facebook · rickhanlonii · Apr 20, 2021 · Mar 11, 2021
diff --git a/packages/eslint-plugin-react-hooks/__tests__/ESLintRuleExhaustiveDeps-test.js b/packages/eslint-plugin-react-hooks/__tests__/ESLintRuleExhaustiveDeps-test.js
@@ -604,10 +604,10 @@ const tests = {
           const [state4, dispatch2] = React.useReducer();
           const [state5, maybeSetState] = useFunnyState();
           const [state6, maybeDispatch] = useFunnyReducer();
-          const [startTransition1] = useTransition();
-          const [startTransition2, isPending2] = useTransition();
-          const [startTransition3] = React.useTransition();
-          const [startTransition4, isPending4] = React.useTransition();
+          const [isPending1] = useTransition();
+          const [isPending2, startTransition2] = useTransition();
+          const [isPending3] = React.useTransition();
+          const [isPending4, startTransition4] = React.useTransition();
           const mySetState = useCallback(() => {}, []);
           let myDispatch = useCallback(() => {}, []);
 

diff --git a/packages/eslint-plugin-react-hooks/src/ExhaustiveDeps.js b/packages/eslint-plugin-react-hooks/src/ExhaustiveDeps.js
@@ -255,9 +255,14 @@ export default {
             }
           }
         } else if (name === 'useTransition') {
-          if (id.type === 'ArrayPattern' && isArray(resolved.identifiers)) {
-            // Is first tuple value the same reference we're checking?
-            if (id.elements[0] === resolved.identifiers[0]) {
+          // Only consider second value in initializing tuple stable.
+          if (
+            id.type === 'ArrayPattern' &&
+            id.elements.length === 2 &&
+            Array.isArray(resolved.identifiers)
+          ) {
+            // Is second tuple value the same reference we're checking?
+            if (id.elements[1] === resolved.identifiers[0]) {
               // Setter is stable.
               return true;
             }

diff --git a/packages/react-debug-tools/src/ReactDebugHooks.js b/packages/react-debug-tools/src/ReactDebugHooks.js
@@ -265,7 +265,7 @@ function useMutableSource<Source, Snapshot>(
   return value;
 }
 
-function useTransition(): [(() => void) => void, boolean] {
+function useTransition(): [boolean, (() => void) => void] {
   // useTransition() composes multiple hooks internally.
   // Advance the current hook index the same number of times
   // so that subsequent hooks have the right memoized state.
@@ -276,7 +276,7 @@ function useTransition(): [(() => void) => void, boolean] {
     stackError: new Error(),
     value: undefined,
   });
-  return [callback => {}, false];
+  return [false, callback => {}];
 }
 
 function useDeferredValue<T>(value: T): T {

diff --git a/...ct-devtools-shared/src/devtools/views/Components/InspectedElementErrorsAndWarningsTree.js b/...ct-devtools-shared/src/devtools/views/Components/InspectedElementErrorsAndWarningsTree.js
@@ -41,8 +41,8 @@ export default function InspectedElementErrorsAndWarningsTree({
   const refresh = useCacheRefresh();
 
   const [
-    startClearErrorsTransition,
     isErrorsTransitionPending,
+    startClearErrorsTransition,
   ] = useTransition();
   const clearErrorsForInspectedElement = () => {
     const {id} = inspectedElement;
@@ -60,8 +60,8 @@ export default function InspectedElementErrorsAndWarningsTree({
   };
 
   const [
-    startClearWarningsTransition,
     isWarningsTransitionPending,
+    startClearWarningsTransition,
   ] = useTransition();
   const clearWarningsForInspectedElement = () => {
     const {id} = inspectedElement;

diff --git a/packages/react-devtools-shared/src/devtools/views/Components/KeyValue.js b/packages/react-devtools-shared/src/devtools/views/Components/KeyValue.js
@@ -90,7 +90,7 @@ export default function KeyValue({
     isReadOnly = value[meta.readonly];
   }
 
-  const [startInspectPathsTransition, isInspectPathsPending] = useTransition();
+  const [isInspectPathsPending, startInspectPathsTransition] = useTransition();
   const toggleIsOpen = () => {
     if (isOpen) {
       setIsOpen(false);

diff --git a/packages/react-dom/src/server/ReactPartialRendererHooks.js b/packages/react-dom/src/server/ReactPartialRendererHooks.js
@@ -467,12 +467,12 @@ function useDeferredValue<T>(value: T): T {
   return value;
 }
 
-function useTransition(): [(callback: () => void) => void, boolean] {
+function useTransition(): [boolean, (callback: () => void) => void] {
   resolveCurrentlyRenderingComponent();
   const startTransition = callback => {
     callback();
   };
-  return [startTransition, false];
+  return [false, startTransition];
 }
 
 function useOpaqueIdentifier(): OpaqueIDType {

diff --git a/packages/react-reconciler/src/ReactFiberHooks.new.js b/packages/react-reconciler/src/ReactFiberHooks.new.js
@@ -1723,27 +1723,27 @@ function startTransition(setPending, callback) {
   }
 }
 
-function mountTransition(): [(() => void) => void, boolean] {
+function mountTransition(): [boolean, (() => void) => void] {
   const [isPending, setPending] = mountState(false);
   // The `start` method never changes.
   const start = startTransition.bind(null, setPending);
   const hook = mountWorkInProgressHook();
   hook.memoizedState = start;
-  return [start, isPending];
+  return [isPending, start];
 }
 
-function updateTransition(): [(() => void) => void, boolean] {
+function updateTransition(): [boolean, (() => void) => void] {
   const [isPending] = updateState(false);
   const hook = updateWorkInProgressHook();
   const start = hook.memoizedState;
-  return [start, isPending];
+  return [isPending, start];
 }
 
-function rerenderTransition(): [(() => void) => void, boolean] {
+function rerenderTransition(): [boolean, (() => void) => void] {
   const [isPending] = rerenderState(false);
   const hook = updateWorkInProgressHook();
   const start = hook.memoizedState;
-  return [start, isPending];
+  return [isPending, start];
 }
 
 let isUpdatingOpaqueValueInRenderPhase = false;
@@ -2283,7 +2283,7 @@ if (__DEV__) {
       mountHookTypesDev();
       return mountDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       mountHookTypesDev();
       return mountTransition();
@@ -2407,7 +2407,7 @@ if (__DEV__) {
       updateHookTypesDev();
       return mountDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       updateHookTypesDev();
       return mountTransition();
@@ -2531,7 +2531,7 @@ if (__DEV__) {
       updateHookTypesDev();
       return updateDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       updateHookTypesDev();
       return updateTransition();
@@ -2656,7 +2656,7 @@ if (__DEV__) {
       updateHookTypesDev();
       return rerenderDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       updateHookTypesDev();
       return rerenderTransition();
@@ -2792,7 +2792,7 @@ if (__DEV__) {
       mountHookTypesDev();
       return mountDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       warnInvalidHookAccess();
       mountHookTypesDev();
@@ -2931,7 +2931,7 @@ if (__DEV__) {
       updateHookTypesDev();
       return updateDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       warnInvalidHookAccess();
       updateHookTypesDev();
@@ -3071,7 +3071,7 @@ if (__DEV__) {
       updateHookTypesDev();
       return rerenderDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       warnInvalidHookAccess();
       updateHookTypesDev();

diff --git a/packages/react-reconciler/src/ReactFiberHooks.old.js b/packages/react-reconciler/src/ReactFiberHooks.old.js
@@ -1723,27 +1723,27 @@ function startTransition(setPending, callback) {
   }
 }
 
-function mountTransition(): [(() => void) => void, boolean] {
+function mountTransition(): [boolean, (() => void) => void] {
   const [isPending, setPending] = mountState(false);
   // The `start` method never changes.
   const start = startTransition.bind(null, setPending);
   const hook = mountWorkInProgressHook();
   hook.memoizedState = start;
-  return [start, isPending];
+  return [isPending, start];
 }
 
-function updateTransition(): [(() => void) => void, boolean] {
+function updateTransition(): [boolean, (() => void) => void] {
   const [isPending] = updateState(false);
   const hook = updateWorkInProgressHook();
   const start = hook.memoizedState;
-  return [start, isPending];
+  return [isPending, start];
 }
 
-function rerenderTransition(): [(() => void) => void, boolean] {
+function rerenderTransition(): [boolean, (() => void) => void] {
   const [isPending] = rerenderState(false);
   const hook = updateWorkInProgressHook();
   const start = hook.memoizedState;
-  return [start, isPending];
+  return [isPending, start];
 }
 
 let isUpdatingOpaqueValueInRenderPhase = false;
@@ -2283,7 +2283,7 @@ if (__DEV__) {
       mountHookTypesDev();
       return mountDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       mountHookTypesDev();
       return mountTransition();
@@ -2407,7 +2407,7 @@ if (__DEV__) {
       updateHookTypesDev();
       return mountDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       updateHookTypesDev();
       return mountTransition();
@@ -2531,7 +2531,7 @@ if (__DEV__) {
       updateHookTypesDev();
       return updateDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       updateHookTypesDev();
       return updateTransition();
@@ -2656,7 +2656,7 @@ if (__DEV__) {
       updateHookTypesDev();
       return rerenderDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       updateHookTypesDev();
       return rerenderTransition();
@@ -2792,7 +2792,7 @@ if (__DEV__) {
       mountHookTypesDev();
       return mountDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       warnInvalidHookAccess();
       mountHookTypesDev();
@@ -2931,7 +2931,7 @@ if (__DEV__) {
       updateHookTypesDev();
       return updateDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       warnInvalidHookAccess();
       updateHookTypesDev();
@@ -3071,7 +3071,7 @@ if (__DEV__) {
       updateHookTypesDev();
       return rerenderDeferredValue(value);
     },
-    useTransition(): [(() => void) => void, boolean] {
+    useTransition(): [boolean, (() => void) => void] {
       currentHookNameInDev = 'useTransition';
       warnInvalidHookAccess();
       updateHookTypesDev();

diff --git a/packages/react-reconciler/src/ReactInternalTypes.js b/packages/react-reconciler/src/ReactInternalTypes.js
@@ -311,7 +311,7 @@ export type Dispatcher = {|
   ): void,
   useDebugValue<T>(value: T, formatterFn: ?(value: T) => mixed): void,
   useDeferredValue<T>(value: T): T,
-  useTransition(): [(() => void) => void, boolean],
+  useTransition(): [boolean, (() => void) => void],
   useMutableSource<Source, Snapshot>(
     source: MutableSource<Source>,
     getSnapshot: MutableSourceGetSnapshotFn<Source, Snapshot>,

diff --git a/packages/react-reconciler/src/__tests__/ReactHooks-test.internal.js b/packages/react-reconciler/src/__tests__/ReactHooks-test.internal.js
@@ -1511,7 +1511,7 @@ describe('ReactHooks', () => {
     ];
 
     if (__EXPERIMENTAL__) {
-      const useTransitionHelper = () => React.useTransition({timeoutMs: 1000});
+      const useTransitionHelper = () => React.useTransition();
       const useDeferredValueHelper = () =>
         React.useDeferredValue(0, {timeoutMs: 1000});
 

diff --git a/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.js b/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.js
@@ -876,14 +876,11 @@ describe('ReactHooksWithNoopRenderer', () => {
     // TODO: This should probably warn
     // @gate experimental
     it('calling startTransition inside render phase', async () => {
-      let startTransition;
       function App() {
         const [counter, setCounter] = useState(0);
-        const [_startTransition] = useTransition();
-        startTransition = _startTransition;
 
         if (counter === 0) {
-          startTransition(() => {
+          React.unstable_startTransition(() => {
             setCounter(c => c + 1);
           });
         }
@@ -3227,9 +3224,7 @@ describe('ReactHooksWithNoopRenderer', () => {
       let transition;
       function App() {
         const [show, setShow] = useState(false);
-        const [startTransition, isPending] = useTransition({
-          timeoutMs: 1000,
-        });
+        const [isPending, startTransition] = useTransition();
         transition = () => {
           startTransition(() => {
             setShow(true);

diff --git a/packages/react-reconciler/src/__tests__/ReactSuspenseWithNoopRenderer-test.js b/packages/react-reconciler/src/__tests__/ReactSuspenseWithNoopRenderer-test.js
@@ -3745,7 +3745,8 @@ describe('ReactSuspenseWithNoopRenderer', () => {
     let startTransition;
     function B() {
       const [textB, _setTextB] = useState('B');
-      const [_startTransition] = useTransition({timeoutMs: 10000});
+      // eslint-disable-next-line no-unused-vars
+      const [_, _startTransition] = useTransition();
       startTransition = _startTransition;
       setTextB = _setTextB;
       return (
@@ -3843,12 +3844,8 @@ describe('ReactSuspenseWithNoopRenderer', () => {
     let setTextWithLongTransition;
 
     function App() {
-      const [startShortTransition, isPending1] = React.unstable_useTransition({
-        timeoutMs: 5000,
-      });
-      const [startLongTransition, isPending2] = React.unstable_useTransition({
-        timeoutMs: 30000,
-      });
+      const [isPending1, startShortTransition] = React.unstable_useTransition();
+      const [isPending2, startLongTransition] = React.unstable_useTransition();
       const isPending = isPending1 || isPending2;
       const [text, setText] = React.useState('');
       const [mirror, setMirror] = React.useState('');

diff --git a/packages/react-reconciler/src/__tests__/ReactTransition-test.js b/packages/react-reconciler/src/__tests__/ReactTransition-test.js
@@ -164,7 +164,7 @@ describe('ReactTransition', () => {
     let start;
     function App() {
       const [show, setShow] = useState(false);
-      const [_start, isPending] = useTransition();
+      const [isPending, _start] = useTransition();
       start = () => _start(() => setShow(true));
       return (
         <Suspense fallback={<Text text="Loading..." />}>
@@ -208,7 +208,7 @@ describe('ReactTransition', () => {
     async () => {
       let update;
       function App() {
-        const [startContentChange, isContentPending] = useTransition();
+        const [isContentPending, startContentChange] = useTransition();
         const [label, setLabel] = useState('A');
         const [contents, setContents] = useState('A');
         update = value => {

diff --git a/packages/react-server/src/ReactFizzHooks.js b/packages/react-server/src/ReactFizzHooks.js
@@ -470,9 +470,9 @@ function unsupportedStartTransition() {
   invariant(false, 'startTransition cannot be called during server rendering.');
 }
 
-function useTransition(): [(callback: () => void) => void, boolean] {
+function useTransition(): [boolean, (callback: () => void) => void] {
   resolveCurrentlyRenderingComponent();
-  return [unsupportedStartTransition, false];
+  return [false, unsupportedStartTransition];
 }
 
 function useOpaqueIdentifier(): OpaqueIDType {

diff --git a/packages/react/src/ReactHooks.js b/packages/react/src/ReactHooks.js
@@ -145,7 +145,7 @@ export function useDebugValue<T>(
 
 export const emptyObject = {};
 
-export function useTransition(): [(() => void) => void, boolean] {
+export function useTransition(): [boolean, (() => void) => void] {
   const dispatcher = resolveDispatcher();
   return dispatcher.useTransition();
 }