Refactor hiding-methods, remove jQuery show/hide, remove `.hide` class, remove inline style=display:none (#22950)

Close #22847

This PR:

* introduce Gitea's own `showElem` and related functions
* remove jQuery show/hide
* remove .hide class
* remove inline style=display:none 

From now on:

do not use:
* "[hidden]" attribute: it's too weak, can not be applied to an element
with "display: flex"
* ".hidden" class: it has been polluted by Fomantic UI in many cases
* inline style="display: none": it's difficult to tweak
* jQuery's show/hide/toggle: it can not show/hide elements with
"display: xxx !important"

only use:
* this ".gt-hidden" class
* showElem/hideElem/toggleElem functions in "utils/dom.js"

cc: @silverwind , this is the all-in-one PR

31 files changed, 246 insertions, 163 deletions

diff --git a/web_src/js/components/DiffFileTree.vue b/web_src/js/components/DiffFileTree.vue
index 3742f3a53..fa59768ee 100644
--- a/web_src/js/components/DiffFileTree.vue
+++ b/web_src/js/components/DiffFileTree.vue
@@ -113,11 +113,11 @@ export default {
     },
     adjustToggleButton(visible) {
       const [toShow, toHide] = document.querySelectorAll('.diff-toggle-file-tree-button .icon');
-      toShow.classList.toggle('hide', visible);  // hide the toShow icon if the tree is visible
-      toHide.classList.toggle('hide', !visible); // similarly
+      toShow.classList.toggle('gt-hidden', visible);  // hide the toShow icon if the tree is visible
+      toHide.classList.toggle('gt-hidden', !visible); // similarly
 
       const diffTree = document.getElementById('diff-file-tree');
-      diffTree.classList.toggle('hide', !visible);
+      diffTree.classList.toggle('gt-hidden', !visible);
     },
     loadMoreData() {
       this.isLoadingNewData = true;
diff --git a/web_src/js/features/admin/common.js b/web_src/js/features/admin/common.js
index d0b3e461d..092cf770b 100644
--- a/web_src/js/features/admin/common.js
+++ b/web_src/js/features/admin/common.js
@@ -1,5 +1,6 @@
 import $ from 'jquery';
 import {checkAppUrl} from '../common-global.js';
+import {hideElem, showElem, toggleElem} from '../../utils/dom.js';
 
 const {csrfToken} = window.config;
 
@@ -18,8 +19,8 @@ export function initAdminCommon() {
       if ($(this).val().substring(0, 1) === '0') {
         $('#user_name').removeAttr('disabled');
         $('#login_name').removeAttr('required');
-        $('.non-local').hide();
-        $('.local').show();
+        hideElem($('.non-local'));
+        showElem($('.local'));
         $('#user_name').focus();
 
         if ($(this).data('password') === 'required') {
@@ -30,8 +31,8 @@ export function initAdminCommon() {
           $('#user_name').attr('disabled', 'disabled');
         }
         $('#login_name').attr('required', 'required');
-        $('.non-local').show();
-        $('.local').hide();
+        showElem($('.non-local'));
+        hideElem($('.local'));
         $('#login_name').focus();
 
         $('#password').removeAttr('required');
@@ -41,38 +42,38 @@ export function initAdminCommon() {
 
   function onSecurityProtocolChange() {
     if ($('#security_protocol').val() > 0) {
-      $('.has-tls').show();
+      showElem($('.has-tls'));
     } else {
-      $('.has-tls').hide();
+      hideElem($('.has-tls'));
     }
   }
 
   function onUsePagedSearchChange() {
     if ($('#use_paged_search').prop('checked')) {
-      $('.search-page-size').show()
+      showElem($('.search-page-size'))
         .find('input').attr('required', 'required');
     } else {
-      $('.search-page-size').hide()
+      hideElem($('.search-page-size'))
         .find('input').removeAttr('required');
     }
   }
 
   function onOAuth2Change(applyDefaultValues) {
-    $('.open_id_connect_auto_discovery_url, .oauth2_use_custom_url').hide();
+    hideElem($('.open_id_connect_auto_discovery_url, .oauth2_use_custom_url'));
     $('.open_id_connect_auto_discovery_url input[required]').removeAttr('required');
 
     const provider = $('#oauth2_provider').val();
     switch (provider) {
       case 'openidConnect':
         $('.open_id_connect_auto_discovery_url input').attr('required', 'required');
-        $('.open_id_connect_auto_discovery_url').show();
+        showElem($('.open_id_connect_auto_discovery_url'));
         break;
       default:
         if ($(`#${provider}_customURLSettings`).data('required')) {
           $('#oauth2_use_custom_url').attr('checked', 'checked');
         }
         if ($(`#${provider}_customURLSettings`).data('available')) {
-          $('.oauth2_use_custom_url').show();
+          showElem($('.oauth2_use_custom_url'));
         }
     }
     onOAuth2UseCustomURLChange(applyDefaultValues);
@@ -80,7 +81,7 @@ export function initAdminCommon() {
 
   function onOAuth2UseCustomURLChange(applyDefaultValues) {
     const provider = $('#oauth2_provider').val();
-    $('.oauth2_use_custom_url_field').hide();
+    hideElem($('.oauth2_use_custom_url_field'));
     $('.oauth2_use_custom_url_field input[required]').removeAttr('required');
 
     if ($('#oauth2_use_custom_url').is(':checked')) {
@@ -90,20 +91,20 @@ export function initAdminCommon() {
         }
         if ($(`#${provider}_${custom}`).data('available')) {
           $(`.oauth2_${custom} input`).attr('required', 'required');
-          $(`.oauth2_${custom}`).show();
+          showElem($(`.oauth2_${custom}`));
         }
       }
     }
   }
 
   function onEnableLdapGroupsChange() {
-    $('#ldap-group-options').toggle($('.js-ldap-group-toggle').is(':checked'));
+    toggleElem($('#ldap-group-options'), $('.js-ldap-group-toggle').is(':checked'));
   }
 
   // New authentication
   if ($('.admin.new.authentication').length > 0) {
     $('#auth_type').on('change', function () {
-      $('.ldap, .dldap, .smtp, .pam, .oauth2, .has-tls, .search-page-size, .sspi').hide();
+      hideElem($('.ldap, .dldap, .smtp, .pam, .oauth2, .has-tls, .search-page-size, .sspi'));
 
       $('.ldap input[required], .binddnrequired input[required], .dldap input[required], .smtp input[required], .pam input[required], .oauth2 input[required], .has-tls input[required], .sspi input[required]').removeAttr('required');
       $('.binddnrequired').removeClass('required');
@@ -111,30 +112,30 @@ export function initAdminCommon() {
       const authType = $(this).val();
       switch (authType) {
         case '2': // LDAP
-          $('.ldap').show();
+          showElem($('.ldap'));
           $('.binddnrequired input, .ldap div.required:not(.dldap) input').attr('required', 'required');
           $('.binddnrequired').addClass('required');
           break;
         case '3': // SMTP
-          $('.smtp').show();
-          $('.has-tls').show();
+          showElem($('.smtp'));
+          showElem($('.has-tls'));
           $('.smtp div.required input, .has-tls').attr('required', 'required');
           break;
         case '4': // PAM
-          $('.pam').show();
+          showElem($('.pam'));
           $('.pam input').attr('required', 'required');
           break;
         case '5': // LDAP
-          $('.dldap').show();
+          showElem($('.dldap'));
           $('.dldap div.required:not(.ldap) input').attr('required', 'required');
           break;
         case '6': // OAuth2
-          $('.oauth2').show();
+          showElem($('.oauth2'));
           $('.oauth2 div.required:not(.oauth2_use_custom_url,.oauth2_use_custom_url_field,.open_id_connect_auto_discovery_url) input').attr('required', 'required');
           onOAuth2Change(true);
           break;
         case '7': // SSPI
-          $('.sspi').show();
+          showElem($('.sspi'));
           $('.sspi div.required input').attr('required', 'required');
           break;
       }
diff --git a/web_src/js/features/common-global.js b/web_src/js/features/common-global.js
index c0acf091c..57a429ed9 100644
--- a/web_src/js/features/common-global.js
+++ b/web_src/js/features/common-global.js
@@ -8,6 +8,7 @@ import {attachCheckboxAria, attachDropdownAria} from './aria.js';
 import {handleGlobalEnterQuickSubmit} from './comp/QuickSubmit.js';
 import {initTooltip} from '../modules/tippy.js';
 import {svg} from '../svg.js';
+import {hideElem, showElem, toggleElem} from '../utils/dom.js';
 
 const {appUrl, csrfToken} = window.config;
 
@@ -118,7 +119,7 @@ export function initGlobalCommon() {
   $('.tabable.menu .item').tab();
 
   $('.toggle.button').on('click', function () {
-    $($(this).data('target')).slideToggle(100);
+    toggleElem($($(this).data('target')));
   });
 
   // make table <tr> and <td> elements clickable like a link
@@ -317,7 +318,7 @@ export function initGlobalLinkActions() {
 
 export function initGlobalButtons() {
   $('.show-panel.button').on('click', function () {
-    $($(this).data('panel')).show();
+    showElem($(this).data('panel'));
   });
 
   $('.hide-panel.button').on('click', function (event) {
@@ -325,12 +326,12 @@ export function initGlobalButtons() {
     event.preventDefault();
     let sel = $(this).attr('data-panel');
     if (sel) {
-      $(sel).hide();
+      hideElem($(sel));
       return;
     }
     sel = $(this).attr('data-panel-closest');
     if (sel) {
-      $(this).closest(sel).hide();
+      hideElem($(this).closest(sel));
       return;
     }
     // should never happen, otherwise there is a bug in code
diff --git a/web_src/js/features/common-issue.js b/web_src/js/features/common-issue.js
index f53dd5081..0965caef1 100644
--- a/web_src/js/features/common-issue.js
+++ b/web_src/js/features/common-issue.js
@@ -1,5 +1,6 @@
 import $ from 'jquery';
 import {updateIssuesMeta} from './repo-issue.js';
+import {toggleElem} from '../utils/dom.js';
 
 export function initCommonIssue() {
   const $issueSelectAllWrapper = $('.issue-checkbox-all');
@@ -19,8 +20,8 @@ export function initCommonIssue() {
       $issueSelectAll.prop({'checked': false, 'indeterminate': false});
     }
     // if any issue is selected, show the action panel, otherwise show the filter panel
-    $('#issue-filters').toggle(!anyChecked);
-    $('#issue-actions').toggle(anyChecked);
+    toggleElem($('#issue-filters'), !anyChecked);
+    toggleElem($('#issue-actions'), anyChecked);
     // there are two panels but only one select-all checkbox, so move the checkbox to the visible panel
     $('#issue-filters, #issue-actions').filter(':visible').find('.column:first').prepend($issueSelectAllWrapper);
   };
diff --git a/web_src/js/features/common-organization.js b/web_src/js/features/common-organization.js
index 218c03904..1796efc6a 100644
--- a/web_src/js/features/common-organization.js
+++ b/web_src/js/features/common-organization.js
@@ -1,5 +1,6 @@
 import $ from 'jquery';
 import {initCompLabelEdit} from './comp/LabelEdit.js';
+import {hideElem, showElem} from '../utils/dom.js';
 
 export function initCommonOrganization() {
   if ($('.organization').length === 0) {
@@ -11,11 +12,11 @@ export function initCommonOrganization() {
       const $prompt = $('#org-name-change-prompt');
       const $prompt_redirect = $('#org-name-change-redirect-prompt');
       if ($(this).val().toString().toLowerCase() !== $(this).data('org-name').toString().toLowerCase()) {
-        $prompt.show();
-        $prompt_redirect.show();
+        showElem($prompt);
+        showElem($prompt_redirect);
       } else {
-        $prompt.hide();
-        $prompt_redirect.hide();
+        hideElem($prompt);
+        hideElem($prompt_redirect);
       }
     });
   }
diff --git a/web_src/js/features/comp/WebHookEditor.js b/web_src/js/features/comp/WebHookEditor.js
index cda0fa391..f4c82898f 100644
--- a/web_src/js/features/comp/WebHookEditor.js
+++ b/web_src/js/features/comp/WebHookEditor.js
@@ -1,4 +1,5 @@
 import $ from 'jquery';
+import {hideElem, showElem, toggleElem} from '../../utils/dom.js';
 
 const {csrfToken} = window.config;
 
@@ -9,18 +10,18 @@ export function initCompWebHookEditor() {
 
   $('.events.checkbox input').on('change', function () {
     if ($(this).is(':checked')) {
-      $('.events.fields').show();
+      showElem($('.events.fields'));
     }
   });
   $('.non-events.checkbox input').on('change', function () {
     if ($(this).is(':checked')) {
-      $('.events.fields').hide();
+      hideElem($('.events.fields'));
     }
   });
 
   const updateContentType = function () {
     const visible = $('#http_method').val() === 'POST';
-    $('#content_type').parent().parent()[visible ? 'show' : 'hide']();
+    toggleElem($('#content_type').parent().parent(), visible);
   };
   updateContentType();
   $('#http_method').on('change', () => {
diff --git a/web_src/js/features/imagediff.js b/web_src/js/features/imagediff.js
index 250ea9579..7a285f1f8 100644
--- a/web_src/js/features/imagediff.js
+++ b/web_src/js/features/imagediff.js
@@ -1,4 +1,5 @@
 import $ from 'jquery';
+import {hideElem} from '../utils/dom.js';
 
 function getDefaultSvgBoundsIfUndefined(svgXml, src) {
   const DefaultSize = 300;
@@ -104,7 +105,7 @@ export function initImageDiff() {
               if (bounds) {
                 info.$image.attr('width', bounds.width);
                 info.$image.attr('height', bounds.height);
-                info.$boundsInfo.hide();
+                hideElem(info.$boundsInfo);
               }
             }
           }
@@ -128,8 +129,8 @@ export function initImageDiff() {
         initOverlay(createContext($imageAfter[2], $imageBefore[2]));
       }
 
-      $container.find('> .loader').hide();
-      $container.find('> .hide').removeClass('hide');
+      hideElem($container.find('> .loader'));
+      $container.find('> .gt-hidden').removeClass('gt-hidden');
     }
 
     function initSideBySide(sizes) {
diff --git a/web_src/js/features/install.js b/web_src/js/features/install.js
index 9468ba9c4..2ba6fe127 100644
--- a/web_src/js/features/install.js
+++ b/web_src/js/features/install.js
@@ -1,4 +1,5 @@
 import $ from 'jquery';
+import {hideElem, showElem} from '../utils/dom.js';
 
 export function initInstall() {
   if ($('.page-content.install').length === 0) {
@@ -21,12 +22,12 @@ export function initInstall() {
   // Database type change detection.
   $('#db_type').on('change', function () {
     const dbType = $(this).val();
-    $('div[data-db-setting-for]').hide();
-    $(`div[data-db-setting-for=${dbType}]`).show();
+    hideElem($('div[data-db-setting-for]'));
+    showElem($(`div[data-db-setting-for=${dbType}]`));
 
     if (dbType !== 'sqlite3') {
       // for most remote database servers
-      $(`div[data-db-setting-for=common-host]`).show();
+      showElem($(`div[data-db-setting-for=common-host]`));
       const lastDbHost = $dbHost.val();
       const isDbHostDefault = !lastDbHost || Object.values(defaultDbHosts).includes(lastDbHost);
       if (isDbHostDefault) {
diff --git a/web_src/js/features/org-team.js b/web_src/js/features/org-team.js
index 9e6c3c7ff..3640bb96f 100644
--- a/web_src/js/features/org-team.js
+++ b/web_src/js/features/org-team.js
@@ -1,4 +1,5 @@
 import $ from 'jquery';
+import {hideElem, showElem} from '../utils/dom.js';
 
 const {appSubUrl} = window.config;
 
@@ -7,9 +8,9 @@ export function initOrgTeamSettings() {
   $('.organization.new.team input[name=permission]').on('change', () => {
     const val = $('input[name=permission]:checked', '.organization.new.team').val();
     if (val === 'admin') {
-      $('.organization.new.team .team-units').hide();
+      hideElem($('.organization.new.team .team-units'));
     } else {
-      $('.organization.new.team .team-units').show();
+      showElem($('.organization.new.team .team-units'));
     }
   });
 }
diff --git a/web_src/js/features/repo-commit.js b/web_src/js/features/repo-commit.js
index 3aba85091..e2eef3ee5 100644
--- a/web_src/js/features/repo-commit.js
+++ b/web_src/js/features/repo-commit.js
@@ -1,5 +1,6 @@
 import $ from 'jquery';
 import {createTippy} from '../modules/tippy.js';
+import {toggleElem} from '../utils/dom.js';
 
 const {csrfToken} = window.config;
 
@@ -7,7 +8,7 @@ export function initRepoEllipsisButton() {
   $('.ellipsis-button').on('click', function (e) {
     e.preventDefault();
     const expanded = $(this).attr('aria-expanded') === 'true';
-    $(this).parent().find('.commit-body').toggle();
+    toggleElem($(this).parent().find('.commit-body'));
     $(this).attr('aria-expanded', String(!expanded));
   });
 }
diff --git a/web_src/js/features/repo-common.js b/web_src/js/features/repo-common.js
index a218c5b30..1a32d7cb6 100644
--- a/web_src/js/features/repo-common.js
+++ b/web_src/js/features/repo-common.js
@@ -1,4 +1,5 @@
 import $ from 'jquery';
+import {hideElem, showElem, toggleElem} from '../utils/dom.js';
 
 const {csrfToken} = window.config;
 
@@ -76,8 +77,8 @@ export function initRepoCommonBranchOrTagDropdown(selector) {
   $(selector).each(function () {
     const $dropdown = $(this);
     $dropdown.find('.reference.column').on('click', function () {
-      $dropdown.find('.scrolling.reference-list-menu').hide();
-      $($(this).data('target')).show();
+      hideElem($dropdown.find('.scrolling.reference-list-menu'));
+      showElem($($(this).data('target')));
       return false;
     });
   });
@@ -102,7 +103,7 @@ export function initRepoCommonLanguageStats() {
   if ($('.language-stats').length > 0) {
     $('.language-stats').on('click', (e) => {
       e.preventDefault();
-      $('.language-stats-details, .repository-menu').slideToggle();
+      toggleElem($('.language-stats-details, .repository-menu'));
     });
   }
 }
diff --git a/web_src/js/features/repo-diff.js b/web_src/js/features/repo-diff.js
index 9b5da7de8..d2559b123 100644
--- a/web_src/js/features/repo-diff.js
+++ b/web_src/js/features/repo-diff.js
@@ -35,8 +35,8 @@ export function initRepoDiffFileViewToggle() {
     $this.addClass('active');
 
     const $target = $($this.data('toggle-selector'));
-    $target.parent().children().addClass('hide');
-    $target.removeClass('hide');
+    $target.parent().children().addClass('gt-hidden');
+    $target.removeClass('gt-hidden');
   });
 }
 
@@ -92,7 +92,7 @@ export function initRepoDiffConversationNav() {
   // Previous/Next code review conversation
   $(document).on('click', '.previous-conversation', (e) => {
     const $conversation = $(e.currentTarget).closest('.comment-code-cloud');
-    const $conversations = $('.comment-code-cloud:not(.hide)');
+    const $conversations = $('.comment-code-cloud:not(.gt-hidden)');
     const index = $conversations.index($conversation);
     const previousIndex = index > 0 ? index - 1 : $conversations.length - 1;
     const $previousConversation = $conversations.eq(previousIndex);
@@ -101,7 +101,7 @@ export function initRepoDiffConversationNav() {
   });
   $(document).on('click', '.next-conversation', (e) => {
     const $conversation = $(e.currentTarget).closest('.comment-code-cloud');
-    const $conversations = $('.comment-code-cloud:not(.hide)');
+    const $conversations = $('.comment-code-cloud:not(.gt-hidden)');
     const index = $conversations.index($conversation);
     const nextIndex = index < $conversations.length - 1 ? index + 1 : 0;
     const $nextConversation = $conversations.eq(nextIndex);
diff --git a/web_src/js/features/repo-editor.js b/web_src/js/features/repo-editor.js
index f32bdbb8c..a9d143847 100644
--- a/web_src/js/features/repo-editor.js
+++ b/web_src/js/features/repo-editor.js
@@ -2,6 +2,7 @@ import $ from 'jquery';
 import {htmlEscape} from 'escape-goat';
 import {initMarkupContent} from '../markup/content.js';
 import {createCodeEditor} from './codeeditor.js';
+import {hideElem, showElem} from '../utils/dom.js';
 
 const {csrfToken} = window.config;
 let previewFileModes;
@@ -81,10 +82,10 @@ export function initRepoEditor() {
 
   $('.js-quick-pull-choice-option').on('change', function () {
     if ($(this).val() === 'commit-to-new-branch') {
-      $('.quick-pull-branch-name').show();
+      showElem($('.quick-pull-branch-name'));
       $('.quick-pull-branch-name input').prop('required', true);
     } else {
-      $('.quick-pull-branch-name').hide();
+      hideElem($('.quick-pull-branch-name'));
       $('.quick-pull-branch-name input').prop('required', false);
     }
     $('#commit-button').text($(this).attr('button_text'));
diff --git a/web_src/js/features/repo-findfile.js b/web_src/js/features/repo-findfile.js
index 0eae4a75d..093f90fe8 100644
--- a/web_src/js/features/repo-findfile.js
+++ b/web_src/js/features/repo-findfile.js
@@ -1,5 +1,6 @@
 import $ from 'jquery';
 import {svg} from '../svg.js';
+import {toggleElem} from '../utils/dom.js';
 
 const {csrf} = window.config;
 
@@ -83,7 +84,7 @@ function filterRepoFiles(filter) {
   const filterResult = filterRepoFilesWeighted(files, filter);
   const tmplRow = `<tr><td><a></a></td></tr>`;
 
-  $repoFindFileNoResult.toggle(filterResult.length === 0);
+  toggleElem($repoFindFileNoResult, filterResult.length === 0);
   for (const r of filterResult) {
     const $row = $(tmplRow);
     const $a = $row.find('a');
diff --git a/web_src/js/features/repo-graph.js b/web_src/js/features/repo-graph.js
index 16d35e66f..e445ae110 100644
--- a/web_src/js/features/repo-graph.js
+++ b/web_src/js/features/repo-graph.js
@@ -56,17 +56,17 @@ export function initRepoGraphGit() {
     ajaxUrl.searchParams.set('div-only', 'true');
     window.history.replaceState({}, '', queryString ? `?${queryString}` : window.location.pathname);
     $('#pagination').empty();
-    $('#rel-container').addClass('hide');
-    $('#rev-container').addClass('hide');
-    $('#loading-indicator').removeClass('hide');
+    $('#rel-container').addClass('gt-hidden');
+    $('#rev-container').addClass('gt-hidden');
+    $('#loading-indicator').removeClass('gt-hidden');
     (async () => {
       const div = $(await $.ajax(String(ajaxUrl)));
       $('#pagination').html(div.find('#pagination').html());
       $('#rel-container').html(div.find('#rel-container').html());
       $('#rev-container').html(div.find('#rev-container').html());
-      $('#loading-indicator').addClass('hide');
-      $('#rel-container').removeClass('hide');
-      $('#rev-container').removeClass('hide');
+      $('#loading-indicator').addClass('gt-hidden');
+      $('#rel-container').removeClass('gt-hidden');
+      $('#rev-container').removeClass('gt-hidden');
     })();
   };
   const dropdownSelected = params.getAll('branch');
diff --git a/web_src/js/features/repo-home.js b/web_src/js/features/repo-home.js
index c4bdf3d45..dfccffc79 100644
--- a/web_src/js/features/repo-home.js
+++ b/web_src/js/features/repo-home.js
@@ -1,5 +1,6 @@
 import $ from 'jquery';
 import {stripTags} from '../utils.js';
+import {hideElem, showElem} from '../utils/dom.js';
 
 const {appSubUrl, csrfToken} = window.config;
 
@@ -13,12 +14,12 @@ export function initRepoTopicBar() {
   const topicPrompts = getPrompts();
 
   mgrBtn.on('click', () => {
-    viewDiv.hide();
-    editDiv.css('display', ''); // show Semantic UI Grid
+    hideElem(viewDiv);
+    showElem(editDiv);
   });
 
   function getPrompts() {
-    const hidePrompt = $('div.hide#validate_prompt');
+    const hidePrompt = $('#validate_prompt');
     const prompts = {
       countPrompt: hidePrompt.children('#count_prompt').text(),
       formatPrompt: hidePrompt.children('#format_prompt').text()
@@ -47,8 +48,8 @@ export function initRepoTopicBar() {
             link.insertBefore(last);
           }
         }
-        editDiv.css('display', 'none');
-        viewDiv.show();
+        hideElem(editDiv);
+        showElem(viewDiv);
       }
     }).fail((xhr) => {
       if (xhr.status === 422) {
diff --git a/web_src/js/features/repo-issue-content.js b/web_src/js/features/repo-issue-content.js
index a96da53f2..87295573e 100644
--- a/web_src/js/features/repo-issue-content.js
+++ b/web_src/js/features/repo-issue-content.js
@@ -16,7 +16,7 @@ function showContentHistoryDetail(issueBaseUrl, commentId, historyId, itemTitleH
   ${svg('octicon-x', 16, 'close icon inside')}
   <div class="header gt-df gt-ac gt-sb">
     <div>${itemTitleHtml}</div>
-    <div class="ui dropdown dialog-header-options gt-df gt-ac gt-mr-5 hide">
+    <div class="ui dropdown dialog-header-options gt-df gt-ac gt-mr-5 gt-hidden">
       ${i18nTextOptions}${svg('octicon-triangle-down', 14, 'dropdown icon')}
       <div class="menu">
         <div class="item red text" data-option-item="delete">${i18nTextDeleteFromHistory}</div>
@@ -62,7 +62,7 @@ function showContentHistoryDetail(issueBaseUrl, commentId, historyId, itemTitleH
         $dialog.find('.comment-diff-data').removeClass('is-loading').html(resp.diffHtml);
         // there is only one option "item[data-option-item=delete]", so the dropdown can be entirely shown/hidden.
         if (resp.canSoftDelete) {
-          $dialog.find('.dialog-header-options').removeClass('hide');
+          $dialog.find('.dialog-header-options').removeClass('gt-hidden');
         }
       });
     },
diff --git a/web_src/js/features/repo-issue.js b/web_src/js/features/repo-issue.js
index 135e3384a..179ca9b72 100644
--- a/web_src/js/features/repo-issue.js
+++ b/web_src/js/features/repo-issue.js
@@ -5,6 +5,7 @@ import {createCommentEasyMDE, getAttachedEasyMDE} from './comp/EasyMDE.js';
 import {initEasyMDEImagePaste} from './comp/ImagePaste.js';
 import {initCompMarkupContentPreviewTab} from './comp/MarkupContentPreview.js';
 import {initTooltip, showTemporaryTooltip} from '../modules/tippy.js';
+import {hideElem, showElem, toggleElem} from '../utils/dom.js';
 
 const {appSubUrl, csrfToken} = window.config;
 
@@ -40,7 +41,7 @@ export function initRepoIssueTimeTracking() {
 }
 
 function updateDeadline(deadlineString) {
-  $('#deadline-err-invalid-date').hide();
+  hideElem($('#deadline-err-invalid-date'));
   $('#deadline-loader').addClass('loading');
 
   let realDeadline = null;
@@ -49,7 +50,7 @@ function updateDeadline(deadlineString) {
 
     if (Number.isNaN(newDate)) {
       $('#deadline-loader').removeClass('loading');
-      $('#deadline-err-invalid-date').show();
+      showElem($('#deadline-err-invalid-date'));
       return false;
     }
     realDeadline = new Date(newDate);
@@ -69,7 +70,7 @@ function updateDeadline(deadlineString) {
     },
     error() {
       $('#deadline-loader').removeClass('loading');
-      $('#deadline-err-invalid-date').show();
+      showElem($('#deadline-err-invalid-date'));
     },
   });
 }
@@ -213,8 +214,8 @@ export function initRepoIssueCodeCommentCancel() {
   $(document).on('click', '.cancel-code-comment', (e) => {
     const form = $(e.currentTarget).closest('form');
     if (form.length > 0 && form.hasClass('comment-form')) {
-      form.addClass('hide');
-      form.closest('.comment-code-cloud').find('button.comment-form-reply').show();
+      form.addClass('gt-hidden');
+      showElem(form.closest('.comment-code-cloud').find('button.comment-form-reply'));
     } else {
       form.closest('.comment-code-cloud').remove();
     }
@@ -269,7 +270,7 @@ export function initRepoPullRequestUpdate() {
 
 export function initRepoPullRequestMergeInstruction() {
   $('.show-instruction').on('click', () => {
-    $('.instruct-content').toggle();
+    toggleElem($('.instruct-content'));
   });
 }
 
@@ -455,9 +456,9 @@ export function initRepoPullRequestReview() {
   $(document).on('click', 'button.comment-form-reply', async function (e) {
     e.preventDefault();
 
-    $(this).hide();
+    hideElem($(this));
     const form = $(this).closest('.comment-code-cloud').find('.comment-form');
-    form.removeClass('hide');
+    form.removeClass('gt-hidden');
     const $textarea = form.find('textarea');
     let easyMDE = getAttachedEasyMDE($textarea);
     if (!easyMDE) {
@@ -488,10 +489,10 @@ export function initRepoPullRequestReview() {
 
   $('.btn-review').on('click', function (e) {
     e.preventDefault();
-    $(this).closest('.dropdown').find('.menu').toggle('visible');
+    $(this).closest('.dropdown').find('.menu').toggle('visible'); // eslint-disable-line
   }).closest('.dropdown').find('.close').on('click', function (e) {
     e.preventDefault();
-    $(this).closest('.menu').toggle('visible');
+    $(this).closest('.menu').toggle('visible'); // eslint-disable-line
   });
 
   $(document).on('click', 'a.add-code-comment', async function (e) {
@@ -551,7 +552,7 @@ export function initRepoIssueReferenceIssue() {
   // Reference issue
   $(document).on('click', '.reference-issue', function (event) {
     const $this = $(this);
-    $this.closest('.dropdown').find('.menu').toggle('visible');
+    $this.closest('.dropdown').find('.menu').toggle('visible');  // eslint-disable-line
 
     const content = $(`#${$this.data('target')}`).text();
     const poster = $this.data('poster-username');
@@ -587,12 +588,12 @@ export function initRepoIssueTitleEdit() {
   const $editInput = $('#edit-title-input input');
 
   const editTitleToggle = function () {
-    $issueTitle.toggle();
-    $('.not-in-edit').toggle();
-    $('#edit-title-input').toggle();
-    $('#pull-desc').toggle();
-    $('#pull-desc-edit').toggle();
-    $('.in-edit').toggle();
+    toggleElem($issueTitle);
+    toggleElem($('.not-in-edit'));
+    toggleElem($('#edit-title-input'));
+    toggleElem($('#pull-desc'));
+    toggleElem($('#pull-desc-edit'));
+    toggleElem($('.in-edit'));
     $('#issue-title-wrapper').toggleClass('edit-active');
     $editInput.focus();
     return false;
diff --git a/web_src/js/features/repo-legacy.js b/web_src/js/features/repo-legacy.js
index 2cf4963b6..e1dc51432 100644
--- a/web_src/js/features/repo-legacy.js
+++ b/web_src/js/features/repo-legacy.js
@@ -25,6 +25,7 @@ import {initCommentContent, initMarkupContent} from '../markup/content.js';
 import {initCompReactionSelector} from './comp/ReactionSelector.js';
 import {initRepoSettingBranches} from './repo-settings.js';
 import {initRepoPullRequestMergeForm} from './repo-issue-pr-form.js';
+import {hideElem, showElem} from '../utils/dom.js';
 
 const {csrfToken} = window.config;
 
@@ -55,9 +56,9 @@ export function initRepoCommentForm() {
       }
     });
     $selectBranch.find('.reference.column').on('click', function () {
-      $selectBranch.find('.scrolling.reference-list-menu').css('display', 'none');
+      hideElem($selectBranch.find('.scrolling.reference-list-menu'));
       $selectBranch.find('.reference .text').removeClass('black');
-      $($(this).data('target')).css('display', 'block');
+      showElem($($(this).data('target')));
       $(this).find('.text').addClass('black');
       return false;
     });
@@ -174,15 +175,15 @@ export function initRepoCommentForm() {
       $(this).parent().find('.item').each(function () {
         if ($(this).hasClass('checked')) {
           listIds.push($(this).data('id'));
-          $($(this).data('id-selector')).removeClass('hide');
+          $($(this).data('id-selector')).removeClass('gt-hidden');
         } else {
-          $($(this).data('id-selector')).addClass('hide');
+          $($(this).data('id-selector')).addClass('gt-hidden');
         }
       });
       if (listIds.length === 0) {
-        $noSelect.removeClass('hide');
+        $noSelect.removeClass('gt-hidden');
       } else {
-        $noSelect.addClass('hide');
+        $noSelect.addClass('gt-hidden');
       }
       $($(this).parent().data('id')).val(listIds.join(','));
       return false;
@@ -208,9 +209,9 @@ export function initRepoCommentForm() {
       }
 
       $list.find('.item').each(function () {
-        $(this).addClass('hide');
+        $(this).addClass('gt-hidden');
       });
-      $noSelect.removeClass('hide');
+      $noSelect.removeClass('gt-hidden');
       $($(this).parent().data('id')).val('');
     });
   }
@@ -257,7 +258,7 @@ export function initRepoCommentForm() {
         </a>
       `);
 
-      $(`.ui${select_id}.list .no-select`).addClass('hide');
+      $(`.ui${select_id}.list .no-select`).addClass('gt-hidden');
       $(input_id).val($(this).data('id'));
     });
     $menu.find('.no-select.item').on('click', function () {
@@ -275,7 +276,7 @@ export function initRepoCommentForm() {
       }
 
       $list.find('.selected').html('');
-      $list.find('.no-select').removeClass('hide');
+      $list.find('.no-select').removeClass('gt-hidden');
       $(input_id).val('');
     });
   }
@@ -290,7 +291,7 @@ export function initRepoCommentForm() {
 async function onEditContent(event) {
   event.preventDefault();
 
-  $(this).closest('.dropdown').find('.menu').toggle('visible');
+  $(this).closest('.dropdown').find('.menu').toggle('visible'); // eslint-disable-line
   const $segment = $(this).closest('.header').next();
   const $editContentZone = $segment.find('.edit-content-zone');
   const $renderContent = $segment.find('.render-content');
@@ -387,16 +388,16 @@ async function onEditContent(event) {
     });
 
     $editContentZone.find('.cancel.button').on('click', () => {
-      $renderContent.show();
-      $editContentZone.hide();
+      showElem($renderContent);
+      hideElem($editContentZone);
       if (dz) {
         dz.emit('reload');
       }
     });
 
     $saveButton.on('click', () => {
-      $renderContent.show();
-      $editContentZone.hide();
+      showElem($renderContent);
+      hideElem($editContentZone);
       const $attachments = $dropzone.find('.files').find('[name=files]').map(function () {
         return $(this).val();
       }).get();
@@ -438,8 +439,8 @@ async function onEditContent(event) {
   }
 
   // Show write/preview tab and copy raw content as needed
-  $editContentZone.show();
-  $renderContent.hide();
+  showElem($editContentZone);
+  hideElem($renderContent);
   if ($textarea.val().length === 0) {
     $textarea.val($rawContent.text());
     easyMDE.value($rawContent.text());
@@ -558,10 +559,10 @@ export function initRepository() {
     // show pull request form
     $repoComparePull.find('button.show-form').on('click', function (e) {
       e.preventDefault();
-      $(this).parent().hide();
+      hideElem($(this).parent());
 
       const $form = $repoComparePull.find('.pullrequest-form');
-      $form.show();
+      showElem($form);
       $form.find('textarea.edit_area').each(function() {
         const easyMDE = getAttachedEasyMDE($(this));
         if (easyMDE) {
@@ -583,7 +584,7 @@ function initRepoIssueCommentEdit() {
 
   // Quote reply
   $(document).on('click', '.quote-reply', function (event) {
-    $(this).closest('.dropdown').find('.menu').toggle('visible');
+    $(this).closest('.dropdown').find('.menu').toggle('visible'); // eslint-disable-line
     const target = $(this).data('target');
     const quote = $(`#${target}`).text().replace(/\n/g, '\n> ');
     const content = `> ${quote}\n\n`;
diff --git a/web_src/js/features/repo-migrate.js b/web_src/js/features/repo-migrate.js
index d44f540c4..93d1390b4 100644
--- a/web_src/js/features/repo-migrate.js
+++ b/web_src/js/features/repo-migrate.js
@@ -1,12 +1,13 @@
 import $ from 'jquery';
+import {hideElem, showElem} from '../utils/dom.js';
 
 const {appSubUrl, csrfToken} = window.config;
 
 export function initRepoMigrationStatusChecker() {
   const migrating = $('#repo_migrating');
-  $('#repo_migrating_failed').hide();
-  $('#repo_migrating_failed_image').hide();
-  $('#repo_migrating_progress_message').hide();
+  hideElem($('#repo_migrating_failed'));
+  hideElem($('#repo_migrating_failed_image'));
+  hideElem($('#repo_migrating_progress_message'));
   if (migrating) {
     const task = migrating.attr('task');
     if (task === undefined) {
@@ -24,15 +25,15 @@ export function initRepoMigrationStatusChecker() {
             window.location.reload();
             return;
           } else if (xhr.responseJSON.status === 3) {
-            $('#repo_migrating_progress').hide();
-            $('#repo_migrating').hide();
-            $('#repo_migrating_failed').show();
-            $('#repo_migrating_failed_image').show();
+            hideElem($('#repo_migrating_progress'));
+            hideElem($('#repo_migrating'));
+            showElem($('#repo_migrating_failed'));
+            showElem($('#repo_migrating_failed_image'));
             $('#repo_migrating_failed_error').text(xhr.responseJSON.message);
             return;
           }
           if (xhr.responseJSON.message) {
-            $('#repo_migrating_progress_message').show();
+            showElem($('#repo_migrating_progress_message'));
             $('#repo_migrating_progress_message').text(xhr.responseJSON.message);
           }
           setTimeout(() => {
@@ -40,10 +41,10 @@ export function initRepoMigrationStatusChecker() {
           }, 2000);
           return;
         }
-        $('#repo_migrating_progress').hide();
-        $('#repo_migrating').hide();
-        $('#repo_migrating_failed').show();
-        $('#repo_migrating_failed_image').show();
+        hideElem($('#repo_migrating_progress'));
+        hideElem($('#repo_migrating'));
+        showElem($('#repo_migrating_failed'));
+        showElem($('#repo_migrating_failed_image'));
       }
     });
   }
diff --git a/web_src/js/features/repo-migration.js b/web_src/js/features/repo-migration.js
index c317c7245..ee2ec0194 100644
--- a/web_src/js/features/repo-migration.js
+++ b/web_src/js/features/repo-migration.js
@@ -1,4 +1,5 @@
 import $ from 'jquery';
+import {hideElem, showElem, toggleElem} from '../utils/dom.js';
 
 const $service = $('#service_type');
 const $user = $('#auth_username');
@@ -18,7 +19,7 @@ export function initRepoMigration() {
   $pass.on('keyup', () => {checkItems(false)});
   $token.on('keyup', () => {checkItems(true)});
   $mirror.on('change', () => {checkItems(true)});
-  $('#lfs_settings_show').on('click', () => { $lfsEndpoint.show(); return false });
+  $('#lfs_settings_show').on('click', () => { showElem($lfsEndpoint); return false });
   $lfs.on('change', setLFSSettingsVisibility);
 
   const $cloneAddr = $('#clone_addr');
@@ -57,6 +58,6 @@ function checkItems(tokenAuth) {
 
 function setLFSSettingsVisibility() {
   const visible = $lfs.is(':checked');
-  $lfsSettings.toggle(visible);
-  $lfsEndpoint.hide();
+  toggleElem($lfsSettings, visible);
+  hideElem($lfsEndpoint);
 }
diff --git a/web_src/js/features/repo-release.js b/web_src/js/features/repo-release.js
index 7589d108f..a061c6b23 100644
--- a/web_src/js/features/repo-release.js
+++ b/web_src/js/features/repo-release.js
@@ -3,13 +3,14 @@ import {attachTribute} from './tribute.js';
 import {initCompMarkupContentPreviewTab} from './comp/MarkupContentPreview.js';
 import {initEasyMDEImagePaste} from './comp/ImagePaste.js';
 import {createCommentEasyMDE} from './comp/EasyMDE.js';
+import {hideElem} from '../utils/dom.js';
 
 export function initRepoRelease() {
   $(document).on('click', '.remove-rel-attach', function() {
     const uuid = $(this).data('uuid');
     const id = $(this).data('id');
     $(`input[name='attachment-del-${uuid}']`).attr('value', true);
-    $(`#attachment-${id}`).hide();
+    hideElem($(`#attachment-${id}`));
   });
 }
 
diff --git a/web_src/js/features/repo-template.js b/web_src/js/features/repo-template.js
index dc4ae1e26..0c5ea5233 100644
--- a/web_src/js/features/repo-template.js
+++ b/web_src/js/features/repo-template.js
@@ -1,5 +1,6 @@
 import $ from 'jquery';
 import {htmlEscape} from 'escape-goat';
+import {hideElem, showElem} from '../utils/dom.js';
 
 const {appSubUrl} = window.config;
 
@@ -9,11 +10,11 @@ export function initRepoTemplateSearch() {
     const $templateUnits = $('#template_units');
     const $nonTemplate = $('#non_template');
     if ($repoTemplate.val() !== '' && $repoTemplate.val() !== '0') {
-      $templateUnits.show();
-      $nonTemplate.hide();
+      showElem($templateUnits);
+      hideElem($nonTemplate);
     } else {
-      $templateUnits.hide();
-      $nonTemplate.show();
+      hideElem($templateUnits);
+      showElem($nonTemplate);
     }
   };
   $repoTemplate.on('change', checkTemplate);
diff --git a/web_src/js/features/repo-unicode-escape.js b/web_src/js/features/repo-unicode-escape.js
index f97bcc7ee..67f2df1d9 100644
--- a/web_src/js/features/repo-unicode-escape.js
+++ b/web_src/js/features/repo-unicode-escape.js
@@ -1,17 +1,18 @@
 import $ from 'jquery';
+import {hideElem, showElem} from '../utils/dom.js';
 
 export function initUnicodeEscapeButton() {
   $(document).on('click', 'a.escape-button', (e) => {
     e.preventDefault();
     $(e.target).parents('.file-content, .non-diff-file-content').find('.file-code, .file-view').addClass('unicode-escaped');
-    $(e.target).hide();
-    $(e.target).siblings('a.unescape-button').show();
+    hideElem($(e.target));
+    showElem($(e.target).siblings('a.unescape-button'));
   });
   $(document).on('click', 'a.unescape-button', (e) => {
     e.preventDefault();
     $(e.target).parents('.file-content, .non-diff-file-content').find('.file-code, .file-view').removeClass('unicode-escaped');
-    $(e.target).hide();
-    $(e.target).siblings('a.escape-button').show();
+    hideElem($(e.target));
+    showElem($(e.target).siblings('a.escape-button'));
   });
   $(document).on('click', 'a.toggle-escape-button', (e) => {
     e.preventDefault();
@@ -19,12 +20,12 @@ export function initUnicodeEscapeButton() {
     const fileView = fileContent.find('.file-code, .file-view');
     if (fileView.hasClass('unicode-escaped')) {
       fileView.removeClass('unicode-escaped');
-      fileContent.find('a.unescape-button').hide();
-      fileContent.find('a.escape-button').show();
+      hideElem(fileContent.find('a.unescape-button'));
+      showElem(fileContent.find('a.escape-button'));
     } else {
       fileView.addClass('unicode-escaped');
-      fileContent.find('a.unescape-button').show();
-      fileContent.find('a.escape-button').hide();
+      showElem(fileContent.find('a.unescape-button'));
+      hideElem(fileContent.find('a.escape-button'));
     }
   });
 }
diff --git a/web_src/js/features/user-auth-webauthn.js b/web_src/js/features/user-auth-webauthn.js
index 9c9fffd99..f30017afc 100644
--- a/web_src/js/features/user-auth-webauthn.js
+++ b/web_src/js/features/user-auth-webauthn.js
@@ -1,5 +1,6 @@
 import $ from 'jquery';
 import {encode, decode} from 'uint8-to-base64';
+import {hideElem, showElem} from '../utils/dom.js';
 
 const {appSubUrl, csrfToken} = window.config;
 
@@ -132,16 +133,18 @@ function webauthnRegistered(newCredential) {
 }
 
 function webAuthnError(errorType, message) {
-  $('#webauthn-error [data-webauthn-error-msg]').hide();
+  hideElem($('#webauthn-error [data-webauthn-error-msg]'));
   const $errorGeneral = $(`#webauthn-error [data-webauthn-error-msg=general]`);
   if (errorType === 'general') {
-    $errorGeneral.show().text(message || 'unknown error');
+    showElem($errorGeneral);
+    $errorGeneral.text(message || 'unknown error');
   } else {
     const $errorTyped = $(`#webauthn-error [data-webauthn-error-msg=${errorType}]`);
     if ($errorTyped.length) {
-      $errorTyped.show();
+      showElem($errorTyped);
     } else {
-      $errorGeneral.show().text(`unknown error type: ${errorType}`);
+      showElem($errorGeneral);
+      $errorGeneral.text(`unknown error type: ${errorType}`);
     }
   }
   $('#webauthn-error').modal('show');
diff --git a/web_src/js/features/user-auth.js b/web_src/js/features/user-auth.js
index 55aace3bc..34e773fe7 100644
--- a/web_src/js/features/user-auth.js
+++ b/web_src/js/features/user-auth.js
@@ -1,4 +1,5 @@
 import $ from 'jquery';
+import {hideElem, showElem} from '../utils/dom.js';
 
 export function initUserAuthOauth2() {
   const $oauth2LoginNav = $('#oauth2-login-navigator');
@@ -8,14 +9,14 @@ export function initUserAuthOauth2() {
     const oauthLoader = $('#oauth2-login-loader');
     const oauthNav = $('#oauth2-login-navigator');
 
-    oauthNav.hide();
+    hideElem(oauthNav);
     oauthLoader.removeClass('disabled');
 
     setTimeout(() => {
       // recover previous content to let user try again
       // usually redirection will be performed before this action
       oauthLoader.addClass('disabled');
-      oauthNav.show();
+      showElem(oauthNav);
     }, 5000);
   });
 }
diff --git a/web_src/js/features/user-settings.js b/web_src/js/features/user-settings.js
index 3ed29f39b..d49bf3927 100644
--- a/web_src/js/features/user-settings.js
+++ b/web_src/js/features/user-settings.js
@@ -1,4 +1,5 @@
 import $ from 'jquery';
+import {hideElem, showElem} from '../utils/dom.js';
 
 export function initUserSettings() {
   if ($('.user.settings.profile').length > 0) {
@@ -6,11 +7,11 @@ export function initUserSettings() {
       const $prompt = $('#name-change-prompt');
       const $prompt_redirect = $('#name-change-redirect-prompt');
       if ($(this).val().toString().toLowerCase() !== $(this).data('name').toString().toLowerCase()) {
-        $prompt.show();
-        $prompt_redirect.show();
+        showElem($prompt);
+        showElem($prompt_redirect);
       } else {
-        $prompt.hide();
-        $prompt_redirect.hide();
+        hideElem($prompt);
+        hideElem($prompt_redirect);
       }
     });
   }
diff --git a/web_src/js/utils/dom.js b/web_src/js/utils/dom.js
new file mode 100644
index 000000000..8872a9e4a
--- /dev/null
+++ b/web_src/js/utils/dom.js
@@ -0,0 +1,65 @@
+function getComputedStyleProperty(el, prop) {
+  const cs = el ? window.getComputedStyle(el) : null;
+  return cs ? cs[prop] : null;
+}
+
+function isShown(el) {
+  return getComputedStyleProperty(el, 'display') !== 'none';
+}
+
+function assertShown(el, expectShown) {
+  if (window.config.runModeIsProd) return;
+
+  // to help developers to catch display bugs, this assertion can be removed after next release cycle or if it has been proved that there is no bug.
+  if (expectShown && !isShown(el)) {
+    throw new Error('element is hidden but should be shown');
+  } else if (!expectShown && isShown(el)) {
+    throw new Error('element is shown but should be hidden');
+  }
+}
+
+function elementsCall(el, func, ...args) {
+  if (el instanceof String) {
+    el = document.querySelectorAll(el);
+  }
+  if (el instanceof Node) {
+    func(el, ...args);
+  } else if (el.length !== undefined) {
+    // this works for: NodeList, HTMLCollection, Array, jQuery
+    for (const e of el) {
+      func(e, ...args);
+    }
+  } else {
+    throw new Error('invalid argument to be shown/hidden');
+  }
+}
+
+function toggleShown(el, force) {
+  if (force === true) {
+    el.classList.remove('gt-hidden');
+    assertShown(el, true);
+  } else if (force === false) {
+    el.classList.add('gt-hidden');
+    assertShown(el, false);
+  } else if (force === undefined) {
+    const wasShown = window.config.runModeIsProd ? undefined : isShown(el);
+    el.classList.toggle('gt-hidden');
+    if (wasShown !== undefined) {
+      assertShown(el, !wasShown);
+    }
+  } else {
+    throw new Error('invalid force argument');
+  }
+}
+
+export function showElem(el) {
+  elementsCall(el, toggleShown, true);
+}
+
+export function hideElem(el) {
+  elementsCall(el, toggleShown, false);
+}
+
+export function toggleElem(el, force) {
+  elementsCall(el, toggleShown, force);
+}
diff --git a/web_src/less/_base.less b/web_src/less/_base.less
index 771049ad3..fae29d0d6 100644
--- a/web_src/less/_base.less
+++ b/web_src/less/_base.less
@@ -1812,11 +1812,6 @@ footer {
   }
 }
 
-// TODO: refactor to use ".gt-hidden" instead (a simple search&replace should do the trick)
-.hide {
-  display: none;
-}
-
 .center:not(.popup) {
   text-align: center;
 }
diff --git a/web_src/less/_repository.less b/web_src/less/_repository.less
index b2c4cdcdf..f48933571 100644
--- a/web_src/less/_repository.less
+++ b/web_src/less/_repository.less
@@ -106,10 +106,6 @@
         margin-right: 8.75px;
       }
 
-      .hide {
-        display: none !important;
-      }
-
       .dependency {
         padding: 0;
         white-space: nowrap;
@@ -2592,18 +2588,10 @@
   }
 }
 
-#issue-filters.hide {
-  display: none;
-}
-
 #issue-actions {
   margin-top: -1rem !important; // counteract padding from Semantic
 }
 
-#issue-actions.hide {
-  display: none;
-}
-
 .ui.menu .item > img:not(.ui) {
   width: auto;
 }
diff --git a/web_src/less/helpers.less b/web_src/less/helpers.less
index 2b09780fb..9cabe0162 100644
--- a/web_src/less/helpers.less
+++ b/web_src/less/helpers.less
@@ -181,5 +181,15 @@
   .gt-js-small { justify-content: flex-start !important; }
 }
 
-// gt-hidden must be placed after all other "display: xxx !important" classes to win the hidden chance
+/*
+gt-hidden must be placed after all other "display: xxx !important" classes to win the chance
+do not use:
+* "[hidden]" attribute: it's too weak, can not be applied to an element with "display: flex"
+* ".hidden" class: it has been polluted by Fomantic UI in many cases
+* inline style="display: none": it's difficult to tweak
+* jQuery's show/hide/toggle: it can not show/hide elements with "display: xxx !important"
+only use:
+* this ".gt-hidden" class
+* showElem/hideElem/toggleElem functions in "utils/dom.js"
+*/
 .gt-hidden { display: none !important; }