Node.js vs Browser

Key Differences

Node.js and browsers both run JavaScript, but they have different environments and capabilities.

Node.js is designed for server-side development, while browsers are for client-side applications.

• APIs: Node.js provides APIs for file system, networking, and OS, which browsers do not. Browsers provide DOM, fetch, and UI APIs not available in Node.js.
• Global Objects: Node.js uses global; browsers use window or self.
• Modules: Node.js uses CommonJS (require) and ES modules (import); browsers use ES modules or plain <script> tags.
• Security: Browsers run in a sandbox with limited access; Node.js has full access to the file system and network.
• Event Loop: Both environments use an event loop, but Node.js has additional APIs for timers, process, etc.
• Environment Variables: Node.js can access environment variables (process.env); browsers cannot.
• Package Management: Node.js uses npm/yarn; browsers use CDNs or bundlers.

This page explains the key differences, with examples for each environment.

Examples

Global Objects

// Node.js
global.mylet = 42;
console.log(global.mylet); // 42

File Access

// Node.js
const fs = require('fs');
fs.readFile('myfile.txt', 'utf8', (err, data) => {
  if (err) throw err;
  console.log(data);
});

HTTP Requests

// Node.js
const https = require('https');
https.get('https://example.com', res => {
  let data = '';
  res.on('data', chunk => data += chunk);
  res.on('end', () => console.log(data));
});

Modules

// Node.js (CommonJS)
const fs = require('fs');

Comparison Table