lib: make navigator properties lazy

jasnell · aduh95 · commit 0f146aac2c39 · 2024-07-16T12:01:08.000+02:00
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: #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>
diff --git 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) {
@@ -102,27 +102,31 @@ class Navigator {
    * @return {string}
    */
   get language() {
+    this.#language ??= Intl?.Collator().resolvedOptions().locale || 'en-US';
     return this.#language;
   }
 
   /**
    * @return {Array<string>}
    */
   get languages() {
+    this.#languages ??= ObjectFreeze([this.language]);
     return this.#languages;
   }
 
   /**
    * @return {string}
    */
   get userAgent() {
+    this.#userAgent ??= `Node.js/${StringPrototypeSlice(nodeVersion, 1, StringPrototypeIndexOf(nodeVersion, '.'))}`;
     return this.#userAgent;
   }
 
   /**
    * @return {string}
    */
   get platform() {
+    this.#platform ??= getNavigatorPlatform(process);
     return this.#platform;
   }
 }
