webpack.config.js

const path = require("path");
const ExtractTextPlugin = require("extract-text-webpack-plugin");
const webpack = require("webpack");
const UglifyJsPlugin = require("uglifyjs-webpack-plugin");

module.exports = env => {
  const isProduction = env === "production";
  const CSSExtract = new ExtractTextPlugin("styles.css");

  return {
    entry: ["babel-polyfill", "./src/App.js"],
    output: {
      path: path.join(__dirname, "public", "dist"),
      filename: "bundle.js"
    },
    module: {
      rules: [
        {
          loader: "babel-loader",
          test: /\.js$/,
          exclude: /node_modules/
        },
        {
          test: /\.s?css$/,
          use: CSSExtract.extract({
            use: [
              {
                loader: "css-loader",
                options: {
                  sourceMap: true
                }
              },
              {
                loader: "sass-loader",
                options: {
                  sourceMap: true
                }
              }
            ]
          })
        }
      ]
    },
    plugins: [
      CSSExtract,
      new UglifyJsPlugin({
        sourceMap: true,
        uglifyOptions: {
          ecma: 8,
          compress: {
            warnings: false
          }
        }
      })
    ],
    devtool: isProduction ? "source-map" : "inline-source-map",
    devServer: {
      contentBase: path.join(__dirname, "public"),
      historyApiFallback: true,
      publicPath: "/dist/",
      proxy: {
        "/api": {
          target: "http://localhost:5000",
          secure: false
        }
      }
    }
  };
};