webpack.config.build_esm.js

const path = require('path');
const webpack = require('webpack');
const TerserPlugin = require('terser-webpack-plugin');
const getPackageJson = require('./scripts/getPackageJson');
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const CssMinimizerPlugin = require("css-minimizer-webpack-plugin");

const {
  version,
  name,
  license,
  repository,
  author
} = getPackageJson('version', 'name', 'license', 'repository', 'author');

const banner = `
  ${name} v${version} (ESM)
  ${repository.url}

  Copyright (c) ${author.replace(/ *<[^)]*> */g, " ")} and project contributors.

  This source code is licensed under the ${license} license found in the
  LICENSE file in the root directory of this source tree.
`;

module.exports = {
  mode: "production",
  entry: './src/lib/index.ts',
  target: [
    'web',
    'es2020'
  ],
  output: {
    filename: 'index.esm.js',
    path: path.resolve(__dirname, 'build'),
    globalObject: 'this',
    hashFunction: 'xxhash64',
    chunkFormat: 'module',
    library: {
      type: 'module'
    }
  },
  experiments: {
    outputModule: true
  },
  externalsType: 'module',
  optimization: {
    minimize: true,
    minimizer: [
      new TerserPlugin({ extractComments: false }),
      new CssMinimizerPlugin()
    ],
  },
  module: {
    rules: [
      {
        test: /\.(m|j|t)s$/,
        exclude: /(node_modules|bower_components)/,
        use: {
          loader: 'babel-loader'
        }
      },
      {
        test: /\.(sa|sc|c)ss$/,
        use: [
          MiniCssExtractPlugin.loader,
          { loader: "css-loader" },
        ],
      },
      {
        test: /\.(png|jpe?g|gif|svg|eot|ttf|woff|woff2)$/,
        use: ['url-loader'],
      }
    ]
  },
  plugins: [
    new MiniCssExtractPlugin({
        filename: 'index.css'
    }),
    new webpack.BannerPlugin(banner)
  ],
  resolve: {
    extensions: ['.ts', '.js', '.json']
  }
};