[Bug]: Event Not Triggered in Firefox

[martinfried]

Version

1.55.0

Steps to reproduce

git clone https://github.com/martinfried/playwright-beforeunload-event-trigger-bug.git
cd playwright-beforeunload-event-trigger-bug
yarn install
yarn playwright install
yarn dev
yarn test

Expected behavior

After page reload, the paragraph should show Dummy page: full indicating that the beforeunload event ran and updated localStorage.

Actual behavior

In Firefox, after reload, the paragraph still shows the previous value (e.g., Dummy page: empty), because the beforeunload event did not run.

Additional context

No response

Environment

System:
  OS: macOS 15.6.1
  CPU: (8) arm64 Apple M1
  Memory: 124.78 MB / 8.00 GB
Binaries:
  Node: 20.18.0 - ~/.nvm/versions/node/v20.18.0/bin/node
  Yarn: 1.22.19 - ~/.nvm/versions/node/v20.18.0/bin/yarn
  npm: 11.5.2 - ~/.nvm/versions/node/v20.18.0/bin/npm
IDEs:
  VSCode: 1.103.2 - /usr/local/bin/code
Languages:
  Bash: 3.2.57 - /bin/bash
npmPackages:
  @playwright/test: ^1.55.0 => 1.55.0 
  playwright: 1.55.0 => 1.55.0

[dgozman]

Minimal repro:

test('beforeunload', async ({ page }) => {
  await page.route('**/*', route => {
    route.fulfill({
      body: `
        <div id=target></div>
        <script>
          window.addEventListener('beforeunload', () => {
            console.log('beforeunload here');
            debugger;
            localStorage.setItem('onBeforeUnload', 'full');
          });
          document.getElementById('target').textContent = localStorage.getItem('onBeforeUnload') || 'none';
        </script>
      `,
      contentType: 'text/html',
    });
  });
  await page.goto('https://example.com');
  await page.locator('#target').click();
  await expect(page.locator('#target')).toHaveText('none');
  await page.reload();
  // await page.evaluate(() => location.reload());
  await expect(page.locator('#target')).toHaveText('full');
});

Note that using location.reload() makes this work. Needs investigation.

[dgozman]

As a workaround, try await page.evaluate(() => location.reload()) for now.

[martinfried]

As a workaround, try await page.evaluate(() => location.reload()) for now.

This workaround works for me. Thanks!