Detect Node

Detect Node is a lightweight JavaScript library that provides reliable Node.js environment detection. It accurately determines whether code is running in a Node.js environment versus a browser or other JavaScript runtime by checking if the global process variable has the specific [[Class]] of 'process' unique to Node.js.

Package Information

• Package Name: detect-node
• Package Type: npm
• Language: JavaScript
• Installation: npm install detect-node

Core Imports

const isNode = require('detect-node');

For ES modules:

import isNode from 'detect-node';

Basic Usage

const isNode = require('detect-node');

if (isNode) {
  console.log("Running under Node.js");
  // Node.js-specific code here
  const fs = require('fs');
  fs.readFileSync('config.json');
} else {
  console.log("Running in browser or other environment");
  // Browser-specific code here
  document.getElementById('app');
}

Architecture

Detect Node uses a unique detection approach that avoids common pitfalls of other environment detection methods:

• Reliable Detection: Uses Object.prototype.toString.call() to check the [[Class]] property of the process object
• Build-Tool Friendly: Doesn't directly reference process in a way that causes bundlers to include Node.js polyfills
• Universal Compatibility: Provides multiple module formats (CommonJS, ES modules, browser-specific)
• Safe Execution: Uses type checking to avoid errors when process is undefined

Capabilities

Environment Detection

Detects whether the current JavaScript environment is Node.js by checking for the unique [[Class]] property of the Node.js process object.

/**
 * Boolean indicating whether the current environment is Node.js
 * Returns true if running in Node.js, false otherwise
 */
const isNode; // boolean

The detection logic uses:

Object.prototype.toString.call(typeof process !== 'undefined' ? process : 0) === '[object process]'

Module Formats:

• CommonJS (index.js): module.exports = [detection logic]
• ES Modules (index.esm.js): export default [detection logic]
• Browser (browser.js): module.exports = false (always returns false for browser builds)

Usage Examples:

// CommonJS
const isNode = require('detect-node');
if (isNode) {
  // Use Node.js APIs
  const path = require('path');
  const __dirname = path.dirname(__filename);
}

// ES Modules
import isNode from 'detect-node';
if (isNode) {
  // Use Node.js APIs
  import { readFile } from 'fs/promises';
  const data = await readFile('data.txt', 'utf8');
}

// Conditional imports based on environment
if (isNode) {
  const nodeSpecificModule = await import('./node-version.js');
} else {
  const browserSpecificModule = await import('./browser-version.js');
}

Build Tool Integration:

The package is designed to work seamlessly with build tools:

• Webpack: Uses the browser field in package.json to automatically substitute browser.js for client bundles
• Browserify: Compatible - doesn't trigger inclusion of Node.js polyfills
• Rollup: Works with both CommonJS and ES module formats
• Parcel: Automatically handles different module formats based on target environment

Error Handling:

The detection is safe and will never throw errors:

• Uses typeof process !== 'undefined' check to avoid ReferenceError
• Falls back to checking 0 if process is undefined
• Returns false for any non-Node.js environment