Skip to content

[pull] main from react:main #618

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
pull merged 1 commit into from
Jul 27, 2026
+176 −45
Merged

[pull] main from react:main #618

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
48 changes: 48 additions & 0 deletions packages/react-dom/src/__tests__/ReactDOMSingletonComponents-test.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -491,6 +491,54 @@ describe('ReactDOM HostSingleton', () => {
expect(onScroll).toHaveBeenCalledTimes(2);
});

// @gate __DEV__
it('does not release or reacquire singletons when double invoking effects during hydration', async () => {
const effectLog = [];
const html = '<span id="managed">managed content</span>';

function Effect() {
React.useLayoutEffect(() => {
effectLog.push('mount');
return () => {
effectLog.push('unmount');
};
}, []);
return <meta name="strict-effect" />;
}

await actIntoEmptyDocument(() => {
const {pipe} = ReactDOMFizzServer.renderToPipeableStream(
<html>
<head>
<meta name="strict-effect" />
</head>
<body dangerouslySetInnerHTML={{__html: html}} />
</html>,
);
pipe(writable);
});
const serverBodyHTML = document.body.innerHTML;
const managedElement = document.getElementById('managed');

ReactDOMClient.hydrateRoot(
document,
<React.StrictMode>
<html>
<head>
<Effect />
</head>
<body dangerouslySetInnerHTML={{__html: serverBodyHTML}} />
</html>
</React.StrictMode>,
);
await waitForAll([]);

// The Strict Mode effects are still double invoked.
expect(effectLog).toEqual(['mount', 'unmount', 'mount']);
// Hydrating a matching tree should preserve the server-rendered nodes.
expect(document.getElementById('managed')).toBe(managedElement);
});

it('renders into html, head, and body persistently so the node identities never change and extraneous styles are retained', async () => {
// Server render some html that will get replaced with a client render
await actIntoEmptyDocument(() => {
Expand Down
Loading
Loading