Fix aria.js bugs: incorrect role element problem, mobile focus problem, tippy problem (#23450)

This PR is extracted from #23346 to address some unclear (I don't
understand) code-belonging concerns.

This PR needs to be backported, otherwise the `aria.js` is too buggy in
some cases. Since there would be two minor conflicts, I will do the
backport manually.

Before: the `aria.js` is still buggy in some cases.

After: tested with AppleVoice, Android TalkBack

* Fix incorrect dropdown init code
* Fix incorrect role element (the menu role should be on the `$menu`
element, but not on the `$focusable`)
* Fix the focus-show-click-hide problem on mobile. Now the language menu
works as expected
* Fix incorrect dropdown template function setting
* Clarify the logic in aria.js
* Hide item's tippy after menu gets hidden
* Fix incorrect tippy `setProps` after `destroy`
* Fix UI lag problem when page gets redirected during menu hiding
animation with screen reader
* Improve comments
* Implement the layout proposed by #19861

<details>


d74a7efb60/web_src/js/features/aria.md (L38-L47)

</details>

templates/base/footer_content.tmpl

@@ -21,7 +21,7 @@
 			{{end}}
 			<div class="ui language bottom floating slide up dropdown link item">
 				{{svg "octicon-globe"}}
-				<div class="text">{{.locale.LangName}}</div>
+				<span>{{.locale.LangName}}</span>
 				<div class="menu language-menu">
 					{{range .AllLangs}}
 						<a lang="{{.Lang}}" data-url="{{AppSubUrl}}/?lang={{.Lang}}" class="item {{if eq $.locale.Lang .Lang}}active selected{{end}}">{{.Name}}</a>

templates/repo/issue/view_content/add_reaction.tmpl

@@ -1,5 +1,5 @@
 {{if .ctxData.IsSigned}}
-<div class="item action ui pointing select-reaction dropdown top right" data-action-url="{{.ActionURL}}">
+<div class="item action ui dropdown jump pointing top right select-reaction" data-action-url="{{.ActionURL}}">
 	<a class="add-reaction">
 		{{svg "octicon-smiley"}}
 	</a>

templates/repo/issue/view_content/context_menu.tmpl

@@ -1,5 +1,5 @@
 {{if .ctxData.IsSigned}}
-<div class="item action ui pointing custom dropdown top right context-dropdown">
+<div class="item action ui dropdown jump pointing top right context-dropdown">
 	<a class="context-menu">
 		{{svg "octicon-kebab-horizontal"}}
 	</a>

web_src/js/features/aria.js

@@ -6,42 +6,16 @@ function generateAriaId() {
   return `_aria_auto_id_${ariaIdCounter++}`;
 }
 
-// make the item has role=option, and add an id if there wasn't one yet.
-function prepareMenuItem($item) {
-  if (!$item.attr('id')) $item.attr('id', generateAriaId());
-  $item.attr({'role': 'menuitem', 'tabindex': '-1'});
-  $item.find('a').attr('tabindex', '-1'); // as above, the elements inside the dropdown menu item should not be focusable, the focus should always be on the dropdown primary element.
-}
-
-// when the menu items are loaded from AJAX requests, the items are created dynamically
-const defaultCreateDynamicMenu = $.fn.dropdown.settings.templates.menu;
-$.fn.dropdown.settings.templates.menu = function(response, fields, preserveHTML, className) {
-  const ret = defaultCreateDynamicMenu(response, fields, preserveHTML, className);
-  const $wrapper = $('<div>').append(ret);
-  const $items = $wrapper.find('> .item');
-  $items.each((_, item) => {
-    prepareMenuItem($(item));
-  });
-  return $wrapper.html();
-};
-
 function attachOneDropdownAria($dropdown) {
-  if ($dropdown.attr('data-aria-attached')) return;
+  if ($dropdown.attr('data-aria-attached') || $dropdown.hasClass('custom')) return;
   $dropdown.attr('data-aria-attached', 1);
 
-  const $textSearch = $dropdown.find('input.search').eq(0);
+  // Dropdown has 2 different focusing behaviors
-  const $focusable = $textSearch.length ? $textSearch : $dropdown; // see comment below
+  // * with search input: the input is focused, and it works with aria-activedescendant pointing another sibling element.
-  if (!$focusable.length) return;
-
-  // prepare menu list
-  const $menu = $dropdown.find('> .menu');
-  if (!$menu.attr('id')) $menu.attr('id', generateAriaId());
-
-  // dropdown has 2 different focusing behaviors
-  // * with search input: the input is focused, and it works perfectly with aria-activedescendant pointing another sibling element.
   // * without search input (but the readonly text), the dropdown itself is focused. then the aria-activedescendant points to the element inside dropdown
+  // Some desktop screen readers may change the focus, but dropdown requires that the focus must be on its primary element, then they don't work well.
 
-  // expected user interactions for dropdown with aria support:
+  // Expected user interactions for dropdown with aria support:
   // * user can use Tab to focus in the dropdown, then the dropdown menu (list) will be shown
   // * user presses Tab on the focused dropdown to move focus to next sibling focusable element (but not the menu item)
   // * user can use arrow key Up/Down to navigate between menu items
@@ -51,31 +25,83 @@ function attachOneDropdownAria($dropdown) {
 
   // TODO: multiple selection is not supported yet.
 
+  const $textSearch = $dropdown.find('input.search').eq(0);
+  const $focusable = $textSearch.length ? $textSearch : $dropdown; // the primary element for focus, see comment above
+  if (!$focusable.length) return;
+
+  // There are 2 possible solutions about the role: combobox or menu.
+  // The idea is that if there is an input, then it's a combobox, otherwise it's a menu.
+  // Since #19861 we have prepared the "combobox" solution, but didn't get enough time to put it into practice and test before.
+  const isComboBox = $dropdown.find('input').length > 0;
+
+  const focusableRole = isComboBox ? 'combobox' : 'button';
+  const listPopupRole = isComboBox ? 'listbox' : 'menu';
+  const listItemRole = isComboBox ? 'option' : 'menuitem';
+
+  // make the item has role=option/menuitem, add an id if there wasn't one yet, make items as non-focusable
+  // the elements inside the dropdown menu item should not be focusable, the focus should always be on the dropdown primary element.
+  function prepareMenuItem($item) {
+    if (!$item.attr('id')) $item.attr('id', generateAriaId());
+    $item.attr({'role': listItemRole, 'tabindex': '-1'});
+    $item.find('a').attr('tabindex', '-1');
+  }
+
+  // delegate the dropdown's template function to add aria attributes.
+  // the "template" functions are used for dynamic creation (eg: AJAX)
+  const dropdownTemplates = {...$dropdown.dropdown('setting', 'templates')};
+  const dropdownTemplatesMenuOld = dropdownTemplates.menu;
+  dropdownTemplates.menu = function(response, fields, preserveHTML, className) {
+    // when the dropdown menu items are loaded from AJAX requests, the items are created dynamically
+    const menuItems = dropdownTemplatesMenuOld(response, fields, preserveHTML, className);
+    const $wrapper = $('<div>').append(menuItems);
+    const $items = $wrapper.find('> .item');
+    $items.each((_, item) => prepareMenuItem($(item)));
+    return $wrapper.html();
+  };
+  $dropdown.dropdown('setting', 'templates', dropdownTemplates);
+
+  // use tooltip's content as aria-label if there is no aria-label
+  if ($dropdown.hasClass('tooltip') && $dropdown.attr('data-content') && !$dropdown.attr('aria-label')) {
+    $dropdown.attr('aria-label', $dropdown.attr('data-content'));
+  }
+
+  // prepare dropdown menu list popup
+  const $menu = $dropdown.find('> .menu');
+  if (!$menu.attr('id')) $menu.attr('id', generateAriaId());
+  $menu.find('> .item').each((_, item) => {
+    prepareMenuItem($(item));
+  });
+  // this role could only be changed after its content is ready, otherwise some browsers+readers (like Chrome+AppleVoice) crash
+  $menu.attr('role', listPopupRole);
+
+  // make the primary element (focusable) aria-friendly
   $focusable.attr({
-    'role': 'menu',
+    'role': $focusable.attr('role') ?? focusableRole,
-    'aria-haspopup': 'menu',
+    'aria-haspopup': listPopupRole,
     'aria-controls': $menu.attr('id'),
     'aria-expanded': 'false',
   });
 
-  if ($dropdown.attr('data-content') && !$dropdown.attr('aria-label')) {
+  // when showing, it has class: ".animating.in"
-    $dropdown.attr('aria-label', $dropdown.attr('data-content'));
+  // when hiding, it has class: ".visible.animating.out"
-  }
+  const isMenuVisible = () => ($menu.hasClass('visible') && !$menu.hasClass('out')) || $menu.hasClass('in');
-
-  $menu.find('> .item').each((_, item) => {
-    prepareMenuItem($(item));
-  });
 
   // update aria attributes according to current active/selected item
   const refreshAria = () => {
-    const isMenuVisible = !$menu.is('.hidden') && !$menu.is('.animating.out');
+    const menuVisible = isMenuVisible();
-    $focusable.attr('aria-expanded', isMenuVisible ? 'true' : 'false');
+    $focusable.attr('aria-expanded', menuVisible ? 'true' : 'false');
 
-    let $active = $menu.find('> .item.active');
+    // if there is an active item, use it (the user is navigating between items)
-    if (!$active.length) $active = $menu.find('> .item.selected'); // it's strange that we need this fallback at the moment
+    // otherwise use the "selected" for combobox (for the last selected item)
-
+    const $active = $menu.find('> .item.active, > .item.selected');
-    // if there is an active item, use its id. if no active item, then the empty string is set
+    // if the popup is visible and has an active/selected item, use its id as aria-activedescendant
-    $focusable.attr('aria-activedescendant', $active.attr('id'));
+    if (menuVisible) {
+      $focusable.attr('aria-activedescendant', $active.attr('id'));
+    } else if (!isComboBox) {
+      // for menu, when the popup is hidden, no need to keep the aria-activedescendant, and clear the active/selected item
+      $focusable.removeAttr('aria-activedescendant');
+      $active.removeClass('active').removeClass('selected');
+    }
   };
 
   $dropdown.on('keydown', (e) => {
@@ -85,16 +111,51 @@ function attachOneDropdownAria($dropdown) {
       if (!$item) $item = $menu.find('> .item.selected'); // when dropdown filters items by input, there is no "value", so query the "selected" item
       // if the selected item is clickable, then trigger the click event.
       // we can not click any item without check, because Fomantic code might also handle the Enter event. that would result in double click.
-      if ($item && ($item.is('a') || $item.is('.js-aria-clickable'))) $item[0].click();
+      if ($item && ($item.is('a') || $item.hasClass('js-aria-clickable'))) $item[0].click();
     }
   });
 
   // use setTimeout to run the refreshAria in next tick (to make sure the Fomantic UI code has finished its work)
-  const deferredRefreshAria = () => { setTimeout(refreshAria, 0) }; // do not return any value, jQuery has return-value related behaviors.
+  // do not return any value, jQuery has return-value related behaviors.
-  $focusable.on('focus', deferredRefreshAria);
+  // when the popup is hiding, it's better to have a small "delay", because there is a Fomantic UI animation
-  $focusable.on('mouseup', deferredRefreshAria);
+  // without the delay for hiding, the UI will be somewhat laggy and sometimes may get stuck in the animation.
-  $focusable.on('blur', deferredRefreshAria);
+  const deferredRefreshAria = (delay = 0) => { setTimeout(refreshAria, delay) };
   $dropdown.on('keyup', (e) => { if (e.key.startsWith('Arrow')) deferredRefreshAria(); });
+
+  // if the dropdown has been opened by focus, do not trigger the next click event again.
+  // otherwise the dropdown will be closed immediately, especially on Android with TalkBack
+  // * desktop event sequence: mousedown -> focus -> mouseup -> click
+  // * mobile event sequence: focus -> mousedown -> mouseup -> click
+  // Fomantic may stop propagation of blur event, use capture to make sure we can still get the event
+  let ignoreClickPreEvents = 0, ignoreClickPreVisible = 0;
+  $dropdown[0].addEventListener('mousedown', () => {
+    ignoreClickPreVisible += isMenuVisible() ? 1 : 0;
+    ignoreClickPreEvents++;
+  }, true);
+  $dropdown[0].addEventListener('focus', () => {
+    ignoreClickPreVisible += isMenuVisible() ? 1 : 0;
+    ignoreClickPreEvents++;
+    deferredRefreshAria();
+  }, true);
+  $dropdown[0].addEventListener('blur', () => {
+    ignoreClickPreVisible = ignoreClickPreEvents = 0;
+    deferredRefreshAria(100);
+  }, true);
+  $dropdown[0].addEventListener('mouseup', () => {
+    setTimeout(() => {
+      ignoreClickPreVisible = ignoreClickPreEvents = 0;
+      deferredRefreshAria(100);
+    }, 0);
+  }, true);
+  $dropdown[0].addEventListener('click', (e) => {
+    if (isMenuVisible() &&
+      ignoreClickPreVisible !== 2 && // dropdown is switch from invisible to visible
+      ignoreClickPreEvents === 2 // the click event is related to mousedown+focus
+    ) {
+      e.stopPropagation(); // if the dropdown menu has been opened by focus, do not trigger the next click event again
+    }
+    ignoreClickPreEvents = ignoreClickPreVisible = 0;
+  }, true);
 }
 
 export function attachDropdownAria($dropdowns) {

web_src/js/features/aria.md

@@ -1,4 +1,27 @@
-**This document is used as aria/a11y reference for future developers**
+# Background
+
+This document is used as aria/accessibility(a11y) reference for future developers.
+
+There are a lot of a11y problems in the Fomantic UI library. This `aria.js` is used
+as a workaround to make the UI more accessible.
+
+The `aria.js` is designed to avoid touching the official Fomantic UI library,
+and to be as independent as possible, so it can be easily modified/removed in the future.
+
+To test the aria/accessibility with screen readers, developers can use the following steps:
+
+* On macOS, you can use VoiceOver.
+  * Press `Command + F5` to turn on VoiceOver.
+  * Try to operate the UI with keyboard-only.
+  * Use Tab/Shift+Tab to switch focus between elements.
+  * Arrow keys to navigate between menu/combobox items (only aria-active, not really focused).
+  * Press Enter to trigger the aria-active element.
+* On Android, you can use TalkBack.
+  * Go to Settings -> Accessibility -> TalkBack, turn it on.
+  * Long-press or press+swipe to switch the aria-active element (not really focused).
+  * Double-tap means old single-tap on the aria-active element.
+  * Double-finger swipe means old single-finger swipe.
+* TODO: on Windows, on Linux, on iOS
 
 # Checkbox
 
@@ -10,7 +33,8 @@ The ideal checkboxes should be:
 <label><input type="checkbox"> ... </label>
 ```
 
-However, related styles aren't supported (not implemented) yet, so at the moment, almost all the checkboxes are still using Fomantic UI checkbox.
+However, related CSS styles aren't supported (not implemented) yet, so at the moment,
+almost all the checkboxes are still using Fomantic UI checkbox.
 
 ## Fomantic UI Checkbox
 
@@ -21,33 +45,52 @@ However, related styles aren't supported (not implemented) yet, so at the moment
 </div>
 ```
 
-Then the JS `$.checkbox()` should be called to make it work with keyboard and label-clicking, then it works like the ideal checkboxes.
+Then the JS `$.checkbox()` should be called to make it work with keyboard and label-clicking,
+then it works like the ideal checkboxes.
 
-There is still a problem: Fomantic UI checkbox is not friendly to screen readers, so we add IDs to all the Fomantic UI checkboxes automatically by JS.
+There is still a problem: Fomantic UI checkbox is not friendly to screen readers,
+so we add IDs to all the Fomantic UI checkboxes automatically by JS.
+If the `label` part is empty, then the checkbox needs to get the `aria-label` attribute manually.
 
 # Dropdown
 
-## ARIA Dropdown
+## Fomantic UI Dropdown
+
+Fomantic Dropdown is designed to be used for many purposes:
+
+* Menu (the profile menu in navbar, the language menu in footer)
+* Popup (the branch/tag panel, the review box)
+* Simple `<select>` , used in many forms
+* Searchable option-list with static items (used in many forms)
+* Searchable option-list with dynamic items (ajax)
+* Searchable multiple selection option-list with dynamic items: the repo topic setting
+* More complex usages, like the Issue Label selector
+
+Fomantic Dropdown requires that the focus must be on its primary element.
+If the focus changes, it hides or panics.
+
+At the moment, `aria.js` only tries to partially resolve the a11y problems for dropdowns with items.
 
 There are different solutions:
-* combobox + listbox + option
-* menu + menuitem
 
-At the moment, `menu + menuitem` seems to work better with Fomantic UI Dropdown, so we only use it now.
+* combobox + listbox + option:
+  * https://www.w3.org/WAI/ARIA/apg/patterns/combobox/
+  * A combobox is an input widget with an associated popup that enables users to select a value for the combobox from
+    a collection of possible values. In some implementations, the popup presents allowed values, while in other implementations,
+    the popup presents suggested values, and users may either select one of the suggestions or type a value.
+* menu + menuitem:
+  * https://www.w3.org/WAI/ARIA/apg/patterns/menubar/
+  * A menu is a widget that offers a list of choices to the user, such as a set of actions or functions.
 
-```html
+The current approach is: detect if the dropdown has an input,
-<div>
+if yes, it works like a combobox, otherwise it works like a menu.
-  <input role="combobox" aria-haspopup="listbox" aria-expanded="false" aria-controls="the-menu-listbox" aria-activedescendant="item-id-123456">
+Multiple selection dropdown is not well-supported yet, it needs more work.
-  <ul id="the-menu-listbox" role="listbox">
-    <li role="option" id="item-id-123456" aria-selected="true">
-      <a tabindex="-1" href="....">....</a>
-    </li>
-  </ul>
-</div>
-```
 
+Some important pages for dropdown testing:
 
-## Fomantic UI Dropdown
+* Home(dashboard) page, the "Create Repo" / "Profile" / "Language" menu.
+* Create New Repo page, a lot of dropdowns as combobox.
+* Collaborators page, the "permission" dropdown (the old behavior was not quite good, it just works).
 
 ```html
 <!-- read-only dropdown -->

web_src/js/features/common-global.js

@@ -89,9 +89,14 @@ export function initGlobalCommon() {
 
   // Semantic UI modules.
   const $uiDropdowns = $('.ui.dropdown');
-  $uiDropdowns.filter(':not(.custom)').dropdown({
+
-    fullTextSearch: 'exact'
+  // do not init "custom" dropdowns, "custom" dropdowns are managed by their own code.
-  });
+  $uiDropdowns.filter(':not(.custom)').dropdown({fullTextSearch: 'exact'});
+
+  // The "jump" means this dropdown is mainly used for "menu" purpose,
+  // clicking an item will jump to somewhere else or trigger an action/function.
+  // When a dropdown is used for non-refresh actions with tippy,
+  // it must have this "jump" class to hide the tippy when dropdown is closed.
   $uiDropdowns.filter('.jump').dropdown({
     action: 'hide',
     onShow() {
@@ -101,17 +106,23 @@ export function initGlobalCommon() {
     },
     onHide() {
       this._tippy?.enable();
+
+      // hide all tippy elements of items after a while. eg: use Enter to click "Copy Link" in the Issue Context Menu
+      setTimeout(() => {
+        const $dropdown = $(this);
+        if ($dropdown.dropdown('is hidden')) {
+          $(this).find('.menu > .item').each((_, item) => {
+            item._tippy?.hide();
+          });
+        }
+      }, 2000);
     },
-    fullTextSearch: 'exact'
-  });
-  $uiDropdowns.filter('.slide.up').dropdown({
-    transition: 'slide up',
-    fullTextSearch: 'exact'
-  });
-  $uiDropdowns.filter('.upward').dropdown({
-    direction: 'upward',
-    fullTextSearch: 'exact'
   });
+
+  // special animations/popup-directions
+  $uiDropdowns.filter('.slide.up').dropdown({transition: 'slide up'});
+  $uiDropdowns.filter('.upward').dropdown({direction: 'upward'});
+
   attachDropdownAria($uiDropdowns);
 
   attachCheckboxAria($('.ui.checkbox'));

web_src/js/features/repo-legacy.js

@@ -602,9 +602,6 @@ export function initRepository() {
 }
 
 function initRepoIssueCommentEdit() {
-  // Issue/PR Context Menus
-  $('.comment-header-right .context-dropdown').dropdown({action: 'hide'});
-
   // Edit issue or comment content
   $(document).on('click', '.edit-content', onEditContent);
 

web_src/js/modules/tippy.js

@@ -53,10 +53,11 @@ export function showTemporaryTooltip(target, content) {
     onHidden: (tippy) => {
       if (oldContent) {
         tippy.setContent(oldContent);
+        tippy.setProps({onHidden: undefined});
       } else {
         tippy.destroy();
+        // after destroy, the `_tippy` is detached, it can't do "setProps (etc...)" anymore
       }
-      tippy.setProps({onHidden: undefined});
     },
   });
 }