Deno Overview

Deno is a secure runtime environment for both Javascript and Typescript. It is built on top of V8, Rust, and TypeScript and developed by Ryan Dahl.

V8 is an open-source JavaScript engine developed by The Chromium Project for Google Chrome and Chromium web browsers.

Rust is a multi-paradigm programming language focused on performance and safety, especially safe concurrency.

Why Deno?

You might be wondering, when we have node.js then why do we need another runtime for executing Javascript?

Deno supports both Javascript and Typescript but this is not the only reason Ryan built another runtime.

He talked about his top 10 regrets with Node.js and those were enough to mark the arrival of deno.

The top reasons were:

• Concerns with the node_module system
• Javascript has changed a lot since Node.js was created
• Wanted more Secure environment

Deno Overview – Highlights

Initial release	13 May 2018
Stable release	1.2.0 / July 13, 2020
Preview release	1.0.0-rc3 / May 12, 2020
Original author	Ryan Dahl
Operating system	Linux, macOS, Windows
Written in	TypeScript, JavaScript, Rust, C++

Deno Features

The features provided by deno as per the official website are:

• Deno is secure by default, we need to explicitly provide access.
• Supports typescript out of the box.
• Works well with standard modules.
• Has built-in utilities like deno info and deno fmt.
• It ships only a single executable file.

Deno Architecture

Deno vs Node

It’s important to know the differences between the two.

Deno	Node
Deno is written in Rust and TypeScript	Node is written in C++ and JavaScript
For importing packages, Deno uses ES6 Modules	For importing packages, Node uses CommonJS syntax
Lets you import any ES Module from URLs	Has a package manager called npm
Deno offers a sandbox security layer through permissions	Node.js program can access anything the user can access
Uses modern ECMAScript features in all its API	Uses the callback-based standard library

In this section, we have covered the deno overview. Let’s learn about setting up the environment and installing Deno in the next section.

Deno is similar to Node and NOT a replacement of Node.