feat(launcher): add new launcher option waitForInitialPage (#7105)

The existing behavior is expected to be unchanged as the value defaults to true.
Adding such option would allow user to skip the initial wait.

Issue: #3630

docs/api.md

@@ -625,6 +625,7 @@ try {
   - `pipe` <[boolean]> Connects to the browser over a pipe instead of a WebSocket. Defaults to `false`.
   - `extraPrefsFirefox` <[Object]> Additional [preferences](https://developer.mozilla.org/en-US/docs/Mozilla/Preferences/Preference_reference) that can be passed to Firefox (see `PUPPETEER_PRODUCT`)
   - `targetFilter` <?[function]\([Protocol.Target.TargetInfo]\):[boolean]> Use this function to decide if Puppeteer should connect to the given target. If a `targetFilter` is provided, Puppeteer only connects to targets for which `targetFilter` returns `true`. By default, Puppeteer connects to all available targets.
+  - `waitForInitialPage` <[boolean]> Whether to wait for the initial page to be ready. Defaults to `true`.
 - returns: <[Promise]<[Browser]>> Promise which resolves to browser instance.
 
 You can use `ignoreDefaultArgs` to filter out `--mute-audio` from default arguments:

src/node/LaunchOptions.ts

@@ -110,6 +110,12 @@ export interface LaunchOptions {
    * {@link https://developer.mozilla.org/en-US/docs/Mozilla/Preferences/Preference_reference | Additional preferences } that can be passed when launching with Firefox.
    */
   extraPrefsFirefox?: Record<string, unknown>;
+  /**
+   * Whether to wait for the initial page to be ready.
+   * Useful when a user explicitly disables that (e.g. `--no-startup-window` for Chrome).
+   * @defaultValue true
+   */
+  waitForInitialPage?: boolean;
 }
 
 /**

src/node/Launcher.ts

@@ -75,6 +75,7 @@ class ChromeLauncher implements ProductLauncher {
       defaultViewport = { width: 800, height: 600 },
       slowMo = 0,
       timeout = 30000,
+      waitForInitialPage = true,
     } = options;
 
     const profilePath = path.join(os.tmpdir(), 'puppeteer_dev_chrome_profile-');
@@ -147,7 +148,8 @@ class ChromeLauncher implements ProductLauncher {
         runner.proc,
         runner.close.bind(runner)
       );
-      await browser.waitForTarget((t) => t.type() === 'page');
+      if (waitForInitialPage)
+        await browser.waitForTarget((t) => t.type() === 'page');
       return browser;
     } catch (error) {
       runner.kill();
@@ -245,6 +247,7 @@ class FirefoxLauncher implements ProductLauncher {
       slowMo = 0,
       timeout = 30000,
       extraPrefsFirefox = {},
+      waitForInitialPage = true,
     } = options;
 
     const firefoxArguments = [];
@@ -313,7 +316,8 @@ class FirefoxLauncher implements ProductLauncher {
         runner.proc,
         runner.close.bind(runner)
       );
-      await browser.waitForTarget((t) => t.type() === 'page');
+      if (waitForInitialPage)
+        await browser.waitForTarget((t) => t.type() === 'page');
       return browser;
     } catch (error) {
       runner.kill();

test/launcher.spec.ts

@@ -21,6 +21,7 @@ import { promisify } from 'util';
 import Protocol from 'devtools-protocol';
 import {
   getTestState,
+  itChromeOnly,
   itFailsFirefox,
   itOnlyRegularInstall,
 } from './mocha-utils'; // eslint-disable-line import/extensions
@@ -430,6 +431,24 @@ describe('Launcher specs', function () {
         expect(screenshot).toBeInstanceOf(Buffer);
         await browser.close();
       });
+      itChromeOnly(
+        'should launch Chrome properly with --no-startup-window and waitForInitialPage=false',
+        async () => {
+          const { defaultBrowserOptions, puppeteer } = getTestState();
+          const options = {
+            args: ['--no-startup-window'],
+            waitForInitialPage: false,
+            // This is needed to prevent Puppeteer from adding an initial blank page.
+            // See also https://github.com/puppeteer/puppeteer/blob/ad6b736039436fcc5c0a262e5b575aa041427be3/src/node/Launcher.ts#L200
+            ignoreDefaultArgs: true,
+            ...defaultBrowserOptions,
+          };
+          const browser = await puppeteer.launch(options);
+          const pages = await browser.pages();
+          expect(pages.length).toBe(0);
+          await browser.close();
+        }
+      );
     });
 
     describe('Puppeteer.launch', function () {