rollup.config.js

import babel from "@rollup/plugin-babel";
import { sizeSnapshot } from "rollup-plugin-size-snapshot";
import pkg from "./package.json";

const external = (id) => !id.startsWith(".") && !id.startsWith("/");

export default [
  {
    input: "./src/system.js",
    output: { file: pkg.main, format: "cjs" },
    external,
    plugins: [
      babel({
        babelHelpers: "bundled",
        configFile: false,
        presets: [
          ["@babel/env", { loose: true }],
          "@babel/react",
          "@babel/flow",
        ],
      }),
    ],
  },
  {
    input: "./src/system.js",
    output: { file: pkg.module, format: "esm" },
    external,
    plugins: [
      babel({
        babelHelpers: "runtime",
        configFile: false,
        presets: [
          ["@babel/env", { loose: true }],
          "@babel/react",
          "@babel/flow",
        ],
        plugins: [["@babel/transform-runtime", { useESModules: true }]],
      }),
      sizeSnapshot(),
    ],
  },
];