Diving into Deno: A Fresh Runtime Environment for JavaScript published 9/13/2023 | 3 min read

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Developed by Ryan Dahl, the original creator of Node.js, Deno is a modern runtime for JavaScript and TypeScript that addresses some key limitations in Node.js. Let's dive headfirst into Deno and examine its unique features, advantages, and how it takes JavaScript development to a fresh level of effectiveness and security.

What is Deno?

Deno is a secure runtime environment for JavaScript and TypeScript built with Rust, V8, and Tokio. It's designed to offer a productive and secure scripting environment for the modern web.

While it may resemble Node.js, Deno serves as an improvement, aiming to fix the design errors in Node.js:

  1. Strong security: Deno restricts file, network, and environment access by default. Scripts cannot access the hard drive, open network connections, or execute external commands unless explicitly given permission.
  2. Better module system: Deno does away the traditional node_modules directory and package.json file. Instead, modules are imported directly from URLs, much like in the browser.
  3. Built-in TypeScript support: Node.js treats TypeScript as a second-class citizen, but Deno fully supports TypeScript 'out of the box.'
  4. Standard libraries: Deno aims to have a rich standard library to replace the need for external dependencies.

These improvements manifest in the practical usage of Deno, as seen when installing and running scripts.

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

// Run a script
$ deno run --allow-read --allow-net index.ts

Why Should Developers Use Deno?

1. Enhanced Security

One of Deno's key goals includes enhancing security in a JavaScript execution environment. Deno restricts the access capabilities of scripts utilizing permissions.

const file = await Deno.open('example.txt');
await Deno.copy(file, Deno.stdout);

Running this code in Deno without explicit permission will result in an error:

$ deno run index.ts
error: Uncaught PermissionDenied: read access to "/Users/me/deno/index.ts", run again with the --allow-read flag

Allowing read access:

$ deno run --allow-read index.ts

2. Simplified Module Management

Traditionally, Node.js uses node_modules for package management, which can become cumbersome. Deno simplifies this by using URLs for imports, similar to ES modules in the browser.

import { serve } from "https://deno.land/std@0.66.0/http/server.ts";

3. Integrated Testing

Deno provides a built-in test runner that ensures codes run as expected—no need for external testing libraries.

import { assertEquals } from "https://deno.land/std@0.66.0/testing/asserts.ts";

Deno.test("testing example", () => {
  assertEquals("world", "world");
  assertEquals({ hello: "world" }, { hello: "world" });

Running tests:

$ deno test index.ts

Wrapping Up

In conclusion, Deno presents an intriguing leap in shaping a more secure and efficient JavaScript runtime environment. Although relatively young, its potential in shaping the future of JavaScript development is vast and worth exploring.

So are you considering switching to Deno? In the comments below, let's discuss the impacts of Deno on JavaScript development. Despite its early stage, who knows? It might just be the turning point in your development journey.

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