Deh, Deh...Deno

A secure runtime for JavaScript and TypeScript.

What is Deno?

It's like NodeJs
Deeply improved in many ways
Was announced in Jun 6, 2018 By Ryan Dahl as JSConf EU

Probably every talk about Deno begins like this

deno run https://deno.land/std/examples/welcome.ts

deno repl
Deno 1.5.3
exit using ctrl+d or close()
>

REPL ( read–eval–print loop)

Static file

Why start this project?

No Promise API
Security/Sandbox
Build system (GYP)
NPM (bundled in node & package.json)
node_modules (not isomorphic, algorithm resolution, etc)
require() without the extension
....
Type script

Accorning to Ryan Dahl

...go and see the video

Let's talk about features

Also, build on top of V8
Modern features of javascript
Has an extensive standard library
Typescript at its core (no need for tsc, ts-node, etc.)
Default ES modules (no esm, not experimental flags, no babel...)
No Package Manager (no NPM)
- Wait! What?!?!?
First-class await (frigging finally...)
Built-in testing capabilities
Isomorphic features - aims to be browser-compatible (built-in fetch, window)
Integrated tooling
More to come

const raw = await fetch('https://jsonplaceholder.typicode.com/users');
const asJson = await raw.json();
console.info(asJson);

Check this...

Is something strange? Missing?

Node API was initially callback-based
Then we got Promises
Then we got promisify()
Then we got Async await
Now we have first class await

Kewl...? so why switch?

Check the video
NPM is not secured
Typescript is great
We did some early mistakes (callback)

Node killer?

No
They work together - influence each other
Node is here to stay - it's huge

Similar

V8 Chromium
A runtime environment for javascript
Written in C++ and Javascript
Official package manager (NPM)
Used CommonJS - require()
No Sandboxing
No single executable

Different

Written in Rust and Typescript
No package manager
ES6 module support
Sandboxing as a default
A single executable

No NPM

Rely on GitHub scripts
The good
- Very flexible
- No need to publish
The bad
- Might not be reliable
- To fix this you can use https://deno.land/x

Lets demo this

No centralized package manager

Tools

deno --help
deno 1.5.3
A secure JavaScript and TypeScript runtime

Docs: https://deno.land/manual
Modules: https://deno.land/std/ https://deno.land/x/
Bugs: https://github.com/denoland/deno/issues

SUBCOMMANDS:
    bundle         Bundle module and dependencies into single file
    cache          Cache the dependencies
    completions    Generate shell completions
    doc            Show documentation for a module
    eval           Eval script
    fmt            Format source files
    help           Prints this message or the help of the given subcommand(s)
    info           Show info about cache or info related to source file
    install        Install script as an executable
    lint           Lint source files
    repl           Read Eval Print Loop
    run            Run a program given a filename or url to the module. Use '-' as a filename to read from stdin.
    test           Run tests
    types          Print runtime TypeScript declarations
    upgrade        Upgrade deno executable to given version

fmt

test

bundle

deno server

import { serve } from 'https://deno.land/std@0.80.0/http/server.ts';

const HTTP_OK = 200;
const DEFAULT_PORT = 8080;

const server = serve({ hostname: '0.0.0.0', port: DEFAULT_PORT });
console.log(`HTTP webserver running.  Access it at:  http://localhost:8080/`);

for await (const request of server) {
  let bodyContent = 'Your user-agent is:\n\n';
  bodyContent += request.headers.get('user-agent') || 'Unknown';
  bodyContent += `\nroute: ${request.url}`;
  const body = Array.from(request.headers.keys()).reduce((acc, value) => {
    return `${acc}\n${value}: ${request.headers.get(value)}`;
  }, bodyContent);
  request.respond({ status: HTTP_OK, body });
}

vscode extention

Native modules

Popular servers

Github

Documentation

Performance