Introduction to Deno: A Secure Runtime for JavaScript and TypeScript

Introduction to Deno: A Secure Runtime for JavaScript and TypeScript


Deno is a relatively new, secure runtime environment for JavaScript and TypeScript that aims to address the shortcomings of Node.js while offering modern features and improved security. Deno was created by Ryan Dahl, the original creator of Node.js, to fix the design mistakes and limitations of Node.js. In this article, we will explore the main features of Deno, learn how to set up a simple Deno application, and discuss its benefits compared to Node.js.

Key Features of Deno:

  1. Security: Unlike Node.js, Deno is built with security in mind. By default, Deno scripts run in a sandbox environment without access to files, the network, or the environment variables. Access to these resources must be explicitly granted through command-line flags, providing a more secure environment for running untrusted code.
  2. First-class TypeScript support: Deno supports TypeScript out of the box, without the need for a separate build step or additional configuration. This enables developers to use TypeScript's powerful type checking and modern syntax features right away.
  3. Simplified dependency management: Deno uses URLs to import modules, similar to browsers, eliminating the need for a centralized package manager like npm. This results in simpler and more manageable dependency trees.
  4. Built-in utilities: Deno comes with a suite of built-in utilities, such as a test runner, code formatter, and bundler, reducing the need for third-party tools.
  5. Modern JavaScript features: Deno supports the latest ECMAScript features, allowing developers to use modern JavaScript syntax and APIs without relying on transpilation tools like Babel.

Setting Up a Simple Deno Application:

1. Install Deno: Follow the instructions on the Deno official website ( to install Deno on your machine.
2. Create a new file called «app.ts» and add the following code to it:

  1. import { serve } from "";
  3. const server = serve({ port: 8000 });
  4. console.log("Server running on http://localhost:8000");
  6. for await (const req of server) {
  7. req.respond({ body: "Hello, Deno!" });
  8. }

3. Run the application: In your terminal, navigate to the directory containing «app.ts» and execute the following command:

  1. deno run --allow-net app.ts

This command grants the script network access and starts the server on port 8000. Visit http://localhost:8000 in your browser to see the «Hello, Deno!» message.

Deno vs. Node.js: Key Differences

  1. Security: Deno provides a more secure runtime environment compared to Node.js by running scripts in a sandbox with limited access to system resources.
  2. TypeScript support: Deno natively supports TypeScript, while Node.js requires additional configuration and build steps to work with TypeScript.
  3. Dependency management: Deno simplifies dependency management by using URLs for imports and removing the need for a centralized package manager.
  4. Built-in utilities: Deno includes a suite of built-in utilities that streamline development, whereas Node.js relies on external tools for tasks like testing, formatting, and bundling.
  5. Modern JavaScript support: Deno supports the latest ECMAScript features out of the box, while Node.js may require additional tooling for certain features.


Deno is a modern, secure runtime for JavaScript and TypeScript that addresses many of the limitations of Node.js. With its focus on security, first-class TypeScript support, simplified dependency management, built-in utilities, and support for modern JavaScript features, Deno is an attractive alternative to Node.js for many developers.

While Deno is still relatively new, it is rapidly gaining adoption, and its ecosystem is growing. If you're starting a new project or looking for a secure and modern runtime environment for your JavaScript or TypeScript applications, Deno is definitely worth considering. Keep in mind, however, that given its relative novelty, some packages and third-party libraries may not be as mature or widely available as those in the Node.js ecosystem.

In summary, Deno offers a fresh perspective on JavaScript and TypeScript development and presents a viable alternative to Node.js. As the Deno ecosystem continues to evolve and mature, it's worth keeping an eye on its progress and considering it for your future web development projects.

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