webpack.config.js

const { readFileSync } = require("fs");
const { resolve } = require("path");

const rxPaths = require("rxjs/_esm5/path-mapping");

const { BannerPlugin, EnvironmentPlugin } = require("webpack");

const merge = require("webpack-merge");
const {
  argv: { mode },
} = require("yargs");

const { name: filename, version } = require("./package.json");

const banner = readFileSync(resolve("./_includes/header.txt"), "utf-8");

const flatten = [(a, x) => a.concat(x), []];

function envConfig() {
  switch (mode) {
    case "production":
      return {
        plugins: [new BannerPlugin({ banner, raw: true }), new EnvironmentPlugin({ DEBUG: false })],
      };

    default:
      return {
        devtool: "source-map",
        plugins: [new EnvironmentPlugin({ DEBUG: true })],
      };
  }
}

module.exports = merge(
  {
    entry: resolve("./_js/src/index.js"),
    output: {
      path: resolve("./assets/js"),
      filename: `${filename}-${version}.js`,
    },
    module: {
      rules: [
        {
          test: /(\.jsx|\.js)$/,
          loader: "babel-loader",
          options: {
            presets: [["@babel/preset-env", { modules: false }]],
            babelrc: false,
          },
        },
      ],
    },
    resolve: {
      modules: [
        resolve("./_js"),
        resolve("./node_modules"),
        process.env.NODE_PATH ? resolve(process.env.NODE_PATH) : [],
      ].reduce(...flatten),
      extensions: [".json", ".js"],
      symlinks: true,
      alias: rxPaths(),
    },
  },
  envConfig()
);