flow like the river

VISUALIZACION/node_modules/get-port/index.js

@@ -0,0 +1,28 @@
+'use strict';
+const net = require('net');
+
+const getPort = options => new Promise((resolve, reject) => {
+	// For backwards compatibility with number-only input
+	// TODO: Remove this in the next major version
+	if (typeof options === 'number') {
+		options = {
+			port: options
+		};
+	}
+
+	const server = net.createServer();
+
+	server.unref();
+	server.on('error', reject);
+
+	server.listen(options, () => {
+		const port = server.address().port;
+		server.close(() => {
+			resolve(port);
+		});
+	});
+});
+
+module.exports = options => options ?
+	getPort(options).catch(() => getPort(0)) :
+	getPort(0);