webpack4 + TypeScript + SCSS構成のwebpack設定（CSSはJSに含めない）

webpack.config.js

const path = require('path');
mode = process.env.NODE_ENV,
    devMode = mode !== 'production',
    MiniCssExtractPlugin = require("mini-css-extract-plugin");

module.exports = {
    mode: mode,
    entry: {
        main: path.resolve(__dirname, './ts/login.ts')
    },
    output: {
        path: path.join(__dirname, 'wwwroot'),
        filename: 'js/[name].js'
    },
    resolve: {
        extensions: ['.ts', '.tsx', '.js']
    },
    devtool: 'source-map',
    plugins: [
        new MiniCssExtractPlugin({
            filename: 'css/[name].css',
            chunkFilename: 'css/[id].css'
        })
    ],
    module: {
        rules: [
            {
                test: /\.ts$/,
                use: 'ts-loader'
            },
            {
                test: /\.(sc|sa|c)ss/,
                use: [
                    {
                        loader: MiniCssExtractPlugin.loader
                    },
                    {
                        loader: 'css-loader',
                        options: {
                            url: false,
                            sourceMap: true,
                            minimize: true,
                            importLoaders: 2
                        }
                    },
                    {
                        loader: 'postcss-loader',
                        options: {
                            sourceMap: true
                        }
                    },
                    {
                        loader: 'sass-loader',
                        options: {
                            sourceMap: true
                        }
                    }
                ]
            }
        ]
    }
};