Nodejs minimal hot reload function

node-minimal-hot-reload.js

const cluster = require('cluster');
const chokidar = require('chokidar');

function start() {
	// do something here
	console.log('START >>');
}

function hot(start, files) {
	if (typeof files == 'string') files = [files];
	if (typeof start !== 'function') return;
	if (cluster.isMaster) {
		const watcher = chokidar.watch(files);
		let worker = cluster.fork();
		watcher.on('ready', () => {
			watcher.on('all', (event, filename) => {
				console.log('[READY] :::');

				worker.send({ type: 'hotreload', args: { filename, id: worker.id } });

				worker.on('exit', function(deadWorker, code, signal) {
					const deadWorker = worker;
					console.log('[EXIT] :::');
					// Restart the worker
					worker = cluster.fork();

					// Note the process IDs
					var newPID = worker.process.pid;
					var oldPID = deadWorker.process.pid;

					// Log the event
					console.log('worker ' + oldPID + ' died.');
					console.log('worker ' + newPID + ' born.');
				});
			});
		});
	} else if (cluster.isWorker) {
		start();
		process.on('message', ({ type, args }) => {
			console.log('MESSAGE', type);
			process.disconnect();
		});
	}
}

module.exports = hot;