webpack.config.js

const { CleanWebpackPlugin } = require('clean-webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const OptimizeCssAssetsPlugin = require('optimize-css-assets-webpack-plugin');
const path = require('path');
const setPublicPath = require('@rushstack/set-webpack-public-path-plugin');
const webpack = require('webpack');

// Only embed assets under 10 KB
const embedLimit = 10240;
const devServerPort = 8080;
const pathRoot = 'frontend';
const pathDist = `yarr/static/yarr`;

/*
 * Rules which change depending on mode
 */

// Image optimisation rule
const moduleRuleOptimiseImages = {
  test: /\.(gif|png|jpe?g|svg)$/iu,
  loader: 'image-webpack-loader',
  options: {
    // Apply the loader before url-loader and svg-url-loader
    enforce: 'pre',
    // Disabled in dev, enable in production
    disable: true,
  },
};

// Style building rule
const moduleRuleScss = {
  test: /\.scss$/u,
  use: [
    // MiniCssExtractPlugin doesn't support HMR, so will replace style-loader
    // in production
    'style-loader',
    'css-loader',
    {
      loader: 'resolve-url-loader',
      options: {
        'sourceMap': true,
      },
    },
    {
      loader: 'sass-loader',
      options: {
        sassOptions: {
          includePaths: ['./node_modules'],
          sourceMap: true,
          sourceMapContents: false
        },
      },
    },
  ],
};


/*
 ** Main config
 */
const config = {
  entry: {
    index: [
      `./${pathRoot}/index.js`,
      `./${pathRoot}/index.scss`,
    ],
  },
  output: {
    filename: '[name].js',
    path: path.resolve(
      __dirname,
      pathDist,
    ),
    publicPath: '/static/yarr/',
  },

  // Enable sourcemaps for debugging webpack's output.
  devtool: 'source-map',
  devServer: {
    contentBase: path.resolve(__dirname, pathDist),
    contentBasePublicPath: '/static/yarr/',
    publicPath: '/static/yarr/',
    hot: true,
    disableHostCheck: true,
    port: devServerPort,
    headers: {
      'Access-Control-Allow-Origin': '*'
    }
  },

  resolve: {
    alias: {
      '~': `${__dirname}/${pathRoot}`,
    },
    extensions: ['.js', '.json'],
  },

  plugins: [
    new CleanWebpackPlugin({
      // Remove built js and css from the dist folder before building
      cleanOnceBeforeBuildPatterns: ['**/*', '!.gitkeep'],
    }),
    new MiniCssExtractPlugin({
      // Options similar to the same options in webpackOptions.output
      // both options are optional
      filename: '[name].css',
    }),
  ],

  module: {
    rules: [
      // All output '.js' files will have any sourcemaps re-processed by 'source-map-loader'.
      {
        test: /\.js$/u,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env'],
          },
        },
      },

      // Optimise images
      moduleRuleOptimiseImages,

      // Embed small images and fonts
      {
        test: /\.(png|jpg|gif|eot|ttf|woff|woff2)$/u,
        loader: 'url-loader',
        options: {
          limit: embedLimit,
        },
      },
      {
        test: /\.svg$/u,
        loader: 'svg-url-loader',
        options: {
          limit: embedLimit,
          noquotes: true,
        }
      },

      // SCSS
      moduleRuleScss,
    ],
  },
};


module.exports = (env, argv) => {
  if (argv.mode === 'production') {
    console.log(`Running in production mode:
* optimising images
* extracting and minifying CSS
    `);

    // Switch from style-loader to generate separate css files
    moduleRuleScss.use[0] = MiniCssExtractPlugin.loader;

    // Activate image optimisation
    moduleRuleOptimiseImages.options.disable = false;

    // Optimise CSS assets
    config.plugins.push(new OptimizeCssAssetsPlugin());
  } else if (process.argv[1].indexOf('webpack-dev-server') > -1) {
    console.log('Running in development mode with HMR');

    // Add HMR and change the public path to pick up the correct hostname
    config.plugins.push(
      new webpack.HotModuleReplacementPlugin(),
      new setPublicPath.SetPublicPathPlugin({
        scriptName: {
          name: '[name].js',
          isTokenized: true,
        },
      }),
    );
  } else {
    console.log(`Running in development mode:
* no optimisation or minification
* single bundle.js
    `);
  }
  return config;
};