webpack.config.dev.js

/**
 * Copyright (c) 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */

var path = require('path');
var autoprefixer = require('autoprefixer');
var webpack = require('webpack');
var HtmlWebpackPlugin = require('html-webpack-plugin');
var CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
var WatchMissingNodeModulesPlugin = require('../scripts/utils/WatchMissingNodeModulesPlugin');
var paths = require('./paths');
var env = require('./env');

// 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 = {
  // This makes the bundle appear split into separate modules in the devtools.
  // We don't use source maps here because they can be confusing:
  // https://github.com/facebookincubator/create-react-app/issues/343#issuecomment-237241875
  // You may want 'cheap-module-source-map' instead if you prefer source maps.
  devtool: 'eval',
  // 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: [
    // Include WebpackDevServer client. It connects to WebpackDevServer via
    // sockets and waits for recompile notifications. When WebpackDevServer
    // recompiles, it sends a message to the client by socket. If only CSS
    // was changed, the app reload just the CSS. Otherwise, it will refresh.
    // The "?/" bit at the end tells the client to look for the socket at
    // the root path, i.e. /sockjs-node/. Otherwise visiting a client-side
    // route like /todos/42 would make it wrongly request /todos/42/sockjs-node.
    // The socket server is a part of WebpackDevServer which we are using.
    // The /sockjs-node/ path I'm referring to is hardcoded in WebpackDevServer.
    require.resolve('webpack-dev-server/client') + '?/',
    // Include Webpack hot module replacement runtime. Webpack is pretty
    // low-level so we need to put all the pieces together. The runtime listens
    // to the events received by the client above, and applies updates (such as
    // new CSS) to the running application.
    require.resolve('webpack/hot/dev-server'),
    // We ship a few polyfills by default.
    require.resolve('./polyfills'),
    // Finally, this is your app's code:
    path.join(paths.appSrc, 'index')
    // 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.
  ],
  output: {
    // Next line is not used in dev but WebpackDevServer crashes without it:
    path: paths.appBuild,
    // 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',
    // In development, we always serve from the root. This makes config easier.
    publicPath: '/'
  },
  resolve: {
    // These are the reasonable defaults supported by the Node ecosystem.
    extensions: ['.js', '.json', ''],
    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'
    }
  },
  // Resolve loaders (webpack plugins for CSS, images, transpilation) from the
  // directory of `react-scripts` itself rather than the project directory.
  // You can remove this after ejecting.
  resolveLoader: {
    root: paths.ownNodeModules,
    moduleTemplates: ['*-loader']
  },
  module: {
    // First, run the linter.
    // It's important to do this before Babel processes the JS.
    preLoaders: [
      {
        test: /\.js$/,
        loader: 'eslint',
        include: paths.appSrc,
      }
    ],
    loaders: [
      // Process JS with Babel.
      {
        test: /\.js$/,
        include: paths.appSrc,
        loader: 'babel',
        query: require('./babel.dev')
      },
      // "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.
      {
        test: /\.css$/,
        loader: 'style!css!postcss'
      },
      // JSON is not enabled by default in Webpack but both Node and Browserify
      // allow it implicitly so we also enable it.
      {
        test: /\.json$/,
        loader: 'json'
      },
      // "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.
      {
        test: /\.(ico|jpg|png|gif|eot|otf|webp|svg|ttf|woff|woff2)(\?.*)?$/,
        exclude: /\/favicon.ico$/,
        loader: 'file',
        query: {
          name: 'static/media/[name].[hash:8].[ext]'
        }
      },
      // A special case for favicon.ico to place it into build root directory.
      {
        test: /\/favicon.ico$/,
        include: [paths.appSrc],
        loader: 'file',
        query: {
          name: 'favicon.ico?[hash:8]'
        }
      },
      // "url" loader works just like "file" loader but it also embeds
      // assets smaller than specified size as data URLs to avoid requests.
      {
        test: /\.(mp4|webm)(\?.*)?$/,
        loader: 'url',
        query: {
          limit: 10000,
          name: 'static/media/[name].[hash:8].[ext]'
        }
      },
      // "html" loader is used to process template page (index.html) to resolve
      // resources linked with <link href="./relative/path"> HTML tags.
      {
        test: /\.html$/,
        loader: 'html',
        query: {
          attrs: ['link:href'],
        }
      }
    ]
  },
  // Point ESLint to our predefined config.
  eslint: {
    configFile: path.join(__dirname, 'eslint.js'),
    useEslintrc: false
  },
  // We use PostCSS for autoprefixing only.
  postcss: function() {
    return [
      autoprefixer({
        browsers: [
          '>1%',
          'last 4 versions',
          'Firefox ESR',
          'not ie < 9', // React doesn't support IE8 anyway
        ]
      }),
    ];
  },
  plugins: [
    // Generates an `index.html` file with the <script> injected.
    new HtmlWebpackPlugin({
      inject: true,
      template: paths.appHtml,
    }),
    // Makes some environment variables available to the JS code, for example:
    // if (process.env.NODE_ENV === 'development') { ... }. See `env.js`.
    new webpack.DefinePlugin(env),
    // 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/facebookincubator/create-react-app/issues/240
    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/facebookincubator/create-react-app/issues/186
    new WatchMissingNodeModulesPlugin(paths.appNodeModules)
  ]
};