JS-Env Utility

A zero-dependency TypeScript utility for detecting the current execution environment: Node.js, Deno, Bun, browsers, and Web Workers.

Live demo

Features

• Detect Node.js, Deno, Bun, browser, and Web Worker runtimes.
• Detect the operating system from Node.js or a user-agent string.
• Detect browser name and version.
• Check selected web APIs and normalized Network Information.
• Return a fully typed environment summary.
• Ship ESM and TypeScript declarations with no runtime dependencies.

Installation

npm install js-env-utility

The published runtime supports Node.js 14.18 and newer as well as modern browsers, Deno, and Bun.

Usage

import {
  detectPlatform,
  detectOperatingSystem,
  detectBrowserInfo,
  detectApiSupport,
  getEnvironmentInfo,
} from 'js-env-utility';

detectPlatform(); // 'Browser'
detectOperatingSystem(); // e.g. 'Windows'
detectBrowserInfo(); // { name: 'Chrome', version: '...' } | null
detectApiSupport(); // API feature flags | null
getEnvironmentInfo(); // typed aggregate object

All public return values are exported as TypeScript types: Platform, OperatingSystem, NodePlatform, WebOperatingSystem, BrowserName, BrowserInfo, ApiSupport, NetworkInfo, and EnvironmentInfo.

API

• isNode(), isDeno(), isBun(): runtime checks. A Node-compatible process object in Bun or Deno does not produce a false Node.js result.
• isBrowser(): true in a DOM browser, excluding Web Workers.
• isWebWorker(): true in DedicatedWorker, SharedWorker, or ServiceWorker global scopes.
• detectPlatform(): returns Node.js, Deno, Bun, Browser, Web Worker, or Unknown.
• detectOperatingSystem(): returns a Node.js platform value or a normalized web OS name.
• detectOSFromUserAgent(userAgent): pure user-agent OS detection.
• detectBrowser() / detectBrowserInfo(): browser name and version, or null outside a DOM browser.
• detectApiSupport(): selected web API support, or null outside a DOM browser.
• detectNetworkInfo(): normalized Network Information, or null when unavailable.
• getEnvironmentInfo(): aggregate environment object.

Development

npm install
npm run check
npm run build
npm run demo

• npm test — Node.js, Deno/Bun marker, browser, and Web Worker tests.
• npm run typecheck — strict TypeScript validation.
• npm run lint — typed ESLint rules.
• npm run build — ESM bundles and declarations in dist/.
• npm run demo — rebuild the static demo; serve the repository root with any static server.

Browser/Worker detection notes

Browser detection intentionally requires window.document; a Web Worker is detected through WorkerGlobalScope before browser or Node.js checks. Network Information and Notifications are non-standard or permission-dependent and may be unavailable even in a browser.

License

MIT