webpack.config.js

const TerserJsPlugin = require('terser-webpack-plugin');

const serverBuild = {
    mode: 'production',
    entry: './src/twig.js',
    target: 'node',
    node: false,
    output: {
        path: __dirname,
        filename: 'twig.js',
        library: 'Twig',
        libraryTarget: 'umd'
    },
    optimization: {
        minimize: false
    }
};

const clientBuild = {
    mode: 'production',
    entry: './src/twig.js',
    target: 'web',
    node: {
        __dirname: false,
        __filename: false
    },
    module: {
        rules: [
            {
                exclude: /(node_modules)/,
                use: {
                    loader: 'babel-loader',
                    options: {
                        presets: ['@babel/preset-env'],
                        plugins: [
                            '@babel/plugin-transform-modules-commonjs',
                            '@babel/plugin-transform-runtime'
                        ]
                    }
                }
            }
        ]
    },
    output: {
        path: __dirname,
        filename: 'twig.min.js',
        library: 'Twig',
        libraryTarget: 'umd'
    },
    optimization: {
        minimize: true,
        minimizer: [new TerserJsPlugin({
            include: /\.min\.js$/
        })]
    }
};

module.exports = [serverBuild, clientBuild];