Use TypeScript by default for new applications (facebook#35165)

Summary:
This change moves the default new application template in OSS from Flow to TypeScript. This better aligns with the communities usage, and aligns to the great work that has been happening for TS codegen and built-in types. This used [`react-native-community/react-native-template-typescript`](https://github.com/react-native-community/react-native-template-typescript) as a main reference, maintained by radko93. A few things are different:
1. Updated `types/*` devDependencies to match bumped libraries (e.g. Jest 26 to 20).
2. Removed `types/react-native`
3. Removed explicit `moduleFileExtensions` to Jest config in package.json (TS and TSX and added by default in current versions)
4. Removed overrides to eslint config to disable `no-shadow` and `no-undef`, since this was fixed in the underlying eslint config with facebook#32644 and facebook#32655
5. Re-translated `App.js` to be a direct translation (e.g. still a raw function instead of React.FC which is sometimes discouraged)
6. Aligns completely to `tsconfig/react-native` maintained configuration (We no longer have the opinionated override of `skipLibCheck`). The important settings are that `strict` is enabled for, but `allowJS` is also enabled to let users import JS modules without anything unexpected. `esModuleInterop` is enabled, which is needed for consistency with Babel import transformations used by Metro. Consistent with our [current documentation](https://reactnative.dev/docs/typescript) built against the community template, `tsc` will typecheck your code without emitting(building) anything.

[Documentation](https://reactnative.dev/docs/typescript) will need to be updated as a followup.

Changelog:
[General][Changed] - Use TypeScript by default for new applications

Pull Request resolved: facebook#35165

Test Plan: Added usage of `tsc` and `jest` when validating a newly built app. Passes in CircleCI `test_js` job. This also meant removing some cases of copying packages into the users app to pull in the root Metro config (we seem to be able to use the template Metro config consistent with what real apps would get).

Reviewed By: cortinico

Differential Revision: D40911951

Pulled By: NickGerleman

fbshipit-source-id: 15994534235695e91cf994ad06ba2183dfc89a50

Author: NickGerleman

scripts/run-ci-e2e-tests.js

@@ -89,19 +89,9 @@ try {
   exec(`rsync -a ${ROOT}/template ${REACT_NATIVE_TEMP_DIR}`);
   cd(REACT_NATIVE_APP_DIR);
 
-  const METRO_CONFIG = path.join(ROOT, 'metro.config.js');
-  const RN_GET_POLYFILLS = path.join(ROOT, 'rn-get-polyfills.js');
-  const RN_POLYFILLS_PATH = 'packages/polyfills/';
-  exec(`mkdir -p ${RN_POLYFILLS_PATH}`);
-
-  cp(METRO_CONFIG, '.');
-  cp(RN_GET_POLYFILLS, '.');
-  exec(
-    `rsync -a ${ROOT}/${RN_POLYFILLS_PATH} ${REACT_NATIVE_APP_DIR}/${RN_POLYFILLS_PATH}`,
-  );
-  mv('_flowconfig', '.flowconfig');
-  mv('_watchmanconfig', '.watchmanconfig');
   mv('_bundle', '.bundle');
+  mv('_eslintrc.js', '.eslintrc.js');
+  mv('_watchmanconfig', '.watchmanconfig');
 
   describe('Install React Native package');
   exec(`npm install ${REACT_NATIVE_PACKAGE}`);
@@ -267,6 +257,7 @@ try {
       exitCode = 1;
       throw Error(exitCode);
     }
+
     describe('Test: Verify packager can generate an iOS bundle');
     if (
       exec(
@@ -277,12 +268,17 @@ try {
       exitCode = 1;
       throw Error(exitCode);
     }
-    describe('Test: Flow check');
-    // The resolve package included a test for a malformed package.json (see https://github.com/browserify/resolve/issues/89)
-    // that is failing the flow check. We're removing it.
-    rm('-rf', './node_modules/resolve/test/resolver/malformed_package_json');
-    if (exec(`${ROOT}/node_modules/.bin/flow check`).code) {
-      echo('Flow check failed.');
+
+    describe('Test: TypeScript typechecking');
+    if (exec('yarn tsc').code) {
+      echo('Typechecking errors were found');
+      exitCode = 1;
+      throw Error(exitCode);
+    }
+
+    describe('Test: Jest tests');
+    if (exec('yarn test').code) {
+      echo('Jest tests failed');
       exitCode = 1;
       throw Error(exitCode);
     }

template/App.js renamed to template/App.tsx

@@ -3,11 +3,10 @@
  * https://github.com/facebook/react-native
  *
  * @format
- * @flow strict-local
  */
 
 import React from 'react';
-import type {Node} from 'react';
+import type {PropsWithChildren} from 'react';
 import {
   SafeAreaView,
   ScrollView,
@@ -26,12 +25,11 @@ import {
   ReloadInstructions,
 } from 'react-native/Libraries/NewAppScreen';
 
-type SectionProps = {
-  title: string,
-  children: Node,
-};
+type SectionProps = PropsWithChildren<{
+  title: string;
+}>;
 
-function Section({children, title}: SectionProps): Node {
+function Section({children, title}: SectionProps): JSX.Element {
   const isDarkMode = useColorScheme() === 'dark';
   return (
     <View style={styles.sectionContainer}>
@@ -57,7 +55,7 @@ function Section({children, title}: SectionProps): Node {
   );
 }
 
-function App(): Node {
+function App(): JSX.Element {
   const isDarkMode = useColorScheme() === 'dark';
 
   const backgroundStyle = {

template/__tests__/App-test.js renamed to template/__tests__/App-test.tsx

@@ -1,4 +1,6 @@
 module.exports = {
   root: true,
   extends: '@react-native-community',
+  parser: '@typescript-eslint/parser',
+  plugins: ['@typescript-eslint'],
 };

template/_buckconfig

@@ -5,9 +5,9 @@
   "scripts": {
     "android": "react-native run-android",
     "ios": "react-native run-ios",
+    "lint": "eslint .",
     "start": "react-native start",
-    "test": "jest",
-    "lint": "eslint ."
+    "test": "jest"
   },
   "dependencies": {
     "react": "18.2.0",
@@ -17,11 +17,18 @@
     "@babel/core": "^7.12.9",
     "@babel/runtime": "^7.12.5",
     "@react-native-community/eslint-config": "^3.0.0",
+    "@tsconfig/react-native": "^2.0.2",
+    "@types/jest": "^29.2.1",
+    "@types/react": "^18.0.24",
+    "@types/react-test-renderer": "^18.0.0",
+    "@typescript-eslint/eslint-plugin": "^5.37.0",
+    "@typescript-eslint/parser": "^5.37.0",
     "babel-jest": "^29.2.1",
     "eslint": "^8.19.0",
     "jest": "^29.2.1",
     "metro-react-native-babel-preset": "0.73.3",
-    "react-test-renderer": "18.2.0"
+    "react-test-renderer": "18.2.0",
+    "typescript": "^4.8.3"
   },
   "jest": {
     "preset": "react-native"

template/_eslintrc.js

@@ -0,0 +1,3 @@
+{
+  "extends": "@tsconfig/react-native/tsconfig.json"
+}