rollup.config.mjs

import nodePolyfills from "rollup-plugin-polyfill-node";
import resolve from "@rollup/plugin-node-resolve";
import commonjs from "@rollup/plugin-commonjs";
import json from "@rollup/plugin-json";
import pkg from "./package.json" assert { type: "json" };

export default [
  // browser-friendly UMD build
  {
    input: "src/main.mjs",
    output: {
      name: "costflow",
      file: pkg.browser,
      format: "umd",
    },
    plugins: [
      json(),
      resolve(), // so Rollup can find `ms`
      commonjs(), // so Rollup can convert `ms` to an ES module
      nodePolyfills({
        include: null,
      }),
    ],
    onwarn(warning, warn) {
      if (warning.code === "THIS_IS_UNDEFINED") return;
      warn(warning); // this requires Rollup 0.46
    },
  },

  // CommonJS (for Node) and ES module (for bundlers) build.
  // (We could have three entries in the configuration array
  // instead of two, but it's quicker to generate multiple
  // builds from a single configuration where possible, using
  // an array for the `output` option, where we can specify
  // `file` and `format` for each target)
  {
    input: "src/main.mjs",
    external: [
      "dayjs",
      "dayjs/plugin/utc.js",
      "dayjs/plugin/timezone.js",
      "lodash",
    ],
    output: [
      { file: pkg.main, format: "cjs" },
      { file: pkg.module, format: "es" },
    ],
  },
];