dark-mode/rollup.config.js

import resolve from "@rollup/plugin-node-resolve";
import { babel } from "@rollup/plugin-babel";
import { terser } from "rollup-plugin-terser";
import eslint from "@rollup/plugin-eslint";
import filesize from "rollup-plugin-filesize";
import copy from "rollup-plugin-copy";

const banner = "/*! Dark Mode Switcheroo | MIT License | jrvs.io/darkmode */";

export default [
  {
    // universal (browser and node)
    input: "src/index.js",
    output: [
      {
        name: "darkMode",
        file: "dist/dark-mode.js",
        format: "umd",
        exports: "named",
        esModule: false,
        banner: banner,
      },
      {
        name: "darkMode",
        file: "dist/dark-mode.min.js",
        format: "umd",
        exports: "named",
        esModule: false,
        plugins: [
          terser({
            output: {
              preamble: banner,
            },
          }),
        ],
      },
    ],
    plugins: [
      copy({
        // clearly this isn't really typescript, so we need to manually copy the type definition file
        targets: [
          {
            src: "src/index.d.ts",
            dest: "dist",
            rename: "dark-mode.d.ts",
          },
        ],
      }),
      resolve(),
      eslint(),
      babel({
        babelHelpers: "bundled",
        presets: [["@babel/preset-env"]],
        exclude: ["node_modules/**"],
      }),
      filesize(),
    ],
  },
  {
    // modules
    input: "src/index.js",
    output: [
      {
        // ES6 module (import)
        file: "dist/dark-mode.esm.js",
        format: "esm",
        exports: "named",
        banner: banner,
      },
      {
        // commonjs (require)
        file: "dist/dark-mode.cjs.js",
        format: "cjs",
        exports: "named",
        banner: banner,
      },
    ],
    plugins: [
      resolve(),
      babel({
        babelHelpers: "bundled",
        exclude: ["node_modules/**"],
      }),
      filesize(),
    ],
  },
];