rollup.config.js

import terser from "@rollup/plugin-terser";
import copy from 'rollup-plugin-copy';
import typescript from "rollup-plugin-typescript2";
import { readFileSync } from "fs";

// Just want to override tslib from the rollup-plugin-typescript2
const tslib = readFileSync("./src/tslib.js", "utf-8");

export default {
    input: 'src/index.ts',
    output: [
        {
            file: './build/bundle.min.mjs',
            format: 'esm',
            sourcemap: true,
            freeze: false
        },
        ...(process.env.FULL ? [
            {
                file: './build/bundle.min.cjs',
                format: 'commonjs',
                sourcemap: true,
                freeze: false
            }, {
                name: '__IteratorHelpersPolyfill',
                file: './build/bundle.min.js',
                format: 'umd',
                sourcemap: true,
                freeze: false
            }
        ] : [])
    ],
    plugins: [
        Object.defineProperty(typescript(), "load", { value: x => x === "\0tslib.js" ? tslib : null }),
        terser({
            format: { comments: false },
            mangle: {
                properties: {
                    builtins: true,
                    regex: /^(?:fn|minimal|results|rejected|lastValue|initializer|methods|fields|positions|index|start|_(?:[^_]\w+)?)$/m
                },
                reserved: ['AsyncIterator', 'Iterator', 'Config']
            },
            compress: { unsafe: true }
        }),
        ...(process.env.FULL ? [
            copy({
                targets: [
                    { src: 'declarations/index.d.ts', dest: 'declarations', rename: 'index.d.cts' },
                    { src: 'declarations/index.d.ts', dest: 'declarations', rename: 'index.d.mts' },
                ]
            })
        ] : [])
    ]
};