rolldown 2019

[tunnckoCore]

const fs = require('fs');
const path = require('path');
const rollup = require('rollup');
const argParser = require('mri');
const commonjs = require('rollup-plugin-commonjs');
const progress = require('rollup-plugin-progress');
const filesize = require('rollup-plugin-filesize');
const resolve = require('rollup-plugin-node-resolve');
const terser = require('rollup-plugin-terser');
const babel = require('rollup-plugin-babel');
const json = require('rollup-plugin-json');
const builtinModules = require('builtin-modules');

function prettierPlugin() {
  return {
    name: 'rollup-plugin-prettier-bundle',
    generateBundle(output) {},
  };
}

async function createConfig(input, options) {
  const opts = Object.assign({}, options);
  const extMap = {
    es: '.mjs',
    cjs: '.js',
  };
  const destMap = {
    es: 'module',
    cjs: 'main',
  };

  const cwd = process.cwd();
  const outDir = (x) => opts.outDir || path.join(cwd, 'dist', destMap[x]);
  const outFile = (x) => path.join(outDir(x), `index${extMap[x]}`);

  const join = (...x) => path.join(cwd, ...x);

  const pkg = require(join('package.json'));

  const exts = arrayify(opts.extensions);
  const extensions =
    exts.length > 0 ? exts : ['.js', '.jsx', '.mjs', '.ts', '.tsx'];

  const possibleInputs = [
    input,
    join('index.js'),
    join('src', 'index.js'),
    join('src', 'index.mjs'),
    join('src', 'index.ts'),
  ];

  // first existing, for now
  const [inputFile] = possibleInputs.filter((x) => fs.existsSync(x));
  const license = `/** Released under the ${opts.license ||
    pkg.license} License. See LICENSE file. */`;

  const outMap = {
    cjs: {
      exports: 'named',
      banner: license,
      file: outFile('cjs'),
      format: 'cjs',
      preferConst: true,

      // don't break oldschool/classic/normal node.js
      outro: 'module.exports = exports.default || exports;',
    },
    es: {
      exports: 'named',
      banner: license,
      file: outFile('es'),
      format: 'es',
      preferConst: true,
    },
  };
  outMap.esm = outMap.es;

  let formats = arrayify(opts.format)
    .reduce((acc, x) => acc.concat(x.indexOf(',') > -1 ? x.split(',') : x), [])
    .filter(Boolean);

  let output = null;

  if (formats.length === 0) {
    formats = ['cjs', 'es'];
  }
  if (formats.length === 1) {
    output = outMap[formats[0]];
  } else {
    output = formats.map((x) => outMap[x]);
  }

  return {
    input: inputFile,
    output,

    external: builtinModules,

    inlineDynamicImports: true,
    experimentalTopLevelAwait: true,

    plugins: [
      progress(),
      resolve({
        preferBuiltins: true,
        module: true,
        jsnext: true,
        main: true,
      }),
      json({ preferConst: true }),
      babel({
        exclude: 'node_modules/**',
        externalHelpers: true,
        extensions,
      }),
      commonjs({
        extensions,
      }),
      opts.minify && terser.terser(),
      filesize({
        showBrotliSize: true,
        showGzippedSize: true,
        showMinifiedSize: true,
      }),
    ],
  };
}

const argv = argParser(process.argv.slice(2), {
  alias: {
    i: 'input',
    d: ['out-dir', 'outdir', 'outDir'],
    f: 'format',
    m: 'minify',
    x: ['ext', 'extensions'],
    l: ['license'],
  },
});

let ROLLUP_CACHE = null;

createConfig(argv.input || argv._[0], argv)
  .then(async (cfg) => {
    const bundle = await rollup.rollup(
      Object.assign({}, cfg, { cache: ROLLUP_CACHE }),
    );

    ROLLUP_CACHE = bundle.cache;

    arrayify(cfg.output).map(async (outputOptions) => {
      await bundle.write(outputOptions);
    });
  })
  .catch(console.error);

function arrayify(val) {
  if (!val) return [];
  if (Array.isArray(val)) return val;
  return [val];
}

run with

node rolldown.js [src/index.js]

by defaults tries index.js, src/index.js, src/index.mjs and src/index.ts, works with TypeScript out of the box and generates CJS and ESM bundles with bundled deps.