Learning Deno

Just one of the things I'm learning. https://github.com/hchiam/learning

https://en.wikipedia.org/wiki/Deno_(software)

Motivation (vs Node.js)

https://medium.com/javascript-in-plain-english/deno-vs-node-js-here-are-the-most-important-differences-62b547443be1

Basically more secure by default, requiring you to explicitly specify what you want/allow access to. Instead of npm and node_modules, you can get deps from https URLs (e.g.: import * as log from "https://deno.land/std/log/mod.ts";). Typescript support out of the box.

Install steps

https://deno.land

Then get updates with deno upgrade.

More

https://deno.land/manual

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

or:

import { serve } from "https://deno.land/std@0.50.0/http/server.ts";

for await (const req of serve({ port: 8000 })) {
  req.respond({ body: "Hello World\n" });
}

(You can try this ^ with deno run demo.ts and then deno run --allow-net demo.ts)

The last example uses https://deno.land/std@0.50.0/http/server.ts

File reading example

const { stdout, open, copy, args } = Deno;

for (let i = 0; i < args.length; i++) {
  const filename = args[i]; // args = CLI arguments
  const file = await open(filename);
  console.log();
  await copy(file, stdout); // zero-copy async copy: file -> stdout
  console.log();
}

deno run --allow-read cat.ts myfile.txt

Set up hot reload

https://deno.land/x/denon

Once:

deno install --allow-read --allow-run --allow-write --allow-net -f --unstable https://deno.land/x/denon@v2.2.0/denon.ts

Then to get http://localhost:8000 running:

denon run --allow-net demo.ts

You can edit demo.ts and then refresh http://localhost:8000 to see it updated - without having to restart in the CLI!

If you see bash: denon: command not found in the CLI, you might need this set up in your .bash_profile:

# replace <your account> with your computer's account name:
export PATH="/Users/<your account>/.deno/bin:$PATH"

or

# replace <your account> with your computer's account name:
export PATH=$PATH:/Users/<your account>/.deno/bin:$PATH