webpack.config.dev.js

'use strict';

const autoprefixer = require('autoprefixer');
const path = require('path');
const webpack = require('webpack');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
const getClientEnvironment = require('./env');
const paths = require('../config/paths');

// Webpack uses `publicPath` to determine where the app is being served from.
// In development, we always serve from the root. This makes config easier.
const 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 = '';
// Get environment variables to inject into our app.
const env = getClientEnvironment(publicUrl);

// This is the development configuration.
// It is focused on developer experience and fast rebuilds.
// The production configuration is different and lives in a separate file.
module.exports = {
  mode: 'development',
  // You may want 'eval' instead if you prefer to see the compiled output in DevTools.
  // See the discussion in https://github.com/facebook/create-react-app/issues/343.
  devtool: '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.
  // The first two entry points enable "hot" CSS and auto-refreshes for JS.
  entry: [
    // We ship a few polyfills by default:
    require.resolve('./polyfills'),
    // 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 Elm 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'),
    // require.resolve('react-dev-utils/webpackHotDevClient'),
    require.resolve('../scripts/utils/webpackHotDevClient'),

    // Errors should be considered fatal in development
    require.resolve('react-error-overlay'),

    paths.appIndexJs,
  ],
  output: {
    // Add /* filename */ comments to generated require()s in the output.
    pathinfo: true,
    // This does not produce a real file. It's just the virtual path that is
    // served by WebpackDevServer in development. This is the JS bundle
    // containing code from all our entry points, and the Webpack runtime.
    filename: 'static/js/bundle.js',
    // There are also additional JS chunk files if you use code splitting.
    chunkFilename: 'static/js/[name].chunk.js',
    // This is the URL that app is served from. We use "/" in development.
    publicPath: publicPath,
    // Point sourcemap entries to original disk location (format as URL on Windows)
    devtoolModuleFilenameTemplate: (info) =>
      path.resolve(info.absoluteResourcePath).replace(/\\/g, '/'),
  },
  optimization: {
    // 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: 'vendors',
    },
    // Keep the runtime chunk seperated to enable long term caching
    // https://twitter.com/wSokra/status/969679223278505985
    runtimeChunk: true,
  },
  resolve: {
    modules: ['node_modules'],
    extensions: ['.js', '.mjs', '.elm'],
  },
  module: {
    strictExportPresence: true,
    rules: [
      // Disable require.ensure as it's not a standard language feature.
      { parser: { requireEnsure: false } },

      {
        test: /\.js$/,
        exclude: [/[/\\\\]elm-stuff[/\\\\]/, /[/\\\\]node_modules[/\\\\]/],
        include: paths.appSrc,
        loader: require.resolve('babel-loader'),
        options: {
          presets: [
            [
              require.resolve('@babel/preset-env'),
              {
                // `entry` transforms `@babel/polyfill` into individual requires for
                // the targeted browsers. This is safer than `usage` which performs
                // static code analysis to determine what's required.
                // This is probably a fine default to help trim down bundles when
                // end-users inevitably import '@babel/polyfill'.
                useBuiltIns: 'entry',
                // Set the corejs version we are using to avoid warnings in console
                corejs: 3,
                // Do not transform modules to CJS
                modules: false,
              },
            ],
          ],
          plugins: [
            // Polyfills the runtime needed for async/await and generators
            [
              require('@babel/plugin-transform-runtime').default,
              {
                helpers: false,
                regenerator: true,
              },
            ],
          ],
        },
      },
      // Process any JS outside of the app with Babel.
      // Unlike the application JS, we only compile the standard ES features.
      {
        test: /\.m?js$/,
        use: [
          {
            loader: require.resolve('babel-loader'),
            options: {
              babelrc: false,
              compact: false,
              presets: [
                [
                  // Latest stable ECMAScript features
                  require('@babel/preset-env').default,
                  {
                    // Do not transform modules to CJS
                    modules: false,
                  },
                ],
              ],
              cacheDirectory: true,
              highlightCode: true,
            },
          },
        ],
      },
      {
        test: /\.elm$/,
        include: paths.appSrc,
        exclude: [/[/\\\\]elm-stuff[/\\\\]/, /[/\\\\]node_modules[/\\\\]/],
        use: [
          {
            loader: require.resolve('elm-hot-webpack-loader'),
          },
          // string-replace-loader works as InterpolateHtmlPlugin for Elm,
          // it replaces all of the %PUBLIC_URL% with the URL of your
          // application, so you could serve static assets outside of the
          // module system.
          {
            loader: require.resolve('string-replace-loader'),
            query: {
              search: '%PUBLIC_URL%',
              replace: publicUrl,
              flags: 'g',
            },
          },
          {
            loader: require.resolve('elm-asset-webpack-loader'),
          },
          {
            loader: require.resolve('elm-webpack-loader'),
            options: {
              verbose: true,
              // If ELM_DEBUGGER was set to "false", disable it. Otherwise
              // for invalid values, "true" and as a default, enable it
              debug: process.env.ELM_DEBUGGER === 'false' ? false : true,
              pathToElm: paths.elm,
              forceWatch: true,
            },
          },
        ],
      },

      // "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 a plugin 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: /\.css/,
        use: [
          require.resolve('style-loader'),
          {
            loader: require.resolve('css-loader'),
            options: {
              importLoaders: 1,
            },
          },
          {
            // 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
              postcssOptions: {
                plugins: () => [
                  require('postcss-flexbugs-fixes'),
                  autoprefixer({
                    flexbox: 'no-2009',
                  }),
                ],
              },
            },
          },
        ],
      },

      {
        exclude: [
          /\.html$/,
          /\.js$/,
          /\.mjs$/,
          /\.elm$/,
          /\.css$/,
          /\.scss$/,
          /\.sass$/,
          /\.json$/,
          /\.svg$/,
        ],
        loader: require.resolve('url-loader'),
        options: {
          limit: 10000,
          name: 'static/media/[name].[hash:8].[ext]',
        },
      },

      // "file" loader for svg
      {
        test: /\.svg$/,
        loader: require.resolve('file-loader'),
        options: {
          name: 'static/media/[name].[hash:8].[ext]',
        },
      },
    ],
  },
  plugins: [
    // Generates an `index.html` file with the <script> injected.
    new HtmlWebpackPlugin({
      inject: true,
      template: paths.appHtml,
    }),
    // 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 development, this will be an empty string.
    new InterpolateHtmlPlugin(HtmlWebpackPlugin, env.raw),
    // Makes some environment variables available to the JS code, for example:
    // if (process.env.NODE_ENV === 'development') { ... }. See `./env.js`.
    new webpack.DefinePlugin(env.stringified),
    // This is necessary to emit hot updates (currently CSS only):
    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
    new CaseSensitivePathsPlugin(),
  ],

  // 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: {
    dgram: 'empty',
    fs: 'empty',
    net: 'empty',
    tls: 'empty',
    child_process: 'empty',
  },
  // Turn off performance processing because we utilize
  // our own hints via the FileSizeReporter
  performance: false,
};