webpack.config.js

const path = require("path");
const glob = require("glob");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const UglifyJsPlugin = require("uglifyjs-webpack-plugin");
const OptimizeCSSAssetsPlugin = require("optimize-css-assets-webpack-plugin");
const CopyWebpackPlugin = require("copy-webpack-plugin");

module.exports = (env, options) => ({
  optimization: {
    minimizer: [
      new UglifyJsPlugin({ cache: true, parallel: true, sourceMap: false }),
      new OptimizeCSSAssetsPlugin({})
    ]
  },
  entry: {
    app: "./assets/js/app.js",
    report: "./assets/js/report/index.js"
  },
  output: {
    filename: "[name].js",
    path: path.resolve(__dirname, "priv/static/js")
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        use: {
          loader: "babel-loader"
        }
      },
      {
        test: /\.scss$/,
        use: [MiniCssExtractPlugin.loader, "css-loader", "sass-loader"]
      }
    ]
  },
  plugins: [
    new MiniCssExtractPlugin({ filename: "../css/[name].css" }),
    new CopyWebpackPlugin([{ from: "assets/static/", to: "../" }])
  ],
  resolve: {
    extensions: [".js", ".jsx", ".json"]
  }
});