webpack.config.js

const path = require("path");
const merge = require("webpack-merge");
const sass = require("./webpack/sass");
const HtmlWebpackPlugin = require("html-webpack-plugin");
const HtmlWebpackPluginConfig = new HtmlWebpackPlugin({
  template: "./public/index.html",
  filename: "index.html",
  inject: "body"
});

const PATHS = {
  source: path.join(__dirname, "src"),
  build: path.join(__dirname, "build")
};

const common = merge([
  {
    entry: PATHS.source + "/index.js",
    output: {
      path: PATHS.build,
      filename: "main.js"
    },
    module: {
      loaders: [
        {
          test: /\.js$/,
          loader: "babel-loader",
          options: {
            presets: ["es2015", "react"],
            plugins: []
          }
        }
      ]
    },
    plugins: [HtmlWebpackPluginConfig]
  }
]);

module.exports = env => {
  if (env === "production") return common;
  if (env === "development") return merge([common, sass()]);
};