Imported config files and start script from new create react app

scripts/start.js

@@ -1,4 +1,4 @@
-/* eslint no-console: "off" */
+'use strict';
 
 // Do this as the first thing so that any code reading it knows the right env.
 process.env.BABEL_ENV = 'development';
@@ -7,13 +7,14 @@ process.env.NODE_ENV = 'development';
 // Makes the script crash on unhandled rejections instead of silently
 // ignoring them. In the future, promise rejections that are not handled will
 // terminate the Node.js process with a non-zero exit code.
-process.on('unhandledRejection', (err) => {
+process.on('unhandledRejection', err => {
   throw err;
 });
 
 // Ensure environment variables are read.
 require('../config/env');
 
+
 const fs = require('fs');
 const chalk = require('chalk');
 const webpack = require('webpack');
@@ -28,20 +29,19 @@ const {
 } = require('react-dev-utils/WebpackDevServerUtils');
 const openBrowser = require('react-dev-utils/openBrowser');
 const paths = require('../config/paths');
-const config = require('../config/webpack.config.dev');
+const configFactory = require('../config/webpack.config');
 const createDevServerConfig = require('../config/webpackDevServer.config');
 
 const useYarn = fs.existsSync(paths.yarnLockFile);
 const isInteractive = process.stdout.isTTY;
 
 // Warn and crash if required files are missing
-if (!checkRequiredFiles([ paths.appHtml, paths.appIndexJs ])) {
+if (!checkRequiredFiles([paths.appHtml, paths.appIndexJs])) {
   process.exit(1);
 }
 
 // Tools like Cloud9 rely on this.
-const FALLBACK_PORT = 3000;
-const DEFAULT_PORT = parseInt(process.env.PORT) || FALLBACK_PORT;
+const DEFAULT_PORT = parseInt(process.env.PORT, 10) || 3000;
 const HOST = process.env.HOST || '0.0.0.0';
 
 if (process.env.HOST) {
@@ -53,68 +53,65 @@ if (process.env.HOST) {
     )
   );
   console.log(
-    'If this was unintentional, check that you haven\'t mistakenly set it in your shell.'
+    `If this was unintentional, check that you haven't mistakenly set it in your shell.`
+  );
+  console.log(
+    `Learn more here: ${chalk.yellow('http://bit.ly/CRA-advanced-config')}`
   );
-  console.log(`Learn more here: ${chalk.yellow('http://bit.ly/2mwWSwH')}`);
   console.log();
 }
 
-// We attempt to use the default port but if it is busy, we offer the user to
-// run on a different port. `choosePort()` Promise resolves to the next free port.
-choosePort(HOST, DEFAULT_PORT)
-  .then((port) => {
-    if (port === null) {
+// We require that you explictly set browsers and do not fall back to
+// browserslist defaults.
+const { checkBrowsers } = require('react-dev-utils/browsersHelper');
+checkBrowsers(paths.appPath, isInteractive)
+  .then(() => {
+    // We attempt to use the default port but if it is busy, we offer the user to
+    // run on a different port. `choosePort()` Promise resolves to the next free port.
+    return choosePort(HOST, DEFAULT_PORT);
+  })
+  .then(port => {
+    if (port == null) {
       // We have not found a port.
       return;
     }
-
+    const config = configFactory('development');
     const protocol = process.env.HTTPS === 'true' ? 'https' : 'http';
     const appName = require(paths.appPackageJson).name;
-
     const urls = prepareUrls(protocol, HOST, port);
-
     // Create a webpack compiler that is configured with custom messages.
     const compiler = createCompiler(webpack, config, appName, urls, useYarn);
-
     // Load proxy config
     const proxySetting = require(paths.appPackageJson).proxy;
-
     const proxyConfig = prepareProxy(proxySetting, paths.appPublic);
-
-    // Serve webpack assets generated by the compiler over a web sever.
+    // Serve webpack assets generated by the compiler over a web server.
     const serverConfig = createDevServerConfig(
       proxyConfig,
       urls.lanUrlForConfig
     );
     const devServer = new WebpackDevServer(compiler, serverConfig);
-
     // Launch WebpackDevServer.
-
-    devServer.listen(port, HOST, (err) => {
+    devServer.listen(port, HOST, err => {
       if (err) {
-        console.log(err);
-
-        return;
+        return console.log(err);
       }
       if (isInteractive) {
         clearConsole();
       }
-
       console.log(chalk.cyan('Starting the development server...\n'));
       openBrowser(urls.localUrlForBrowser);
     });
 
-    [ 'SIGINT', 'SIGTERM' ].forEach((sig) => {
-      process.on(sig, () => {
+    ['SIGINT', 'SIGTERM'].forEach(function(sig) {
+      process.on(sig, function() {
         devServer.close();
         process.exit();
       });
     });
   })
-  .catch((err) => {
+  .catch(err => {
     if (err && err.message) {
       console.log(err.message);
     }
-
     process.exit(1);
   });