Implement identifierPrefix option for useId

packages/react-art/src/ReactART.js

@@ -66,7 +66,15 @@ class Surface extends React.Component {
 
     this._surface = Mode.Surface(+width, +height, this._tagRef);
 
-    this._mountNode = createContainer(this._surface, LegacyRoot, false, null);
+    this._mountNode = createContainer(
+      this._surface,
+      LegacyRoot,
+      false,
+      null,
+      false,
+      false,
+      '',
+    );
     updateContainer(this.props.children, this._mountNode, this);
   }
 

packages/react-dom/src/__tests__/ReactDOMUseId-test.js

@@ -94,7 +94,7 @@ describe('useId', () => {
 
   function normalizeTreeIdForTesting(id) {
     const [serverClientPrefix, base32, hookIndex] = id.split(':');
-    if (serverClientPrefix === 'r') {
+    if (serverClientPrefix.endsWith('r')) {
       // Client ids aren't stable. For testing purposes, strip out the counter.
       return (
         'CLIENT_GENERATED_ID' +
@@ -569,4 +569,66 @@ describe('useId', () => {
     // Should have hydrated successfully
     expect(span.current).toBe(dehydratedSpan);
   });
+
+  test('identifierPrefix option', async () => {
+    function Child() {
+      const id = useId();
+      return <div>{id}</div>;
+    }
+
+    function App({showMore}) {
+      return (
+        <>
+          <Child />
+          <Child />
+          {showMore && <Child />}
+        </>
+      );
+    }
+
+    await serverAct(async () => {
+      const {pipe} = ReactDOMFizzServer.renderToPipeableStream(<App />, {
+        identifierPrefix: 'custom-prefix-',
+      });
+      pipe(writable);
+    });
+    let root;
+    await clientAct(async () => {
+      root = ReactDOM.hydrateRoot(container, <App />, {
+        identifierPrefix: 'custom-prefix-',
+      });
+    });
+    expect(container).toMatchInlineSnapshot(`
+      <div
+        id="container"
+      >
+        <div>
+          custom-prefix-R:1
+        </div>
+        <div>
+          custom-prefix-R:2
+        </div>
+      </div>
+    `);
+
+    // Mount a new, client-only id
+    await clientAct(async () => {
+      root.render(<App showMore={true} />);
+    });
+    expect(container).toMatchInlineSnapshot(`
+      <div
+        id="container"
+      >
+        <div>
+          custom-prefix-R:1
+        </div>
+        <div>
+          custom-prefix-R:2
+        </div>
+        <div>
+          custom-prefix-r:0
+        </div>
+      </div>
+    `);
+  });
 });

packages/react-dom/src/client/ReactDOMLegacy.js

@@ -121,6 +121,7 @@ function legacyCreateRootFromDOMContainer(
     null, // hydrationCallbacks
     false, // isStrictMode
     false, // concurrentUpdatesByDefaultOverride,
+    '', // identiferPrefix
   );
   markContainerAsRoot(root.current, container);
 

packages/react-dom/src/client/ReactDOMRoot.js

@@ -32,6 +32,7 @@ export type CreateRootOptions = {
   // END OF TODO
   unstable_strictMode?: boolean,
   unstable_concurrentUpdatesByDefault?: boolean,
+  identifierPrefix?: string,
   ...
 };
 
@@ -43,6 +44,7 @@ export type HydrateRootOptions = {
   // Options for all roots
   unstable_strictMode?: boolean,
   unstable_concurrentUpdatesByDefault?: boolean,
+  identifierPrefix?: string,
   ...
 };
 
@@ -158,13 +160,22 @@ export function createRoot(
     null;
   // END TODO
 
-  const isStrictMode = options != null && options.unstable_strictMode === true;
-  let concurrentUpdatesByDefaultOverride = null;
-  if (allowConcurrentByDefault) {
-    concurrentUpdatesByDefaultOverride =
-      options != null && options.unstable_concurrentUpdatesByDefault != null
-        ? options.unstable_concurrentUpdatesByDefault
-        : null;
+  let isStrictMode = false;
+  let concurrentUpdatesByDefaultOverride = false;
+  let identifierPrefix = '';
+  if (options !== null && options !== undefined) {
+    if (options.unstable_strictMode === true) {
+      isStrictMode = true;
+    }
+    if (
+      allowConcurrentByDefault &&
+      options.unstable_concurrentUpdatesByDefault === true
+    ) {
+      concurrentUpdatesByDefaultOverride = true;
+    }
+    if (options.identifierPrefix !== undefined) {
+      identifierPrefix = options.identifierPrefix;
+    }
   }
 
   const root = createContainer(
@@ -174,6 +185,7 @@ export function createRoot(
     hydrationCallbacks,
     isStrictMode,
     concurrentUpdatesByDefaultOverride,
+    identifierPrefix,
   );
   markContainerAsRoot(root.current, container);
 
@@ -217,15 +229,25 @@ export function hydrateRoot(
   // For now we reuse the whole bag of options since they contain
   // the hydration callbacks.
   const hydrationCallbacks = options != null ? options : null;
+  // TODO: Delete this option
   const mutableSources = (options != null && options.hydratedSources) || null;
-  const isStrictMode = options != null && options.unstable_strictMode === true;
-
-  let concurrentUpdatesByDefaultOverride = null;
-  if (allowConcurrentByDefault) {
-    concurrentUpdatesByDefaultOverride =
-      options != null && options.unstable_concurrentUpdatesByDefault != null
-        ? options.unstable_concurrentUpdatesByDefault
-        : null;
+
+  let isStrictMode = false;
+  let concurrentUpdatesByDefaultOverride = false;
+  let identifierPrefix = '';
+  if (options !== null && options !== undefined) {
+    if (options.unstable_strictMode === true) {
+      isStrictMode = true;
+    }
+    if (
+      allowConcurrentByDefault &&
+      options.unstable_concurrentUpdatesByDefault === true
+    ) {
+      concurrentUpdatesByDefaultOverride = true;
+    }
+    if (options.identifierPrefix !== undefined) {
+      identifierPrefix = options.identifierPrefix;
+    }
   }
 
   const root = createContainer(
@@ -235,6 +257,7 @@ export function hydrateRoot(
     hydrationCallbacks,
     isStrictMode,
     concurrentUpdatesByDefaultOverride,
+    identifierPrefix,
   );
   markContainerAsRoot(root.current, container);
   // This can't be a comment node since hydration doesn't work on comment nodes anyway.

packages/react-dom/src/server/ReactDOMServerFormatConfig.js

@@ -64,6 +64,7 @@ export type ResponseState = {
   placeholderPrefix: PrecomputedChunk,
   segmentPrefix: PrecomputedChunk,
   boundaryPrefix: string,
+  idPrefix: string,
   nextSuspenseID: number,
   sentCompleteSegmentFunction: boolean,
   sentCompleteBoundaryFunction: boolean,
@@ -125,6 +126,7 @@ export function createResponseState(
     placeholderPrefix: stringToPrecomputedChunk(idPrefix + 'P:'),
     segmentPrefix: stringToPrecomputedChunk(idPrefix + 'S:'),
     boundaryPrefix: idPrefix + 'B:',
+    idPrefix: idPrefix + 'R:',
     nextSuspenseID: 0,
     sentCompleteSegmentFunction: false,
     sentCompleteBoundaryFunction: false,
@@ -229,6 +231,25 @@ export function assignSuspenseBoundaryID(
   );
 }
 
+export function makeId(
+  responseState: ResponseState,
+  treeId: string,
+  localId: number,
+): string {
+  const idPrefix = responseState.idPrefix;
+
+  let id = idPrefix + treeId;
+
+  // Unless this is the first id at this level, append a number at the end
+  // that represents the position of this useId hook among all the useId
+  // hooks for this fiber.
+  if (localId > 0) {
+    id += ':' + localId.toString(32);
+  }
+
+  return id;
+}
+
 function encodeHTMLTextNode(text: string): string {
   return escapeTextForBrowser(text);
 }

packages/react-dom/src/server/ReactDOMServerLegacyFormatConfig.js

@@ -34,6 +34,7 @@ export type ResponseState = {
   placeholderPrefix: PrecomputedChunk,
   segmentPrefix: PrecomputedChunk,
   boundaryPrefix: string,
+  idPrefix: string,
   nextSuspenseID: number,
   sentCompleteSegmentFunction: boolean,
   sentCompleteBoundaryFunction: boolean,
@@ -54,6 +55,7 @@ export function createResponseState(
     placeholderPrefix: responseState.placeholderPrefix,
     segmentPrefix: responseState.segmentPrefix,
     boundaryPrefix: responseState.boundaryPrefix,
+    idPrefix: responseState.idPrefix,
     nextSuspenseID: responseState.nextSuspenseID,
     sentCompleteSegmentFunction: responseState.sentCompleteSegmentFunction,
     sentCompleteBoundaryFunction: responseState.sentCompleteBoundaryFunction,
@@ -79,6 +81,7 @@ export {
   getChildFormatContext,
   UNINITIALIZED_SUSPENSE_BOUNDARY_ID,
   assignSuspenseBoundaryID,
+  makeId,
   pushStartInstance,
   pushEndInstance,
   pushStartCompletedSuspenseBoundary,

packages/react-native-renderer/src/ReactFabric.js

@@ -213,6 +213,7 @@ function render(
       null,
       false,
       null,
+      '',
     );
     roots.set(containerTag, root);
   }

packages/react-native-renderer/src/ReactNativeRenderer.js

@@ -202,7 +202,15 @@ function render(
   if (!root) {
     // TODO (bvaughn): If we decide to keep the wrapper component,
     // We could create a wrapper for containerTag as well to reduce special casing.
-    root = createContainer(containerTag, LegacyRoot, false, null, false, null);
+    root = createContainer(
+      containerTag,
+      LegacyRoot,
+      false,
+      null,
+      false,
+      null,
+      '',
+    );
     roots.set(containerTag, root);
   }
   updateContainer(element, root, null, callback);

packages/react-native-renderer/src/server/ReactNativeServerFormatConfig.js

@@ -107,6 +107,14 @@ export function assignSuspenseBoundaryID(
   return responseState.nextSuspenseID++;
 }
 
+export function makeId(
+  responseState: ResponseState,
+  treeId: string,
+  localId: number,
+): string {
+  throw new Error('Not implemented');
+}
+
 const RAW_TEXT = stringToPrecomputedChunk('RCTRawText');
 
 export function pushTextInstance(

packages/react-noop-renderer/src/createReactNoop.js

@@ -973,6 +973,8 @@ function createReactNoop(reconciler: Function, useMutation: boolean) {
         false,
         null,
         null,
+        false,
+        '',
       );
       return {
         _Scheduler: Scheduler,
@@ -1000,6 +1002,8 @@ function createReactNoop(reconciler: Function, useMutation: boolean) {
         false,
         null,
         null,
+        false,
+        '',
       );
       return {
         _Scheduler: Scheduler,

packages/react-reconciler/src/ReactFiberHooks.new.js

@@ -2035,12 +2035,20 @@ export function getIsUpdatingOpaqueValueInRenderPhaseInDEV(): boolean | void {
 function mountId(): string {
   const hook = mountWorkInProgressHook();
 
+  const root = ((getWorkInProgressRoot(): any): FiberRoot);
+  // TODO: In Fizz, id generation is specific to each server config. Maybe we
+  // should do this in Fiber, too? Deferring this decision for now because
+  // there's no other place to store the prefix except for an internal field on
+  // the public createRoot object, which the fiber tree does not currently have
+  // a reference to.
+  const identifierPrefix = root.identifierPrefix;
+
   let id;
   if (getIsHydrating()) {
     const treeId = getTreeId();
 
     // Use a captial R prefix for server-generated ids.
-    id = 'R:' + treeId;
+    id = identifierPrefix + 'R:' + treeId;
 
     // Unless this is the first id at this level, append a number at the end
     // that represents the position of this useId hook among all the useId
@@ -2052,7 +2060,7 @@ function mountId(): string {
   } else {
     // Use a lowercase r prefix for client-generated ids.
     const globalClientId = globalClientIdCounter++;
-    id = 'r:' + globalClientId.toString(32);
+    id = identifierPrefix + 'r:' + globalClientId.toString(32);
   }
 
   hook.memoizedState = id;

packages/react-reconciler/src/ReactFiberHooks.old.js

@@ -2035,12 +2035,20 @@ export function getIsUpdatingOpaqueValueInRenderPhaseInDEV(): boolean | void {
 function mountId(): string {
   const hook = mountWorkInProgressHook();
 
+  const root = ((getWorkInProgressRoot(): any): FiberRoot);
+  // TODO: In Fizz, id generation is specific to each server config. Maybe we
+  // should do this in Fiber, too? Deferring this decision for now because
+  // there's no other place to store the prefix except for an internal field on
+  // the public createRoot object, which the fiber tree does not currently have
+  // a reference to.
+  const identifierPrefix = root.identifierPrefix;
+
   let id;
   if (getIsHydrating()) {
     const treeId = getTreeId();
 
     // Use a captial R prefix for server-generated ids.
-    id = 'R:' + treeId;
+    id = identifierPrefix + 'R:' + treeId;
 
     // Unless this is the first id at this level, append a number at the end
     // that represents the position of this useId hook among all the useId
@@ -2052,7 +2060,7 @@ function mountId(): string {
   } else {
     // Use a lowercase r prefix for client-generated ids.
     const globalClientId = globalClientIdCounter++;
-    id = 'r:' + globalClientId.toString(32);
+    id = identifierPrefix + 'r:' + globalClientId.toString(32);
   }
 
   hook.memoizedState = id;

packages/react-reconciler/src/ReactFiberReconciler.new.js

@@ -241,6 +241,7 @@ export function createContainer(
   hydrationCallbacks: null | SuspenseHydrationCallbacks,
   isStrictMode: boolean,
   concurrentUpdatesByDefaultOverride: null | boolean,
+  identifierPrefix: string,
 ): OpaqueRoot {
   return createFiberRoot(
     containerInfo,
@@ -249,6 +250,7 @@ export function createContainer(
     hydrationCallbacks,
     isStrictMode,
     concurrentUpdatesByDefaultOverride,
+    identifierPrefix,
   );
 }