Hello Deno

Hello Deno

Deno is a new JavaScript runtime from the creator of Node.js Ryan Dahl. In 2018 he talked about 10 Things I Regret About Node.js at JSConf and thats when we came to know about Deno and the motivation behind it.

Deno 1.0 is out and publicly available now. We will try to get our hands on it and do a “Hello World” with Deno.

Main highlights of Deno

  • Security at its core – Deno won’t access anything unless you allow it to and it includes file, network, or environment acess
  • Out of the box TypeScript support
  • Built in dependency inspector and code formatter

Let’s start with installation.

Installing Deno on Mac

Installation of Deno is pretty straightforward and instructions are available for every platform.
I am using Homebrew to install Deno on my Macbook Pro.

brew install deno

Once the installation is finished, lets verify and check version of Deno with following command

deno --version

and we get following response which confirms the installation was successful

deno 1.2.0
v8 8.5.216
typescript 3.9.2

Hello World with Deno

Deno provides a REPL environment which can be used to execute quick commands. Just enter “deno” on your command prompt and you are good to go. Here is an example:

$ deno
Deno 1.2.0
exit using ctrl+d or close()
> console.log("Hello World")
Hello World

Running script from an external file hellodeno.ts

console.log("Welcome to Deno 🦕");

Now execute this file with Deno

deno run hellodeno.ts

and we get following output
Welcome to Deno 🦕