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lib: make navigator properties lazy #53649

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nodejs-github-bot merged 1 commit into from
Jul 4, 2024
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lib: make navigator properties lazy #53649

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lib: make navigator properties lazy 
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.
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@jasnell
jasnell committed Jun 30, 2024
commit 875952b226f893c42eaa91e7be2f45e9a807a517
12 changes: 8 additions & 4 deletions lib/internal/navigator.js
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Original file line number Diff line number Diff line change
Expand Up @@ -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) {
Expand All @@ -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]);
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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;
}
}
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