fix: only lookup localhost for DNS lookups

src/node/NodeWebSocketTransport.ts

@@ -23,13 +23,15 @@ export class NodeWebSocketTransport implements ConnectionTransport {
     // TODO(jrandolf): Starting in Node 17, IPv6 is favoured over IPv4 due to a change
     // in a default option:
     // - https://github.com/nodejs/node/issues/40537,
-    // Due to this, we parse and resolve the hostname manually with the previous
-    // behavior according to:
+    // Due to this, for Firefox, we must parse and resolve the `localhost` hostname
+    // manually with the previous behavior according to:
     // - https://nodejs.org/api/dns.html#dnslookuphostname-options-callback
     // because of https://bugzilla.mozilla.org/show_bug.cgi?id=1769994.
     const url = new URL(urlString);
-    const { address } = await dns.lookup(url.hostname, { verbatim: false });
-    url.hostname = address;
+    if (url.hostname === 'localhost') {
+      const { address } = await dns.lookup(url.hostname, { verbatim: false });
+      url.hostname = address;
+    }
 
     return new Promise((resolve, reject) => {
       const ws = new NodeWebSocket(url, [], {