diff --git a/packages/react-scripts/config/webpack.config.dev.js b/packages/react-scripts/config/webpack.config.dev.js
index 3cf137781..3c27696e9 100644
--- a/packages/react-scripts/config/webpack.config.dev.js
+++ b/packages/react-scripts/config/webpack.config.dev.js
@@ -41,6 +41,7 @@ module.exports = {
   // This means they will be the "root" imports that are included in JS bundle.
   // The first two entry points enable "hot" CSS and auto-refreshes for JS.
   entry: [
+    'core-js/es6/symbol',
     // We ship a few polyfills by default:
     require.resolve('./polyfills'),
     // Include an alternative client for WebpackDevServer. A client's job is to
@@ -90,7 +91,18 @@ module.exports = {
     // https://github.com/facebookincubator/create-react-app/issues/290
     // `web` extension prefixes have been added for better support
     // for React Native Web.
-    extensions: ['.web.ts', '.ts', '.web.tsx', '.tsx', '.web.js', '.mjs', '.js', '.json', '.web.jsx', '.jsx'],
+    extensions: [
+      '.web.ts',
+      '.ts',
+      '.web.tsx',
+      '.tsx',
+      '.web.js',
+      '.mjs',
+      '.js',
+      '.json',
+      '.web.jsx',
+      '.jsx',
+    ],
     alias: {
       // @remove-on-eject-begin
       // Resolve Babel runtime relative to react-scripts.
diff --git a/packages/react-scripts/config/webpack.config.prod.js b/packages/react-scripts/config/webpack.config.prod.js
index 8badecf54..e8dfdc0ee 100644
--- a/packages/react-scripts/config/webpack.config.prod.js
+++ b/packages/react-scripts/config/webpack.config.prod.js
@@ -64,7 +64,11 @@ module.exports = {
   // You can exclude the *.map files from the build during deployment.
   devtool: shouldUseSourceMap ? 'source-map' : false,
   // In production, we only want to load the polyfills and the app code.
-  entry: [require.resolve('./polyfills'), paths.appIndexJs],
+  entry: [
+    'core-js/es6/symbol',
+    require.resolve('./polyfills'),
+    paths.appIndexJs,
+  ],
   output: {
     // The build folder.
     path: paths.appBuild,
@@ -96,7 +100,18 @@ module.exports = {
     // https://github.com/facebookincubator/create-react-app/issues/290
     // `web` extension prefixes have been added for better support
     // for React Native Web.
-    extensions: ['.web.ts', '.ts', '.web.tsx', '.tsx', '.web.js', '.mjs', '.js', '.json', '.web.jsx', '.jsx'],
+    extensions: [
+      '.web.ts',
+      '.ts',
+      '.web.tsx',
+      '.tsx',
+      '.web.js',
+      '.mjs',
+      '.js',
+      '.json',
+      '.web.jsx',
+      '.jsx',
+    ],
     alias: {
       // @remove-on-eject-begin
       // Resolve Babel runtime relative to react-scripts.
@@ -151,6 +166,7 @@ module.exports = {
           {
             test: /\.(ts|tsx)$/,
             include: paths.appSrc,
+
             use: [
               {
                 loader: require.resolve('ts-loader'),
diff --git a/packages/react-scripts/template/tsconfig.json b/packages/react-scripts/template/tsconfig.json
index 58294bb97..a99139099 100644
--- a/packages/react-scripts/template/tsconfig.json
+++ b/packages/react-scripts/template/tsconfig.json
@@ -15,7 +15,8 @@
     "noImplicitAny": true,
     "strictNullChecks": true,
     "suppressImplicitAnyIndexErrors": true,
-    "noUnusedLocals": true
+    "noUnusedLocals": true,
+    "downlevelIteration": true
   },
   "exclude": [
     "node_modules",