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 usewindoworself. - 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.myVar); // 42
// Browser
window.mylet = 42;
console.log(window.myVar); // 42
File Access
// Node.js
const fs = require('fs');
fs.readFile('myfile.txt', 'utf8', (err, data) => {
if (err) throw err;
console.log(data);
});
// Browser
// Not allowed for security reasons
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));
});
// Browser
fetch('https://example.com')
.then(response => response.text())
.then(console.log);
Modules
// Node.js (CommonJS)
const fs = require('fs');
// Node.js & Browser (ES Modules)
// import fs from 'fs'; // Node.js only, not browser
// import _ from 'https://cdn.jsdelivr.net/npm/lodash-es/lodash.js'; // Browser
Comparison Table
| Feature | Node.js | Browser |
|---|---|---|
| File System Access | Yes | No |
| Networking (TCP/UDP) | Yes | No |
| DOM Access | No | Yes |
| Global Object | global | window/self |
| Modules | CommonJS/ESM | ESM/Scripts |
| Environment Variables | Yes (process.env) | No |
| Security | Full OS access | Sandboxed |
| Package Management | npm/yarn | CDN/Bundler |
