Add simple JS init performance trace (#31459)

Related to #23461, and help some cases like #31412

For developers, they could use browser's Performance tool to collect
performance data, while this PR is also quite handy to optimize the
`index.js`.

For end users, this PR is simple enough and could figure out the slow
function quickly.


![image](https://github.com/go-gitea/gitea/assets/2114189/a557b08e-6594-474b-81a3-03d5ac2bd68e)

web_src/js/index.js

@@ -94,110 +94,138 @@ import {
 import {initGlobalDropzone} from './features/dropzone.js';
 import {initGlobalEnterQuickSubmit, initGlobalFormDirtyLeaveConfirm} from './features/common-form.js';
 
-// Init Gitea's Fomantic settings
 initGiteaFomantic();
 initDirAuto();
 initSubmitEventPolyfill();
 
+function callInitFunctions(functions) {
+  // Start performance trace by accessing a URL by "https://localhost/?_ui_performance_trace=1" or "https://localhost/?key=value&_ui_performance_trace=1"
+  // It is a quick check, no side effect so no need to do slow URL parsing.
+  const initStart = performance.now();
+  if (window.location.search.includes('_ui_performance_trace=1')) {
+    let results = [];
+    for (const func of functions) {
+      const start = performance.now();
+      func();
+      results.push({name: func.name, dur: performance.now() - start});
+    }
+    results = results.sort((a, b) => b.dur - a.dur);
+    for (let i = 0; i < 20 && i < results.length; i++) {
+      // eslint-disable-next-line no-console
+      console.log(`performance trace: ${results[i].name} ${results[i].dur.toFixed(3)}`);
+    }
+  } else {
+    for (const func of functions) {
+      func();
+    }
+  }
+  const initDur = performance.now() - initStart;
+  if (initDur > 500) {
+    console.error(`slow init functions took ${initDur.toFixed(3)}ms`);
+  }
+}
+
 onDomReady(() => {
-  initGlobalDropdown();
+  callInitFunctions([
-  initGlobalTabularMenu();
+    initGlobalDropdown,
-  initGlobalShowModal();
+    initGlobalTabularMenu,
-  initGlobalFetchAction();
+    initGlobalShowModal,
-  initGlobalTooltips();
+    initGlobalFetchAction,
-  initGlobalButtonClickOnEnter();
+    initGlobalTooltips,
-  initGlobalButtons();
+    initGlobalButtonClickOnEnter,
-  initGlobalCopyToClipboardListener();
+    initGlobalButtons,
-  initGlobalDropzone();
+    initGlobalCopyToClipboardListener,
-  initGlobalEnterQuickSubmit();
+    initGlobalDropzone,
-  initGlobalFormDirtyLeaveConfirm();
+    initGlobalEnterQuickSubmit,
-  initGlobalDeleteButton();
+    initGlobalFormDirtyLeaveConfirm,
-
+    initGlobalDeleteButton,
-  initCommonOrganization();
+
-  initCommonIssueListQuickGoto();
+    initCommonOrganization,
-
+    initCommonIssueListQuickGoto,
-  initCompSearchUserBox();
+
-  initCompWebHookEditor();
+    initCompSearchUserBox,
-
+    initCompWebHookEditor,
-  initInstall();
+
-
+    initInstall,
-  initHeadNavbarContentToggle();
+
-  initFootLanguageMenu();
+    initHeadNavbarContentToggle,
-
+    initFootLanguageMenu,
-  initCommentContent();
+
-  initContextPopups();
+    initCommentContent,
-  initHeatmap();
+    initContextPopups,
-  initImageDiff();
+    initHeatmap,
-  initMarkupAnchors();
+    initImageDiff,
-  initMarkupContent();
+    initMarkupAnchors,
-  initSshKeyFormParser();
+    initMarkupContent,
-  initStopwatch();
+    initSshKeyFormParser,
-  initTableSort();
+    initStopwatch,
-  initAutoFocusEnd();
+    initTableSort,
-  initFindFileInRepo();
+    initAutoFocusEnd,
-  initCopyContent();
+    initFindFileInRepo,
-
+    initCopyContent,
-  initAdminCommon();
+
-  initAdminEmails();
+    initAdminCommon,
-  initAdminUserListSearchForm();
+    initAdminEmails,
-  initAdminConfigs();
+    initAdminUserListSearchForm,
-  initAdminSelfCheck();
+    initAdminConfigs,
-
+    initAdminSelfCheck,
-  initDashboardRepoList();
+
-
+    initDashboardRepoList,
-  initNotificationCount();
+
-  initNotificationsTable();
+    initNotificationCount,
-
+    initNotificationsTable,
-  initOrgTeamSearchRepoBox();
+
-  initOrgTeamSettings();
+    initOrgTeamSearchRepoBox,
-
+    initOrgTeamSettings,
-  initRepoActivityTopAuthorsChart();
+
-  initRepoArchiveLinks();
+    initRepoActivityTopAuthorsChart,
-  initRepoBranchButton();
+    initRepoArchiveLinks,
-  initRepoCodeView();
+    initRepoBranchButton,
-  initRepoCommentForm();
+    initRepoCodeView,
-  initRepoEllipsisButton();
+    initRepoCommentForm,
-  initRepoDiffCommitBranchesAndTags();
+    initRepoEllipsisButton,
-  initRepoEditor();
+    initRepoDiffCommitBranchesAndTags,
-  initRepoGraphGit();
+    initRepoEditor,
-  initRepoIssueContentHistory();
+    initRepoGraphGit,
-  initRepoIssueDue();
+    initRepoIssueContentHistory,
-  initRepoIssueList();
+    initRepoIssueDue,
-  initRepoIssueSidebarList();
+    initRepoIssueList,
-  initArchivedLabelHandler();
+    initRepoIssueSidebarList,
-  initRepoIssueReferenceRepositorySearch();
+    initArchivedLabelHandler,
-  initRepoIssueTimeTracking();
+    initRepoIssueReferenceRepositorySearch,
-  initRepoIssueWipTitle();
+    initRepoIssueTimeTracking,
-  initRepoMigration();
+    initRepoIssueWipTitle,
-  initRepoMigrationStatusChecker();
+    initRepoMigration,
-  initRepoProject();
+    initRepoMigrationStatusChecker,
-  initRepoPullRequestMergeInstruction();
+    initRepoProject,
-  initRepoPullRequestAllowMaintainerEdit();
+    initRepoPullRequestMergeInstruction,
-  initRepoPullRequestReview();
+    initRepoPullRequestAllowMaintainerEdit,
-  initRepoRelease();
+    initRepoPullRequestReview,
-  initRepoReleaseNew();
+    initRepoRelease,
-  initRepoSettingGitHook();
+    initRepoReleaseNew,
-  initRepoSettingSearchTeamBox();
+    initRepoSettingGitHook,
-  initRepoSettingsCollaboration();
+    initRepoSettingSearchTeamBox,
-  initRepoTemplateSearch();
+    initRepoSettingsCollaboration,
-  initRepoTopicBar();
+    initRepoTemplateSearch,
-  initRepoWikiForm();
+    initRepoTopicBar,
-  initRepository();
+    initRepoWikiForm,
-  initRepositoryActionView();
+    initRepository,
-  initRepositorySearch();
+    initRepositoryActionView,
-  initRepoContributors();
+    initRepositorySearch,
-  initRepoCodeFrequency();
+    initRepoContributors,
-  initRepoRecentCommits();
+    initRepoCodeFrequency,
-
+    initRepoRecentCommits,
-  initCommitStatuses();
+
-  initCaptcha();
+    initCommitStatuses,
-
+    initCaptcha,
-  initUserAuthOauth2();
+
-  initUserAuthWebAuthn();
+    initUserAuthOauth2,
-  initUserAuthWebAuthnRegister();
+    initUserAuthWebAuthn,
-  initUserSettings();
+    initUserAuthWebAuthnRegister,
-  initRepoDiffView();
+    initUserSettings,
-  initPdfViewer();
+    initRepoDiffView,
-  initScopedAccessTokenCategories();
+    initPdfViewer,
-  initColorPickers();
+    initScopedAccessTokenCategories,
+    initColorPickers,
+  ]);
 });