xplat/js/react-native-github

Reviewed By: panagosg7

Differential Revision: D16657770

fbshipit-source-id: 4e260842c838a35317515044c54ccf55a083da33

IntegrationTests/AppEventsTest.js

@@ -36,7 +36,7 @@ class AppEventsTest extends React.Component<{}, State> {
     this.setState({sent: event});
   }
 
-  receiveEvent = (event: any) => {
+  receiveEvent: (event: any) => void = (event: any) => {
     if (deepDiffer(event.data, TEST_PAYLOAD)) {
       throw new Error('Received wrong event: ' + JSON.stringify(event));
     }
@@ -46,7 +46,7 @@ class AppEventsTest extends React.Component<{}, State> {
     });
   };
 
-  render() {
+  render(): React.Node {
     return (
       <View style={styles.container}>
         <Text>{JSON.stringify(this.state, null, '  ')}</Text>

IntegrationTests/AsyncStorageTest.js

@@ -172,7 +172,7 @@ function testOptimizedMultiGet() {
 }
 
 class AsyncStorageTest extends React.Component<{}, $FlowFixMeState> {
-  state = {
+  state: any | $TEMPORARY$object<{|done: boolean, messages: string|}> = {
     messages: 'Initializing...',
     done: false,
   };
@@ -189,7 +189,7 @@ class AsyncStorageTest extends React.Component<{}, $FlowFixMeState> {
     AsyncStorage.clear(testSetAndGet);
   }
 
-  render() {
+  render(): React.Node {
     return (
       <View style={styles.container}>
         <Text>

IntegrationTests/ImageCachePolicyTest.js

@@ -36,9 +36,9 @@ type State = {
 };
 
 class ImageCachePolicyTest extends React.Component<Props, $FlowFixMeState> {
-  state = {};
+  state: $FlowFixMe | $TEMPORARY$object<{||}> = {};
 
-  shouldComponentUpdate(nextProps: Props, nextState: State) {
+  shouldComponentUpdate(nextProps: Props, nextState: State): boolean {
     const results: Array<?boolean> = TESTS.map(x => nextState[x]);
 
     if (!results.includes(undefined)) {
@@ -56,7 +56,7 @@ class ImageCachePolicyTest extends React.Component<Props, $FlowFixMeState> {
     this.setState({[name]: pass});
   }
 
-  render() {
+  render(): React.Node {
     return (
       <View style={styles.container}>
         <Text>Hello</Text>

IntegrationTests/ImageSnapshotTest.js

@@ -22,11 +22,11 @@ class ImageSnapshotTest extends React.Component<{}> {
     }
   }
 
-  done = (success: boolean) => {
+  done: (success: boolean) => void = (success: boolean) => {
     TestModule.markTestPassed(success);
   };
 
-  render() {
+  render(): React.Node {
     return (
       <Image
         source={require('./blue_square.png')}

IntegrationTests/IntegrationTestHarnessTest.js

@@ -10,9 +10,10 @@
 
 'use strict';
 
-const requestAnimationFrame = require('fbjs/lib/requestAnimationFrame');
 const React = require('react');
 const ReactNative = require('react-native');
+
+const requestAnimationFrame = require('fbjs/lib/requestAnimationFrame');
 const {Text, View, StyleSheet} = ReactNative;
 const {TestModule} = ReactNative.NativeModules;
 
@@ -26,7 +27,7 @@ type State = {|
 |};
 
 class IntegrationTestHarnessTest extends React.Component<Props, State> {
-  state = {
+  state: State = {
     done: false,
   };
 
@@ -38,7 +39,7 @@ class IntegrationTestHarnessTest extends React.Component<Props, State> {
     }
   }
 
-  runTest = () => {
+  runTest: () => void = () => {
     if (this.props.shouldThrow) {
       throw new Error('Throwing error because shouldThrow');
     }
@@ -52,7 +53,7 @@ class IntegrationTestHarnessTest extends React.Component<Props, State> {
     });
   };
 
-  render() {
+  render(): React.Node {
     return (
       <View style={styles.container}>
         <Text>

IntegrationTests/LayoutEventsTest.js

@@ -58,7 +58,7 @@ class LayoutEventsTest extends React.Component<Props, State> {
     this.setState({viewStyle: {margin: 60}});
   }
 
-  addWrapText = () => {
+  addWrapText: () => void = () => {
     debug('addWrapText invoked');
     this.setState(
       {extraText: '  And a bunch more text to wrap around a few lines.'},
@@ -66,14 +66,14 @@ class LayoutEventsTest extends React.Component<Props, State> {
     );
   };
 
-  changeContainer = () => {
+  changeContainer: () => void = () => {
     debug('changeContainer invoked');
     this.setState({containerStyle: {width: 280}}, () =>
       this.checkLayout(TestModule.markTestCompleted),
     );
   };
 
-  checkLayout = (next?: ?() => void) => {
+  checkLayout: (next?: ?() => void) => void = (next?: ?() => void) => {
     const view = this._view;
     const txt = this._txt;
     const img = this._img;
@@ -117,22 +117,22 @@ class LayoutEventsTest extends React.Component<Props, State> {
     }
   }
 
-  onViewLayout = (e: LayoutEvent) => {
+  onViewLayout: (e: LayoutEvent) => void = (e: LayoutEvent) => {
     debug('received view layout event\n', e.nativeEvent);
     this.setState({viewLayout: e.nativeEvent.layout}, this.checkLayout);
   };
 
-  onTextLayout = (e: LayoutEvent) => {
+  onTextLayout: (e: LayoutEvent) => void = (e: LayoutEvent) => {
     debug('received text layout event\n', e.nativeEvent);
     this.setState({textLayout: e.nativeEvent.layout}, this.checkLayout);
   };
 
-  onImageLayout = (e: LayoutEvent) => {
+  onImageLayout: (e: LayoutEvent) => void = (e: LayoutEvent) => {
     debug('received image layout event\n', e.nativeEvent);
     this.setState({imageLayout: e.nativeEvent.layout}, this.checkLayout);
   };
 
-  render() {
+  render(): React.Node {
     const viewStyle = [styles.view, this.state.viewStyle];
     const textLayout = this.state.textLayout || {width: '?', height: '?'};
     const imageLayout = this.state.imageLayout || {x: '?', y: '?'};

IntegrationTests/PromiseTest.js

@@ -16,10 +16,10 @@ const {View} = ReactNative;
 const {TestModule} = ReactNative.NativeModules;
 
 class PromiseTest extends React.Component<{}> {
-  shouldResolve = false;
-  shouldReject = false;
-  shouldSucceedAsync = false;
-  shouldThrowAsync = false;
+  shouldResolve: boolean = false;
+  shouldReject: boolean = false;
+  shouldSucceedAsync: boolean = false;
+  shouldThrowAsync: boolean = false;
 
   componentDidMount() {
     Promise.all([
@@ -37,19 +37,19 @@ class PromiseTest extends React.Component<{}> {
     );
   }
 
-  testShouldResolve = () => {
+  testShouldResolve: () => any = () => {
     return TestModule.shouldResolve()
       .then(() => (this.shouldResolve = true))
       .catch(() => (this.shouldResolve = false));
   };
 
-  testShouldReject = () => {
+  testShouldReject: () => any = () => {
     return TestModule.shouldReject()
       .then(() => (this.shouldReject = false))
       .catch(() => (this.shouldReject = true));
   };
 
-  testShouldSucceedAsync = async (): Promise<any> => {
+  testShouldSucceedAsync: () => Promise<any> = async (): Promise<any> => {
     try {
       await TestModule.shouldResolve();
       this.shouldSucceedAsync = true;
@@ -58,7 +58,7 @@ class PromiseTest extends React.Component<{}> {
     }
   };
 
-  testShouldThrowAsync = async (): Promise<any> => {
+  testShouldThrowAsync: () => Promise<any> = async (): Promise<any> => {
     try {
       await TestModule.shouldReject();
       this.shouldThrowAsync = false;

IntegrationTests/ReactContentSizeUpdateTest.js

@@ -10,9 +10,9 @@
 
 'use strict';
 
+const RCTNativeAppEventEmitter = require('react-native/Libraries/EventEmitter/RCTNativeAppEventEmitter');
 const React = require('react');
 const ReactNative = require('react-native');
-const RCTNativeAppEventEmitter = require('react-native/Libraries/EventEmitter/RCTNativeAppEventEmitter');
 
 const {View} = ReactNative;
 
@@ -35,7 +35,7 @@ class ReactContentSizeUpdateTest extends React.Component<Props, State> {
   _timeoutID: ?TimeoutID = null;
   _subscription: ?EmitterSubscription = null;
 
-  state = {
+  state: State = {
     height: reactViewHeight,
     width: reactViewWidth,
   };
@@ -70,7 +70,9 @@ class ReactContentSizeUpdateTest extends React.Component<Props, State> {
     });
   }
 
-  rootViewDidChangeIntrinsicSize = (intrinsicSize: State) => {
+  rootViewDidChangeIntrinsicSize: (intrinsicSize: State) => void = (
+    intrinsicSize: State,
+  ) => {
     if (
       intrinsicSize.height === newReactViewHeight &&
       intrinsicSize.width === newReactViewWidth
@@ -79,7 +81,7 @@ class ReactContentSizeUpdateTest extends React.Component<Props, State> {
     }
   };
 
-  render() {
+  render(): React.Node {
     return (
       <View style={{height: this.state.height, width: this.state.width}} />
     );

IntegrationTests/SimpleSnapshotTest.js

@@ -12,6 +12,7 @@
 
 const React = require('react');
 const ReactNative = require('react-native');
+
 const requestAnimationFrame = require('fbjs/lib/requestAnimationFrame');
 
 const {StyleSheet, View} = ReactNative;
@@ -25,11 +26,11 @@ class SimpleSnapshotTest extends React.Component<{}> {
     requestAnimationFrame(() => TestModule.verifySnapshot(this.done));
   }
 
-  done = (success: boolean) => {
+  done: (success: boolean) => void = (success: boolean) => {
     TestModule.markTestPassed(success);
   };
 
-  render() {
+  render(): React.Node {
     return (
       <View style={styles.container}>
         <View style={styles.box1} />

IntegrationTests/SizeFlexibilityUpdateTest.js

@@ -10,9 +10,9 @@
 
 'use strict';
 
+const RCTNativeAppEventEmitter = require('react-native/Libraries/EventEmitter/RCTNativeAppEventEmitter');
 const React = require('react');
 const ReactNative = require('react-native');
-const RCTNativeAppEventEmitter = require('react-native/Libraries/EventEmitter/RCTNativeAppEventEmitter');
 const {View} = ReactNative;
 
 const {TestModule} = ReactNative.NativeModules;
@@ -46,15 +46,15 @@ class SizeFlexibilityUpdateTest extends React.Component<Props> {
     }
   }
 
-  markPassed = () => {
+  markPassed: () => void = () => {
     TestModule.markTestPassed(true);
     finalState = true;
   };
 
-  rootViewDidChangeIntrinsicSize = (intrinsicSize: {
-    width: number,
+  rootViewDidChangeIntrinsicSize: (intrinsicSize: {
     height: number,
-  }) => {
+    width: number,
+  }) => void = (intrinsicSize: {width: number, height: number}) => {
     if (finalState) {
       // If a test reaches its final state, it is not expected to do anything more
       TestModule.markTestPassed(false);
@@ -99,7 +99,7 @@ class SizeFlexibilityUpdateTest extends React.Component<Props> {
     }
   };
 
-  render() {
+  render(): React.Node {
     return <View style={{height: reactViewHeight, width: reactViewWidth}} />;
   }
 }

IntegrationTests/TimersTest.js

@@ -33,7 +33,7 @@ class TimersTest extends React.Component<Props, State> {
   _immediateIDs: Set<ImmediateID> = new Set();
   _animationFrameIDs: Set<AnimationFrameID> = new Set();
 
-  state = {
+  state: State = {
     count: 0,
     done: false,
   };
@@ -228,7 +228,7 @@ class TimersTest extends React.Component<Props, State> {
     }
   }
 
-  render() {
+  render(): React.Node {
     return (
       <View style={styles.container}>
         <Text>

IntegrationTests/WebSocketTest.js

@@ -113,7 +113,7 @@ class WebSocketTest extends React.Component<{}, State> {
     this.testConnect();
   }
 
-  testConnect = () => {
+  testConnect: () => void = () => {
     this._connect();
     this._waitFor(this._socketIsConnected, 5, connectSucceeded => {
       if (!connectSucceeded) {
@@ -124,7 +124,7 @@ class WebSocketTest extends React.Component<{}, State> {
     });
   };
 
-  testSendAndReceive = () => {
+  testSendAndReceive: () => void = () => {
     this._sendTestMessage();
     this._waitFor(this._receivedTestExpectedResponse, 5, messageReceived => {
       if (!messageReceived) {
@@ -135,7 +135,7 @@ class WebSocketTest extends React.Component<{}, State> {
     });
   };
 
-  testDisconnect = () => {
+  testDisconnect: () => void = () => {
     this._disconnect();
     this._waitFor(this._socketIsDisconnected, 5, disconnectSucceeded => {
       TestModule.markTestPassed(disconnectSucceeded);

Libraries/ActionSheetIOS/NativeActionSheetManager.js

@@ -47,4 +47,4 @@ export interface Spec extends TurboModule {
   ) => void;
 }
 
-export default TurboModuleRegistry.get<Spec>('ActionSheetManager');
+export default (TurboModuleRegistry.get<Spec>('ActionSheetManager'): ?Spec);

Libraries/Alert/NativeAlertManager.js

@@ -31,4 +31,4 @@ export interface Spec extends TurboModule {
   ) => void;
 }
 
-export default TurboModuleRegistry.get<Spec>('AlertManager');
+export default (TurboModuleRegistry.get<Spec>('AlertManager'): ?Spec);

Libraries/Animated/src/AnimatedEvent.js

@@ -14,6 +14,7 @@ const NativeAnimatedHelper = require('./NativeAnimatedHelper');
 const ReactNative = require('../../Renderer/shims/ReactNative');
 
 const invariant = require('invariant');
+
 const {shouldUseNativeDriver} = require('./NativeAnimatedHelper');
 
 export type Mapping = {[key: string]: Mapping} | AnimatedValue;
@@ -26,7 +27,7 @@ function attachNativeEvent(
   viewRef: any,
   eventName: string,
   argMapping: Array<?Mapping>,
-) {
+): $TEMPORARY$object<{|detach: () => void|}> {
   // Find animated values in `argMapping` and create an array representing their
   // key path inside the `nativeEvent` object. Ex.: ['contentOffset', 'x'].
   const eventMappings = [];
@@ -130,7 +131,7 @@ class AnimatedEvent {
     this._attachedEvent && this._attachedEvent.detach();
   }
 
-  __getHandler() {
+  __getHandler(): any | ((...args: any) => void) {
     if (this.__isNative) {
       return this._callListeners;
     }

Libraries/Animated/src/AnimatedWeb.js

@@ -14,7 +14,7 @@ const AnimatedImplementation = require('./AnimatedImplementation');
 
 module.exports = {
   ...AnimatedImplementation,
-  div: AnimatedImplementation.createAnimatedComponent('div'),
-  span: AnimatedImplementation.createAnimatedComponent('span'),
-  img: AnimatedImplementation.createAnimatedComponent('img'),
+  div: (AnimatedImplementation.createAnimatedComponent('div'): $FlowFixMe),
+  span: (AnimatedImplementation.createAnimatedComponent('span'): $FlowFixMe),
+  img: (AnimatedImplementation.createAnimatedComponent('img'): $FlowFixMe),
 };

Libraries/Animated/src/Easing.js

@@ -61,14 +61,14 @@ class Easing {
   /**
    * A stepping function, returns 1 for any positive value of `n`.
    */
-  static step0(n: number) {
+  static step0(n: number): number {
     return n > 0 ? 1 : 0;
   }
 
   /**
    * A stepping function, returns 1 if `n` is greater than or equal to 1.
    */
-  static step1(n: number) {
+  static step1(n: number): number {
     return n >= 1 ? 1 : 0;
   }
 
@@ -78,7 +78,7 @@ class Easing {
    *
    * http://cubic-bezier.com/#0,0,1,1
    */
-  static linear(t: number) {
+  static linear(t: number): number {
     return t;
   }
 
@@ -101,7 +101,7 @@ class Easing {
    *
    * http://easings.net/#easeInQuad
    */
-  static quad(t: number) {
+  static quad(t: number): number {
     return t * t;
   }
 
@@ -111,7 +111,7 @@ class Easing {
    *
    * http://easings.net/#easeInCubic
    */
-  static cubic(t: number) {
+  static cubic(t: number): number {
     return t * t * t;
   }
 
@@ -121,7 +121,7 @@ class Easing {
    * n = 4: http://easings.net/#easeInQuart
    * n = 5: http://easings.net/#easeInQuint
    */
-  static poly(n: number) {
+  static poly(n: number): (t: number) => number {
     return (t: number) => Math.pow(t, n);
   }
 
@@ -130,7 +130,7 @@ class Easing {
    *
    * http://easings.net/#easeInSine
    */
-  static sin(t: number) {
+  static sin(t: number): number {
     return 1 - Math.cos((t * Math.PI) / 2);
   }
 
@@ -139,7 +139,7 @@ class Easing {
    *
    * http://easings.net/#easeInCirc
    */
-  static circle(t: number) {
+  static circle(t: number): number {
     return 1 - Math.sqrt(1 - t * t);
   }
 
@@ -148,7 +148,7 @@ class Easing {
    *
    * http://easings.net/#easeInExpo
    */
-  static exp(t: number) {
+  static exp(t: number): number {
     return Math.pow(2, 10 * (t - 1));
   }
 

Libraries/Animated/src/NativeAnimatedHelper.js

@@ -10,17 +10,16 @@
 'use strict';
 
 import NativeEventEmitter from '../../EventEmitter/NativeEventEmitter';
+import type {EventConfig} from './AnimatedEvent';
+import NativeAnimatedModule from './NativeAnimatedModule';
 import type {
   EventMapping,
   AnimatedNodeConfig,
   AnimatingNodeConfig,
 } from './NativeAnimatedModule';
-import NativeAnimatedModule from './NativeAnimatedModule';
-import invariant from 'invariant';
-
 import type {AnimationConfig, EndCallback} from './animations/Animation';
 import type {InterpolationConfigType} from './nodes/AnimatedInterpolation';
-import type {EventConfig} from './AnimatedEvent';
+import invariant from 'invariant';
 
 let __nativeAnimatedNodeTagCount = 1; /* used for animated nodes */
 let __nativeAnimationIdCount = 1; /* used for started animations */
@@ -312,7 +311,7 @@ module.exports = {
   shouldUseNativeDriver,
   transformDataType,
   // $FlowExpectedError - unsafe getter lint suppresion
-  get nativeEventEmitter() {
+  get nativeEventEmitter(): NativeEventEmitter {
     if (!nativeEventEmitter) {
       nativeEventEmitter = new NativeEventEmitter(NativeAnimatedModule);
     }

Libraries/Animated/src/NativeAnimatedModule.js

@@ -67,4 +67,4 @@ export interface Spec extends TurboModule {
   +removeListeners: (count: number) => void;
 }
 
-export default TurboModuleRegistry.get<Spec>('NativeAnimatedModule');
+export default (TurboModuleRegistry.get<Spec>('NativeAnimatedModule'): ?Spec);

Libraries/Animated/src/animations/DecayAnimation.js

@@ -13,8 +13,8 @@ const Animation = require('./Animation');
 
 const {shouldUseNativeDriver} = require('../NativeAnimatedHelper');
 
-import type {AnimationConfig, EndCallback} from './Animation';
 import type AnimatedValue from '../nodes/AnimatedValue';
+import type {AnimationConfig, EndCallback} from './Animation';
 
 export type DecayAnimationConfig = AnimationConfig & {
   velocity: number | {x: number, y: number},
@@ -45,7 +45,12 @@ class DecayAnimation extends Animation {
     this.__iterations = config.iterations ?? 1;
   }
 
-  __getNativeAnimationConfig() {
+  __getNativeAnimationConfig(): $TEMPORARY$object<{|
+    deceleration: number,
+    iterations: number,
+    type: $TEMPORARY$string<'decay'>,
+    velocity: number,
+  |}> {
     return {
       type: 'decay',
       deceleration: this._deceleration,

Libraries/Animated/src/animations/SpringAnimation.js

@@ -15,6 +15,7 @@ const Animation = require('./Animation');
 const SpringConfig = require('../SpringConfig');
 
 const invariant = require('invariant');
+
 const {shouldUseNativeDriver} = require('../NativeAnimatedHelper');
 
 import type {AnimationConfig, EndCallback} from './Animation';
@@ -137,7 +138,18 @@ class SpringAnimation extends Animation {
     invariant(this._mass > 0, 'Mass value must be greater than 0');
   }
 
-  __getNativeAnimationConfig() {
+  __getNativeAnimationConfig(): $TEMPORARY$object<{|
+    damping: number,
+    initialVelocity: number,
+    iterations: number,
+    mass: number,
+    overshootClamping: boolean,
+    restDisplacementThreshold: number,
+    restSpeedThreshold: number,
+    stiffness: number,
+    toValue: any,
+    type: $TEMPORARY$string<'spring'>,
+  |}> {
     return {
       type: 'spring',
       overshootClamping: this._overshootClamping,

Libraries/Animated/src/bezier.js

@@ -84,7 +84,7 @@ module.exports = function bezier(
   mY1: number,
   mX2: number,
   mY2: number,
-) {
+): (x: number) => number {
   if (!(mX1 >= 0 && mX1 <= 1 && mX2 >= 0 && mX2 <= 1)) {
     throw new Error('bezier x values must be in [0, 1] range');
   }

Libraries/Animated/src/components/AnimatedFlatList.js

@@ -14,6 +14,6 @@ const FlatList = require('../../../Lists/FlatList');
 
 const createAnimatedComponent = require('../createAnimatedComponent');
 
-module.exports = createAnimatedComponent(FlatList, {
+module.exports = (createAnimatedComponent(FlatList, {
   scrollEventThrottle: 0.0001,
-});
+}): $FlowFixMe);

Libraries/Animated/src/components/AnimatedImage.js

@@ -14,4 +14,4 @@ const Image = require('../../../Image/Image');
 
 const createAnimatedComponent = require('../createAnimatedComponent');
 
-module.exports = createAnimatedComponent(Image);
+module.exports = (createAnimatedComponent(Image): $FlowFixMe);

Libraries/Animated/src/components/AnimatedScrollView.js

@@ -14,6 +14,6 @@ const ScrollView = require('../../../Components/ScrollView/ScrollView');
 
 const createAnimatedComponent = require('../createAnimatedComponent');
 
-module.exports = createAnimatedComponent(ScrollView, {
+module.exports = (createAnimatedComponent(ScrollView, {
   scrollEventThrottle: 0.0001,
-});
+}): $FlowFixMe);

Libraries/Animated/src/components/AnimatedSectionList.js

@@ -14,6 +14,6 @@ const SectionList = require('../../../Lists/SectionList');
 
 const createAnimatedComponent = require('../createAnimatedComponent');
 
-module.exports = createAnimatedComponent(SectionList, {
+module.exports = (createAnimatedComponent(SectionList, {
   scrollEventThrottle: 0.0001,
-});
+}): $FlowFixMe);

Libraries/Animated/src/components/AnimatedText.js

@@ -14,4 +14,4 @@ const Text = require('../../../Text/Text');
 
 const createAnimatedComponent = require('../createAnimatedComponent');
 
-module.exports = createAnimatedComponent(Text);
+module.exports = (createAnimatedComponent(Text): $FlowFixMe);

Libraries/Animated/src/components/AnimatedView.js

@@ -14,4 +14,4 @@ const View = require('../../../Components/View/View');
 
 const createAnimatedComponent = require('../createAnimatedComponent');
 
-module.exports = createAnimatedComponent(View);
+module.exports = (createAnimatedComponent(View): $FlowFixMe);

Libraries/AppState/NativeAppState.js

@@ -27,4 +27,4 @@ export interface Spec extends TurboModule {
   +removeListeners: (count: number) => void;
 }
 
-export default TurboModuleRegistry.getEnforcing<Spec>('AppState');
+export default (TurboModuleRegistry.getEnforcing<Spec>('AppState'): Spec);

Libraries/BatchedBridge/BatchedBridge.js

@@ -12,7 +12,7 @@
 
 const MessageQueue = require('./MessageQueue');
 
-const BatchedBridge = new MessageQueue();
+const BatchedBridge: MessageQueue = new MessageQueue();
 
 // Wire up the batched bridge on the global object so that we can call into it.
 // Ideally, this would be the inverse relationship. I.e. the native environment

Libraries/BatchedBridge/MessageQueue.js

@@ -101,7 +101,11 @@ class MessageQueue {
     }
   }
 
-  callFunctionReturnFlushedQueue(module: string, method: string, args: any[]) {
+  callFunctionReturnFlushedQueue(
+    module: string,
+    method: string,
+    args: any[],
+  ): null | [Array<number>, Array<number>, Array<any>, number] {
     this.__guard(() => {
       this.__callFunction(module, method, args);
     });
@@ -113,7 +117,7 @@ class MessageQueue {
     module: string,
     method: string,
     args: any[],
-  ) {
+  ): $TEMPORARY$array<?[Array<number>, Array<number>, Array<any>, number]> {
     let result;
     this.__guard(() => {
       result = this.__callFunction(module, method, args);
@@ -122,7 +126,10 @@ class MessageQueue {
     return [result, this.flushedQueue()];
   }
 
-  invokeCallbackAndReturnFlushedQueue(cbID: number, args: any[]) {
+  invokeCallbackAndReturnFlushedQueue(
+    cbID: number,
+    args: any[],
+  ): null | [Array<number>, Array<number>, Array<any>, number] {
     this.__guard(() => {
       this.__invokeCallback(cbID, args);
     });
@@ -130,7 +137,7 @@ class MessageQueue {
     return this.flushedQueue();
   }
 
-  flushedQueue() {
+  flushedQueue(): null | [Array<number>, Array<number>, Array<any>, number] {
     this.__guard(() => {
       this.__callImmediates();
     });
@@ -140,7 +147,7 @@ class MessageQueue {
     return queue[0].length ? queue : null;
   }
 
-  getEventLoopRunningTime() {
+  getEventLoopRunningTime(): number {
     return Date.now() - this._eventLoopStartTime;
   }
 
@@ -160,7 +167,7 @@ class MessageQueue {
     };
   }
 
-  getCallableModule(name: string) {
+  getCallableModule(name: string): any | null {
     const getValue = this._lazyCallableModules[name];
     return getValue ? getValue() : null;
   }
@@ -171,7 +178,7 @@ class MessageQueue {
     params: any[],
     onFail: ?Function,
     onSucc: ?Function,
-  ) {
+  ): any {
     if (__DEV__) {
       invariant(
         global.nativeCallSyncHook,
@@ -383,7 +390,7 @@ class MessageQueue {
   // This makes stacktraces to be placed at MessageQueue rather than at where they were launched
   // The parameter DebuggerInternal.shouldPauseOnThrow is used to check before catching all exceptions and
   // can be configured by the VM or any Inspector
-  __shouldPauseOnThrow() {
+  __shouldPauseOnThrow(): boolean {
     return (
       // $FlowFixMe
       typeof DebuggerInternal !== 'undefined' &&

Libraries/Blob/BlobManager.js

@@ -12,10 +12,10 @@
 
 const Blob = require('./Blob');
 const BlobRegistry = require('./BlobRegistry');
-import NativeBlobModule from './NativeBlobModule';
-import invariant from 'invariant';
 
 import type {BlobData, BlobOptions, BlobCollector} from './BlobTypes';
+import NativeBlobModule from './NativeBlobModule';
+import invariant from 'invariant';
 
 /*eslint-disable no-bitwise */
 /*eslint-disable eqeqeq */
@@ -54,7 +54,7 @@ class BlobManager {
   /**
    * If the native blob module is available.
    */
-  static isAvailable = !!NativeBlobModule;
+  static isAvailable: boolean = !!NativeBlobModule;
 
   /**
    * Create blob from existing array of blobs.

Libraries/Blob/BlobRegistry.js

@@ -27,7 +27,7 @@ const unregister = (id: string) => {
   }
 };
 
-const has = (id: string) => {
+const has = (id: string): number | boolean => {
   return registry[id] && registry[id] > 0;
 };
 

Libraries/Blob/FileReader.js

@@ -10,8 +10,9 @@
 
 'use strict';
 
-const EventTarget = require('event-target-shim');
 const Blob = require('./Blob');
+const EventTarget = require('event-target-shim');
+
 import NativeFileReaderModule from './NativeFileReaderModule';
 
 type ReadyState =
@@ -34,14 +35,14 @@ const EMPTY = 0;
 const LOADING = 1;
 const DONE = 2;
 
-class FileReader extends EventTarget(...READER_EVENTS) {
-  static EMPTY = EMPTY;
-  static LOADING = LOADING;
-  static DONE = DONE;
+class FileReader extends (EventTarget(...READER_EVENTS): any) {
+  static EMPTY: number = EMPTY;
+  static LOADING: number = LOADING;
+  static DONE: number = DONE;
 
-  EMPTY = EMPTY;
-  LOADING = LOADING;
-  DONE = DONE;
+  EMPTY: number = EMPTY;
+  LOADING: number = LOADING;
+  DONE: number = DONE;
 
   _readyState: ReadyState;
   _error: ?Error;

Libraries/Blob/NativeBlobModule.js

@@ -23,4 +23,4 @@ export interface Spec extends TurboModule {
   +release: (blobId: string) => void;
 }
 
-export default TurboModuleRegistry.get<Spec>('BlobModule');
+export default (TurboModuleRegistry.get<Spec>('BlobModule'): ?Spec);

Libraries/Blob/NativeFileReaderModule.js

@@ -18,4 +18,6 @@ export interface Spec extends TurboModule {
   +readAsText: (data: Object, encoding: string) => Promise<string>;
 }
 
-export default TurboModuleRegistry.getEnforcing<Spec>('FileReaderModule');
+export default (TurboModuleRegistry.getEnforcing<Spec>(
+  'FileReaderModule',
+): Spec);

Libraries/Blob/__mocks__/FileReaderModule.js

@@ -8,10 +8,10 @@
  * @format
  */
 const FileReaderModule = {
-  async readAsText() {
+  async readAsText(): Promise<string> {
     return '';
   },
-  async readAsDataURL() {
+  async readAsDataURL(): Promise<string> {
     return 'data:text/plain;base64,NDI=';
   },
 };

Libraries/BugReporting/dumpReactTree.js

@@ -23,7 +23,7 @@ const MAX_STRING_LENGTH = 50;
  * it best to get the content but ultimately relies on implementation details
  * of React and will fail in future versions.
  */
-function dumpReactTree() {
+function dumpReactTree(): string {
   try {
     return getReactTree();
   } catch (e) {

Libraries/Components/AccessibilityInfo/AccessibilityInfo.ios.js

@@ -10,11 +10,11 @@
 
 'use strict';
 
-import NativeAccessibilityManager from './NativeAccessibilityManager';
-
 const Promise = require('../../Promise');
 const RCTDeviceEventEmitter = require('../../EventEmitter/RCTDeviceEventEmitter');
 
+import NativeAccessibilityManager from './NativeAccessibilityManager';
+
 const CHANGE_EVENT_NAME = {
   announcementFinished: 'announcementFinished',
   boldTextChanged: 'boldTextChanged',
@@ -164,7 +164,7 @@ const AccessibilityInfo = {
    *
    * Same as `isScreenReaderEnabled`
    */
-  get fetch() {
+  get fetch(): $FlowFixMe {
     return this.isScreenReaderEnabled;
   },
 

Libraries/Components/AccessibilityInfo/NativeAccessibilityInfo.js

@@ -24,4 +24,4 @@ export interface Spec extends TurboModule {
   +announceForAccessibility: (announcement: string) => void;
 }
 
-export default TurboModuleRegistry.get<Spec>('AccessibilityInfo');
+export default (TurboModuleRegistry.get<Spec>('AccessibilityInfo'): ?Spec);

Libraries/Components/AccessibilityInfo/NativeAccessibilityManager.js

@@ -42,4 +42,4 @@ export interface Spec extends TurboModule {
   +announceForAccessibility: (announcement: string) => void;
 }
 
-export default TurboModuleRegistry.get<Spec>('AccessibilityManager');
+export default (TurboModuleRegistry.get<Spec>('AccessibilityManager'): ?Spec);

Libraries/Components/AppleTV/NativeTVNavigationEventEmitter.js

@@ -18,4 +18,6 @@ export interface Spec extends TurboModule {
   +removeListeners: (count: number) => void;
 }
 
-export default TurboModuleRegistry.get<Spec>('TVNavigationEventEmitter');
+export default (TurboModuleRegistry.get<Spec>(
+  'TVNavigationEventEmitter',
+): ?Spec);

Libraries/Components/Clipboard/NativeClipboard.js

@@ -19,4 +19,4 @@ export interface Spec extends TurboModule {
   +setString: (content: string) => void;
 }
 
-export default TurboModuleRegistry.getEnforcing<Spec>('Clipboard');
+export default (TurboModuleRegistry.getEnforcing<Spec>('Clipboard'): Spec);

Libraries/Components/DatePicker/DatePickerIOS.ios.js

@@ -13,16 +13,15 @@
 
 'use strict';
 
+const RCTDatePickerNativeComponent = require('./RCTDatePickerNativeComponent');
 const React = require('react');
 const StyleSheet = require('../../StyleSheet/StyleSheet');
 const View = require('../View/View');
 
 const invariant = require('invariant');
 
-import type {ViewProps} from '../View/ViewPropTypes';
 import type {SyntheticEvent} from '../../Types/CoreEventTypes';
-
-const RCTDatePickerNativeComponent = require('./RCTDatePickerNativeComponent');
+import type {ViewProps} from '../View/ViewPropTypes';
 
 type Event = SyntheticEvent<
   $ReadOnly<{|
@@ -113,7 +112,9 @@ type Props = $ReadOnly<{|
  * source of truth.
  */
 class DatePickerIOS extends React.Component<Props> {
-  static DefaultProps = {
+  static DefaultProps: $TEMPORARY$object<{|
+    mode: $TEMPORARY$string<'datetime'>,
+  |}> = {
     mode: 'datetime',
   };
 
@@ -137,7 +138,7 @@ class DatePickerIOS extends React.Component<Props> {
     this.props.onChange && this.props.onChange(event);
   };
 
-  render() {
+  render(): React.Node {
     const props = this.props;
     invariant(
       props.date || props.initialDate,

Libraries/Components/DatePickerAndroid/NativeDatePickerAndroid.js

@@ -17,4 +17,6 @@ export interface Spec extends TurboModule {
   +open: (options: Object) => Promise<Object>;
 }
 
-export default TurboModuleRegistry.getEnforcing<Spec>('DatePickerAndroid');
+export default (TurboModuleRegistry.getEnforcing<Spec>(
+  'DatePickerAndroid',
+): Spec);

Libraries/Components/DrawerAndroid/AndroidDrawerLayoutNativeComponent.js

@@ -10,17 +10,17 @@
 
 'use strict';
 
-import codegenNativeCommands from 'react-native/Libraries/Utilities/codegenNativeCommands';
-import codegenNativeComponent from 'react-native/Libraries/Utilities/codegenNativeComponent';
-import * as React from 'react';
 import type {ViewProps} from 'react-native/Libraries/Components/View/ViewPropTypes';
+import type {ColorValue} from 'react-native/Libraries/StyleSheet/StyleSheetTypes';
 import type {
   WithDefault,
   DirectEventHandler,
   Int32,
   Float,
 } from 'react-native/Libraries/Types/CodegenTypes';
-import type {ColorValue} from 'react-native/Libraries/StyleSheet/StyleSheetTypes';
+import codegenNativeCommands from 'react-native/Libraries/Utilities/codegenNativeCommands';
+import codegenNativeComponent from 'react-native/Libraries/Utilities/codegenNativeComponent';
+import * as React from 'react';
 
 type DrawerStateEvent = $ReadOnly<{|
   drawerState: Int32,
@@ -113,7 +113,7 @@ type NativeProps = $ReadOnly<{|
   statusBarBackgroundColor?: ?ColorValue,
 |}>;
 
-export const Commands = codegenNativeCommands<NativeCommands>({
+export const Commands: NativeCommands = codegenNativeCommands<NativeCommands>({
   supportedCommands: ['openDrawer', 'closeDrawer'],
 });
 

Libraries/Components/Keyboard/Keyboard.js

@@ -11,9 +11,10 @@
 'use strict';
 
 const LayoutAnimation = require('../../LayoutAnimation/LayoutAnimation');
-const invariant = require('invariant');
 const NativeEventEmitter = require('../../EventEmitter/NativeEventEmitter');
+
 const dismissKeyboard = require('../../Utilities/dismissKeyboard');
+const invariant = require('invariant');
 
 import NativeKeyboardObserver from './NativeKeyboardObserver';
 const KeyboardEventEmitter = new NativeEventEmitter(NativeKeyboardObserver);
@@ -108,7 +109,21 @@ type KeyboardEventListener = (e: KeyboardEvent) => void;
  *```
  */
 
-let Keyboard = {
+let Keyboard:
+  | NativeEventEmitter
+  | $TEMPORARY$object<{|
+      addListener: (
+        eventName: KeyboardEventName,
+        callback: KeyboardEventListener,
+      ) => $FlowFixMe,
+      dismiss: () => $FlowFixMe,
+      removeAllListeners: (eventName: KeyboardEventName) => $FlowFixMe,
+      removeListener: (
+        eventName: KeyboardEventName,
+        callback: KeyboardEventListener,
+      ) => $FlowFixMe,
+      scheduleLayoutAnimation: (event: KeyboardEvent) => $FlowFixMe,
+    |}> = {
   /**
    * The `addListener` function connects a JavaScript function to an identified native
    * keyboard notification event.

Libraries/Components/Keyboard/KeyboardAvoidingView.js

@@ -17,8 +17,8 @@ const React = require('react');
 const StyleSheet = require('../../StyleSheet/StyleSheet');
 const View = require('../View/View');
 
-import type EmitterSubscription from '../../vendor/emitter/EmitterSubscription';
 import type {ViewStyleProp} from '../../StyleSheet/StyleSheet';
+import type EmitterSubscription from '../../vendor/emitter/EmitterSubscription';
 import type {
   ViewProps,
   ViewLayout,
@@ -61,7 +61,10 @@ type State = {|
  * adjusting its height, position, or bottom padding.
  */
 class KeyboardAvoidingView extends React.Component<Props, State> {
-  static defaultProps = {
+  static defaultProps: $TEMPORARY$object<{|
+    enabled: boolean,
+    keyboardVerticalOffset: number,
+  |}> = {
     enabled: true,
     keyboardVerticalOffset: 0,
   };

Libraries/Components/Keyboard/NativeKeyboardObserver.js

@@ -18,4 +18,4 @@ export interface Spec extends TurboModule {
   +removeListeners: (count: number) => void;
 }
 
-export default TurboModuleRegistry.get<Spec>('KeyboardObserver');
+export default (TurboModuleRegistry.get<Spec>('KeyboardObserver'): ?Spec);

Libraries/Components/MaskedView/MaskedViewIOS.ios.js

@@ -11,9 +11,9 @@
 const React = require('react');
 const StyleSheet = require('../../StyleSheet/StyleSheet');
 const View = require('../View/View');
-import RCTMaskedViewNativeComponent from './RCTMaskedViewNativeComponent';
 
 import type {ViewProps} from '../View/ViewPropTypes';
+import RCTMaskedViewNativeComponent from './RCTMaskedViewNativeComponent';
 
 type Props = $ReadOnly<{|
   ...ViewProps,
@@ -65,7 +65,7 @@ type Props = $ReadOnly<{|
 class MaskedViewIOS extends React.Component<Props> {
   _hasWarnedInvalidRenderMask = false;
 
-  render() {
+  render(): React.Node {
     const {maskElement, children, ...otherViewProps} = this.props;
 
     if (!React.isValidElement(maskElement)) {

Libraries/Components/Picker/Picker.js

@@ -121,20 +121,22 @@ class Picker extends React.Component<PickerProps> {
   /**
    * On Android, display the options in a dialog.
    */
-  static MODE_DIALOG = MODE_DIALOG;
+  static MODE_DIALOG: $TEMPORARY$string<'dialog'> = MODE_DIALOG;
 
   /**
    * On Android, display the options in a dropdown (this is the default).
    */
-  static MODE_DROPDOWN = MODE_DROPDOWN;
+  static MODE_DROPDOWN: $TEMPORARY$string<'dropdown'> = MODE_DROPDOWN;
 
-  static Item = PickerItem;
+  static Item: typeof PickerItem = PickerItem;
 
-  static defaultProps = {
+  static defaultProps: $TEMPORARY$object<{|
+    mode: $TEMPORARY$string<'dialog'>,
+  |}> = {
     mode: MODE_DIALOG,
   };
 
-  render() {
+  render(): React.Node {
     if (Platform.OS === 'ios') {
       /* $FlowFixMe(>=0.81.0 site=react_native_ios_fb) This suppression was
        * added when renaming suppression sites. */

Libraries/Components/Picker/PickerIOS.ios.js

@@ -13,17 +13,18 @@
 
 'use strict';
 
+const RCTPickerNativeComponent = require('./RCTPickerNativeComponent');
 const React = require('react');
 const ReactNative = require('../../Renderer/shims/ReactNative');
 const StyleSheet = require('../../StyleSheet/StyleSheet');
 const View = require('../View/View');
-const processColor = require('../../StyleSheet/processColor');
-const RCTPickerNativeComponent = require('./RCTPickerNativeComponent');
 
-import type {SyntheticEvent} from '../../Types/CoreEventTypes';
-import type {ColorValue} from '../../StyleSheet/StyleSheetTypes';
-import type {ViewProps} from '../View/ViewPropTypes';
+const processColor = require('../../StyleSheet/processColor');
+
 import type {TextStyleProp} from '../../StyleSheet/StyleSheet';
+import type {ColorValue} from '../../StyleSheet/StyleSheetTypes';
+import type {SyntheticEvent} from '../../Types/CoreEventTypes';
+import type {ViewProps} from '../View/ViewPropTypes';
 
 type PickerIOSChangeEvent = SyntheticEvent<
   $ReadOnly<{|
@@ -74,19 +75,19 @@ type ItemProps = $ReadOnly<{|
   color?: ?ColorValue,
 |}>;
 
-const PickerIOSItem = (props: ItemProps) => {
+const PickerIOSItem = (props: ItemProps): null => {
   return null;
 };
 
 class PickerIOS extends React.Component<Props, State> {
   _picker: ?React.ElementRef<RCTPickerIOSType> = null;
 
-  state = {
+  state: State = {
     selectedIndex: 0,
     items: [],
   };
 
-  static Item = PickerIOSItem;
+  static Item: (props: ItemProps) => null = PickerIOSItem;
 
   static getDerivedStateFromProps(props: Props): State {
     let selectedIndex = 0;
@@ -106,7 +107,7 @@ class PickerIOS extends React.Component<Props, State> {
     return {selectedIndex, items};
   }
 
-  render() {
+  render(): React.Node {
     return (
       <View style={this.props.style}>
         <RCTPickerNativeComponent

Libraries/Components/RefreshControl/__mocks__/RefreshControlMock.js

@@ -21,7 +21,7 @@ class RefreshControlMock extends React.Component<{}> {
   componentDidMount() {
     RefreshControlMock.latestRef = this;
   }
-  render() {
+  render(): React.Element<string> {
     return <RCTRefreshControl />;
   }
 }

Libraries/Components/SafeAreaView/SafeAreaView.js

@@ -12,15 +12,15 @@ const Platform = require('../../Utilities/Platform');
 const React = require('react');
 const View = require('../View/View');
 
-import type {ViewProps} from '../View/ViewPropTypes';
 import type {NativeComponent} from '../../Renderer/shims/ReactNative';
+import type {ViewProps} from '../View/ViewPropTypes';
 
 type Props = $ReadOnly<{|
   ...ViewProps,
   emulateUnlessSupported?: boolean,
 |}>;
 
-let exported;
+let exported: Class<React$Component<Props>> | Class<NativeComponent<Props>>;
 
 /**
  * Renders nested content and automatically applies paddings reflect the portion

Libraries/Components/ScrollView/ScrollView.js

@@ -27,20 +27,19 @@ const requireNativeComponent = require('../../ReactNative/requireNativeComponent
 const resolveAssetSource = require('../../Image/resolveAssetSource');
 const splitLayoutProps = require('../../StyleSheet/splitLayoutProps');
 
+import type {NativeMethodsMixinType} from '../../Renderer/shims/ReactNativeTypes';
+import type {EdgeInsetsProp} from '../../StyleSheet/EdgeInsetsPropType';
+import type {PointProp} from '../../StyleSheet/PointPropType';
+import type {ViewStyleProp} from '../../StyleSheet/StyleSheet';
+import type {ColorValue} from '../../StyleSheet/StyleSheetTypes';
 import type {
   PressEvent,
   ScrollEvent,
   LayoutEvent,
 } from '../../Types/CoreEventTypes';
-import type {EdgeInsetsProp} from '../../StyleSheet/EdgeInsetsPropType';
-import type {NativeMethodsMixinType} from '../../Renderer/shims/ReactNativeTypes';
-import type {ViewStyleProp} from '../../StyleSheet/StyleSheet';
-import type {ViewProps} from '../View/ViewPropTypes';
-import type {PointProp} from '../../StyleSheet/PointPropType';
-import type {Props as ScrollViewStickyHeaderProps} from './ScrollViewStickyHeader';
-
-import type {ColorValue} from '../../StyleSheet/StyleSheetTypes';
 import type {State as ScrollResponderState} from '../ScrollResponder';
+import type {ViewProps} from '../View/ViewPropTypes';
+import type {Props as ScrollViewStickyHeaderProps} from './ScrollViewStickyHeader';
 
 let AndroidScrollView;
 let AndroidHorizontalScrollContentView;
@@ -628,7 +627,7 @@ const standardVerticalContext: ContextType = Object.freeze({horizontal: false});
  * supports out of the box.
  */
 class ScrollView extends React.Component<Props, State> {
-  static Context = Context;
+  static Context: React$Context<ContextType> = Context;
   /**
    * Part 1: Removing ScrollResponder.Mixin:
    *
@@ -688,7 +687,7 @@ class ScrollView extends React.Component<Props, State> {
   _stickyHeaderRefs: Map<string, StickyHeaderComponentType> = new Map();
   _headerLayoutYs: Map<string, number> = new Map();
 
-  state = {
+  state: State = {
     layoutHeight: null,
     ...ScrollResponder.Mixin.scrollResponderMixinGetInitialState(),
   };
@@ -941,7 +940,7 @@ class ScrollView extends React.Component<Props, State> {
     this._innerViewRef = ref;
   };
 
-  render() {
+  render(): React.Node | React.Element<string> {
     let ScrollViewClass;
     let ScrollContentContainerViewClass;
     if (Platform.OS === 'android') {

Libraries/Components/ScrollView/ScrollViewStickyHeader.js

@@ -38,7 +38,7 @@ type State = {
 };
 
 class ScrollViewStickyHeader extends React.Component<Props, State> {
-  state = {
+  state: State = {
     measured: false,
     layoutY: 0,
     layoutHeight: 0,
@@ -63,7 +63,7 @@ class ScrollViewStickyHeader extends React.Component<Props, State> {
     }
   };
 
-  render() {
+  render(): React.Node {
     const {inverted, scrollViewHeight} = this.props;
     const {measured, layoutHeight, layoutY, nextHeaderLayoutY} = this.state;
     const inputRange: Array<number> = [-1, 0];

Libraries/Components/ScrollView/__mocks__/ScrollViewMock.js

@@ -19,10 +19,10 @@ const requireNativeComponent = require('../../../ReactNative/requireNativeCompon
 
 const RCTScrollView = requireNativeComponent('RCTScrollView');
 
-const ScrollViewComponent = jest.genMockFromModule('../ScrollView');
+const ScrollViewComponent: $FlowFixMe = jest.genMockFromModule('../ScrollView');
 
 class ScrollViewMock extends ScrollViewComponent {
-  render() {
+  render(): React.Element<string> {
     return (
       <RCTScrollView {...this.props}>
         {this.props.refreshControl}

Libraries/Components/Sound/NativeSoundManager.js

@@ -20,4 +20,4 @@ export interface Spec extends TurboModule {
   +playTouchSound: () => void;
 }
 
-export default TurboModuleRegistry.getEnforcing<Spec>('SoundManager');
+export default (TurboModuleRegistry.getEnforcing<Spec>('SoundManager'): Spec);

Libraries/Components/StaticContainer.react.js

@@ -43,7 +43,7 @@ class StaticContainer extends React.Component<Props> {
     return !!nextProps.shouldUpdate;
   }
 
-  render() {
+  render(): null | React$Node {
     const child = this.props.children;
     return child === null || child === false
       ? null

Libraries/Components/StatusBar/NativeStatusBarManager.js

@@ -45,4 +45,6 @@ export interface Spec extends TurboModule {
   +setHidden: (hidden: boolean, withAnimation?: ?string) => void;
 }
 
-export default TurboModuleRegistry.getEnforcing<Spec>('StatusBarManager');
+export default (TurboModuleRegistry.getEnforcing<Spec>(
+  'StatusBarManager',
+): Spec);

Libraries/Components/StatusBar/StatusBar.js

@@ -10,10 +10,11 @@
 
 'use strict';
 
-const React = require('react');
 const Platform = require('../../Utilities/Platform');
+const React = require('react');
 
 const processColor = require('../../StyleSheet/processColor');
+
 import NativeStatusBarManager from './NativeStatusBarManager';
 
 /**
@@ -245,7 +246,7 @@ class StatusBar extends React.Component<Props> {
    *
    * @platform android
    */
-  static currentHeight = NativeStatusBarManager.getConstants().HEIGHT;
+  static currentHeight: number = NativeStatusBarManager.getConstants().HEIGHT;
 
   // Provide an imperative API as static functions of the component.
   // See the corresponding prop for more detail.
@@ -339,7 +340,7 @@ class StatusBar extends React.Component<Props> {
    *
    * @param props Object containing the StatusBar props to use in the stack entry.
    */
-  static pushStackEntry(props: any) {
+  static pushStackEntry(props: any): any {
     const entry = createStackEntry(props);
     StatusBar._propsStack.push(entry);
     StatusBar._updatePropsStack();
@@ -365,7 +366,7 @@ class StatusBar extends React.Component<Props> {
    * @param entry Entry returned from `pushStackEntry` to replace.
    * @param props Object containing the StatusBar props to use in the replacement stack entry.
    */
-  static replaceStackEntry(entry: any, props: any) {
+  static replaceStackEntry(entry: any, props: any): any {
     const newEntry = createStackEntry(props);
     const index = StatusBar._propsStack.indexOf(entry);
     if (index !== -1) {
@@ -375,7 +376,10 @@ class StatusBar extends React.Component<Props> {
     return newEntry;
   }
 
-  static defaultProps = {
+  static defaultProps: $TEMPORARY$object<{|
+    animated: boolean,
+    showHideTransition: $TEMPORARY$string<'fade'>,
+  |}> = {
     animated: false,
     showHideTransition: 'fade',
   };

Libraries/Components/StatusBar/StatusBarIOS.ios.js

@@ -11,6 +11,7 @@
 'use strict';
 
 const NativeEventEmitter = require('../../EventEmitter/NativeEventEmitter');
+
 import NativeStatusBarManager from './NativeStatusBarManager';
 
 /**
@@ -18,4 +19,4 @@ import NativeStatusBarManager from './NativeStatusBarManager';
  */
 class StatusBarIOS extends NativeEventEmitter {}
 
-module.exports = new StatusBarIOS(NativeStatusBarManager);
+module.exports = (new StatusBarIOS(NativeStatusBarManager): StatusBarIOS);

Libraries/Components/Switch/Switch.js

@@ -10,15 +10,15 @@
 
 'use strict';
 
-import SwitchNativeComponent from './SwitchNativeComponent';
 const AndroidSwitchNativeComponent = require('./AndroidSwitchNativeComponent');
 const Platform = require('../../Utilities/Platform');
 const React = require('react');
 const StyleSheet = require('../../StyleSheet/StyleSheet');
 
-import type {SyntheticEvent} from '../../Types/CoreEventTypes';
 import type {ColorValue} from '../../StyleSheet/StyleSheetTypes';
+import type {SyntheticEvent} from '../../Types/CoreEventTypes';
 import type {ViewProps} from '../View/ViewPropTypes';
+import SwitchNativeComponent from './SwitchNativeComponent';
 
 type SwitchChangeEvent = SyntheticEvent<
   $ReadOnly<{|
@@ -93,7 +93,7 @@ class Switch extends React.Component<Props> {
     typeof SwitchNativeComponent | typeof AndroidSwitchNativeComponent,
   >;
 
-  render() {
+  render(): React.Node {
     const {
       disabled,
       ios_backgroundColor,

Libraries/Components/TextInput/AndroidTextInputNativeComponent.js

@@ -12,7 +12,7 @@
 
 import {requireNativeComponent} from 'react-native';
 
-const AndroidTextInputNativeComponent = requireNativeComponent(
+const AndroidTextInputNativeComponent: string = requireNativeComponent(
   'AndroidTextInput',
 );
 

Libraries/Components/TextInput/TextInputState.js

@@ -79,7 +79,7 @@ function unregisterInput(textFieldID: number) {
   inputs.delete(textFieldID);
 }
 
-function isTextInput(textFieldID: number) {
+function isTextInput(textFieldID: number): boolean {
   return inputs.has(textFieldID);
 }
 

Libraries/Components/TimePickerAndroid/NativeTimePickerAndroid.js

@@ -30,4 +30,4 @@ export interface Spec extends TurboModule {
   +open: (options: TimePickerOptions) => Promise<TimePickerResult>;
 }
 
-export default TurboModuleRegistry.get<Spec>('TimePickerAndroid');
+export default (TurboModuleRegistry.get<Spec>('TimePickerAndroid'): ?Spec);

Libraries/Components/ToastAndroid/NativeToastAndroid.js

@@ -36,4 +36,4 @@ export interface Spec extends TurboModule {
   ) => void;
 }
 
-export default TurboModuleRegistry.getEnforcing<Spec>('ToastAndroid');
+export default (TurboModuleRegistry.getEnforcing<Spec>('ToastAndroid'): Spec);

Libraries/Components/Touchable/Touchable.js

@@ -23,8 +23,8 @@ const View = require('../View/View');
 const keyMirror = require('fbjs/lib/keyMirror');
 const normalizeColor = require('../../Color/normalizeColor');
 
-import type {PressEvent} from '../../Types/CoreEventTypes';
 import type {EdgeInsetsProp} from '../../StyleSheet/EdgeInsetsPropType';
+import type {PressEvent} from '../../Types/CoreEventTypes';
 
 const extractSingleTouch = nativeEvent => {
   const touches = nativeEvent.touches;
@@ -409,7 +409,9 @@ const TouchableMixin = {
    * @return {object} State object to be placed inside of
    * `this.state.touchable`.
    */
-  touchableGetInitialState: function() {
+  touchableGetInitialState: function(): $TEMPORARY$object<{|
+    touchable: $TEMPORARY$object<{|responderID: null, touchState: void|}>,
+  |}> {
     return {
       touchable: {touchState: undefined, responderID: null},
     };
@@ -419,21 +421,21 @@ const TouchableMixin = {
   /**
    * Must return true if embedded in a native platform scroll view.
    */
-  touchableHandleResponderTerminationRequest: function() {
+  touchableHandleResponderTerminationRequest: function(): any {
     return !this.props.rejectResponderTermination;
   },
 
   /**
    * Must return true to start the process of `Touchable`.
    */
-  touchableHandleStartShouldSetResponder: function() {
+  touchableHandleStartShouldSetResponder: function(): any {
     return !this.props.disabled;
   },
 
   /**
    * Return true to cancel press on long press.
    */
-  touchableLongPressCancelsPress: function() {
+  touchableLongPressCancelsPress: function(): boolean {
     return true;
   },
 
@@ -784,7 +786,7 @@ const TouchableMixin = {
     this.longPressDelayTimeout = null;
   },
 
-  _isHighlight: function(state: State) {
+  _isHighlight: function(state: State): boolean {
     return (
       state === States.RESPONDER_ACTIVE_PRESS_IN ||
       state === States.RESPONDER_ACTIVE_LONG_PRESS_IN
@@ -805,7 +807,7 @@ const TouchableMixin = {
     aY: number,
     bX: number,
     bY: number,
-  ) {
+  ): number {
     const deltaX = aX - bX;
     const deltaY = aY - bY;
     return Math.sqrt(deltaX * deltaX + deltaY * deltaY);
@@ -907,7 +909,7 @@ const TouchableMixin = {
     }
   },
 
-  withoutDefaultFocusAndBlur: {},
+  withoutDefaultFocusAndBlur: ({}: $TEMPORARY$object<{||}>),
 };
 
 /**
@@ -935,7 +937,7 @@ const Touchable = {
   }: {
     color: string | number,
     hitSlop: EdgeInsetsProp,
-  }) => {
+  }): null | React.Node => {
     if (!Touchable.TOUCH_TARGET_DEBUG) {
       return null;
     }

Libraries/Components/UnimplementedViews/UnimplementedView.js

@@ -23,7 +23,7 @@ class UnimplementedView extends React.Component<$FlowFixMeProps> {
     // See ensureComponentIsNative.js for more info
   }
 
-  render() {
+  render(): React.Node {
     // Workaround require cycle from requireNativeComponent
     const View = require('../View/View');
     return (

Libraries/Components/View/ReactNativeViewViewConfig.js

@@ -15,8 +15,8 @@ const ReactNativeViewConfig = {
   uiViewClassName: 'RCTView',
   baseModuleName: null,
   Manager: 'ViewManager',
-  Commands: {},
-  Constants: {},
+  Commands: ({}: $TEMPORARY$object<{||}>),
+  Constants: ({}: $TEMPORARY$object<{||}>),
   bubblingEventTypes: {
     ...ReactNativeViewViewConfigAndroid.bubblingEventTypes,
     topBlur: {

Libraries/Components/View/ViewNativeComponent.js

@@ -10,10 +10,11 @@
 
 'use strict';
 
-const ReactNative = require('../../Renderer/shims/ReactNative');
 const Platform = require('../../Utilities/Platform');
-const registerGeneratedViewConfig = require('../../Utilities/registerGeneratedViewConfig');
+const ReactNative = require('../../Renderer/shims/ReactNative');
 const ReactNativeViewViewConfigAndroid = require('./ReactNativeViewViewConfigAndroid');
+
+const registerGeneratedViewConfig = require('../../Utilities/registerGeneratedViewConfig');
 const requireNativeComponent = require('../../ReactNative/requireNativeComponent');
 
 import type {ViewProps} from './ViewPropTypes';
@@ -23,7 +24,30 @@ export type ViewNativeComponentType = Class<
 >;
 
 let NativeViewComponent;
-let viewConfig;
+let viewConfig:
+  | $TEMPORARY$object<{||}>
+  | $TEMPORARY$object<{|
+      bubblingEventTypes?: $ReadOnly<{
+        [eventName: string]: $ReadOnly<{|
+          phasedRegistrationNames: $ReadOnly<{|
+            bubbled: string,
+            captured: string,
+          |}>,
+        |}>,
+      }>,
+      directEventTypes?: $ReadOnly<{
+        [eventName: string]: $ReadOnly<{|registrationName: string|}>,
+      }>,
+      uiViewClassName: string,
+      validAttributes?: {
+        [propName: string]:
+          | true
+          | $ReadOnly<{|
+              diff?: <T>(arg1: any, arg2: any) => boolean,
+              process?: (arg1: any) => any,
+            |}>,
+      },
+    |}>;
 
 // Only use the JS view config in DEV
 if (__DEV__) {

Libraries/Core/ExceptionsManager.js

@@ -13,7 +13,7 @@
 import type {ExtendedError} from './Devtools/parseErrorStack';
 
 class SyntheticError extends Error {
-  name = '';
+  name: string = '';
 }
 
 /**

Libraries/Core/SegmentFetcher/NativeSegmentFetcher.js

@@ -25,4 +25,4 @@ export interface Spec extends TurboModule {
   ) => void;
 }
 
-export default TurboModuleRegistry.getEnforcing<Spec>('SegmentFetcher');
+export default (TurboModuleRegistry.getEnforcing<Spec>('SegmentFetcher'): Spec);

Libraries/Core/Timers/JSTimers.js

@@ -9,15 +9,14 @@
  */
 'use strict';
 
+const BatchedBridge = require('../../BatchedBridge/BatchedBridge');
 const Platform = require('../../Utilities/Platform');
 const Systrace = require('../../Performance/Systrace');
 
 const invariant = require('invariant');
-const BatchedBridge = require('../../BatchedBridge/BatchedBridge');
-
-import NativeTiming from './NativeTiming';
 
 import type {ExtendedError} from '../Devtools/parseErrorStack';
+import NativeTiming from './NativeTiming';
 
 let _performanceNow = null;
 function performanceNow() {
@@ -498,7 +497,22 @@ function setSendIdleEvents(sendIdleEvents: boolean): void {
   NativeTiming.setSendIdleEvents(sendIdleEvents);
 }
 
-let ExportedJSTimers;
+let ExportedJSTimers: $TEMPORARY$object<{|
+  callIdleCallbacks: (frameTime: number) => any | void,
+  callImmediates: () => void,
+  callTimers: (timersToCall: Array<number>) => any | void,
+  cancelAnimationFrame: (timerID: number) => void,
+  cancelIdleCallback: (timerID: number) => void,
+  clearImmediate: (timerID: number) => void,
+  clearInterval: (timerID: number) => void,
+  clearTimeout: (timerID: number) => void,
+  emitTimeDriftWarning: (warningMessage: string) => any | void,
+  requestAnimationFrame: (func: any) => any | number,
+  requestIdleCallback: (func: any, options: ?any) => any | number,
+  setImmediate: (func: any, ...args: any) => number,
+  setInterval: (func: any, duration: number, ...args: any) => number,
+  setTimeout: (func: any, duration: number, ...args: any) => number,
+|}>;
 if (!NativeTiming) {
   console.warn("Timing native module is not available, can't set timers.");
   // $FlowFixMe: we can assume timers are generally available

Libraries/Core/Timers/NativeTiming.js

@@ -24,4 +24,4 @@ export interface Spec extends TurboModule {
   +setSendIdleEvents: (sendIdleEvents: boolean) => void;
 }
 
-export default TurboModuleRegistry.get<Spec>('Timing');
+export default (TurboModuleRegistry.get<Spec>('Timing'): ?Spec);

Libraries/DeprecatedPropTypes/DeprecatedEdgeInsetsPropType.js

@@ -12,7 +12,12 @@
 
 const PropTypes = require('prop-types');
 
-const DeprecatedEdgeInsetsPropType = PropTypes.shape({
+const DeprecatedEdgeInsetsPropType: React$PropType$Primitive<{
+  bottom?: number,
+  left?: number,
+  right?: number,
+  top?: number,
+}> = PropTypes.shape({
   top: PropTypes.number,
   left: PropTypes.number,
   bottom: PropTypes.number,

Libraries/DeprecatedPropTypes/DeprecatedImagePropType.js

@@ -17,9 +17,11 @@ const DeprecatedStyleSheetPropType = require('./DeprecatedStyleSheetPropType');
 const PropTypes = require('prop-types');
 
 module.exports = {
-  style: DeprecatedStyleSheetPropType(DeprecatedImageStylePropTypes),
+  style: (DeprecatedStyleSheetPropType(
+    DeprecatedImageStylePropTypes,
+  ): ReactPropsCheckType),
   source: DeprecatedImageSourcePropType,
-  defaultSource: PropTypes.oneOfType([
+  defaultSource: (PropTypes.oneOfType([
     PropTypes.shape({
       uri: PropTypes.string,
       width: PropTypes.number,
@@ -27,7 +29,9 @@ module.exports = {
       scale: PropTypes.number,
     }),
     PropTypes.number,
-  ]),
+  ]): React$PropType$Primitive<
+    {height?: number, scale?: number, uri?: string, width?: number} | number,
+  >),
 
   accessible: PropTypes.bool,
 
@@ -37,15 +41,21 @@ module.exports = {
 
   capInsets: DeprecatedEdgeInsetsPropType,
 
-  resizeMethod: PropTypes.oneOf(['auto', 'resize', 'scale']),
+  resizeMethod: (PropTypes.oneOf([
+    'auto',
+    'resize',
+    'scale',
+  ]): React$PropType$Primitive<'auto' | 'resize' | 'scale'>),
 
-  resizeMode: PropTypes.oneOf([
+  resizeMode: (PropTypes.oneOf([
     'cover',
     'contain',
     'stretch',
     'repeat',
     'center',
-  ]),
+  ]): React$PropType$Primitive<
+    'cover' | 'contain' | 'stretch' | 'repeat' | 'center',
+  >),
 
   testID: PropTypes.string,
 

Libraries/DeprecatedPropTypes/DeprecatedImageStylePropTypes.js

@@ -11,27 +11,35 @@
 
 const DeprecatedColorPropType = require('./DeprecatedColorPropType');
 const DeprecatedLayoutPropTypes = require('./DeprecatedLayoutPropTypes');
-const ReactPropTypes = require('prop-types');
 const DeprecatedShadowPropTypesIOS = require('./DeprecatedShadowPropTypesIOS');
 const DeprecatedTransformPropTypes = require('./DeprecatedTransformPropTypes');
+const ReactPropTypes = require('prop-types');
 
 const ImageStylePropTypes = {
   ...DeprecatedLayoutPropTypes,
   ...DeprecatedShadowPropTypesIOS,
   ...DeprecatedTransformPropTypes,
-  resizeMode: ReactPropTypes.oneOf([
+  resizeMode: (ReactPropTypes.oneOf([
     'center',
     'contain',
     'cover',
     'repeat',
     'stretch',
-  ]),
-  backfaceVisibility: ReactPropTypes.oneOf(['visible', 'hidden']),
+  ]): React$PropType$Primitive<
+    'center' | 'contain' | 'cover' | 'repeat' | 'stretch',
+  >),
+  backfaceVisibility: (ReactPropTypes.oneOf([
+    'visible',
+    'hidden',
+  ]): React$PropType$Primitive<'visible' | 'hidden'>),
   backgroundColor: DeprecatedColorPropType,
   borderColor: DeprecatedColorPropType,
   borderWidth: ReactPropTypes.number,
   borderRadius: ReactPropTypes.number,
-  overflow: ReactPropTypes.oneOf(['visible', 'hidden']),
+  overflow: (ReactPropTypes.oneOf([
+    'visible',
+    'hidden',
+  ]): React$PropType$Primitive<'visible' | 'hidden'>),
 
   /**
    * Changes the color of all the non-transparent pixels to the tintColor.

Libraries/DeprecatedPropTypes/DeprecatedLayoutPropTypes.js

@@ -13,121 +13,129 @@
 const ReactPropTypes = require('prop-types');
 
 const LayoutPropTypes = {
-  display: ReactPropTypes.oneOf(['none', 'flex']),
-  width: ReactPropTypes.oneOfType([
+  display: (ReactPropTypes.oneOf(['none', 'flex']): React$PropType$Primitive<
+    'none' | 'flex',
+  >),
+  width: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  height: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  height: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  start: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  start: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  end: ReactPropTypes.oneOfType([ReactPropTypes.number, ReactPropTypes.string]),
-  top: ReactPropTypes.oneOfType([ReactPropTypes.number, ReactPropTypes.string]),
-  left: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  end: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  right: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  top: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  bottom: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  left: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  minWidth: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  right: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  maxWidth: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  bottom: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  minHeight: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  minWidth: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  maxHeight: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  maxWidth: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  margin: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  minHeight: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  marginVertical: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  maxHeight: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  marginHorizontal: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  margin: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  marginTop: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  marginVertical: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  marginBottom: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  marginHorizontal: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  marginLeft: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  marginTop: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  marginRight: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  marginBottom: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  marginStart: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  marginLeft: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  marginEnd: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  marginRight: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  padding: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  marginStart: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  paddingVertical: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  marginEnd: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  paddingHorizontal: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  padding: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  paddingTop: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  paddingVertical: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  paddingBottom: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  paddingHorizontal: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  paddingLeft: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  paddingTop: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  paddingRight: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  paddingBottom: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  paddingStart: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  paddingLeft: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
-  paddingEnd: ReactPropTypes.oneOfType([
+  ]): React$PropType$Primitive<number | string>),
+  paddingRight: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
+  ]): React$PropType$Primitive<number | string>),
+  paddingStart: (ReactPropTypes.oneOfType([
+    ReactPropTypes.number,
+    ReactPropTypes.string,
+  ]): React$PropType$Primitive<number | string>),
+  paddingEnd: (ReactPropTypes.oneOfType([
+    ReactPropTypes.number,
+    ReactPropTypes.string,
+  ]): React$PropType$Primitive<number | string>),
   borderWidth: ReactPropTypes.number,
   borderTopWidth: ReactPropTypes.number,
   borderStartWidth: ReactPropTypes.number,
@@ -135,56 +143,91 @@ const LayoutPropTypes = {
   borderRightWidth: ReactPropTypes.number,
   borderBottomWidth: ReactPropTypes.number,
   borderLeftWidth: ReactPropTypes.number,
-  position: ReactPropTypes.oneOf(['absolute', 'relative']),
-  flexDirection: ReactPropTypes.oneOf([
+  position: (ReactPropTypes.oneOf([
+    'absolute',
+    'relative',
+  ]): React$PropType$Primitive<'absolute' | 'relative'>),
+  flexDirection: (ReactPropTypes.oneOf([
     'row',
     'row-reverse',
     'column',
     'column-reverse',
-  ]),
-  flexWrap: ReactPropTypes.oneOf(['wrap', 'nowrap', 'wrap-reverse']),
-  justifyContent: ReactPropTypes.oneOf([
+  ]): React$PropType$Primitive<
+    'row' | 'row-reverse' | 'column' | 'column-reverse',
+  >),
+  flexWrap: (ReactPropTypes.oneOf([
+    'wrap',
+    'nowrap',
+    'wrap-reverse',
+  ]): React$PropType$Primitive<'wrap' | 'nowrap' | 'wrap-reverse'>),
+  justifyContent: (ReactPropTypes.oneOf([
     'flex-start',
     'flex-end',
     'center',
     'space-between',
     'space-around',
     'space-evenly',
-  ]),
-  alignItems: ReactPropTypes.oneOf([
+  ]): React$PropType$Primitive<
+    | 'flex-start'
+    | 'flex-end'
+    | 'center'
+    | 'space-between'
+    | 'space-around'
+    | 'space-evenly',
+  >),
+  alignItems: (ReactPropTypes.oneOf([
     'flex-start',
     'flex-end',
     'center',
     'stretch',
     'baseline',
-  ]),
-  alignSelf: ReactPropTypes.oneOf([
+  ]): React$PropType$Primitive<
+    'flex-start' | 'flex-end' | 'center' | 'stretch' | 'baseline',
+  >),
+  alignSelf: (ReactPropTypes.oneOf([
     'auto',
     'flex-start',
     'flex-end',
     'center',
     'stretch',
     'baseline',
-  ]),
-  alignContent: ReactPropTypes.oneOf([
+  ]): React$PropType$Primitive<
+    'auto' | 'flex-start' | 'flex-end' | 'center' | 'stretch' | 'baseline',
+  >),
+  alignContent: (ReactPropTypes.oneOf([
     'flex-start',
     'flex-end',
     'center',
     'stretch',
     'space-between',
     'space-around',
-  ]),
-  overflow: ReactPropTypes.oneOf(['visible', 'hidden', 'scroll']),
+  ]): React$PropType$Primitive<
+    | 'flex-start'
+    | 'flex-end'
+    | 'center'
+    | 'stretch'
+    | 'space-between'
+    | 'space-around',
+  >),
+  overflow: (ReactPropTypes.oneOf([
+    'visible',
+    'hidden',
+    'scroll',
+  ]): React$PropType$Primitive<'visible' | 'hidden' | 'scroll'>),
   flex: ReactPropTypes.number,
   flexGrow: ReactPropTypes.number,
   flexShrink: ReactPropTypes.number,
-  flexBasis: ReactPropTypes.oneOfType([
+  flexBasis: (ReactPropTypes.oneOfType([
     ReactPropTypes.number,
     ReactPropTypes.string,
-  ]),
+  ]): React$PropType$Primitive<number | string>),
   aspectRatio: ReactPropTypes.number,
   zIndex: ReactPropTypes.number,
-  direction: ReactPropTypes.oneOf(['inherit', 'ltr', 'rtl']),
+  direction: (ReactPropTypes.oneOf([
+    'inherit',
+    'ltr',
+    'rtl',
+  ]): React$PropType$Primitive<'inherit' | 'ltr' | 'rtl'>),
 };
 
 module.exports = LayoutPropTypes;

Libraries/DeprecatedPropTypes/DeprecatedPointPropType.js

@@ -12,7 +12,10 @@
 
 const PropTypes = require('prop-types');
 
-const PointPropType = PropTypes.shape({
+const PointPropType: React$PropType$Primitive<{
+  x?: number,
+  y?: number,
+}> = PropTypes.shape({
   x: PropTypes.number,
   y: PropTypes.number,
 });

Libraries/DeprecatedPropTypes/DeprecatedShadowPropTypesIOS.js

@@ -14,10 +14,10 @@ const ReactPropTypes = require('prop-types');
 
 const DeprecatedShadowPropTypesIOS = {
   shadowColor: DeprecatedColorPropType,
-  shadowOffset: ReactPropTypes.shape({
+  shadowOffset: (ReactPropTypes.shape({
     width: ReactPropTypes.number,
     height: ReactPropTypes.number,
-  }),
+  }): React$PropType$Primitive<{height?: number, width?: number}>),
   shadowOpacity: ReactPropTypes.number,
   shadowRadius: ReactPropTypes.number,
 };

Libraries/DeprecatedPropTypes/DeprecatedTextPropTypes.js

@@ -16,12 +16,23 @@ const DeprecatedStyleSheetPropType = require('./DeprecatedStyleSheetPropType');
 const PropTypes = require('prop-types');
 const TextStylePropTypes = require('../Text/TextStylePropTypes');
 
-const stylePropType = DeprecatedStyleSheetPropType(TextStylePropTypes);
+const stylePropType: ReactPropsCheckType = DeprecatedStyleSheetPropType(
+  TextStylePropTypes,
+);
 
 module.exports = {
-  ellipsizeMode: PropTypes.oneOf(['head', 'middle', 'tail', 'clip']),
+  ellipsizeMode: (PropTypes.oneOf([
+    'head',
+    'middle',
+    'tail',
+    'clip',
+  ]): React$PropType$Primitive<'head' | 'middle' | 'tail' | 'clip'>),
   numberOfLines: PropTypes.number,
-  textBreakStrategy: PropTypes.oneOf(['simple', 'highQuality', 'balanced']),
+  textBreakStrategy: (PropTypes.oneOf([
+    'simple',
+    'highQuality',
+    'balanced',
+  ]): React$PropType$Primitive<'simple' | 'highQuality' | 'balanced'>),
   onLayout: PropTypes.func,
   onPress: PropTypes.func,
   onLongPress: PropTypes.func,

Libraries/DeprecatedPropTypes/DeprecatedTransformPropTypes.js

@@ -41,7 +41,7 @@ const DecomposedMatrixPropType = function(
 };
 
 const DeprecatedTransformPropTypes = {
-  transform: ReactPropTypes.arrayOf(
+  transform: (ReactPropTypes.arrayOf(
     ReactPropTypes.oneOfType([
       ReactPropTypes.shape({perspective: ReactPropTypes.number}),
       ReactPropTypes.shape({rotate: ReactPropTypes.string}),
@@ -56,29 +56,44 @@ const DeprecatedTransformPropTypes = {
       ReactPropTypes.shape({skewX: ReactPropTypes.string}),
       ReactPropTypes.shape({skewY: ReactPropTypes.string}),
     ]),
-  ),
+  ): React$PropType$Primitive<
+    Array<
+      | {perspective?: number}
+      | {rotate?: string}
+      | {rotateX?: string}
+      | {rotateY?: string}
+      | {rotateZ?: string}
+      | {scale?: number}
+      | {scaleX?: number}
+      | {scaleY?: number}
+      | {translateX?: number}
+      | {translateY?: number}
+      | {skewX?: string}
+      | {skewY?: string},
+    >,
+  >),
   transformMatrix: TransformMatrixPropType,
   decomposedMatrix: DecomposedMatrixPropType,
-  scaleX: deprecatedPropType(
+  scaleX: (deprecatedPropType(
     ReactPropTypes.number,
     'Use the transform prop instead.',
-  ),
-  scaleY: deprecatedPropType(
+  ): ReactPropsCheckType),
+  scaleY: (deprecatedPropType(
     ReactPropTypes.number,
     'Use the transform prop instead.',
-  ),
-  rotation: deprecatedPropType(
+  ): ReactPropsCheckType),
+  rotation: (deprecatedPropType(
     ReactPropTypes.number,
     'Use the transform prop instead.',
-  ),
-  translateX: deprecatedPropType(
+  ): ReactPropsCheckType),
+  translateX: (deprecatedPropType(
     ReactPropTypes.number,
     'Use the transform prop instead.',
-  ),
-  translateY: deprecatedPropType(
+  ): ReactPropsCheckType),
+  translateY: (deprecatedPropType(
     ReactPropTypes.number,
     'Use the transform prop instead.',
-  ),
+  ): ReactPropsCheckType),
 };
 
 module.exports = DeprecatedTransformPropTypes;

Libraries/DeprecatedPropTypes/DeprecatedViewPropTypes.js

@@ -11,17 +11,17 @@
 'use strict';
 
 const DeprecatedEdgeInsetsPropType = require('./DeprecatedEdgeInsetsPropType');
-const PlatformViewPropTypes = require('../Components/View/PlatformViewPropTypes');
-const PropTypes = require('prop-types');
 const DeprecatedStyleSheetPropType = require('./DeprecatedStyleSheetPropType');
 const DeprecatedViewStylePropTypes = require('./DeprecatedViewStylePropTypes');
+const PlatformViewPropTypes = require('../Components/View/PlatformViewPropTypes');
+const PropTypes = require('prop-types');
 
 const {
   DeprecatedAccessibilityRoles,
   DeprecatedAccessibilityStates,
 } = require('./DeprecatedViewAccessibility');
 
-const stylePropType = DeprecatedStyleSheetPropType(
+const stylePropType: ReactPropsCheckType = DeprecatedStyleSheetPropType(
   DeprecatedViewStylePropTypes,
 );
 
@@ -58,7 +58,9 @@ module.exports = {
    *
    * @platform ios
    */
-  accessibilityActions: PropTypes.arrayOf(PropTypes.string),
+  accessibilityActions: (PropTypes.arrayOf(
+    PropTypes.string,
+  ): React$PropType$Primitive<Array<string>>),
 
   /**
    * Prevents view from being inverted if set to true and color inversion is turned on.
@@ -70,14 +72,55 @@ module.exports = {
   /**
    * Indicates to accessibility services to treat UI component like a specific role.
    */
-  accessibilityRole: PropTypes.oneOf(DeprecatedAccessibilityRoles),
+  accessibilityRole: (PropTypes.oneOf(
+    DeprecatedAccessibilityRoles,
+  ): React$PropType$Primitive<
+    | 'none'
+    | 'button'
+    | 'link'
+    | 'search'
+    | 'image'
+    | 'keyboardkey'
+    | 'text'
+    | 'adjustable'
+    | 'imagebutton'
+    | 'header'
+    | 'summary'
+    | 'alert'
+    | 'checkbox'
+    | 'combobox'
+    | 'menu'
+    | 'menubar'
+    | 'menuitem'
+    | 'progressbar'
+    | 'radio'
+    | 'radiogroup'
+    | 'scrollbar'
+    | 'spinbutton'
+    | 'switch'
+    | 'tab'
+    | 'tablist'
+    | 'timer'
+    | 'toolbar',
+  >),
 
   /**
    * Indicates to accessibility services that UI Component is in a specific State.
    */
-  accessibilityStates: PropTypes.arrayOf(
+  accessibilityStates: (PropTypes.arrayOf(
     PropTypes.oneOf(DeprecatedAccessibilityStates),
-  ),
+  ): React$PropType$Primitive<
+    Array<
+      | 'selected'
+      | 'disabled'
+      | 'checked'
+      | 'unchecked'
+      | 'busy'
+      | 'expanded'
+      | 'collapsed'
+      | 'hasPopup',
+    >,
+  >),
   accessibilityState: PropTypes.object,
   /**
    * Indicates to accessibility services whether the user should be notified
@@ -87,7 +130,11 @@ module.exports = {
    *
    * See http://facebook.github.io/react-native/docs/view.html#accessibilityliveregion
    */
-  accessibilityLiveRegion: PropTypes.oneOf(['none', 'polite', 'assertive']),
+  accessibilityLiveRegion: (PropTypes.oneOf([
+    'none',
+    'polite',
+    'assertive',
+  ]): React$PropType$Primitive<'none' | 'polite' | 'assertive'>),
 
   /**
    * Controls how view is important for accessibility which is if it
@@ -98,12 +145,12 @@ module.exports = {
    *
    * See http://facebook.github.io/react-native/docs/view.html#importantforaccessibility
    */
-  importantForAccessibility: PropTypes.oneOf([
+  importantForAccessibility: (PropTypes.oneOf([
     'auto',
     'yes',
     'no',
     'no-hide-descendants',
-  ]),
+  ]): React$PropType$Primitive<'auto' | 'yes' | 'no' | 'no-hide-descendants'>),
 
   /**
    * A value indicating whether VoiceOver should ignore the elements
@@ -314,7 +361,12 @@ module.exports = {
    *
    * See http://facebook.github.io/react-native/docs/view.html#pointerevents
    */
-  pointerEvents: PropTypes.oneOf(['box-none', 'none', 'box-only', 'auto']),
+  pointerEvents: (PropTypes.oneOf([
+    'box-none',
+    'none',
+    'box-only',
+    'auto',
+  ]): React$PropType$Primitive<'box-none' | 'none' | 'box-only' | 'auto'>),
 
   /**
    * See http://facebook.github.io/react-native/docs/style.html

Libraries/DeprecatedPropTypes/DeprecatedViewStylePropTypes.js

@@ -12,9 +12,9 @@
 
 const DeprecatedColorPropType = require('./DeprecatedColorPropType');
 const DeprecatedLayoutPropTypes = require('./DeprecatedLayoutPropTypes');
-const ReactPropTypes = require('prop-types');
 const DeprecatedShadowPropTypesIOS = require('./DeprecatedShadowPropTypesIOS');
 const DeprecatedTransformPropTypes = require('./DeprecatedTransformPropTypes');
+const ReactPropTypes = require('prop-types');
 
 /**
  * Warning: Some of these properties may not be supported in all releases.
@@ -23,7 +23,10 @@ const DeprecatedViewStylePropTypes = {
   ...DeprecatedLayoutPropTypes,
   ...DeprecatedShadowPropTypesIOS,
   ...DeprecatedTransformPropTypes,
-  backfaceVisibility: ReactPropTypes.oneOf(['visible', 'hidden']),
+  backfaceVisibility: (ReactPropTypes.oneOf([
+    'visible',
+    'hidden',
+  ]): React$PropType$Primitive<'visible' | 'hidden'>),
   backgroundColor: DeprecatedColorPropType,
   borderColor: DeprecatedColorPropType,
   borderTopColor: DeprecatedColorPropType,
@@ -41,7 +44,11 @@ const DeprecatedViewStylePropTypes = {
   borderBottomRightRadius: ReactPropTypes.number,
   borderBottomStartRadius: ReactPropTypes.number,
   borderBottomEndRadius: ReactPropTypes.number,
-  borderStyle: ReactPropTypes.oneOf(['solid', 'dotted', 'dashed']),
+  borderStyle: (ReactPropTypes.oneOf([
+    'solid',
+    'dotted',
+    'dashed',
+  ]): React$PropType$Primitive<'solid' | 'dotted' | 'dashed'>),
   borderWidth: ReactPropTypes.number,
   borderTopWidth: ReactPropTypes.number,
   borderRightWidth: ReactPropTypes.number,

Libraries/EventEmitter/RCTDeviceEventEmitter.js

@@ -81,4 +81,4 @@ class RCTDeviceEventEmitter extends EventEmitter {
   }
 }
 
-module.exports = new RCTDeviceEventEmitter();
+module.exports = (new RCTDeviceEventEmitter(): RCTDeviceEventEmitter);

Libraries/Experimental/Incremental.js

@@ -11,9 +11,8 @@
 'use strict';
 
 const InteractionManager = require('../Interaction/InteractionManager');
-const React = require('react');
-
 const PropTypes = require('prop-types');
+const React = require('react');
 
 const infoLog = require('../Utilities/infoLog');
 
@@ -104,11 +103,16 @@ class Incremental extends React.Component<Props, State> {
   _mounted: boolean;
   _rendered: boolean;
 
-  static defaultProps = {
+  static defaultProps: $TEMPORARY$object<{|name: string|}> = {
     name: '',
   };
 
-  static contextTypes = {
+  static contextTypes:
+    | any
+    | $TEMPORARY$object<{|
+        incrementalGroup: React$PropType$Primitive<any>,
+        incrementalGroupEnabled: React$PropType$Primitive<boolean>,
+      |}> = {
     incrementalGroup: PropTypes.object,
     incrementalGroupEnabled: PropTypes.bool,
   };

Libraries/Experimental/IncrementalExample.js

@@ -93,8 +93,9 @@ function Block(props: Object) {
 const Row = (props: Object) => <View style={styles.row} {...props} />;
 
 class IncrementalExample extends React.Component<mixed, {stats: ?Object}> {
-  static title = '<Incremental*>';
-  static description = 'Enables incremental rendering of complex components.';
+  static title: string = '<Incremental*>';
+  static description: string =
+    'Enables incremental rendering of complex components.';
   start: number;
   constructor(props: mixed, context: mixed) {
     super(props, context);

Libraries/Experimental/IncrementalPresenter.js

@@ -15,9 +15,9 @@ const PropTypes = require('prop-types');
 const React = require('react');
 const View = require('../Components/View/View');
 
-import type {Context} from './Incremental';
 import type {ViewStyleProp} from '../StyleSheet/StyleSheet';
 import type {LayoutEvent} from '../Types/CoreEventTypes';
+import type {Context} from './Incremental';
 
 /**
  * WARNING: EXPERIMENTAL. Breaking changes will probably happen a lot and will
@@ -44,7 +44,12 @@ class IncrementalPresenter extends React.Component<Props> {
   context: Context;
   _isDone: boolean;
 
-  static contextTypes = {
+  static contextTypes:
+    | any
+    | $TEMPORARY$object<{|
+        incrementalGroup: React$PropType$Primitive<any>,
+        incrementalGroupEnabled: React$PropType$Primitive<boolean>,
+      |}> = {
     incrementalGroup: PropTypes.object,
     incrementalGroupEnabled: PropTypes.bool,
   };
@@ -67,7 +72,7 @@ class IncrementalPresenter extends React.Component<Props> {
     }
     this.props.onDone && this.props.onDone();
   }
-  render() {
+  render(): React.Node {
     let style: ViewStyleProp;
     if (
       this.props.disabled !== true &&

Libraries/Experimental/WindowedListView.js

@@ -170,7 +170,15 @@ class WindowedListView extends React.Component<Props, State> {
   _scrollRef: ?ScrollView;
   _viewabilityHelper: ViewabilityHelper;
 
-  static defaultProps = {
+  static defaultProps: $TEMPORARY$object<{|
+    disableIncrementalRendering: boolean,
+    initialNumToRender: number,
+    maxNumToRender: number,
+    numToRenderAhead: number,
+    recomputeRowsBatchingPeriod: number,
+    renderScrollComponent: (props: any) => React.Node,
+    viewablePercentThreshold: number,
+  |}> = {
     initialNumToRender: 10,
     maxNumToRender: 30,
     numToRenderAhead: 10,

Libraries/HeapCapture/NativeHeapCapture.js

@@ -21,4 +21,4 @@ export interface Spec extends TurboModule {
   +captureComplete: (path: string, error: ?string) => void;
 }
 
-export default TurboModuleRegistry.get<Spec>('HeapCapture');
+export default (TurboModuleRegistry.get<Spec>('HeapCapture'): ?Spec);

Libraries/Image/Image.ios.js

@@ -47,7 +47,7 @@ function getSizeWithHeaders(
   headers: {[string]: string},
   success: (width: number, height: number) => void,
   failure?: (error: any) => void,
-) {
+): any {
   return ImageViewManager.getSizeWithHeaders({uri, headers})
     .then(function(sizes) {
       success(sizes.width, sizes.height);
@@ -60,7 +60,7 @@ function getSizeWithHeaders(
     );
 }
 
-function prefetch(url: string) {
+function prefetch(url: string): any {
   return ImageViewManager.prefetchImage(url);
 }
 

Libraries/Image/ImageBackground.js

@@ -56,7 +56,7 @@ class ImageBackground extends React.Component<$FlowFixMeProps> {
     this._viewRef = ref;
   };
 
-  render() {
+  render(): React.Node {
     const {children, style, imageStyle, imageRef, ...props} = this.props;
 
     return (

Libraries/Image/ImagePickerIOS.js

@@ -14,11 +14,11 @@ import NativeImagePickerIOS from './NativeImagePickerIOS';
 import invariant from 'invariant';
 
 const ImagePickerIOS = {
-  canRecordVideos: function(callback: (result: boolean) => void) {
+  canRecordVideos: function(callback: (result: boolean) => void): void {
     invariant(NativeImagePickerIOS, 'ImagePickerIOS is not available');
     return NativeImagePickerIOS.canRecordVideos(callback);
   },
-  canUseCamera: function(callback: (result: boolean) => void) {
+  canUseCamera: function(callback: (result: boolean) => void): void {
     invariant(NativeImagePickerIOS, 'ImagePickerIOS is not available');
     return NativeImagePickerIOS.canUseCamera(callback);
   },
@@ -29,7 +29,7 @@ const ImagePickerIOS = {
     |}>,
     successCallback: (imageURL: string, height: number, width: number) => void,
     cancelCallback: () => void,
-  ) {
+  ): void {
     invariant(NativeImagePickerIOS, 'ImagePickerIOS is not available');
 
     var newConfig = {
@@ -58,7 +58,7 @@ const ImagePickerIOS = {
     |}>,
     successCallback: (imageURL: string, height: number, width: number) => void,
     cancelCallback: () => void,
-  ) {
+  ): void {
     invariant(NativeImagePickerIOS, 'ImagePickerIOS is not available');
 
     var newConfig = {

Libraries/Image/ImageViewNativeComponent.js

@@ -12,6 +12,6 @@
 
 const requireNativeComponent = require('../ReactNative/requireNativeComponent');
 
-const ImageViewNativeComponent = requireNativeComponent('RCTImageView');
+const ImageViewNativeComponent: string = requireNativeComponent('RCTImageView');
 
 module.exports = ImageViewNativeComponent;

Libraries/Image/NativeImagePickerIOS.js

@@ -35,4 +35,4 @@ export interface Spec extends TurboModule {
   ) => void;
 }
 
-export default TurboModuleRegistry.get<Spec>('ImagePickerIOS');
+export default (TurboModuleRegistry.get<Spec>('ImagePickerIOS'): ?Spec);

Libraries/Image/RelativeImageStub.js

@@ -15,7 +15,7 @@
 
 const AssetRegistry = require('./AssetRegistry');
 
-module.exports = AssetRegistry.registerAsset({
+module.exports = (AssetRegistry.registerAsset({
   __packager_asset: true,
   fileSystemLocation: '/full/path/to/directory',
   httpServerLocation: '/assets/full/path/to/directory',
@@ -25,4 +25,4 @@ module.exports = AssetRegistry.registerAsset({
   hash: 'nonsense',
   name: 'icon',
   type: 'png',
-});
+}): number);

Libraries/Image/TextInlineImageNativeComponent.js

@@ -12,6 +12,6 @@
 
 const requireNativeComponent = require('../ReactNative/requireNativeComponent');
 
-const TextInlineImage = requireNativeComponent('RCTTextInlineImage');
+const TextInlineImage: string = requireNativeComponent('RCTTextInlineImage');
 
 module.exports = TextInlineImage;

Libraries/Image/assetPathUtils.js

@@ -44,7 +44,10 @@ const drawableFileTypes = new Set([
   'xml',
 ]);
 
-function getAndroidResourceFolderName(asset: PackagerAsset, scale: number) {
+function getAndroidResourceFolderName(
+  asset: PackagerAsset,
+  scale: number,
+): string | $TEMPORARY$string<'raw'> {
   if (!drawableFileTypes.has(asset.type)) {
     return 'raw';
   }
@@ -63,7 +66,7 @@ function getAndroidResourceFolderName(asset: PackagerAsset, scale: number) {
   return androidFolder;
 }
 
-function getAndroidResourceIdentifier(asset: PackagerAsset) {
+function getAndroidResourceIdentifier(asset: PackagerAsset): string {
   var folderPath = getBasePath(asset);
   return (folderPath + '/' + asset.name)
     .toLowerCase()
@@ -72,7 +75,7 @@ function getAndroidResourceIdentifier(asset: PackagerAsset) {
     .replace(/^assets_/, ''); // Remove "assets_" prefix
 }
 
-function getBasePath(asset: PackagerAsset) {
+function getBasePath(asset: PackagerAsset): string {
   var basePath = asset.httpServerLocation;
   if (basePath[0] === '/') {
     basePath = basePath.substr(1);

Libraries/Inspector/BorderBox.js

@@ -14,7 +14,7 @@ const React = require('react');
 const View = require('../Components/View/View');
 
 class BorderBox extends React.Component<$FlowFixMeProps> {
-  render() {
+  render(): $FlowFixMe | React.Node {
     const box = this.props.box;
     if (!box) {
       return this.props.children;