Make issue meta dropdown support Enter, confirm before reloading (#23014)

As the title. Label/assignee share the same code.

* Close #22607
* Close #20727

Also:

* partially fix for #21742, now the comment reaction and menu work with
keyboard.
* partially fix for #17705, in most cases the comment won't be lost.
* partially fix for #21539
* partially fix for #20347
* partially fix for #7329

### The `Enter` support

Before, if user presses Enter, the dropdown just disappears and nothing
happens or the window reloads.

After, Enter can be used to select/deselect labels, and press Esc to
hide the dropdown to update the labels (still no way to cancel ....
maybe you can do a Cmd+R or F5 to refresh the window to discard the
changes .....)


This is only a quick patch, the UX is still not perfect, but it's much
better than before.


### The `confirm` before reloading

And more fixes for the `reload` problem, the new behaviors:

* If nothing changes (just show/hide the dropdown), then the page won't
be reloaded.
* If there are draft comments, show a confirm dialog before reloading,
to avoid losing comments.

That's the best effect can be done at the moment, unless completely
refactor these dropdown related code.

Screenshot of the confirm dialog:

<details>


![image](https://user-images.githubusercontent.com/2114189/220538288-e2da8459-6a4e-43cb-8596-74057f8a03a2.png)

</details>

---------

Co-authored-by: Brecht Van Lommel <brecht@blender.org>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

web_src/js/features/aria.js

@@ -81,7 +81,8 @@ function attachOneDropdownAria($dropdown) {
   $dropdown.on('keydown', (e) => {
     // here it must use keydown event before dropdown's keyup handler, otherwise there is no Enter event in our keyup handler
     if (e.key === 'Enter') {
-      const $item = $dropdown.dropdown('get item', $dropdown.dropdown('get value'));
+      let $item = $dropdown.dropdown('get item', $dropdown.dropdown('get value'));
+      if (!$item) $item = $menu.find('> .item.selected'); // when dropdown filters items by input, there is no "value", so query the "selected" item
       // if the selected item is clickable, then trigger the click event. in the future there could be a special CSS class for it.
       if ($item && $item.is('a')) $item[0].click();
     }

web_src/js/features/repo-legacy.js

@@ -29,6 +29,26 @@ import {hideElem, showElem} from '../utils/dom.js';
 
 const {csrfToken} = window.config;
 
+// if there are draft comments (more than 20 chars), confirm before reloading, to avoid losing comments
+function reloadConfirmDraftComment() {
+  const commentTextareas = [
+    document.querySelector('.edit-content-zone:not(.gt-hidden) textarea'),
+    document.querySelector('.edit_area'),
+  ];
+  for (const textarea of commentTextareas) {
+    // Most users won't feel too sad if they lose a comment with 10 or 20 chars, they can re-type these in seconds.
+    // But if they have typed more (like 50) chars and the comment is lost, they will be very unhappy.
+    if (textarea && textarea.value.trim().length > 20) {
+      textarea.parentElement.scrollIntoView();
+      if (!window.confirm('Page will be reloaded, but there are draft comments. Continuing to reload will discard the comments. Continue?')) {
+        return;
+      }
+      break;
+    }
+  }
+  window.location.reload();
+}
+
 export function initRepoCommentForm() {
   const $commentForm = $('.comment.form');
   if ($commentForm.length === 0) {
@@ -86,12 +106,15 @@ export function initRepoCommentForm() {
     let hasUpdateAction = $listMenu.data('action') === 'update';
     const items = {};
 
-    $(`.${selector}`).dropdown('setting', 'onHide', () => {
-      hasUpdateAction = $listMenu.data('action') === 'update'; // Update the var
-      if (hasUpdateAction) {
-        // TODO: Add batch functionality and make this 1 network request.
-        (async function() {
-          for (const [elementId, item] of Object.entries(items)) {
+    $(`.${selector}`).dropdown({
+      'action': 'nothing', // do not hide the menu if user presses Enter
+      fullTextSearch: 'exact',
+      async onHide() {
+        hasUpdateAction = $listMenu.data('action') === 'update'; // Update the var
+        if (hasUpdateAction) {
+          // TODO: Add batch functionality and make this 1 network request.
+          const itemEntries = Object.entries(items);
+          for (const [elementId, item] of itemEntries) {
             await updateIssuesMeta(
               item['update-url'],
               item.action,
@@ -99,9 +122,11 @@ export function initRepoCommentForm() {
               elementId,
             );
           }
-          window.location.reload();
-        })();
-      }
+          if (itemEntries.length) {
+            reloadConfirmDraftComment();
+          }
+        }
+      },
     });
 
     $listMenu.find('.item:not(.no-select)').on('click', function (e) {
@@ -196,7 +221,7 @@ export function initRepoCommentForm() {
           'clear',
           $listMenu.data('issue-id'),
           '',
-        ).then(() => window.location.reload());
+        ).then(reloadConfirmDraftComment);
       }
 
       $(this).parent().find('.item').each(function () {
@@ -239,7 +264,7 @@ export function initRepoCommentForm() {
           '',
           $menu.data('issue-id'),
           $(this).data('id'),
-        ).then(() => window.location.reload());
+        ).then(reloadConfirmDraftComment);
       }
 
       let icon = '';
@@ -272,7 +297,7 @@ export function initRepoCommentForm() {
           '',
           $menu.data('issue-id'),
           $(this).data('id'),
-        ).then(() => window.location.reload());
+        ).then(reloadConfirmDraftComment);
       }
 
       $list.find('.selected').html('');