safe-react/config/webpack.config.dev.js

const autoprefixer = require('autoprefixer');
const cssvars = require('postcss-simple-vars');
const webpack = require('webpack');
const HtmlWebPackPlugin = require("html-webpack-plugin");

const paths = require('./paths');
const getClientEnvironment = require('./env');

const publicPath = '/';

// `publicUrl` 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_PATH%/xyz looks better than %PUBLIC_PATH%xyz.
var publicUrl = '';
// Get environment variables to inject into our app.
var env = getClientEnvironment(publicUrl);

const cssvariables = require(paths.appSrc + '/theme/variables');

const postcssPlugins = [
  autoprefixer({
    browsers: [
      '>1%',
      'last 4 versions',
      'Firefox ESR',
      'not ie < 9', // React doesn't support IE8 anyway
    ]
  }),
  cssvars({
    variables: function () {
        return Object.assign({}, cssvariables);
    },
    silent: false
  }),
];

module.exports = {
  devtool: 'cheap-module-source-map',
  mode: 'development',
  entry: [
    "babel-polyfill",
    // 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'),
    require.resolve('react-dev-utils/webpackHotDevClient'),
    // We ship a few polyfills by default:
    require.resolve('./polyfills'),
    // 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.
  ],
  resolve: { 
    // 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/facebookincubator/create-react-app/issues/290
    extensions: ['.js', '.json', '.jsx'],
    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'
    }
  },
  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',
    // This is the URL that app is served from. We use "/" in development.
    publicPath: publicPath
  },  
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        use: {
          loader: "babel-loader"
        }
      },
      {
        test: /\.(scss|css)$/,
        use: [
          'style-loader',
          { loader: 'css-loader',
            options: {
              importLoaders: 1,
              modules: true,
              minimize: false,
              localIdentName: '[name]__[local]___[hash:base64:5]',
            }
          },
          {
            loader: 'postcss-loader',
            options: {
              sourceMap: true,
              plugins: postcssPlugins,
            },
          },
        ],
    },
      {
        test: /\.html$/,
        use: [
          {
            loader: "html-loader",
            options: { minimize: true }
          }
        ]
      }
    ]
  },
  plugins: [
    new HtmlWebPackPlugin({
      template: paths.appHtml,
    }),
    new webpack.DefinePlugin(env),
    new webpack.HotModuleReplacementPlugin(),
  ]
};