webpack.config.js

const path = require("path");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const CopyWebpackPlugin = require("copy-webpack-plugin");

module.exports = {
  entry: "./src/index.js",
  output: {
    path: path.resolve(__dirname, "lib"),
    filename: "index.js",
    libraryTarget: "umd",
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: "babel-loader",
      },
      {
        test: /\.css$/,
        use: [MiniCssExtractPlugin.loader, "css-loader"],
      },
    ],
  },
  plugins: [
    new MiniCssExtractPlugin({
      filename: "index.css",
    }),
    new CopyWebpackPlugin({
      patterns: [
        {
          from: path.resolve(__dirname, "src/styles/css"),
          to: path.resolve(__dirname, "lib/styles/css"),
          noErrorOnMissing: true,
        },
      ],
    }),
  ],
  resolve: {
    extensions: [".js", ".css"],
  },
};