From 1f6fcd66feb76097d4b557fee49cd8cf68da1669 Mon Sep 17 00:00:00 2001
From: James M Snell <jasnell@gmail.com>
Date: Thu, 4 Jul 2024 07:35:28 -0700
Subject: [PATCH] lib: make navigator properties lazy
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Noticed in some benchmarking/profiling that the Navigator object
constructor was rather expensive and slow due to initialization
of properties during construction. It makes more sense for these
to be lazily initialized on first access.

PR-URL: https://github.com/nodejs/node/pull/53649
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Yagiz Nizipli <yagiz.nizipli@sentry.io>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
---
 lib/internal/navigator.js | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/lib/internal/navigator.js b/lib/internal/navigator.js
index 546505e9460103..e56b2da5e339e3 100644
--- a/lib/internal/navigator.js
+++ b/lib/internal/navigator.js
@@ -78,10 +78,10 @@ function getNavigatorPlatform(process) {
 class Navigator {
   // Private properties are used to avoid brand validations.
   #availableParallelism;
-  #userAgent = `Node.js/${StringPrototypeSlice(nodeVersion, 1, StringPrototypeIndexOf(nodeVersion, '.'))}`;
-  #platform = getNavigatorPlatform(process);
-  #language = Intl?.Collator().resolvedOptions().locale || 'en-US';
-  #languages = ObjectFreeze([this.#language]);
+  #userAgent;
+  #platform;
+  #language;
+  #languages;
 
   constructor() {
     if (arguments[0] === kInitialize) {
@@ -102,6 +102,7 @@ class Navigator {
    * @return {string}
    */
   get language() {
+    this.#language ??= Intl?.Collator().resolvedOptions().locale || 'en-US';
     return this.#language;
   }
 
@@ -109,6 +110,7 @@ class Navigator {
    * @return {Array<string>}
    */
   get languages() {
+    this.#languages ??= ObjectFreeze([this.language]);
     return this.#languages;
   }
 
@@ -116,6 +118,7 @@ class Navigator {
    * @return {string}
    */
   get userAgent() {
+    this.#userAgent ??= `Node.js/${StringPrototypeSlice(nodeVersion, 1, StringPrototypeIndexOf(nodeVersion, '.'))}`;
     return this.#userAgent;
   }
 
@@ -123,6 +126,7 @@ class Navigator {
    * @return {string}
    */
   get platform() {
+    this.#platform ??= getNavigatorPlatform(process);
     return this.#platform;
   }
 }