Parcel.js: moving static resources to a separate folder

parcel.postbuild.js

/* Copyright 2019 by Paolo Mioni (@paolomioni)
 * Based on the article https://medium.com/hceverything/parcel-js-moving-static-resources-to-a-separate-folder-aef63a038cbd.
 *
 * EXAMPLE OF USAGE:
 * build": "parcel build pages/index.hbs --out-dir public --no-cache && node postbuild.js
 */

const fs = require('fs');
const path = require('path');
const replace = require('replace-in-file');
const escapeRegExp = require('lodash.escaperegexp');

// the directory in which you're outputting your build
let baseDir = 'public'
// the name for the directory where your static files will be moved to
let staticDir = 'static'
// the directory where your built files (css and JavaScript) will be moved  to
let assetsDir = 'build'

// if the staticDir directory isn't there, create it
if (!fs.existsSync(path.join(__dirname, baseDir, staticDir))){
	fs.mkdirSync(path.join(__dirname, baseDir, staticDir));
}

// same for the assetsDir directory
if (!fs.existsSync(path.join(__dirname, baseDir, assetsDir))){
	fs.mkdirSync(path.join(__dirname, baseDir, assetsDir));
}

// Loop through the baseDir directory
fs.readdir(`./${baseDir}`, (err, files) => {
	// store all files in custom arrays by type
	let html = []
	let js = []
	let css = []
	let maps = []
	let staticAssets = []

	files.forEach(file => {
		// first HTML files
		if(file.match(/.+\.(html)$/)) {
			console.log('html match', file)
			html.push(file)
		} else  if(file.match(/.+\.(js)$/)) { // then JavaScripts
			js.push(file)
		} else if(file.match(/.+\.(map)$/)) { // then CSS
			maps.push(file)
		} else if(file.match(/.+\.(css)$/)) { // then sourcemaps
			css.push(file)
		} else if(file.match(/.+\..+$/)){ // all other files, exclude current directory and directory one level up
			staticAssets.push(file)
		}
	});
	// check what went where
	console.log('html', html, 'css', css, 'js', js, 'staticAssets', staticAssets)

	// create an array for all compiled assets
	let assets = css.concat(js).concat(maps)

	// replace all other resources in html
	html.forEach(
		file => {
			staticAssets.forEach(name => {
				let options = {
					files: path.join('public', file),
					from: new RegExp(escapeRegExp(name), 'g'),
					to: staticDir + '/' + name
				}
				try {
					let changedFiles = replace.sync(options);
					console.log('Modified files:', changedFiles.join(', '));
				}
				catch (error) {
					console.error('Error occurred:', error);
				}
			})
			assets.forEach(name => {
				let options = {
					files: path.join('public', file),
					from: new RegExp(escapeRegExp(name), 'g'),
					to: assetsDir + '/' + name
				}
				try {
					let changedFiles = replace.sync(options);
					console.log('Modified files:', changedFiles.join(', '));
				}
				catch (error) {
					console.error('Error occurred:', error);
				}
			})
		}
	)

	// replace map links in js
	js.forEach(
		file => {
			maps.forEach(name => {
				let options = {
					files: path.join('public', file),
					from: name,
					to: '../' + assetsDir + '/' + name
				}
				try {
					let changedFiles = replace.sync(options);
					console.log('Modified files:', changedFiles.join(', '));
				}
				catch (error) {
					console.error('Error occurred:', error);
				}
			})
		}
	)

	// replace links in css
	css.forEach(
		file => {
			staticAssets.forEach(name => {
				let options = {
					files: path.join('public', file),
					from: new RegExp(escapeRegExp(name), 'g'),
					to: '../' + staticDir + '/' + name
				}
				try {
					let changedFiles = replace.sync(options);
					console.log('Modified files:', changedFiles.join(', '));
				}
				catch (error) {
					console.error('Error occurred:', error);
				}
			})
		}
	)

	// move js and css and maps
	assets.forEach(
		name => {
			fs.rename(path.join(__dirname, 'public', name), path.join(__dirname, 'public', assetsDir,  name), function (err) {
				if (err) throw err
				console.log(`Successfully moved ${name}`)
			})
		}
	)
	// move staticAssets
	staticAssets.forEach(
		name => {
			fs.rename(path.join(__dirname, 'public', name), path.join(__dirname, 'public', staticDir,  name), function (err) {
				if (err) throw err
				console.log(`Successfully moved ${name}`)
			})
		}
	)
});