基础搭建完成

config/env.js

+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+const paths = require('./paths');
+
+// Make sure that including paths.js after env.js will read .env variables.
+delete require.cache[require.resolve('./paths')];
+
+const NODE_ENV = process.env.NODE_ENV;
+if (!NODE_ENV) {
+  throw new Error(
+    'The NODE_ENV environment variable is required but was not specified.'
+  );
+}
+
+// https://github.com/bkeepers/dotenv#what-other-env-files-can-i-use
+const dotenvFiles = [
+  `${paths.dotenv}.${NODE_ENV}.local`,
+  `${paths.dotenv}.${NODE_ENV}`,
+  // Don't include `.env.local` for `test` environment
+  // since normally you expect tests to produce the same
+  // results for everyone
+  NODE_ENV !== 'test' && `${paths.dotenv}.local`,
+  paths.dotenv,
+].filter(Boolean);
+
+// Load environment variables from .env* files. Suppress warnings using silent
+// if this file is missing. dotenv will never modify any environment variables
+// that have already been set.  Variable expansion is supported in .env files.
+// https://github.com/motdotla/dotenv
+// https://github.com/motdotla/dotenv-expand
+dotenvFiles.forEach(dotenvFile => {
+  if (fs.existsSync(dotenvFile)) {
+    require('dotenv-expand')(
+      require('dotenv').config({
+        path: dotenvFile,
+      })
+    );
+  }
+});
+
+// We support resolving modules according to `NODE_PATH`.
+// This lets you use absolute paths in imports inside large monorepos:
+// https://github.com/facebook/create-react-app/issues/253.
+// It works similar to `NODE_PATH` in Node itself:
+// https://nodejs.org/api/modules.html#modules_loading_from_the_global_folders
+// Note that unlike in Node, only *relative* paths from `NODE_PATH` are honored.
+// Otherwise, we risk importing Node.js core modules into an app instead of Webpack shims.
+// https://github.com/facebook/create-react-app/issues/1023#issuecomment-265344421
+// We also resolve them to make sure all tools using them work consistently.
+const appDirectory = fs.realpathSync(process.cwd());
+process.env.NODE_PATH = (process.env.NODE_PATH || '')
+  .split(path.delimiter)
+  .filter(folder => folder && !path.isAbsolute(folder))
+  .map(folder => path.resolve(appDirectory, folder))
+  .join(path.delimiter);
+
+// Grab NODE_ENV and REACT_APP_* environment variables and prepare them to be
+// injected into the application via DefinePlugin in Webpack configuration.
+const REACT_APP = /^REACT_APP_/i;
+
+function getClientEnvironment(publicUrl) {
+  const raw = Object.keys(process.env)
+    .filter(key => REACT_APP.test(key))
+    .reduce(
+      (env, key) => {
+        env[key] = process.env[key];
+        return env;
+      },
+      {
+        // Useful for determining whether we’re running in production mode.
+        // Most importantly, it switches React into the correct mode.
+        NODE_ENV: process.env.NODE_ENV || 'development',
+        // Useful for resolving the correct path to static assets in `public`.
+        // For example, <img src={process.env.PUBLIC_URL + '/img/logo.png'} />.
+        // This should only be used as an escape hatch. Normally you would put
+        // images into the `src` and `import` them in code to get their paths.
+        PUBLIC_URL: publicUrl,
+      }
+    );
+  // Stringify all values so we can feed into Webpack DefinePlugin
+  const stringified = {
+    'process.env': Object.keys(raw).reduce((env, key) => {
+      env[key] = JSON.stringify(raw[key]);
+      return env;
+    }, {}),
+  };
+
+  return { raw, stringified };
+}
+
+module.exports = getClientEnvironment;

config/jest/cssTransform.js

+'use strict';
+
+// This is a custom Jest transformer turning style imports into empty objects.
+// http://facebook.github.io/jest/docs/en/webpack.html
+
+module.exports = {
+  process() {
+    return 'module.exports = {};';
+  },
+  getCacheKey() {
+    // The output is always the same.
+    return 'cssTransform';
+  },
+};

config/jest/fileTransform.js

+'use strict';
+
+const path = require('path');
+const camelcase = require('camelcase');
+
+// This is a custom Jest transformer turning file imports into filenames.
+// http://facebook.github.io/jest/docs/en/webpack.html
+
+module.exports = {
+  process(src, filename) {
+    const assetFilename = JSON.stringify(path.basename(filename));
+
+    if (filename.match(/\.svg$/)) {
+      // Based on how SVGR generates a component name:
+      // https://github.com/smooth-code/svgr/blob/01b194cf967347d43d4cbe6b434404731b87cf27/packages/core/src/state.js#L6
+      const pascalCaseFilename = camelcase(path.parse(filename).name, {
+        pascalCase: true,
+      });
+      const componentName = `Svg${pascalCaseFilename}`;
+      return `const React = require('react');
+      module.exports = {
+        __esModule: true,
+        default: ${assetFilename},
+        ReactComponent: React.forwardRef(function ${componentName}(props, ref) {
+          return {
+            $$typeof: Symbol.for('react.element'),
+            type: 'svg',
+            ref: ref,
+            key: null,
+            props: Object.assign({}, props, {
+              children: ${assetFilename}
+            })
+          };
+        }),
+      };`;
+    }
+
+    return `module.exports = ${assetFilename};`;
+  },
+};

config/modules.js

+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+const paths = require('./paths');
+const chalk = require('react-dev-utils/chalk');
+const resolve = require('resolve');
+
+/**
+ * Get additional module paths based on the baseUrl of a compilerOptions object.
+ *
+ * @param {Object} options
+ */
+function getAdditionalModulePaths(options = {}) {
+  const baseUrl = options.baseUrl;
+
+  // We need to explicitly check for null and undefined (and not a falsy value) because
+  // TypeScript treats an empty string as `.`.
+  if (baseUrl == null) {
+    // If there's no baseUrl set we respect NODE_PATH
+    // Note that NODE_PATH is deprecated and will be removed
+    // in the next major release of create-react-app.
+
+    const nodePath = process.env.NODE_PATH || '';
+    return nodePath.split(path.delimiter).filter(Boolean);
+  }
+
+  const baseUrlResolved = path.resolve(paths.appPath, baseUrl);
+
+  // We don't need to do anything if `baseUrl` is set to `node_modules`. This is
+  // the default behavior.
+  if (path.relative(paths.appNodeModules, baseUrlResolved) === '') {
+    return null;
+  }
+
+  // Allow the user set the `baseUrl` to `appSrc`.
+  if (path.relative(paths.appSrc, baseUrlResolved) === '') {
+    return [paths.appSrc];
+  }
+
+  // If the path is equal to the root directory we ignore it here.
+  // We don't want to allow importing from the root directly as source files are
+  // not transpiled outside of `src`. We do allow importing them with the
+  // absolute path (e.g. `src/Components/Button.js`) but we set that up with
+  // an alias.
+  if (path.relative(paths.appPath, baseUrlResolved) === '') {
+    return null;
+  }
+
+  // Otherwise, throw an error.
+  throw new Error(
+    chalk.red.bold(
+      "Your project's `baseUrl` can only be set to `src` or `node_modules`." +
+        ' Create React App does not support other values at this time.'
+    )
+  );
+}
+
+/**
+ * Get webpack aliases based on the baseUrl of a compilerOptions object.
+ *
+ * @param {*} options
+ */
+function getWebpackAliases(options = {}) {
+  const baseUrl = options.baseUrl;
+
+  if (!baseUrl) {
+    return {};
+  }
+
+  const baseUrlResolved = path.resolve(paths.appPath, baseUrl);
+
+  if (path.relative(paths.appPath, baseUrlResolved) === '') {
+    return {
+      src: paths.appSrc,
+    };
+  }
+}
+
+/**
+ * Get jest aliases based on the baseUrl of a compilerOptions object.
+ *
+ * @param {*} options
+ */
+function getJestAliases(options = {}) {
+  const baseUrl = options.baseUrl;
+
+  if (!baseUrl) {
+    return {};
+  }
+
+  const baseUrlResolved = path.resolve(paths.appPath, baseUrl);
+
+  if (path.relative(paths.appPath, baseUrlResolved) === '') {
+    return {
+      'src/(.*)$': '<rootDir>/src/$1',
+    };
+  }
+}
+
+function getModules() {
+  // Check if TypeScript is setup
+  const hasTsConfig = fs.existsSync(paths.appTsConfig);
+  const hasJsConfig = fs.existsSync(paths.appJsConfig);
+
+  if (hasTsConfig && hasJsConfig) {
+    throw new Error(
+      'You have both a tsconfig.json and a jsconfig.json. If you are using TypeScript please remove your jsconfig.json file.'
+    );
+  }
+
+  let config;
+
+  // If there's a tsconfig.json we assume it's a
+  // TypeScript project and set up the config
+  // based on tsconfig.json
+  if (hasTsConfig) {
+    const ts = require(resolve.sync('typescript', {
+      basedir: paths.appNodeModules,
+    }));
+    config = ts.readConfigFile(paths.appTsConfig, ts.sys.readFile).config;
+    // Otherwise we'll check if there is jsconfig.json
+    // for non TS projects.
+  } else if (hasJsConfig) {
+    config = require(paths.appJsConfig);
+  }
+
+  config = config || {};
+  const options = config.compilerOptions || {};
+
+  const additionalModulePaths = getAdditionalModulePaths(options);
+
+  return {
+    additionalModulePaths: additionalModulePaths,
+    webpackAliases: getWebpackAliases(options),
+    jestAliases: getJestAliases(options),
+    hasTsConfig,
+  };
+}
+
+module.exports = getModules();

config/paths.js

+'use strict';
+
+const path = require('path');
+const fs = require('fs');
+const url = require('url');
+
+// Make sure any symlinks in the project folder are resolved:
+// https://github.com/facebook/create-react-app/issues/637
+const appDirectory = fs.realpathSync(process.cwd());
+const resolveApp = relativePath => path.resolve(appDirectory, relativePath);
+
+const envPublicUrl = process.env.PUBLIC_URL;
+
+function ensureSlash(inputPath, needsSlash) {
+  const hasSlash = inputPath.endsWith('/');
+  if (hasSlash && !needsSlash) {
+    return inputPath.substr(0, inputPath.length - 1);
+  } else if (!hasSlash && needsSlash) {
+    return `${inputPath}/`;
+  } else {
+    return inputPath;
+  }
+}
+
+const getPublicUrl = appPackageJson =>
+  envPublicUrl || require(appPackageJson).homepage;
+
+// We use `PUBLIC_URL` environment variable or "homepage" field to infer
+// "public path" at which the app is served.
+// Webpack needs to know it to put the right <script> hrefs into HTML even in
+// single-page apps that may serve index.html for nested URLs like /todos/42.
+// We can't use a relative path in HTML because we don't want to load something
+// like /todos/42/static/js/bundle.7289d.js. We have to know the root.
+function getServedPath(appPackageJson) {
+  const publicUrl = getPublicUrl(appPackageJson);
+  const servedUrl =
+    envPublicUrl || (publicUrl ? url.parse(publicUrl).pathname : '/');
+  return ensureSlash(servedUrl, true);
+}
+
+const moduleFileExtensions = [
+  'web.mjs',
+  'mjs',
+  'web.js',
+  'js',
+  'web.ts',
+  'ts',
+  'web.tsx',
+  'tsx',
+  'json',
+  'web.jsx',
+  'jsx',
+];
+
+// Resolve file paths in the same order as webpack
+const resolveModule = (resolveFn, filePath) => {
+  const extension = moduleFileExtensions.find(extension =>
+    fs.existsSync(resolveFn(`${filePath}.${extension}`))
+  );
+
+  if (extension) {
+    return resolveFn(`${filePath}.${extension}`);
+  }
+
+  return resolveFn(`${filePath}.js`);
+};
+
+// config after eject: we're in ./config/
+module.exports = {
+  dotenv: resolveApp('.env'),
+  appPath: resolveApp('.'),
+  appBuild: resolveApp('build'),
+  appPublic: resolveApp('public'),
+  appHtml: resolveApp('public/index.html'),
+  appIndexJs: resolveModule(resolveApp, 'src/index'),
+  appPackageJson: resolveApp('package.json'),
+  appSrc: resolveApp('src'),
+  appTsConfig: resolveApp('tsconfig.json'),
+  appJsConfig: resolveApp('jsconfig.json'),
+  yarnLockFile: resolveApp('yarn.lock'),
+  testsSetup: resolveModule(resolveApp, 'src/setupTests'),
+  proxySetup: resolveApp('src/setupProxy.js'),
+  appNodeModules: resolveApp('node_modules'),
+  publicUrl: getPublicUrl(resolveApp('package.json')),
+  servedPath: getServedPath(resolveApp('package.json')),
+};
+
+
+
+module.exports.moduleFileExtensions = moduleFileExtensions;

config/pnpTs.js

+'use strict';
+
+const { resolveModuleName } = require('ts-pnp');
+
+exports.resolveModuleName = (
+  typescript,
+  moduleName,
+  containingFile,
+  compilerOptions,
+  resolutionHost
+) => {
+  return resolveModuleName(
+    moduleName,
+    containingFile,
+    compilerOptions,
+    resolutionHost,
+    typescript.resolveModuleName
+  );
+};
+
+exports.resolveTypeReferenceDirective = (
+  typescript,
+  moduleName,
+  containingFile,
+  compilerOptions,
+  resolutionHost
+) => {
+  return resolveModuleName(
+    moduleName,
+    containingFile,
+    compilerOptions,
+    resolutionHost,
+    typescript.resolveTypeReferenceDirective
+  );
+};

config/webpack.config.js

+'use strict';
+
+const fs = require('fs');
+const isWsl = require('is-wsl');
+const path = require('path');
+const webpack = require('webpack');
+const resolve = require('resolve');
+const PnpWebpackPlugin = require('pnp-webpack-plugin');
+const HtmlWebpackPlugin = require('html-webpack-plugin');
+const CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
+const InlineChunkHtmlPlugin = require('react-dev-utils/InlineChunkHtmlPlugin');
+const TerserPlugin = require('terser-webpack-plugin');
+const MiniCssExtractPlugin = require('mini-css-extract-plugin');
+const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin');
+const safePostCssParser = require('postcss-safe-parser');
+const ManifestPlugin = require('webpack-manifest-plugin');
+const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
+const WorkboxWebpackPlugin = require('workbox-webpack-plugin');
+const WatchMissingNodeModulesPlugin = require('react-dev-utils/WatchMissingNodeModulesPlugin');
+const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
+const getCSSModuleLocalIdent = require('react-dev-utils/getCSSModuleLocalIdent');
+const paths = require('./paths');
+const modules = require('./modules');
+const getClientEnvironment = require('./env');
+const ModuleNotFoundPlugin = require('react-dev-utils/ModuleNotFoundPlugin');
+const ForkTsCheckerWebpackPlugin = require('react-dev-utils/ForkTsCheckerWebpackPlugin');
+const typescriptFormatter = require('react-dev-utils/typescriptFormatter');
+const eslint = require('eslint');
+
+const postcssNormalize = require('postcss-normalize');
+
+const appPackageJson = require(paths.appPackageJson);
+
+// Source maps are resource heavy and can cause out of memory issue for large source files.
+const shouldUseSourceMap = process.env.GENERATE_SOURCEMAP !== 'false';
+// Some apps do not need the benefits of saving a web request, so not inlining the chunk
+// makes for a smoother build process.
+const shouldInlineRuntimeChunk = process.env.INLINE_RUNTIME_CHUNK !== 'false';
+
+const imageInlineSizeLimit = parseInt(
+  process.env.IMAGE_INLINE_SIZE_LIMIT || '10000'
+);
+
+// Check if TypeScript is setup
+const useTypeScript = fs.existsSync(paths.appTsConfig);
+
+// style files regexes
+const cssRegex = /\.css$/;
+const cssModuleRegex = /\.module\.css$/;
+const sassRegex = /\.(scss|sass)$/;
+const sassModuleRegex = /\.module\.(scss|sass)$/;
+
+// This is the production and development configuration.
+// It is focused on developer experience, fast rebuilds, and a minimal bundle.
+module.exports = function(webpackEnv) {
+  const isEnvDevelopment = webpackEnv === 'development';
+  const isEnvProduction = webpackEnv === 'production';
+
+  // Variable used for enabling profiling in Production
+  // passed into alias object. Uses a flag if passed into the build command
+  const isEnvProductionProfile =
+    isEnvProduction && process.argv.includes('--profile');
+
+  // Webpack uses `publicPath` to determine where the app is being served from.
+  // It requires a trailing slash, or the file assets will get an incorrect path.
+  // In development, we always serve from the root. This makes config easier.
+  const publicPath = isEnvProduction
+    ? paths.servedPath
+    : isEnvDevelopment && '/';
+  // Some apps do not use client-side routing with pushState.
+  // For these, "homepage" can be set to "." to enable relative asset paths.
+  const shouldUseRelativeAssetPaths = publicPath === './';
+
+  // `publicUrl` is just like `publicPath`, but we will provide it to our app
+  // as %PUBLIC_URL% in `index.html` and `process.env.PUBLIC_URL` in JavaScript.
+  // Omit trailing slash as %PUBLIC_URL%/xyz looks better than %PUBLIC_URL%xyz.
+  const publicUrl = isEnvProduction
+    ? publicPath.slice(0, -1)
+    : isEnvDevelopment && '';
+  // Get environment variables to inject into our app.
+  const env = getClientEnvironment(publicUrl);
+
+  // common function to get style loaders
+  const getStyleLoaders = (cssOptions, preProcessor) => {
+    const loaders = [
+      isEnvDevelopment && require.resolve('style-loader'),
+      isEnvProduction && {
+        loader: MiniCssExtractPlugin.loader,
+        options: shouldUseRelativeAssetPaths ? { publicPath: '../../' } : {},
+      },
+      {
+        loader: require.resolve('css-loader'),
+        options: cssOptions,
+      },
+      {
+        // Options for PostCSS as we reference these options twice
+        // Adds vendor prefixing based on your specified browser support in
+        // package.json
+        loader: require.resolve('postcss-loader'),
+        options: {
+          // Necessary for external CSS imports to work
+          // https://github.com/facebook/create-react-app/issues/2677
+          ident: 'postcss',
+          plugins: () => [
+            require('postcss-flexbugs-fixes'),
+            require('postcss-preset-env')({
+              autoprefixer: {
+                flexbox: 'no-2009',
+              },
+              stage: 3,
+            }),
+            // Adds PostCSS Normalize as the reset css with default options,
+            // so that it honors browserslist config in package.json
+            // which in turn let's users customize the target behavior as per their needs.
+            postcssNormalize(),
+          ],
+          sourceMap: isEnvProduction && shouldUseSourceMap,
+        },
+      },
+    ].filter(Boolean);
+    if (preProcessor) {
+      loaders.push(
+        {
+          loader: require.resolve('resolve-url-loader'),
+          options: {
+            sourceMap: isEnvProduction && shouldUseSourceMap,
+          },
+        },
+        {
+          loader: require.resolve(preProcessor),
+          options: {
+            sourceMap: true,
+          },
+        }
+      );
+    }
+    return loaders;
+  };
+
+  return {
+    mode: isEnvProduction ? 'production' : isEnvDevelopment && 'development',
+    // Stop compilation early in production
+    bail: isEnvProduction,
+    devtool: isEnvProduction
+      ? shouldUseSourceMap
+        ? 'source-map'
+        : false
+      : isEnvDevelopment && 'cheap-module-source-map',
+    // These are the "entry points" to our application.
+    // This means they will be the "root" imports that are included in JS bundle.
+    entry: [
+      // Include an alternative client for WebpackDevServer. A client's job is to
+      // connect to WebpackDevServer by a socket and get notified about changes.
+      // When you save a file, the client will either apply hot updates (in case
+      // of CSS changes), or refresh the page (in case of JS changes). When you
+      // make a syntax error, this client will display a syntax error overlay.
+      // Note: instead of the default WebpackDevServer client, we use a custom one
+      // to bring better experience for Create React App users. You can replace
+      // the line below with these two lines if you prefer the stock client:
+      // require.resolve('webpack-dev-server/client') + '?/',
+      // require.resolve('webpack/hot/dev-server'),
+      isEnvDevelopment &&
+        require.resolve('react-dev-utils/webpackHotDevClient'),
+      // Finally, this is your app's code:
+      paths.appIndexJs,
+      // We include the app code last so that if there is a runtime error during
+      // initialization, it doesn't blow up the WebpackDevServer client, and
+      // changing JS code would still trigger a refresh.
+    ].filter(Boolean),
+    output: {
+      // The build folder.
+      path: isEnvProduction ? paths.appBuild : undefined,
+      // Add /* filename */ comments to generated require()s in the output.
+      pathinfo: isEnvDevelopment,
+      // There will be one main bundle, and one file per asynchronous chunk.
+      // In development, it does not produce real files.
+      filename: isEnvProduction
+        ? 'static/js/[name].[contenthash:8].js'
+        : isEnvDevelopment && 'static/js/bundle.js',
+      // TODO: remove this when upgrading to webpack 5
+      futureEmitAssets: true,
+      // There are also additional JS chunk files if you use code splitting.
+      chunkFilename: isEnvProduction
+        ? 'static/js/[name].[contenthash:8].chunk.js'
+        : isEnvDevelopment && 'static/js/[name].chunk.js',
+      // We inferred the "public path" (such as / or /my-project) from homepage.
+      // We use "/" in development.
+      publicPath: publicPath,
+      // Point sourcemap entries to original disk location (format as URL on Windows)
+      devtoolModuleFilenameTemplate: isEnvProduction
+        ? info =>
+            path
+              .relative(paths.appSrc, info.absoluteResourcePath)
+              .replace(/\\/g, '/')
+        : isEnvDevelopment &&
+          (info => path.resolve(info.absoluteResourcePath).replace(/\\/g, '/')),
+      // Prevents conflicts when multiple Webpack runtimes (from different apps)
+      // are used on the same page.
+      jsonpFunction: `webpackJsonp${appPackageJson.name}`,
+      // this defaults to 'window', but by setting it to 'this' then
+      // module chunks which are built will work in web workers as well.
+      globalObject: 'this',
+    },
+    optimization: {
+      minimize: isEnvProduction,
+      minimizer: [
+        // This is only used in production mode
+        new TerserPlugin({
+          terserOptions: {
+            parse: {
+              // We want terser to parse ecma 8 code. However, we don't want it
+              // to apply any minification steps that turns valid ecma 5 code
+              // into invalid ecma 5 code. This is why the 'compress' and 'output'
+              // sections only apply transformations that are ecma 5 safe
+              // https://github.com/facebook/create-react-app/pull/4234
+              ecma: 8,
+            },
+            compress: {
+              ecma: 5,
+              warnings: false,
+              // Disabled because of an issue with Uglify breaking seemingly valid code:
+              // https://github.com/facebook/create-react-app/issues/2376
+              // Pending further investigation:
+              // https://github.com/mishoo/UglifyJS2/issues/2011
+              comparisons: false,
+              // Disabled because of an issue with Terser breaking valid code:
+              // https://github.com/facebook/create-react-app/issues/5250
+              // Pending further investigation:
+              // https://github.com/terser-js/terser/issues/120
+              inline: 2,
+            },
+            mangle: {
+              safari10: true,
+            },
+            // Added for profiling in devtools
+            keep_classnames: isEnvProductionProfile,
+            keep_fnames: isEnvProductionProfile,
+            output: {
+              ecma: 5,
+              comments: false,
+              // Turned on because emoji and regex is not minified properly using default
+              // https://github.com/facebook/create-react-app/issues/2488
+              ascii_only: true,
+            },
+          },
+          // Use multi-process parallel running to improve the build speed
+          // Default number of concurrent runs: os.cpus().length - 1
+          // Disabled on WSL (Windows Subsystem for Linux) due to an issue with Terser
+          // https://github.com/webpack-contrib/terser-webpack-plugin/issues/21
+          parallel: !isWsl,
+          // Enable file caching
+          cache: true,
+          sourceMap: shouldUseSourceMap,
+        }),
+        // This is only used in production mode
+        new OptimizeCSSAssetsPlugin({
+          cssProcessorOptions: {
+            parser: safePostCssParser,
+            map: shouldUseSourceMap
+              ? {
+                  // `inline: false` forces the sourcemap to be output into a
+                  // separate file
+                  inline: false,
+                  // `annotation: true` appends the sourceMappingURL to the end of
+                  // the css file, helping the browser find the sourcemap
+                  annotation: true,
+                }
+              : false,
+          },
+        }),
+      ],
+      // Automatically split vendor and commons
+      // https://twitter.com/wSokra/status/969633336732905474
+      // https://medium.com/webpack/webpack-4-code-splitting-chunk-graph-and-the-splitchunks-optimization-be739a861366
+      splitChunks: {
+        chunks: 'all',
+        name: false,
+      },
+      // Keep the runtime chunk separated to enable long term caching
+      // https://twitter.com/wSokra/status/969679223278505985
+      // https://github.com/facebook/create-react-app/issues/5358
+      runtimeChunk: {
+        name: entrypoint => `runtime-${entrypoint.name}`,
+      },
+    },
+    resolve: {
+      // This allows you to set a fallback for where Webpack should look for modules.
+      // We placed these paths second because we want `node_modules` to "win"
+      // if there are any conflicts. This matches Node resolution mechanism.
+      // https://github.com/facebook/create-react-app/issues/253
+      modules: ['node_modules', paths.appNodeModules].concat(
+        modules.additionalModulePaths || []
+      ),
+      // These are the reasonable defaults supported by the Node ecosystem.
+      // We also include JSX as a common component filename extension to support
+      // some tools, although we do not recommend using it, see:
+      // https://github.com/facebook/create-react-app/issues/290
+      // `web` extension prefixes have been added for better support
+      // for React Native Web.
+      extensions: paths.moduleFileExtensions
+        .map(ext => `.${ext}`)
+        .filter(ext => useTypeScript || !ext.includes('ts')),
+      alias: {
+        // Support React Native Web
+        // https://www.smashingmagazine.com/2016/08/a-glimpse-into-the-future-with-react-native-for-web/
+        'react-native': 'react-native-web',
+        // Allows for better profiling with ReactDevTools
+        ...(isEnvProductionProfile && {
+          'react-dom$': 'react-dom/profiling',
+          'scheduler/tracing': 'scheduler/tracing-profiling',
+        }),
+        ...(modules.webpackAliases || {}),
+      },
+      plugins: [
+        // Adds support for installing with Plug'n'Play, leading to faster installs and adding
+        // guards against forgotten dependencies and such.
+        PnpWebpackPlugin,
+        // Prevents users from importing files from outside of src/ (or node_modules/).
+        // This often causes confusion because we only process files within src/ with babel.
+        // To fix this, we prevent you from importing files out of src/ -- if you'd like to,
+        // please link the files into your node_modules/ and let module-resolution kick in.
+        // Make sure your source files are compiled, as they will not be processed in any way.
+        new ModuleScopePlugin(paths.appSrc, [paths.appPackageJson]),
+      ],
+    },
+    resolveLoader: {
+      plugins: [
+        // Also related to Plug'n'Play, but this time it tells Webpack to load its loaders
+        // from the current package.
+        PnpWebpackPlugin.moduleLoader(module),
+      ],
+    },
+    module: {
+      strictExportPresence: true,
+      rules: [
+        // Disable require.ensure as it's not a standard language feature.
+        { parser: { requireEnsure: false } },
+
+        // First, run the linter.
+        // It's important to do this before Babel processes the JS.
+        {
+          test: /\.(js|mjs|jsx|ts|tsx)$/,
+          enforce: 'pre',
+          use: [
+            {
+              options: {
+                cache: true,
+                formatter: require.resolve('react-dev-utils/eslintFormatter'),
+                eslintPath: require.resolve('eslint'),
+                resolvePluginsRelativeTo: __dirname,
+                
+              },
+              loader: require.resolve('eslint-loader'),
+            },
+          ],
+          include: paths.appSrc,
+        },
+        {
+          // "oneOf" will traverse all following loaders until one will
+          // match the requirements. When no loader matches it will fall
+          // back to the "file" loader at the end of the loader list.
+          oneOf: [
+            // "url" loader works like "file" loader except that it embeds assets
+            // smaller than specified limit in bytes as data URLs to avoid requests.
+            // A missing `test` is equivalent to a match.
+            {
+              test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
+              loader: require.resolve('url-loader'),
+              options: {
+                limit: imageInlineSizeLimit,
+                name: 'static/media/[name].[hash:8].[ext]',
+              },
+            },
+            // Process application JS with Babel.
+            // The preset includes JSX, Flow, TypeScript, and some ESnext features.
+            {
+              test: /\.(js|mjs|jsx|ts|tsx)$/,
+              include: paths.appSrc,
+              loader: require.resolve('babel-loader'),
+              options: {
+                customize: require.resolve(
+                  'babel-preset-react-app/webpack-overrides'
+                ),
+                
+                plugins: [
+                  [
+                    require.resolve('babel-plugin-named-asset-import'),
+                    {
+                      loaderMap: {
+                        svg: {
+                          ReactComponent:
+                            '@svgr/webpack?-svgo,+titleProp,+ref![path]',
+                        },
+                      },
+                    },
+                  ],
+                ],
+                // This is a feature of `babel-loader` for webpack (not Babel itself).
+                // It enables caching results in ./node_modules/.cache/babel-loader/
+                // directory for faster rebuilds.
+                cacheDirectory: true,
+                // See #6846 for context on why cacheCompression is disabled
+                cacheCompression: false,
+                compact: isEnvProduction,
+              },
+            },
+            // Process any JS outside of the app with Babel.
+            // Unlike the application JS, we only compile the standard ES features.
+            {
+              test: /\.(js|mjs)$/,
+              exclude: /@babel(?:\/|\\{1,2})runtime/,
+              loader: require.resolve('babel-loader'),
+              options: {
+                babelrc: false,
+                configFile: false,
+                compact: false,
+                presets: [
+                  [
+                    require.resolve('babel-preset-react-app/dependencies'),
+                    { helpers: true },
+                  ],
+                ],
+                cacheDirectory: true,
+                // See #6846 for context on why cacheCompression is disabled
+                cacheCompression: false,
+                
+                // If an error happens in a package, it's possible to be
+                // because it was compiled. Thus, we don't want the browser
+                // debugger to show the original code. Instead, the code
+                // being evaluated would be much more helpful.
+                sourceMaps: false,
+              },
+            },
+            // "postcss" loader applies autoprefixer to our CSS.
+            // "css" loader resolves paths in CSS and adds assets as dependencies.
+            // "style" loader turns CSS into JS modules that inject <style> tags.
+            // In production, we use MiniCSSExtractPlugin to extract that CSS
+            // to a file, but in development "style" loader enables hot editing
+            // of CSS.
+            // By default we support CSS Modules with the extension .module.css
+            {
+              test: cssRegex,
+              exclude: cssModuleRegex,
+              use: getStyleLoaders({
+                importLoaders: 1,
+                sourceMap: isEnvProduction && shouldUseSourceMap,
+              }),
+              // Don't consider CSS imports dead code even if the
+              // containing package claims to have no side effects.
+              // Remove this when webpack adds a warning or an error for this.
+              // See https://github.com/webpack/webpack/issues/6571
+              sideEffects: true,
+            },
+            // Adds support for CSS Modules (https://github.com/css-modules/css-modules)
+            // using the extension .module.css
+            {
+              test: cssModuleRegex,
+              use: getStyleLoaders({
+                importLoaders: 1,
+                sourceMap: isEnvProduction && shouldUseSourceMap,
+                modules: true,
+                getLocalIdent: getCSSModuleLocalIdent,
+              }),
+            },
+            // Opt-in support for SASS (using .scss or .sass extensions).
+            // By default we support SASS Modules with the
+            // extensions .module.scss or .module.sass
+            {
+              test: sassRegex,
+              exclude: sassModuleRegex,
+              use: getStyleLoaders(
+                {
+                  importLoaders: 2,
+                  sourceMap: isEnvProduction && shouldUseSourceMap,
+                },
+                'sass-loader'
+              ),
+              // Don't consider CSS imports dead code even if the
+              // containing package claims to have no side effects.
+              // Remove this when webpack adds a warning or an error for this.
+              // See https://github.com/webpack/webpack/issues/6571
+              sideEffects: true,
+            },
+            // Adds support for CSS Modules, but using SASS
+            // using the extension .module.scss or .module.sass
+            {
+              test: sassModuleRegex,
+              use: getStyleLoaders(
+                {
+                  importLoaders: 2,
+                  sourceMap: isEnvProduction && shouldUseSourceMap,
+                  modules: true,
+                  getLocalIdent: getCSSModuleLocalIdent,
+                },
+                'sass-loader'
+              ),
+            },
+            // "file" loader makes sure those assets get served by WebpackDevServer.
+            // When you `import` an asset, you get its (virtual) filename.
+            // In production, they would get copied to the `build` folder.
+            // This loader doesn't use a "test" so it will catch all modules
+            // that fall through the other loaders.
+            {
+              loader: require.resolve('file-loader'),
+              // Exclude `js` files to keep "css" loader working as it injects
+              // its runtime that would otherwise be processed through "file" loader.
+              // Also exclude `html` and `json` extensions so they get processed
+              // by webpacks internal loaders.
+              exclude: [/\.(js|mjs|jsx|ts|tsx)$/, /\.html$/, /\.json$/],
+              options: {
+                name: 'static/media/[name].[hash:8].[ext]',
+              },
+            },
+            // ** STOP ** Are you adding a new loader?
+            // Make sure to add the new loader(s) before the "file" loader.
+          ],
+        },
+      ],
+    },
+    plugins: [
+      // Generates an `index.html` file with the <script> injected.
+      new HtmlWebpackPlugin(
+        Object.assign(
+          {},
+          {
+            inject: true,
+            template: paths.appHtml,
+          },
+          isEnvProduction
+            ? {
+                minify: {
+                  removeComments: true,
+                  collapseWhitespace: true,
+                  removeRedundantAttributes: true,
+                  useShortDoctype: true,
+                  removeEmptyAttributes: true,
+                  removeStyleLinkTypeAttributes: true,
+                  keepClosingSlash: true,
+                  minifyJS: true,
+                  minifyCSS: true,
+                  minifyURLs: true,
+                },
+              }
+            : undefined
+        )
+      ),
+      // Inlines the webpack runtime script. This script is too small to warrant
+      // a network request.
+      // https://github.com/facebook/create-react-app/issues/5358
+      isEnvProduction &&
+        shouldInlineRuntimeChunk &&
+        new InlineChunkHtmlPlugin(HtmlWebpackPlugin, [/runtime-.+[.]js/]),
+      // Makes some environment variables available in index.html.
+      // The public URL is available as %PUBLIC_URL% in index.html, e.g.:
+      // <link rel="icon" href="%PUBLIC_URL%/favicon.ico">
+      // In production, it will be an empty string unless you specify "homepage"
+      // in `package.json`, in which case it will be the pathname of that URL.
+      // In development, this will be an empty string.
+      new InterpolateHtmlPlugin(HtmlWebpackPlugin, env.raw),
+      // This gives some necessary context to module not found errors, such as
+      // the requesting resource.
+      new ModuleNotFoundPlugin(paths.appPath),
+      // Makes some environment variables available to the JS code, for example:
+      // if (process.env.NODE_ENV === 'production') { ... }. See `./env.js`.
+      // It is absolutely essential that NODE_ENV is set to production
+      // during a production build.
+      // Otherwise React will be compiled in the very slow development mode.
+      new webpack.DefinePlugin(env.stringified),
+      // This is necessary to emit hot updates (currently CSS only):
+      isEnvDevelopment && new webpack.HotModuleReplacementPlugin(),
+      // Watcher doesn't work well if you mistype casing in a path so we use
+      // a plugin that prints an error when you attempt to do this.
+      // See https://github.com/facebook/create-react-app/issues/240
+      isEnvDevelopment && new CaseSensitivePathsPlugin(),
+      // If you require a missing module and then `npm install` it, you still have
+      // to restart the development server for Webpack to discover it. This plugin
+      // makes the discovery automatic so you don't have to restart.
+      // See https://github.com/facebook/create-react-app/issues/186
+      isEnvDevelopment &&
+        new WatchMissingNodeModulesPlugin(paths.appNodeModules),
+      isEnvProduction &&
+        new MiniCssExtractPlugin({
+          // Options similar to the same options in webpackOptions.output
+          // both options are optional
+          filename: 'static/css/[name].[contenthash:8].css',
+          chunkFilename: 'static/css/[name].[contenthash:8].chunk.css',
+        }),
+      // Generate an asset manifest file with the following content:
+      // - "files" key: Mapping of all asset filenames to their corresponding
+      //   output file so that tools can pick it up without having to parse
+      //   `index.html`
+      // - "entrypoints" key: Array of files which are included in `index.html`,
+      //   can be used to reconstruct the HTML if necessary
+      new ManifestPlugin({
+        fileName: 'asset-manifest.json',
+        publicPath: publicPath,
+        generate: (seed, files, entrypoints) => {
+          const manifestFiles = files.reduce((manifest, file) => {
+            manifest[file.name] = file.path;
+            return manifest;
+          }, seed);
+          const entrypointFiles = entrypoints.main.filter(
+            fileName => !fileName.endsWith('.map')
+          );
+
+          return {
+            files: manifestFiles,
+            entrypoints: entrypointFiles,
+          };
+        },
+      }),
+      // Moment.js is an extremely popular library that bundles large locale files
+      // by default due to how Webpack interprets its code. This is a practical
+      // solution that requires the user to opt into importing specific locales.
+      // https://github.com/jmblog/how-to-optimize-momentjs-with-webpack
+      // You can remove this if you don't use Moment.js:
+      new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/),
+      // Generate a service worker script that will precache, and keep up to date,
+      // the HTML & assets that are part of the Webpack build.
+      isEnvProduction &&
+        new WorkboxWebpackPlugin.GenerateSW({
+          clientsClaim: true,
+          exclude: [/\.map$/, /asset-manifest\.json$/],
+          importWorkboxFrom: 'cdn',
+          navigateFallback: publicUrl + '/index.html',
+          navigateFallbackBlacklist: [
+            // Exclude URLs starting with /_, as they're likely an API call
+            new RegExp('^/_'),
+            // Exclude any URLs whose last part seems to be a file extension
+            // as they're likely a resource and not a SPA route.
+            // URLs containing a "?" character won't be blacklisted as they're likely
+            // a route with query params (e.g. auth callbacks).
+            new RegExp('/[^/?]+\\.[^/]+$'),
+          ],
+        }),
+      // TypeScript type checking
+      useTypeScript &&
+        new ForkTsCheckerWebpackPlugin({
+          typescript: resolve.sync('typescript', {
+            basedir: paths.appNodeModules,
+          }),
+          async: isEnvDevelopment,
+          useTypescriptIncrementalApi: true,
+          checkSyntacticErrors: true,
+          resolveModuleNameModule: process.versions.pnp
+            ? `${__dirname}/pnpTs.js`
+            : undefined,
+          resolveTypeReferenceDirectiveModule: process.versions.pnp
+            ? `${__dirname}/pnpTs.js`
+            : undefined,
+          tsconfig: paths.appTsConfig,
+          reportFiles: [
+            '**',
+            '!**/__tests__/**',
+            '!**/?(*.)(spec|test).*',
+            '!**/src/setupProxy.*',
+            '!**/src/setupTests.*',
+          ],
+          silent: true,
+          // The formatter is invoked directly in WebpackDevServerUtils during development
+          formatter: isEnvProduction ? typescriptFormatter : undefined,
+        }),
+    ].filter(Boolean),
+    // Some libraries import Node modules but don't use them in the browser.
+    // Tell Webpack to provide empty mocks for them so importing them works.
+    node: {
+      module: 'empty',
+      dgram: 'empty',
+      dns: 'mock',
+      fs: 'empty',
+      http2: 'empty',
+      net: 'empty',
+      tls: 'empty',
+      child_process: 'empty',
+    },
+    // Turn off performance processing because we utilize
+    // our own hints via the FileSizeReporter
+    performance: false,
+  };
+};

config/webpackDevServer.config.js

+'use strict';
+
+const errorOverlayMiddleware = require('react-dev-utils/errorOverlayMiddleware');
+const evalSourceMapMiddleware = require('react-dev-utils/evalSourceMapMiddleware');
+const noopServiceWorkerMiddleware = require('react-dev-utils/noopServiceWorkerMiddleware');
+const ignoredFiles = require('react-dev-utils/ignoredFiles');
+const paths = require('./paths');
+const fs = require('fs');
+
+const protocol = process.env.HTTPS === 'true' ? 'https' : 'http';
+const host = process.env.HOST || '0.0.0.0';
+
+module.exports = function(proxy, allowedHost) {
+  return {
+    // WebpackDevServer 2.4.3 introduced a security fix that prevents remote
+    // websites from potentially accessing local content through DNS rebinding:
+    // https://github.com/webpack/webpack-dev-server/issues/887
+    // https://medium.com/webpack/webpack-dev-server-middleware-security-issues-1489d950874a
+    // However, it made several existing use cases such as development in cloud
+    // environment or subdomains in development significantly more complicated:
+    // https://github.com/facebook/create-react-app/issues/2271
+    // https://github.com/facebook/create-react-app/issues/2233
+    // While we're investigating better solutions, for now we will take a
+    // compromise. Since our WDS configuration only serves files in the `public`
+    // folder we won't consider accessing them a vulnerability. However, if you
+    // use the `proxy` feature, it gets more dangerous because it can expose
+    // remote code execution vulnerabilities in backends like Django and Rails.
+    // So we will disable the host check normally, but enable it if you have
+    // specified the `proxy` setting. Finally, we let you override it if you
+    // really know what you're doing with a special environment variable.
+    disableHostCheck:
+      !proxy || process.env.DANGEROUSLY_DISABLE_HOST_CHECK === 'true',
+    // Enable gzip compression of generated files.
+    compress: true,
+    // Silence WebpackDevServer's own logs since they're generally not useful.
+    // It will still show compile warnings and errors with this setting.
+    clientLogLevel: 'none',
+    // By default WebpackDevServer serves physical files from current directory
+    // in addition to all the virtual build products that it serves from memory.
+    // This is confusing because those files won’t automatically be available in
+    // production build folder unless we copy them. However, copying the whole
+    // project directory is dangerous because we may expose sensitive files.
+    // Instead, we establish a convention that only files in `public` directory
+    // get served. Our build script will copy `public` into the `build` folder.
+    // In `index.html`, you can get URL of `public` folder with %PUBLIC_URL%:
+    // <link rel="icon" href="%PUBLIC_URL%/favicon.ico">
+    // In JavaScript code, you can access it with `process.env.PUBLIC_URL`.
+    // Note that we only recommend to use `public` folder as an escape hatch
+    // for files like `favicon.ico`, `manifest.json`, and libraries that are
+    // for some reason broken when imported through Webpack. If you just want to
+    // use an image, put it in `src` and `import` it from JavaScript instead.
+    contentBase: paths.appPublic,
+    // By default files from `contentBase` will not trigger a page reload.
+    watchContentBase: true,
+    // Enable hot reloading server. It will provide /sockjs-node/ endpoint
+    // for the WebpackDevServer client so it can learn when the files were
+    // updated. The WebpackDevServer client is included as an entry point
+    // in the Webpack development configuration. Note that only changes
+    // to CSS are currently hot reloaded. JS changes will refresh the browser.
+    hot: true,
+    // It is important to tell WebpackDevServer to use the same "root" path
+    // as we specified in the config. In development, we always serve from /.
+    publicPath: '/',
+    // WebpackDevServer is noisy by default so we emit custom message instead
+    // by listening to the compiler events with `compiler.hooks[...].tap` calls above.
+    quiet: true,
+    // Reportedly, this avoids CPU overload on some systems.
+    // https://github.com/facebook/create-react-app/issues/293
+    // src/node_modules is not ignored to support absolute imports
+    // https://github.com/facebook/create-react-app/issues/1065
+    watchOptions: {
+      ignored: ignoredFiles(paths.appSrc),
+    },
+    // Enable HTTPS if the HTTPS environment variable is set to 'true'
+    https: protocol === 'https',
+    host,
+    overlay: false,
+    historyApiFallback: {
+      // Paths with dots should still use the history fallback.
+      // See https://github.com/facebook/create-react-app/issues/387.
+      disableDotRule: true,
+    },
+    public: allowedHost,
+    proxy,
+    before(app, server) {
+      if (fs.existsSync(paths.proxySetup)) {
+        // This registers user provided middleware for proxy reasons
+        require(paths.proxySetup)(app);
+      }
+
+      // This lets us fetch source contents from webpack for the error overlay
+      app.use(evalSourceMapMiddleware(server));
+      // This lets us open files from the runtime error overlay.
+      app.use(errorOverlayMiddleware());
+
+      // This service worker file is effectively a 'no-op' that will reset any
+      // previous service worker registered for the same host:port combination.
+      // We do this in development to avoid hitting the production cache if
+      // it used the same host and port.
+      // https://github.com/facebook/create-react-app/issues/2272#issuecomment-302832432
+      app.use(noopServiceWorkerMiddleware());
+    },
+  };
+};

scripts/build.js

+'use strict';
+
+// Do this as the first thing so that any code reading it knows the right env.
+process.env.BABEL_ENV = 'production';
+process.env.NODE_ENV = 'production';
+
+// 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 => {
+  throw err;
+});
+
+// Ensure environment variables are read.
+require('../config/env');
+
+
+const path = require('path');
+const chalk = require('react-dev-utils/chalk');
+const fs = require('fs-extra');
+const webpack = require('webpack');
+const configFactory = require('../config/webpack.config');
+const paths = require('../config/paths');
+const checkRequiredFiles = require('react-dev-utils/checkRequiredFiles');
+const formatWebpackMessages = require('react-dev-utils/formatWebpackMessages');
+const printHostingInstructions = require('react-dev-utils/printHostingInstructions');
+const FileSizeReporter = require('react-dev-utils/FileSizeReporter');
+const printBuildError = require('react-dev-utils/printBuildError');
+
+const measureFileSizesBeforeBuild =
+  FileSizeReporter.measureFileSizesBeforeBuild;
+const printFileSizesAfterBuild = FileSizeReporter.printFileSizesAfterBuild;
+const useYarn = fs.existsSync(paths.yarnLockFile);
+
+// These sizes are pretty large. We'll warn for bundles exceeding them.
+const WARN_AFTER_BUNDLE_GZIP_SIZE = 512 * 1024;
+const WARN_AFTER_CHUNK_GZIP_SIZE = 1024 * 1024;
+
+const isInteractive = process.stdout.isTTY;
+
+// Warn and crash if required files are missing
+if (!checkRequiredFiles([paths.appHtml, paths.appIndexJs])) {
+  process.exit(1);
+}
+
+// Generate configuration
+const config = configFactory('production');
+
+// We require that you explicitly set browsers and do not fall back to
+// browserslist defaults.
+const { checkBrowsers } = require('react-dev-utils/browsersHelper');
+checkBrowsers(paths.appPath, isInteractive)
+  .then(() => {
+    // First, read the current file sizes in build directory.
+    // This lets us display how much they changed later.
+    return measureFileSizesBeforeBuild(paths.appBuild);
+  })
+  .then(previousFileSizes => {
+    // Remove all content but keep the directory so that
+    // if you're in it, you don't end up in Trash
+    fs.emptyDirSync(paths.appBuild);
+    // Merge with the public folder
+    copyPublicFolder();
+    // Start the webpack build
+    return build(previousFileSizes);
+  })
+  .then(
+    ({ stats, previousFileSizes, warnings }) => {
+      if (warnings.length) {
+        console.log(chalk.yellow('Compiled with warnings.\n'));
+        console.log(warnings.join('\n\n'));
+        console.log(
+          '\nSearch for the ' +
+            chalk.underline(chalk.yellow('keywords')) +
+            ' to learn more about each warning.'
+        );
+        console.log(
+          'To ignore, add ' +
+            chalk.cyan('// eslint-disable-next-line') +
+            ' to the line before.\n'
+        );
+      } else {
+        console.log(chalk.green('Compiled successfully.\n'));
+      }
+
+      console.log('File sizes after gzip:\n');
+      printFileSizesAfterBuild(
+        stats,
+        previousFileSizes,
+        paths.appBuild,
+        WARN_AFTER_BUNDLE_GZIP_SIZE,
+        WARN_AFTER_CHUNK_GZIP_SIZE
+      );
+      console.log();
+
+      const appPackage = require(paths.appPackageJson);
+      const publicUrl = paths.publicUrl;
+      const publicPath = config.output.publicPath;
+      const buildFolder = path.relative(process.cwd(), paths.appBuild);
+      printHostingInstructions(
+        appPackage,
+        publicUrl,
+        publicPath,
+        buildFolder,
+        useYarn
+      );
+    },
+    err => {
+      const tscCompileOnError = process.env.TSC_COMPILE_ON_ERROR === 'true';
+      if (tscCompileOnError) {
+        console.log(chalk.yellow(
+          'Compiled with the following type errors (you may want to check these before deploying your app):\n'
+        ));
+        printBuildError(err);
+      } else {
+        console.log(chalk.red('Failed to compile.\n'));
+        printBuildError(err);
+        process.exit(1);
+      }
+    }
+  )
+  .catch(err => {
+    if (err && err.message) {
+      console.log(err.message);
+    }
+    process.exit(1);
+  });
+
+// Create the production build and print the deployment instructions.
+function build(previousFileSizes) {
+  // We used to support resolving modules according to `NODE_PATH`.
+  // This now has been deprecated in favor of jsconfig/tsconfig.json
+  // This lets you use absolute paths in imports inside large monorepos:
+  if (process.env.NODE_PATH) {
+    console.log(
+      chalk.yellow(
+        'Setting NODE_PATH to resolve modules absolutely has been deprecated in favor of setting baseUrl in jsconfig.json (or tsconfig.json if you are using TypeScript) and will be removed in a future major release of create-react-app.'
+      )
+    );
+    console.log();
+  }
+
+  console.log('Creating an optimized production build...');
+
+  const compiler = webpack(config);
+  return new Promise((resolve, reject) => {
+    compiler.run((err, stats) => {
+      let messages;
+      if (err) {
+        if (!err.message) {
+          return reject(err);
+        }
+        messages = formatWebpackMessages({
+          errors: [err.message],
+          warnings: [],
+        });
+      } else {
+        messages = formatWebpackMessages(
+          stats.toJson({ all: false, warnings: true, errors: true })
+        );
+      }
+      if (messages.errors.length) {
+        // Only keep the first error. Others are often indicative
+        // of the same problem, but confuse the reader with noise.
+        if (messages.errors.length > 1) {
+          messages.errors.length = 1;
+        }
+        return reject(new Error(messages.errors.join('\n\n')));
+      }
+      if (
+        process.env.CI &&
+        (typeof process.env.CI !== 'string' ||
+          process.env.CI.toLowerCase() !== 'false') &&
+        messages.warnings.length
+      ) {
+        console.log(
+          chalk.yellow(
+            '\nTreating warnings as errors because process.env.CI = true.\n' +
+              'Most CI servers set it automatically.\n'
+          )
+        );
+        return reject(new Error(messages.warnings.join('\n\n')));
+      }
+
+      return resolve({
+        stats,
+        previousFileSizes,
+        warnings: messages.warnings,
+      });
+    });
+  });
+}
+
+function copyPublicFolder() {
+  fs.copySync(paths.appPublic, paths.appBuild, {
+    dereference: true,
+    filter: file => file !== paths.appHtml,
+  });
+}

scripts/start.js

+'use strict';
+
+// Do this as the first thing so that any code reading it knows the right env.
+process.env.BABEL_ENV = 'development';
+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 => {
+  throw err;
+});
+
+// Ensure environment variables are read.
+require('../config/env');
+
+
+const fs = require('fs');
+const chalk = require('react-dev-utils/chalk');
+const webpack = require('webpack');
+const WebpackDevServer = require('webpack-dev-server');
+const clearConsole = require('react-dev-utils/clearConsole');
+const checkRequiredFiles = require('react-dev-utils/checkRequiredFiles');
+const {
+  choosePort,
+  createCompiler,
+  prepareProxy,
+  prepareUrls,
+} = require('react-dev-utils/WebpackDevServerUtils');
+const openBrowser = require('react-dev-utils/openBrowser');
+const paths = require('../config/paths');
+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])) {
+  process.exit(1);
+}
+
+// Tools like Cloud9 rely on this.
+const DEFAULT_PORT = parseInt(process.env.PORT, 10) || 3000;
+const HOST = process.env.HOST || '0.0.0.0';
+
+if (process.env.HOST) {
+  console.log(
+    chalk.cyan(
+      `Attempting to bind to HOST environment variable: ${chalk.yellow(
+        chalk.bold(process.env.HOST)
+      )}`
+    )
+  );
+  console.log(
+    `If this was unintentional, check that you haven't mistakenly set it in your shell.`
+  );
+  console.log(
+    `Learn more here: ${chalk.yellow('https://bit.ly/CRA-advanced-config')}`
+  );
+  console.log();
+}
+
+// We require that you explicitly 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 useTypeScript = fs.existsSync(paths.appTsConfig);
+    const tscCompileOnError = process.env.TSC_COMPILE_ON_ERROR === 'true';
+    const urls = prepareUrls(protocol, HOST, port);
+    const devSocket = {
+      warnings: warnings =>
+        devServer.sockWrite(devServer.sockets, 'warnings', warnings),
+      errors: errors =>
+        devServer.sockWrite(devServer.sockets, 'errors', errors),
+    };
+    // Create a webpack compiler that is configured with custom messages.
+    const compiler = createCompiler({
+      appName,
+      config,
+      devSocket,
+      urls,
+      useYarn,
+      useTypeScript,
+      tscCompileOnError,
+      webpack,
+    });
+    // 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 server.
+    const serverConfig = createDevServerConfig(
+      proxyConfig,
+      urls.lanUrlForConfig
+    );
+    const devServer = new WebpackDevServer(compiler, serverConfig);
+    // Launch WebpackDevServer.
+    devServer.listen(port, HOST, err => {
+      if (err) {
+        return console.log(err);
+      }
+      if (isInteractive) {
+        clearConsole();
+      }
+
+      // We used to support resolving modules according to `NODE_PATH`.
+      // This now has been deprecated in favor of jsconfig/tsconfig.json
+      // This lets you use absolute paths in imports inside large monorepos:
+      if (process.env.NODE_PATH) {
+        console.log(
+          chalk.yellow(
+            'Setting NODE_PATH to resolve modules absolutely has been deprecated in favor of setting baseUrl in jsconfig.json (or tsconfig.json if you are using TypeScript) and will be removed in a future major release of create-react-app.'
+          )
+        );
+        console.log();
+      }
+
+      console.log(chalk.cyan('Starting the development server...\n'));
+      openBrowser(urls.localUrlForBrowser);
+    });
+
+    ['SIGINT', 'SIGTERM'].forEach(function(sig) {
+      process.on(sig, function() {
+        devServer.close();
+        process.exit();
+      });
+    });
+  })
+  .catch(err => {
+    if (err && err.message) {
+      console.log(err.message);
+    }
+    process.exit(1);
+  });

scripts/test.js

+'use strict';
+
+// Do this as the first thing so that any code reading it knows the right env.
+process.env.BABEL_ENV = 'test';
+process.env.NODE_ENV = 'test';
+process.env.PUBLIC_URL = '';
+
+// 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 => {
+  throw err;
+});
+
+// Ensure environment variables are read.
+require('../config/env');
+
+
+const jest = require('jest');
+const execSync = require('child_process').execSync;
+let argv = process.argv.slice(2);
+
+function isInGitRepository() {
+  try {
+    execSync('git rev-parse --is-inside-work-tree', { stdio: 'ignore' });
+    return true;
+  } catch (e) {
+    return false;
+  }
+}
+
+function isInMercurialRepository() {
+  try {
+    execSync('hg --cwd . root', { stdio: 'ignore' });
+    return true;
+  } catch (e) {
+    return false;
+  }
+}
+
+// Watch unless on CI or explicitly running all tests
+if (
+  !process.env.CI &&
+  argv.indexOf('--watchAll') === -1 &&
+  argv.indexOf('--watchAll=false') === -1
+) {
+  // https://github.com/facebook/create-react-app/issues/5210
+  const hasSourceControl = isInGitRepository() || isInMercurialRepository();
+  argv.push(hasSourceControl ? '--watch' : '--watchAll');
+}
+
+
+jest.run(argv);