rollup.config.js

import typescript from "@rollup/plugin-typescript";
import { terser } from "rollup-plugin-terser";
import livereload from "rollup-plugin-livereload";
import serve from "rollup-plugin-serve";
import pkg from "./package.json";

const input = "./src/index.ts";

const commonTSPluginOptions = {
  lib: ["es5", "es6", "ESNext", "dom"],
};

const umdConfig = (min, plugins = []) => ({
  input,
  output: {
    name: pkg.umdName,
    file: min ? pkg.browser.replace(".js", ".min.js") : pkg.browser,
    exports: "default",
    format: "umd",
  },
  plugins: [typescript(commonTSPluginOptions), ...(min ? [terser()] : []), ...plugins],
});

const esConfig = (min, plugins = []) => ({
  input,
  output: {
    file: min ? pkg.module.replace(".js", ".min.js") : pkg.module,
    format: "es",
  },
  plugins: [typescript({ ...commonTSPluginOptions, target: "es6" }), ...(min ? [terser()] : []), ...plugins],
});

export default process.env.BUILD === "watch"
  ? [
      umdConfig(false, [
        serve({
          open: true,
          contentBase: ".",
        }),
        livereload({
          watch: "dist",
        }),
      ]),
    ]
  : [esConfig(true), esConfig(false), umdConfig(true), umdConfig(false)];