Force HTTP check under corresponding protocols

index.js

@@ -38,10 +38,11 @@ const checkHttp = async (url, timeout) => {
 const getAddress = async hostname => net.isIP(hostname) ? hostname : (await dnsLookupP(hostname)).address;
 
 const isTargetReachable = timeout => async target => {
+	const isHTTP = target.startsWith('https://') || target.startsWith('http://');
 	const url = new URL(prependHttp(target));
 
-	if (!url.port) {
-		url.port = url.protocol === 'http:' ? 80 : 443;
+	if (!url.port && !isHTTP) {
+		url.port = 443;
 	}
 
 	let address;
@@ -55,7 +56,7 @@ const isTargetReachable = timeout => async target => {
 		return false;
 	}
 
-	if ([80, 443].includes(url.port)) {
+	if (isHTTP) {
 		return checkHttp(url.toString(), timeout);
 	}
 

test.js

@@ -1,5 +1,6 @@
 import {promisify} from 'util';
 import dns from 'dns';
+import http from 'http';
 import test from 'ava';
 import isReachable from '.';
 
@@ -26,6 +27,18 @@ test('multiple https urls', async t => {
 	t.true(await isReachable(['https://google.com', 'https://baidu.com']));
 });
 
+test('http server on custom port', async t => {
+	const server = http.createServer((_, response) => {
+		response.writeHead(200).end();
+	}).listen(8080);
+	t.true(await isReachable('http://localhost:8080'));
+	server.close();
+});
+
+test('unreachable http server on custom port', async t => {
+	t.false(await isReachable('http://localhost:8081'));
+});
+
 test('imap host and port', async t => {
 	t.true(await isReachable('imap.gmail.com:995'));
 });