Skip to content

Commit

Permalink
Allow forms to skip hydration of hidden inputs (#26735)
Browse files Browse the repository at this point in the history 
This allows us to emit extra ephemeral data that will only be used on
server rendered forms.

First I refactored the shouldSkip functions to now just do that work
inside the canHydrate methods. This makes the Config bindings a little
less surface area but it also helps us optimize a bit since we now can
look at the code together and find shared paths.

canHydrate returns the instance if it matches, that used to just be
there to refine the type but it can also be used to just return a
different instance later that we find. If we don't find one, we'll bail
out and error regardless so no need to skip past anything.
  • Loading branch information
@sebmarkbage
sebmarkbage authored May 1, 2023
1 parent 8ea96ef commit 67f4fb0
Show file tree
Hide file tree
Showing 5 changed files with 202 additions and 209 deletions.
281 changes: 153 additions & 128 deletions packages/react-dom-bindings/src/client/ReactFiberConfigDOM.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,7 @@ import {
enableHostSingletons,
enableTrustedTypesIntegration,
diffInCommitPhase,
enableFormActions,
} from 'shared/ReactFeatureFlags';
import {
HostComponent,
Expand Down Expand Up @@ -1038,160 +1039,182 @@ export function isHydratableText(text: string): boolean {
return text !== '';
}

export function shouldSkipHydratableForInstance(
export function canHydrateInstance(
instance: HydratableInstance,
type: string,
props: Props,
): boolean {
if (instance.nodeType !== ELEMENT_NODE) {
// This is a suspense boundary or Text node.
// Suspense Boundaries are never expected to be injected by 3rd parties. If we see one it should be matched
// and this is a hydration error.
// Text Nodes are also not expected to be injected by 3rd parties. This is less of a guarantee for <body>
// but it seems reasonable and conservative to reject this as a hydration error as well
return false;
} else if (
instance.nodeName.toLowerCase() !== type.toLowerCase() ||
isMarkedHoistable(instance)
) {
// We are either about to
return true;
} else {
// We have an Element with the right type.
inRootOrSingleton: boolean,
): null | Instance {
while (instance.nodeType === ELEMENT_NODE) {
const element: Element = (instance: any);
const anyProps = (props: any);

// We are going to try to exclude it if we can definitely identify it as a hoisted Node or if
// we can guess that the node is likely hoisted or was inserted by a 3rd party script or browser extension
// using high entropy attributes for certain types. This technique will fail for strange insertions like
// extension prepending <div> in the <body> but that already breaks before and that is an edge case.
switch (type) {
// case 'title':
//We assume all titles are matchable. You should only have one in the Document, at least in a hoistable scope
// and if you are a HostComponent with type title we must either be in an <svg> context or this title must have an `itemProp` prop.
case 'meta': {
// The only way to opt out of hoisting meta tags is to give it an itemprop attribute. We assume there will be
// not 3rd party meta tags that are prepended, accepting the cases where this isn't true because meta tags
// are usually only functional for SSR so even in a rare case where we did bind to an injected tag the runtime
// implications are minimal
if (!element.hasAttribute('itemprop')) {
// This is a Hoistable
return true;
}
break;
}
case 'link': {
// Links come in many forms and we do expect 3rd parties to inject them into <head> / <body>. We exclude known resources
// and then use high-entroy attributes like href which are almost always used and almost always unique to filter out unlikely
// matches.
const rel = element.getAttribute('rel');
if (rel === 'stylesheet' && element.hasAttribute('data-precedence')) {
// This is a stylesheet resource
return true;
} else if (
rel !== anyProps.rel ||
element.getAttribute('href') !==
(anyProps.href == null ? null : anyProps.href) ||
element.getAttribute('crossorigin') !==
(anyProps.crossOrigin == null ? null : anyProps.crossOrigin) ||
element.getAttribute('title') !==
(anyProps.title == null ? null : anyProps.title)
if (element.nodeName.toLowerCase() !== type.toLowerCase()) {
if (!inRootOrSingleton || !enableHostSingletons) {
// Usually we error for mismatched tags.
if (
enableFormActions &&
element.nodeName === 'INPUT' &&
(element: any).type === 'hidden'
) {
// rel + href should usually be enough to uniquely identify a link however crossOrigin can vary for rel preconnect
// and title could vary for rel alternate
return true;
// If we have extra hidden inputs, we don't mismatch. This allows us to embed
// extra form data in the original form.
} else {
return null;
}
break;
}
case 'style': {
// Styles are hard to match correctly. We can exclude known resources but otherwise we accept the fact that a non-hoisted style tags
// in <head> or <body> are likely never going to be unmounted given their position in the document and the fact they likely hold global styles
if (element.hasAttribute('data-precedence')) {
// This is a style resource
return true;
}
break;
// In root or singleton parents we skip past mismatched instances.
} else if (!inRootOrSingleton || !enableHostSingletons) {
// Match
if (
enableFormActions &&
type === 'input' &&
(element: any).type === 'hidden' &&
anyProps.type !== 'hidden'
) {
// Skip past hidden inputs unless that's what we're looking for. This allows us
// embed extra form data in the original form.
} else {
return element;
}
case 'script': {
// Scripts are a little tricky, we exclude known resources and then similar to links try to use high-entropy attributes
// to reject poor matches. One challenge with scripts are inline scripts. We don't attempt to check text content which could
// in theory lead to a hydration error later if a 3rd party injected an inline script before the React rendered nodes.
// Falling back to client rendering if this happens should be seemless though so we will try this hueristic and revisit later
// if we learn it is problematic
const srcAttr = element.getAttribute('src');
if (
srcAttr &&
element.hasAttribute('async') &&
!element.hasAttribute('itemprop')
) {
// This is an async script resource
return true;
} else if (
srcAttr !== (anyProps.src == null ? null : anyProps.src) ||
element.getAttribute('type') !==
(anyProps.type == null ? null : anyProps.type) ||
element.getAttribute('crossorigin') !==
(anyProps.crossOrigin == null ? null : anyProps.crossOrigin)
) {
// This script is for a different src
return true;
} else if (isMarkedHoistable(element)) {
// We've already claimed this as a hoistable which isn't hydrated this way so we skip past it.
} else {
// We have an Element with the right type.

// We are going to try to exclude it if we can definitely identify it as a hoisted Node or if
// we can guess that the node is likely hoisted or was inserted by a 3rd party script or browser extension
// using high entropy attributes for certain types. This technique will fail for strange insertions like
// extension prepending <div> in the <body> but that already breaks before and that is an edge case.
switch (type) {
// case 'title':
//We assume all titles are matchable. You should only have one in the Document, at least in a hoistable scope
// and if you are a HostComponent with type title we must either be in an <svg> context or this title must have an `itemProp` prop.
case 'meta': {
// The only way to opt out of hoisting meta tags is to give it an itemprop attribute. We assume there will be
// not 3rd party meta tags that are prepended, accepting the cases where this isn't true because meta tags
// are usually only functional for SSR so even in a rare case where we did bind to an injected tag the runtime
// implications are minimal
if (!element.hasAttribute('itemprop')) {
// This is a Hoistable
break;
}
return element;
}
case 'link': {
// Links come in many forms and we do expect 3rd parties to inject them into <head> / <body>. We exclude known resources
// and then use high-entroy attributes like href which are almost always used and almost always unique to filter out unlikely
// matches.
const rel = element.getAttribute('rel');
if (rel === 'stylesheet' && element.hasAttribute('data-precedence')) {
// This is a stylesheet resource
break;
} else if (
rel !== anyProps.rel ||
element.getAttribute('href') !==
(anyProps.href == null ? null : anyProps.href) ||
element.getAttribute('crossorigin') !==
(anyProps.crossOrigin == null ? null : anyProps.crossOrigin) ||
element.getAttribute('title') !==
(anyProps.title == null ? null : anyProps.title)
) {
// rel + href should usually be enough to uniquely identify a link however crossOrigin can vary for rel preconnect
// and title could vary for rel alternate
break;
}
return element;
}
case 'style': {
// Styles are hard to match correctly. We can exclude known resources but otherwise we accept the fact that a non-hoisted style tags
// in <head> or <body> are likely never going to be unmounted given their position in the document and the fact they likely hold global styles
if (element.hasAttribute('data-precedence')) {
// This is a style resource
break;
}
return element;
}
case 'script': {
// Scripts are a little tricky, we exclude known resources and then similar to links try to use high-entropy attributes
// to reject poor matches. One challenge with scripts are inline scripts. We don't attempt to check text content which could
// in theory lead to a hydration error later if a 3rd party injected an inline script before the React rendered nodes.
// Falling back to client rendering if this happens should be seemless though so we will try this hueristic and revisit later
// if we learn it is problematic
const srcAttr = element.getAttribute('src');
if (
srcAttr &&
element.hasAttribute('async') &&
!element.hasAttribute('itemprop')
) {
// This is an async script resource
break;
} else if (
srcAttr !== (anyProps.src == null ? null : anyProps.src) ||
element.getAttribute('type') !==
(anyProps.type == null ? null : anyProps.type) ||
element.getAttribute('crossorigin') !==
(anyProps.crossOrigin == null ? null : anyProps.crossOrigin)
) {
// This script is for a different src
break;
}
return element;
}
default: {
// We have excluded the most likely cases of mismatch between hoistable tags, 3rd party script inserted tags,
// and browser extension inserted tags. While it is possible this is not the right match it is a decent hueristic
// that should work in the vast majority of cases.
return element;
}
break;
}
}
// We have excluded the most likely cases of mismatch between hoistable tags, 3rd party script inserted tags,
// and browser extension inserted tags. While it is possible this is not the right match it is a decent hueristic
// that should work in the vast majority of cases.
return false;
}
}

export function shouldSkipHydratableForTextInstance(
instance: HydratableInstance,
): boolean {
return instance.nodeType === ELEMENT_NODE;
}

export function shouldSkipHydratableForSuspenseInstance(
instance: HydratableInstance,
): boolean {
return instance.nodeType === ELEMENT_NODE;
}

export function canHydrateInstance(
instance: HydratableInstance,
type: string,
props: Props,
): null | Instance {
if (
instance.nodeType !== ELEMENT_NODE ||
instance.nodeName.toLowerCase() !== type.toLowerCase()
) {
return null;
} else {
return ((instance: any): Instance);
const nextInstance = getNextHydratableSibling(element);
if (nextInstance === null) {
break;
}
instance = nextInstance;
}
// This is a suspense boundary or Text node or we got the end.
// Suspense Boundaries are never expected to be injected by 3rd parties. If we see one it should be matched
// and this is a hydration error.
// Text Nodes are also not expected to be injected by 3rd parties. This is less of a guarantee for <body>
// but it seems reasonable and conservative to reject this as a hydration error as well
return null;
}

export function canHydrateTextInstance(
instance: HydratableInstance,
text: string,
inRootOrSingleton: boolean,
): null | TextInstance {
// Empty strings are not parsed by HTML so there won't be a correct match here.
if (text === '') return null;

if (instance.nodeType !== TEXT_NODE) {
// Empty strings are not parsed by HTML so there won't be a correct match here.
return null;
while (instance.nodeType !== TEXT_NODE) {
if (!inRootOrSingleton || !enableHostSingletons) {
return null;
}
const nextInstance = getNextHydratableSibling(instance);
if (nextInstance === null) {
return null;
}
instance = nextInstance;
}
// This has now been refined to a text node.
return ((instance: any): TextInstance);
}

export function canHydrateSuspenseInstance(
instance: HydratableInstance,
inRootOrSingleton: boolean,
): null | SuspenseInstance {
if (instance.nodeType !== COMMENT_NODE) {
return null;
while (instance.nodeType !== COMMENT_NODE) {
if (!inRootOrSingleton || !enableHostSingletons) {
return null;
}
const nextInstance = getNextHydratableSibling(instance);
if (nextInstance === null) {
return null;
}
instance = nextInstance;
}
// This has now been refined to a suspense node.
return ((instance: any): SuspenseInstance);
Expand Down Expand Up @@ -1416,12 +1439,14 @@ export function commitHydratedSuspenseInstance(
retryIfBlockedOn(suspenseInstance);
}

// @TODO remove this function once float lands and hydrated tail nodes
// are controlled by HostSingleton fibers
export function shouldDeleteUnhydratedTailInstances(
parentType: string,
): boolean {
return parentType !== 'head' && parentType !== 'body';
return (
(enableHostSingletons ||
(parentType !== 'head' && parentType !== 'body')) &&
(!enableFormActions || parentType !== 'form')
);
}

export function didNotMatchHydratedContainerTextInstance(
Expand Down
37 changes: 37 additions & 0 deletions packages/react-dom/src/__tests__/ReactServerRenderingHydration-test.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -695,4 +695,41 @@ describe('ReactDOMServerHydration', () => {
);
}
});

// @gate enableFormActions
it('allows rendering extra hidden inputs in a form', async () => {
const element = document.createElement('div');
element.innerHTML =
'<form>' +
'<input type="hidden" /><input type="hidden" name="a" value="A" />' +
'<input type="hidden" /><input type="submit" name="b" value="B" />' +
'<input type="hidden" /><button name="c" value="C"></button>' +
'<input type="hidden" />' +
'</form>';
const form = element.firstChild;
const ref = React.createRef();
const a = React.createRef();
const b = React.createRef();
const c = React.createRef();
await act(async () => {
ReactDOMClient.hydrateRoot(
element,
<form ref={ref}>
<input type="hidden" name="a" value="A" ref={a} />
<input type="submit" name="b" value="B" ref={b} />
<button name="c" value="C" ref={c} />
</form>,
);
});

// The content should not have been client rendered.
expect(ref.current).toBe(form);

expect(a.current.name).toBe('a');
expect(a.current.value).toBe('A');
expect(b.current.name).toBe('b');
expect(b.current.value).toBe('B');
expect(c.current.name).toBe('c');
expect(c.current.value).toBe('C');
});
});
3 changes: 0 additions & 3 deletions packages/react-reconciler/src/ReactFiberConfigWithNoHydration.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -31,9 +31,6 @@ export const getNextHydratableSibling = shim;
export const getFirstHydratableChild = shim;
export const getFirstHydratableChildWithinContainer = shim;
export const getFirstHydratableChildWithinSuspenseInstance = shim;
export const shouldSkipHydratableForInstance = shim;
export const shouldSkipHydratableForTextInstance = shim;
export const shouldSkipHydratableForSuspenseInstance = shim;
export const canHydrateInstance = shim;
export const canHydrateTextInstance = shim;
export const canHydrateSuspenseInstance = shim;
Expand Down
Loading

0 comments on commit 67f4fb0

Please sign in to comment.