webpack.config.js

const HtmlWebPackPlugin = require("html-webpack-plugin");
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const OptimizeCssAssetsPlugin = require('optimize-css-assets-webpack-plugin');

module.exports = {
    module: {
        rules: [
            {
                test: /\.(css|sass|scss)$/,
                use: [
                    MiniCssExtractPlugin.loader,
                    {
                        loader: 'css-loader',
                        options: {
                            importLoaders: 2,
                            sourceMap: true
                        }
                    },
                    {
                        loader: 'postcss-loader',
                        options: {
                            plugins: () => [
                                require('autoprefixer')
                            ],
                            sourceMap: true
                        }
                    },
                    {
                        loader: 'sass-loader',
                        options: {
                            sourceMap: true
                        }
                    }
                ]
            },
            {
                test: /bootstrap\.native/,
                use: {
                    loader: 'bootstrap.native-loader',
                    options: {
                        only: ['modal', 'dropdown']
                    }
                }
            },
            {
                test: /\.(js|jsx)$/,
                exclude: /node_modules/,
                use: {
                    loader: "babel-loader"
                }
            },
            {
                test: /\.html$/,
                use: [
                    {
                        loader: "html-loader"
                    }
                ]
            }
        ]
    },
    plugins: [
        new MiniCssExtractPlugin({
            // Options similar to the same options in webpackOptions.output
            // both options are optional
            filename: '[name].css',
            chunkFilename: '[id].css',
        }),
        new OptimizeCssAssetsPlugin(),
        new HtmlWebPackPlugin({
            template: "./src/index.html",
            filename: "./index.html"
        }),
    ]
};