postinstall/commands/concat.js

Deploy files from modules after npm install

const fs = require("node:fs");

module.exports = function (inputs, output, options) {
	const to = fs.createWriteStream(output, { flags: 'a' });
	return new Promise((resolve, reject) => {
		write(inputs.slice(), to, resolve, reject);
	});
};

function write(files, to, resolve, reject) {
	if (files.length) {
		const readStream = fs.createReadStream(files.shift());
		readStream.pipe(to, {
			end: false
		});
		readStream.on('error', reject);
		readStream.on('end', () => {
			write(files, to, resolve, reject);
		});
	} else {
		to.end();
		resolve();
	}
}