Node.js vs Deno: A Detailed Comparison and Guide

Node.js vs Deno: A Comprehensive Guide

Deno is a modern runtime for JavaScript and TypeScript, created by Ryan Dahl, the original creator of Node.js. While Node.js has been the industry standard for running server-side JavaScript, Deno addresses many of its shortcomings. Deno provides better security, built-in TypeScript support, and a streamlined dependency management system. This guide explains how Deno works, how it differs from Node.js, and provides practical examples to illustrate its usage.

Syntax:

To install Deno, use the following command:

# Install Deno (macOS/Linux)
curl -fsSL https://deno.land/x/install/install.sh | sh

# Install Deno (Windows)
iwr https://deno.land/x/install/install.ps1 -useb | iex

To run a Deno script:

deno run <script.ts>

Node.js vs Deno Key Differences

Examples and Code

Below are examples showing how Deno works and compares with Node.js.

1. Basic Deno Script

A simple "Hello World" example written in Deno:

hello.ts

Code:

// Log a message to the console
console.log("Hello from Deno!");

Run the Script:

Code:

deno run hello.ts

Output:

Hello from Deno!

2. Fetching Data in Deno

Here is an example that fetches data from an API using Deno's fetch API:

fetch-data.ts

Code:

// Import a specific API URL
const url = "https://jsonplaceholder.typicode.com/posts/1";

// Fetch data from the API
const response = await fetch(url);

// Parse the response as JSON
const data = await response.json();

// Log the data to the console
console.log("Fetched Data:", data);

Run the Script:

Code:

deno run --allow-net fetch-data.ts

Explanation:

• --allow-net: Deno requires explicit permissions to access the network for enhanced security.

3. Importing Modules in Deno

Unlike Node.js, Deno does not use package.json. Modules are imported directly via URLs.

import-example.ts

Code:

// Import a utility module directly from a URL
import { serve } from "https://deno.land/[email protected]/http/server.ts";

// Start a simple HTTP server
console.log("HTTP server is running at http://localhost:8000");

serve((req) => new Response("Hello from Deno Server!"), { port: 8000 });

Run the Script:

Code:

deno run --allow-net import-example.ts

Output:

Visit http://localhost:8000 in your browser to see:

Hello from Deno Server!

Explanation:

• Modules are imported directly via a URL.
• serve: A utility for creating HTTP servers, provided by Deno's standard library.

4. Comparing Node.js to Deno

Below is the equivalent example of a basic HTTP server in Node.js and Deno:

Node.js Example

server.js

Code:

const http = require('http');

// Create a server
const server = http.createServer((req, res) => {
    res.end('Hello from Node.js Server!');
});

// Start the server
server.listen(8000, () => {
    console.log('Server is running at http://localhost:8000');
});

Run the Script:

Code:

node server.js

Deno Example

server.ts

Code:

import { serve } from "https://deno.land/[email protected]/http/server.ts";

// Start the server
console.log("Server running at http://localhost:8000");
serve(() => new Response("Hello from Deno Server!"), { port: 8000 });

Run the Script:

Code:

deno run --allow-net server.ts

Key Differences:

• Node.js uses require and http module.
• Deno uses ES Modules (import) and a built-in HTTP library from the standard modules.

Advantages of Deno

1. Security: Deno runs scripts in a secure sandbox, requiring permissions for file, network, or environment access.

2. Built-in TypeScript Support: Deno natively supports TypeScript without additional tools or configurations.

3. Modern Module System: Deno uses ES Modules with direct URL imports, removing the need for package.json.

4. Clean API: Deno provides modern APIs like fetch and Response for HTTP operations, similar to browser environments.

Best Practices

1. Use --allow-* flags cautiously to enable required permissions.

2. Always pin module URLs to specific versions for stability.

3. Prefer Deno's standard library for common utilities.

4. Enable TypeScript for type safety and cleaner code.