[Fiber] Replay onChange Events if input/textarea/select has changed before hydration (facebook#33129)

This fixes a long standing issue that controlled inputs gets out of sync
with the browser state if it's changed before we hydrate.

This resolves the issue by replaying the change events (click, input and
change) if the value has changed by the time we commit the hydration.
That way you can reflect the new value in state to bring it in sync. It
does this whether controlled or uncontrolled.

The idea is that this should be ok to replay because it's similar to the
continuous events in that it doesn't replay a sequence but only reflects
the current state of the tree.

Since this is a breaking change I added it behind
`enableHydrationChangeEvent` flag.

There is still an additional issue remaining that I intend to address in
a follow up. If a `useLayoutEffect` triggers an sync rerender on
hydration (always a bad idea) then that can rerender before we have had
a chance to replay the change events. If that renders through a input
then that input will always override the browser value with the
controlled value. Which will reset it before we've had a change to
update to the new value.

Author: sebmarkbage

packages/react-dom-bindings/src/client/ReactDOMComponent.js

@@ -49,7 +49,6 @@ import {
 } from './ReactDOMTextarea';
 import {setSrcObject} from './ReactDOMSrcObject';
 import {validateTextNesting} from './validateDOMNesting';
-import {track} from './inputValueTracking';
 import setTextContent from './setTextContent';
 import {
   createDangerousStringForStyles,
@@ -67,6 +66,7 @@ import sanitizeURL from '../shared/sanitizeURL';
 import {trackHostMutation} from 'react-reconciler/src/ReactFiberMutationTracking';
 
 import {
+  enableHydrationChangeEvent,
   enableScrollEndPolyfill,
   enableSrcObject,
   enableTrustedTypesIntegration,
@@ -1187,7 +1187,6 @@ export function setInitialProperties(
         name,
         false,
       );
-      track((domElement: any));
       return;
     }
     case 'select': {
@@ -1285,7 +1284,6 @@ export function setInitialProperties(
       // up necessary since we never stop tracking anymore.
       validateTextareaProps(domElement, props);
       initTextarea(domElement, value, defaultValue, children);
-      track((domElement: any));
       return;
     }
     case 'option': {
@@ -3100,17 +3098,18 @@ export function hydrateProperties(
       // option and select we don't quite do the same thing and select
       // is not resilient to the DOM state changing so we don't do that here.
       // TODO: Consider not doing this for input and textarea.
-      initInput(
-        domElement,
-        props.value,
-        props.defaultValue,
-        props.checked,
-        props.defaultChecked,
-        props.type,
-        props.name,
-        true,
-      );
-      track((domElement: any));
+      if (!enableHydrationChangeEvent) {
+        initInput(
+          domElement,
+          props.value,
+          props.defaultValue,
+          props.checked,
+          props.defaultChecked,
+          props.type,
+          props.name,
+          true,
+        );
+      }
       break;
     case 'option':
       validateOptionProps(domElement, props);
@@ -3134,8 +3133,14 @@ export function hydrateProperties(
       // TODO: Make sure we check if this is still unmounted or do any clean
       // up necessary since we never stop tracking anymore.
       validateTextareaProps(domElement, props);
-      initTextarea(domElement, props.value, props.defaultValue, props.children);
-      track((domElement: any));
+      if (!enableHydrationChangeEvent) {
+        initTextarea(
+          domElement,
+          props.value,
+          props.defaultValue,
+          props.children,
+        );
+      }
       break;
   }
 

packages/react-dom-bindings/src/client/ReactDOMInput.js

@@ -12,13 +12,17 @@ import {getCurrentFiberOwnerNameInDevOrNull} from 'react-reconciler/src/ReactCur
 
 import {getFiberCurrentPropsFromNode} from './ReactDOMComponentTree';
 import {getToStringValue, toString} from './ToStringValue';
-import {updateValueIfChanged} from './inputValueTracking';
+import {track, trackHydrated, updateValueIfChanged} from './inputValueTracking';
 import getActiveElement from './getActiveElement';
-import {disableInputAttributeSyncing} from 'shared/ReactFeatureFlags';
+import {
+  disableInputAttributeSyncing,
+  enableHydrationChangeEvent,
+} from 'shared/ReactFeatureFlags';
 import {checkAttributeStringCoercion} from 'shared/CheckStringCoercion';
 
 import type {ToStringValue} from './ToStringValue';
 import escapeSelectorAttributeValueInsideDoubleQuotes from './escapeSelectorAttributeValueInsideDoubleQuotes';
+import {queueChangeEvent} from '../events/ReactDOMEventReplaying';
 
 let didWarnValueDefaultValue = false;
 let didWarnCheckedDefaultChecked = false;
@@ -229,6 +233,8 @@ export function initInput(
     // Avoid setting value attribute on submit/reset inputs as it overrides the
     // default value provided by the browser. See: #12872
     if (isButton && (value === undefined || value === null)) {
+      // We track the value just in case it changes type later on.
+      track((element: any));
       return;
     }
 
@@ -239,7 +245,7 @@ export function initInput(
 
     // Do not assign value if it is already set. This prevents user text input
     // from being lost during SSR hydration.
-    if (!isHydrating) {
+    if (!isHydrating || enableHydrationChangeEvent) {
       if (disableInputAttributeSyncing) {
         // When not syncing the value attribute, the value property points
         // directly to the React prop. Only assign it if it exists.
@@ -297,7 +303,7 @@ export function initInput(
     typeof checkedOrDefault !== 'symbol' &&
     !!checkedOrDefault;
 
-  if (isHydrating) {
+  if (isHydrating && !enableHydrationChangeEvent) {
     // Detach .checked from .defaultChecked but leave user input alone
     node.checked = node.checked;
   } else {
@@ -335,6 +341,43 @@ export function initInput(
     }
     node.name = name;
   }
+  track((element: any));
+}
+
+export function hydrateInput(
+  element: Element,
+  value: ?string,
+  defaultValue: ?string,
+  checked: ?boolean,
+  defaultChecked: ?boolean,
+): void {
+  const node: HTMLInputElement = (element: any);
+
+  const defaultValueStr =
+    defaultValue != null ? toString(getToStringValue(defaultValue)) : '';
+  const initialValue =
+    value != null ? toString(getToStringValue(value)) : defaultValueStr;
+
+  const checkedOrDefault = checked != null ? checked : defaultChecked;
+  // TODO: This 'function' or 'symbol' check isn't replicated in other places
+  // so this semantic is inconsistent.
+  const initialChecked =
+    typeof checkedOrDefault !== 'function' &&
+    typeof checkedOrDefault !== 'symbol' &&
+    !!checkedOrDefault;
+
+  // Detach .checked from .defaultChecked but leave user input alone
+  node.checked = node.checked;
+
+  const changed = trackHydrated((node: any), initialValue, initialChecked);
+  if (changed) {
+    // If the current value is different, that suggests that the user
+    // changed it before hydration. Queue a replay of the change event.
+    // For radio buttons the change event only fires on the selected one.
+    if (node.type !== 'radio' || node.checked) {
+      queueChangeEvent(node);
+    }
+  }
 }
 
 export function restoreControlledInputState(element: Element, props: Object) {

packages/react-dom-bindings/src/client/ReactDOMSelect.js

@@ -12,6 +12,7 @@ import {getCurrentFiberOwnerNameInDevOrNull} from 'react-reconciler/src/ReactCur
 
 import {getToStringValue, toString} from './ToStringValue';
 import isArray from 'shared/isArray';
+import {queueChangeEvent} from '../events/ReactDOMEventReplaying';
 
 let didWarnValueDefaultValue;
 
@@ -86,7 +87,7 @@ function updateOptions(
   } else {
     // Do not set `select.value` as exact behavior isn't consistent across all
     // browsers for all cases.
-    const selectedValue = toString(getToStringValue((propValue: any)));
+    const selectedValue = toString(getToStringValue(propValue));
     let defaultSelected = null;
     for (let i = 0; i < options.length; i++) {
       if (options[i].value === selectedValue) {
@@ -157,6 +158,59 @@ export function initSelect(
   }
 }
 
+export function hydrateSelect(
+  element: Element,
+  value: ?string,
+  defaultValue: ?string,
+  multiple: ?boolean,
+): void {
+  const node: HTMLSelectElement = (element: any);
+  const options: HTMLOptionsCollection = node.options;
+
+  const propValue: any = value != null ? value : defaultValue;
+
+  let changed = false;
+
+  if (multiple) {
+    const selectedValues = (propValue: ?Array<string>);
+    const selectedValue: {[string]: boolean} = {};
+    if (selectedValues != null) {
+      for (let i = 0; i < selectedValues.length; i++) {
+        // Prefix to avoid chaos with special keys.
+        selectedValue['$' + selectedValues[i]] = true;
+      }
+    }
+    for (let i = 0; i < options.length; i++) {
+      const expectedSelected = selectedValue.hasOwnProperty(
+        '$' + options[i].value,
+      );
+      if (options[i].selected !== expectedSelected) {
+        changed = true;
+        break;
+      }
+    }
+  } else {
+    let selectedValue =
+      propValue == null ? null : toString(getToStringValue(propValue));
+    for (let i = 0; i < options.length; i++) {
+      if (selectedValue == null && !options[i].disabled) {
+        // We expect the first non-disabled option to be selected if the selected is null.
+        selectedValue = options[i].value;
+      }
+      const expectedSelected = options[i].value === selectedValue;
+      if (options[i].selected !== expectedSelected) {
+        changed = true;
+        break;
+      }
+    }
+  }
+  if (changed) {
+    // If the current selection is different than our initial that suggests that the user
+    // changed it before hydration. Queue a replay of the change event.
+    queueChangeEvent(node);
+  }
+}
+
 export function updateSelect(
   element: Element,
   value: ?string,

packages/react-dom-bindings/src/client/ReactDOMTextarea.js

@@ -13,6 +13,9 @@ import {getCurrentFiberOwnerNameInDevOrNull} from 'react-reconciler/src/ReactCur
 import {getToStringValue, toString} from './ToStringValue';
 import {disableTextareaChildren} from 'shared/ReactFeatureFlags';
 
+import {track, trackHydrated} from './inputValueTracking';
+import {queueChangeEvent} from '../events/ReactDOMEventReplaying';
+
 let didWarnValDefaultVal = false;
 
 /**
@@ -140,6 +143,33 @@ export function initTextarea(
       node.value = textContent;
     }
   }
+
+  track((element: any));
+}
+
+export function hydrateTextarea(
+  element: Element,
+  value: ?string,
+  defaultValue: ?string,
+): void {
+  const node: HTMLTextAreaElement = (element: any);
+  let initialValue = value;
+  if (initialValue == null) {
+    if (defaultValue == null) {
+      defaultValue = '';
+    }
+    initialValue = defaultValue;
+  }
+  // Track the value that we last observed which is the hydrated value so
+  // that any change event that fires will trigger onChange on the actual
+  // current value.
+  const stringValue = toString(getToStringValue(initialValue));
+  const changed = trackHydrated((node: any), stringValue, false);
+  if (changed) {
+    // If the current value is different, that suggests that the user
+    // changed it before hydration. Queue a replay of the change event.
+    queueChangeEvent(node);
+  }
 }
 
 export function restoreControlledTextareaState(

packages/react-dom-bindings/src/client/ReactFiberConfigDOM.js

@@ -75,6 +75,9 @@ import {
   diffHydratedText,
   trapClickOnNonInteractiveElement,
 } from './ReactDOMComponent';
+import {hydrateInput} from './ReactDOMInput';
+import {hydrateTextarea} from './ReactDOMTextarea';
+import {hydrateSelect} from './ReactDOMSelect';
 import {getSelectionInformation, restoreSelection} from './ReactInputSelection';
 import setTextContent from './setTextContent';
 import {
@@ -108,6 +111,7 @@ import {
   enableSuspenseyImages,
   enableSrcObject,
   enableViewTransition,
+  enableHydrationChangeEvent,
 } from 'shared/ReactFeatureFlags';
 import {
   HostComponent,
@@ -154,6 +158,10 @@ export type Props = {
   top?: null | number,
   is?: string,
   size?: number,
+  value?: string,
+  defaultValue?: string,
+  checked?: boolean,
+  defaultChecked?: boolean,
   multiple?: boolean,
   src?: string | Blob | MediaSource | MediaStream, // TODO: Response
   srcSet?: string,
@@ -611,6 +619,27 @@ export function finalizeInitialChildren(
   }
 }
 
+export function finalizeHydratedChildren(
+  domElement: Instance,
+  type: string,
+  props: Props,
+  hostContext: HostContext,
+): boolean {
+  // TOOD: Consider unifying this with hydrateInstance.
+  if (!enableHydrationChangeEvent) {
+    return false;
+  }
+  switch (type) {
+    case 'input':
+    case 'select':
+    case 'textarea':
+    case 'img':
+      return true;
+    default:
+      return false;
+  }
+}
+
 export function shouldSetTextContent(type: string, props: Props): boolean {
   return (
     type === 'textarea' ||
@@ -819,6 +848,49 @@ export function commitMount(
   }
 }
 
+export function commitHydratedInstance(
+  domElement: Instance,
+  type: string,
+  props: Props,
+  internalInstanceHandle: Object,
+): void {
+  if (!enableHydrationChangeEvent) {
+    return;
+  }
+  // This fires in the commit phase if a hydrated instance needs to do further
+  // work in the commit phase. Similar to commitMount. However, this should not
+  // do things that would've already happened such as set auto focus since that
+  // would steal focus. It's only scheduled if finalizeHydratedChildren returns
+  // true.
+  switch (type) {
+    case 'input': {
+      hydrateInput(
+        domElement,
+        props.value,
+        props.defaultValue,
+        props.checked,
+        props.defaultChecked,
+      );
+      break;
+    }
+    case 'select': {
+      hydrateSelect(
+        domElement,
+        props.value,
+        props.defaultValue,
+        props.multiple,
+      );
+      break;
+    }
+    case 'textarea':
+      hydrateTextarea(domElement, props.value, props.defaultValue);
+      break;
+    case 'img':
+      // TODO: Should we replay onLoad events?
+      break;
+  }
+}
+
 export function commitUpdate(
   domElement: Instance,
   type: string,