Support array of preferred ports

index.js

@@ -1,6 +1,22 @@
 'use strict';
 const net = require('net');
 
+const isAvailable = (options, callback) => {
+	const server = net.createServer();
+
+	server.unref();
+	server.on('error', () => {
+		callback(false);
+	});
+
+	server.listen(options, () => {
+		const port = server.address().port;
+		server.close(() => {
+			callback(port);
+		});
+	});
+};
+
 const getPort = options => new Promise((resolve, reject) => {
 	// For backwards compatibility with number-only input
 	// TODO: Remove this in the next major version
@@ -10,19 +26,44 @@ const getPort = options => new Promise((resolve, reject) => {
 		};
 	}
 
-	const server = net.createServer();
-
-	server.unref();
-	server.on('error', reject);
-
-	server.listen(options, () => {
-		const port = server.address().port;
-		server.close(() => {
-			resolve(port);
+	if ('ports' in options) {
+		options.ports.forEach((e, index) => {
+			const input = getOptions(e, options.host);
+			isAvailable(input, res => {
+				if (res === false) {
+					if (index !== options.ports.length - 1) {
+						return;
+					}
+					reject();
+				}
+				resolve(res);
+			});
 		});
-	});
+	} else {
+		isAvailable(options, res => {
+			if (res === false) {
+				reject();
+			}
+			resolve(res);
+		});
+	}
 });
 
+function getOptions(portnumber, hostname) {
+	let options;
+	if (typeof hostname === undefined) {
+		options = {
+			port: portnumber
+		};
+	} else {
+		options = {
+			port: portnumber,
+			host: hostname
+		};
+	}
+	return options;
+}
+
 module.exports = options => options ?
 	getPort(options).catch(() => getPort(0)) :
 	getPort(0);

package.json

@@ -1,6 +1,6 @@
 {
   "name": "get-port",
-  "version": "3.2.0",
+  "version": "3.3.0",
   "description": "Get an available port",
   "license": "MIT",
   "repository": "sindresorhus/get-port",

readme.md

@@ -21,7 +21,7 @@ getPort().then(port => {
 });
 ```
 
-Optionally, pass in a preferred port:
+To pass in a preferred port:
 
 ```js
 getPort({port: 3000}).then(port => {
@@ -30,6 +30,14 @@ getPort({port: 3000}).then(port => {
 });
 ```
 
+To pass in an arrays of preferred ports:
+
+```js
+getPort({ports: [3000, 3001, 3002]}).then(port => {
+	console.log(port);
+	// Will use any element in the preferred ports array if available, otherwise fall back to a random port
+});
+```
 
 ## API
 
@@ -47,6 +55,12 @@ Type: `number`
 
 The preferred port to use.
 
+##### ports 
+
+Type: `Array`
+
+The array of preferred ports to use
+
 ##### host
 
 Type: `string`

test.js

@@ -54,3 +54,44 @@ test('preferred port given IPv4 host', async t => {
 
 	t.is(port, desiredPort);
 });
+
+test('preferred ports', async t => {
+	const desiredPorts = [9910, 9912, 9913];
+	const port = await m({
+		ports: desiredPorts,
+		host: '0.0.0.0'
+	});
+
+	t.is(port, desiredPorts[0]);
+});
+
+test('first port in preferred ports array is unavailable', async t => {
+	const desiredPorts = [9090, 9091];
+
+	const server = net.createServer();
+	await pify(server.listen.bind(server))(desiredPorts[0]);
+
+	const port = await m({
+		ports: desiredPorts
+	});
+
+	t.is(port, desiredPorts[1]);
+});
+
+test('all preferred ports in array are unavailable', async t => {
+	const desiredPorts = [9990, 9991];
+
+	const server1 = net.createServer();
+	await pify(server1.listen.bind(server1))(desiredPorts[0]);
+	const server2 = net.createServer();
+	await pify(server2.listen.bind(server2))(desiredPorts[1]);
+
+	const port = await m({
+		ports: desiredPorts
+	});
+
+	t.is(typeof port, 'number');
+	t.true(port > 0 && port < 65536);
+	t.not(port, desiredPorts[0]);
+	t.not(port, desiredPorts[1]);
+});