    // Request the group details testing page.
+    $this->drupalGet('form-test/group-details');
+
+    $page = $session->getPage();
+
+    $session->executeScript($reset_js);
+
+    $child_selector = '#edit-element';
+    $child = $page->find('css', $child_selector);
+
+    // Assert that the child is not visible.
+    $this->assertFalse($child->isVisible(), 'Child is not visible');
+
+    // Trigger a URI fragment change (hashchange) to open all parent details
+    // elements of the child.
+    $session->executeScript("location.replace('$child_selector')");
+
+    // Assert that the child becomes visible again after a hash change.
+    $web_assert->waitForElementVisible('css', $child_selector, 50);
+
+    $session->executeScript($reset_js);
+
+    // Click on a fragment link pointing to an invisible child inside a closed
+    // details element.
+    $session->executeScript("jQuery('<a href=\"$child_selector\"></a>').insertAfter('h1')[0].click()");
+
+    // Assert that the child is visible again after a fragment link click.
+    $web_assert->waitForElementVisible('css', $child_selector, 50);
+
+    // Find the summary belonging to the closest details element.
+    $summary = $page->find('css', '#edit-meta > summary');
+
+    // Assert that both aria-expanded and aria-pressed are true.
+    $this->assertTrue($summary->getAttribute('aria-expanded'));
+    $this->assertTrue($summary->getAttribute('aria-pressed'));
+  }
+
+}