Esbuild with the ability to define custom entry points and with ability to copy static assets from node modules

esbuild-custom-configuration.js

#!/usr/bin/env node

const fs = require('fs');
const path = require('path');
const esbuild = require('esbuild')

// Scan entrypoints
function scanFiles(dir, options = {}, result = []) {
  let { recursive = false, ext = null } = options;
  fs.readdirSync(dir).forEach(file => {
    let fullPath = path.join(dir, file);
    if (fs.lstatSync(fullPath).isDirectory()) {
      if (recursive) scanFiles(fullPath, options, result);
    } else {
      result.push(fullPath);
    }
  });
  if (ext) result = result.filter(src => src.endsWith(ext));
  return result;
}

// Plugin
let copyStaticFiles = (options = {}) =>({
  name: 'copyFonts',
  setup(build) {
    build.onStart(result => {
      options.forEach(({ source, target, ext }) => {
        fs.mkdirSync(target, { recursive: true });
        scanFiles(source, { recursive: true, ext: ext }).forEach(path => {
          const targetFile = `${target}/${path.split('/').pop()}`;
          fs.writeFileSync(targetFile, fs.readFileSync(path));
        });
      });
    });
  },
});

const entrypoints = scanFiles(`${__dirname}/app/assets/javascripts`, { ext: '.js' });
const fontawesome = {
  source: `${__dirname}/node_modules/@fortawesome/fontawesome-free/webfonts`,
  target: `${__dirname}/public/assets/awesome_fonts`
};

esbuild.build({
  entryPoints: entrypoints,
  sourcemap: true,
  bundle: true,
  minify: true,
  watch: process.argv.includes('--watch'),
  outdir: 'app/assets/builds',
  plugins: [copyStaticFiles([fontawesome])],
}).catch(() => process.exit(1))