*esbuild-vs-terser.md

Terser (blocking, on main thread)

total:	79.062Kb
index.a5e146fc.js	15.427Kb
chunks/index.92b04243.js	283b
chunks/compat.f7a82e1d.js	59.642Kb
chunks/_wmr.4e88e8af.js	125b
assets/hello.359cce80.js	22b

            Mean        Std.Dev.    Min         Median      Max
real        3.311       0.119       3.189       3.271       3.536       
user        4.509       0.055       4.433       4.502       4.600       
sys         0.332       0.027       0.311       0.319       0.382 

Terser (in a single Worker via worker_threads)

Wrote 79.062Kb to disk: (same as single-threaded)

            Mean        Std.Dev.    Min         Median      Max
real        2.875       0.039       2.825       2.902       2.911       
user        5.522       0.046       5.468       5.511       5.604       
sys         0.409       0.008       0.399       0.406       0.421 

Terser (unlimited concurrency via worker_threads)

Wrote 79.062Kb to disk: (same as single-threaded)

            Mean        Std.Dev.    Min         Median      Max
real        2.996       0.028       2.947       3.014       3.019       
user        6.444       0.069       6.343       6.456       6.552       
sys         0.507       0.006       0.499       0.508       0.515

ESBuild

total:	80.608Kb
index.a5e146fc.js	15.486Kb
chunks/index.92b04243.js	303b
chunks/compat.f7a82e1d.js	61.108Kb
chunks/_wmr.4e88e8af.js	126b
assets/hello.359cce80.js	22b

            Mean        Std.Dev.    Min         Median      Max
real        1.782       0.015       1.768       1.776       1.811       
user        2.028       0.019       2.003       2.028       2.061       
sys         0.294       0.004       0.289       0.294       0.301

esbuild-service.js

import * as esbuild from 'esbuild';

/** @type {esbuild.Service} */
let inst,
	svc,
	timer,
	usage = 0;

function free() {
	if (--usage) return;
	clearTimeout(timer);
	timer = setTimeout(shutdown, 10);
}

function use() {
	clearTimeout(timer);
	usage++;
}

export function keepalive() {
	use();
	free();
}

export function shutdown() {
	if (inst) inst.stop();
	else if (svc) svc.then(inst => usage || inst.stop());
	inst = svc = null;
}
process.on('beforeExit', shutdown);

/**
 * This function is the same shape as Terser.minify, except that it is async.
 * @param {string} code
 * @param {esbuild.TransformOptions} opts
 */
export async function transform(code, opts) {
	if (!inst) {
		if (!svc) {
			svc = ((esbuild && esbuild.default) || esbuild).startService();
		}
		inst = await svc;
	}
	use();
	try {
		const result = await inst.transform(code, opts);
		return {
			code: result.js,
			map: result.jsSourceMap || null,
			warnings: result.warnings.map(warning => warning.text)
		};
	} catch (err) {
		return {
			error: err
		};
	} finally {
		free();
	}
}

rollup-plugin-minify.js

import { transform, keepalive } from './esbuild-service.js';

/** @returns {import('rollup').Plugin} */
export default function minifyPlugin({ sourcemap } = {}) {
  return {
    name: 'minify',
    buildStart: keepalive,
    async renderChunk(code, chunk) {
      const out = await transform(code, {
        minify: true,
        sourcefile: chunk.fileName,
        sourcemap: !!sourcemap,
        strict: false,
        target: 'es6' // 'es5' not fully supported (yet?)
      });

      if (out.warnings) for (const warn of out.warnings) this.warn(warn);
      return {
        code: result.js,
        map: sourcemap ? JSON.parse(out.jsSourceMap) : null
      };
    }
  };
}