webpack.config.js

const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const path = require('path');

module.exports = {
    mode: 'development',
    entry: path.resolve(__dirname, 'src/index.js'),
    output: {
        path: __dirname+'/dist',
        filename: 'index.js',
        libraryTarget: 'commonjs2',
    },
    devtool: 'source-map',
    module: {
        rules: [
            {
                enforce: 'pre',
                test: /\.(js|jsx)$/,
                exclude: /node_modules/,
                use: 'eslint-loader',
            },
            {
                test: /\.(js|jsx)$/,
                exclude: /node_modules/,
                use: {
                    loader: 'babel-loader',
                    options: {
                        presets: [
                            '@babel/preset-env',
                            '@babel/preset-react',
                        ],
                    },
                },
            },
            {
                test: /(\.css|\.scss|\.sass)$/,
                use: [
                    {
                        loader: MiniCssExtractPlugin.loader,
                        options: {
                            includePaths: ['./node_modules'],
                        },
                    },
                    {
                        loader: 'css-loader',
                    },
                    {
                        loader: 'sass-loader',
                        options: {
                            includePaths: ['./node_modules'],
                        },
                    },
                ],
            },
        ],
    },
    plugins: [
        new MiniCssExtractPlugin({
            // Options similar to the same options in webpackOptions.output
            // both options are optional
            filename: 'index.css',
        }),
    ],
    externals: {
        'react': 'commonjs react',
    },
};