Fix #843

Author: delvedor

lib/Connection.js

@@ -191,7 +191,8 @@ class Connection {
       path: '',
       href: url.href,
       origin: url.origin,
-      port: url.port,
+      // https://github.com/elastic/elasticsearch-js/issues/843
+      port: url.port !== '' ? url.port : undefined,
       headers: this.headers,
       auth: !!url.username === true || !!url.password === true
         ? `${url.username}:${url.password}`