Getting started with Deno

Deno is more secure and simpler alternative to Node.js

• Deno focuses on security and restricts permissions by default
• You can easily allow permissions for specific actions

Deno supports JavaScript and TypeScript

• You can write your code in JavaScript or TypeScript
• Deno handles TypeScript, code formatting, linting, and type checking out of the box

Deno has a built-in Key/Value store

• Deno provides a JavaScript friendly database with a few lines of code
• It uses SQLite in custom deployments and a cloud-based store in Deno Deploy

Deno is backwards compatible with npm packages

• You can still use npm libraries with Deno
• There is an --no-npm flag to avoid node_modules

Installing Deno

• MacOS or Linux

curl -fsSL https://deno.land/x/install/install.sh | sh

• Windows

irm https://deno.land/install.ps1 | iex

Getting started with Deno is simple

• Open a text editor and start writing Deno apps
• No need to install anything else
• For example, create a hello.ts file and write:

console.log('Hello, Deno!');
// Run the program with `deno run hello.ts`.
// You'll see the output "Hello, Deno!"

Importing packages in Deno

• Import JavaScript/TypeScript modules directly from URLs
• Use deno.land/x for packages and deno-types for npm packages
• Example

// @deno-types="npm:@types/express@4.17.20"
import express from 'npm:express@4.18.2';

const app = express();

app.get('/', (req, res) => {
  res.send('Hello Deno!');
});

app.listen(3000);