Allow to use the Profiler when no client is connected in standalone DevTools

packages/react-devtools-core/src/standalone.js

@@ -30,7 +30,11 @@ import {readFileSync} from 'fs';
 import {installHook} from 'react-devtools-shared/src/hook';
 import DevTools from 'react-devtools-shared/src/devtools/views/DevTools';
 import {doesFilePathExist, launchEditor} from './editor';
-import {__DEBUG__} from 'react-devtools-shared/src/constants';
+import {
+  __DEBUG__,
+  LOCAL_STORAGE_DEFAULT_TAB_KEY,
+} from 'react-devtools-shared/src/constants';
+import {localStorageSetItem} from '../../react-devtools-shared/src/storage';
 
 import type {FrontendBridge} from 'react-devtools-shared/src/bridge';
 import type {InspectedElement} from 'react-devtools-shared/src/devtools/views/Components/types';
@@ -179,6 +183,20 @@ function onError({code, message}) {
   }
 }
 
+function openProfiler() {
+  // Mocked up bridge and store to allow the DevTools to be rendered
+  bridge = new Bridge({listen: () => {}, send: () => {}});
+  store = new Store(bridge, {});
+
+  // Ensure the Profiler tab is shown initially.
+  localStorageSetItem(
+    LOCAL_STORAGE_DEFAULT_TAB_KEY,
+    JSON.stringify('profiler'),
+  );
+
+  reload();
+}
+
 function initialize(socket: WebSocket) {
   const listeners = [];
   socket.onmessage = event => {
@@ -372,6 +390,7 @@ const DevtoolsUI = {
   setProjectRoots,
   setStatusListener,
   startServer,
+  openProfiler,
 };
 
 export default DevtoolsUI;

packages/react-devtools-shared/src/constants.js

@@ -20,6 +20,8 @@ export const TREE_OPERATION_UPDATE_TREE_BASE_DURATION = 4;
 export const TREE_OPERATION_UPDATE_ERRORS_OR_WARNINGS = 5;
 export const TREE_OPERATION_REMOVE_ROOT = 6;
 
+export const LOCAL_STORAGE_DEFAULT_TAB_KEY = 'React::DevTools::defaultTab';
+
 export const LOCAL_STORAGE_FILTER_PREFERENCES_KEY =
   'React::DevTools::componentFilters';
 

packages/react-devtools-shared/src/devtools/views/DevTools.js

@@ -38,6 +38,7 @@ import UnsupportedVersionDialog from './UnsupportedVersionDialog';
 import WarnIfLegacyBackendDetected from './WarnIfLegacyBackendDetected';
 import {useLocalStorage} from './hooks';
 import ThemeProvider from './ThemeProvider';
+import {LOCAL_STORAGE_DEFAULT_TAB_KEY} from '../../constants';
 
 import styles from './DevTools.css';
 
@@ -143,7 +144,7 @@ export default function DevTools({
   hideViewSourceAction,
 }: Props) {
   const [currentTab, setTab] = useLocalStorage<TabID>(
-    'React::DevTools::defaultTab',
+    LOCAL_STORAGE_DEFAULT_TAB_KEY,
     defaultTab,
   );
 

packages/react-devtools/app.html

@@ -142,6 +142,16 @@
             <strong>before</strong> importing React DOM.
           </div>
         </div>
+        <div class="box">
+          <div class="box-header">Profiler</div>
+          <div class="box-content">
+            Open the <a
+              id="profiler"
+              class="link"
+              href="#"
+            >Profiler tab</a> to inspect saved profiles.
+          </div>
+        </div>
         <div id="loading-status">Starting the server…</div>
       </div>
     </div>
@@ -201,6 +211,12 @@
         }
       }
 
+      function openProfiler() {
+        window.devtools
+          .setContentDOMNode(document.getElementById("container"))
+          .openProfiler();
+      }
+
       const link = $('#rn-help-link');
       link.addEventListener('click', event => {
         event.preventDefault();
@@ -217,6 +233,9 @@
       $byIp.addEventListener('click', selectAllAndCopy);
       $byIp.addEventListener('focus', selectAllAndCopy);
 
+      const $profiler = $("#profiler");
+      $profiler.addEventListener('click', openProfiler);
+
       let devtools;
       try {
         devtools = require("react-devtools-core/standalone").default;