Learning Deno

• What is it?

  According to the website: A secure runtime for JavaScript and TypeScript.

  Deno is a simple, modern and secure runtime for JavaScript and TypeScript that uses V8 and is built in Rust.

  • Secure by default. No file, network, or environment access, unless explicitly enabled.
  • Supports TypeScript out of the box.
  • Ships only a single executable file.
  • Has built-in utilities like a dependency inspector (deno info) and a code formatter (deno fmt).
  • Has a set of reviewed (audited) standard modules that are guaranteed to work with Deno: deno.land/std
  • Scripts can be bundled into a single javascript file.
  • It doesn't have a package management.
  • Remote code is fetched and cached on first execution, and never updated until the code is run with the --reload flag. (So, this will still work on an airplane.)
  • Modules/files loaded from remote URLs are intended to be immutable and cacheable.
  • Created by the same author of Node.js (Ryan Dahl).

So if you're familiar with Node.js, Deno is very similar. Some will say it's the new Node.js.

• Installation

$ curl -fsSL https://deno.land/x/install/install.sh | sh
$ deno completions bash > ~/.deno/deno.bash

Remember to edit your $HOME/.bashrc to add the Deno installation directory as the install script will say at the end.

Also, load the deno.bash with:

$ vim ~/.bashrc
(or similar file)

[...]
# Configuring deno installation dir
export DENO_INSTALL="/home/your-username/.deno"
export PATH="$PATH:$DENO_INSTALL/bin"
# Loading deno bash completion
if [ -f $DENO_INSTALL/deno.bash ]
then
  . $DENO_INSTALL/deno.bash
fi
[...]

Reload with source ~/.bashrc or close and open a new terminal window.

• Hello Deno!

Download this repo and run in a terminal:

$ deno run hello-deno/main.ts

• Google search

Download this repo and run in a terminal:

$ deno run --allow-net google-search/main.ts deno

• Arnold Schwarzenegger Quotes

Download this repo and run in a terminal:

$ deno run --unstable --allow-read quotes/main.ts

• Simple chat application

Download this repo and run in a terminal:

$ cd chat
$ deno run --unstable --allow-net --allow-env --allow-read main.ts

Open more than one private/incognito window to test it.

• Using a file watcher

Install with:

$ deno install --allow-read --allow-run --allow-write -f --unstable https://deno.land/x/denon/denon.ts
$ denon -h
$ cd file-watcher
$ denon start

Find some file in file-watcher directory to change while the denon is running.

• Create a sample web application
  • Pokemon API
    • Setup
    • CREATE a pokemon
    • GET a pokemon
    • LIST pokemons
    • UPDATE a pokemon
    • DELETE a pokemon