Deno YouTube Thumbnail Downloader

.gitignore

/.vs

downloader.ts

// deno run --allow-net --allow-write .\demo_script.ts

// YouTube Thumbnail Downloader
// By Hevanafa, 31-01-2023
// Edit 03-02-2023: trailing query string detection
// Edit 05-02-2023: hqdefault & maxresdefault_live detection

import { DOMParser } from "https://deno.land/x/deno_dom/deno-dom-wasm.ts";
import { copy, readerFromStreamReader } from "https://deno.land/std@0.175.0/streams/mod.ts";

if (Deno.args.length < 1) {
	console.log("URL is required.");
	Deno.exit(0);
}

// Obtain the download link
let href = "";

try {
	const origin = Deno.args[0]; // "https://www.youtube.com/watch?v=kJGsWORSg-4";

	const res = await fetch(origin);
	const html = await res.text();
	const document = new DOMParser().parseFromString(html, "text/html");

	const link = document?.querySelector("link[itemprop=\"thumbnailUrl\"]");
	href = link?.getAttribute("href") ?? "";

	console.log("Got the link: %s", href);
} catch (e) {
	console.error(e);
	Deno.exit(1);
}

// Obtain the filename

// const chunks = href.split("/");
// const hash = chunks.at(-2) ?? "";
// const ext = (chunks.at(-1) ?? "").split(".")[1];

let match = href.match(/\/vi\/(.*?)\/maxresdefault\.(jpg|png)/);

// console.log(match);
// Deno.exit(0);

if (!match) {
	console.error("Attempt 1 failed: Couldn't find maxresdefault.");

	match = href.match(/\/vi\/(.*?)\/hqdefault\.(jpg|png)/);

	if (!match) {
		console.error("Attempt 2 failed: Couldn't find hqdefault.");

		match = href.match(/\/vi\/(.*?)\/maxresdefault_live\.(jpg|png)/);

		if (!match) {
			console.error("Attempt 3 failed: Couldn't find maxresdefault_live.");

			Deno.exit(1);
		}
	}
}

const hash = match[1];
const ext = match[2];
const filename = `${hash}.${ext}`;

console.log("%c%s", "color: #00ff00", filename);

// Create the "thumbs" folder
try {
	await Deno.mkdir("thumbs");
} catch (e) {
	// console.error(e);
}

// Download the thumbnail
try {
	const origin = href;

	const response = await fetch(origin);
	const reader = response.body?.getReader();

	if (reader) {
		const r = readerFromStreamReader(reader);
		const f = await Deno.open(`./thumbs/${filename}`, { create: true, write: true });
		await copy(r, f);
		f.close();

		console.log("Thumbnail has been downloaded.");
	}
} catch (e) {
	console.error(e);
	Deno.exit(1);
}

run.ps1

# .\run_deno [YouTube_url]
# .\run_deno https://www.youtube.com/watch?v=dQw4w9WgXcQ
deno run --allow-net --allow-write .\downloader.ts $args

shortcut.ps1

# Refs:
# https://stackoverflow.com/questions/45760457/how-can-i-run-a-powershell-script-with-white-spaces-in-the-path-from-the-command
# https://lazyadmin.nl/powershell/run-a-powershell-script/
# powershell -noexit -file "{}"

# Ref: https://caiomsouza.medium.com/fix-for-powershell-script-not-digitally-signed-69f0ed518715
Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass

# Ref: https://superuser.com/questions/446827/configure-windows-powershell-to-display-only-the-current-folder-name-in-the-shel
function prompt { "$p> " }

write-output "This program requires Deno in order to work."
write-output "Enter .\run_deno to start."
write-output "Enter ""explorer .\thumbs"" to open downloaded thumbnails."
write-output ""