webpack.common.js

const path = require("path");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const outputDir = "./dist";

module.exports = {
    entry: path.resolve(__dirname, "src", "index.js"),
    output: {
        path: path.join(__dirname, outputDir),
        filename: "[name].js",
        publicPath: "/dist/"
    },
    resolve: {
        extensions: [".js", ".css", ".scss"]
    },
    module: {
        rules: [
            {
                test: /\.js$/,
                use: {
                    loader: "babel-loader",
                    options: { presets: ["env"] }
                }
            },
            {
                test: /\.css$/,
                use: [
                    {
                        loader: MiniCssExtractPlugin.loader,
                        options: {
                            publicPath: "../",
                            hmr: process.env.NODE_ENV === "development"
                        }
                    },
                    "css-loader",
                    "postcss-loader"
                ]
            },
            {
                test: /\.scss/,
                use: [
                    {
                        loader: MiniCssExtractPlugin.loader,
                        options: {
                            publicPath: "../",
                            hmr: process.env.NODE_ENV === "development"
                        }
                    },
                    "css-loader",
                    "sass-loader",
                    "postcss-loader"
                ]
            }
        ]
    },
    plugins: [new MiniCssExtractPlugin({
        filename: "[name].css",
        chunkFilename: "[id].css",
        ignoreOrder: false
    }), require("autoprefixer")]
};