webpack.prod.js

const merge = require('webpack-merge');
const UglifyJsPlugin = require("uglifyjs-webpack-plugin");
const OptimizeCSSAssetsPlugin = require("optimize-css-assets-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const common = require('./webpack.common.js');
const webpack = require('webpack');

module.exports = merge(common, {
  mode: 'production',
  devtool: 'source-map',
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        cache: true,
        parallel: true,
        sourceMap: true // set to true if you want JS source maps
      }),
      new OptimizeCSSAssetsPlugin({})
    ]
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['env']
          }
        }
      },
      {
        test: /\.(sa|sc|c)ss$/,
        use: [
          MiniCssExtractPlugin.loader,
          'css-loader',
          {
            loader: 'postcss-loader', // Run post css actions
            options: {
              plugins: function () { // post css plugins, can be exported to postcss.config.js
                return [
                  require('autoprefixer')
                ];
              }
            }
          },
          'sass-loader'
        ]
      },
      {
        test: /\.(gif|png|jpe?g|svg)$/i,
        use: [
          {
            loader: 'image-webpack-loader',
            options: {
              mozjpeg: {
                progressive: true,
                quality: 65
              },
              // optipng.enabled: false will disable optipng
              optipng: {
                enabled: false,
              },
              pngquant: {
                quality: '65-90',
                speed: 4
              },
              gifsicle: {
                interlaced: false,
              },
              // the webp option will enable WEBP
              webp: {
                quality: 75
              }
            }
          },
        ],
      },
    ]
  },
  plugins: [
    new MiniCssExtractPlugin({
      filename: "[name].css",
      chunkFilename: "[id].css"
    }),
    new webpack.DefinePlugin({
      'process.env.NODE_ENV': JSON.stringify('production')
    })
  ]
});