Find valid Telegram Group invite link. This is a challenge from my friend.

check-link.mjs

/**
 * Find valid Telegram Group invite link.
 * This is a challenge from my friend.
 */

const config = {
	url: 'https://t.me/+zUufcmk***E3nGQ1', // asterisks are hidden chars
	name: 'Mine', // name of group
	process_count: 100, // how many process should run at a time
};

const valid_chars = `abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789`;
const candidates = [];
const possible_urls = [];
const pattern = /\*+/g.exec(config.url)[0];

if (!pattern) {
	console.error('failed to get pattern', pattern);
	process.exit(1);
}

console.log('preparing candidates ...');
function generate_candidates(prefix, level) {
	if (level === pattern.length) {
		candidates.push(prefix);
		return;
	}

	for (const c of valid_chars) {
		generate_candidates(prefix + c, level + 1);
	}
}
generate_candidates('', 0);

console.log('begin ...');
for (
	let i = 0;
	i < candidates.length - config.process_count - 1;
	i += config.process_count
) {
	await Promise.all(
		Array.from({ length: config.process_count }) //
			.map((_, j) => try_candidate(i + j))
	);
	process.stdout.write(`test left: ${candidates.length}\r`);

	if (possible_urls.length) {
		console.log('found:', possible_urls);
		break;
	}
}

async function try_candidate(index) {
	const candidate = candidates[index];
	if (!candidate) return;
	try {
		const new_url = config.url.replace(pattern, candidate);
		const response = await fetch(new_url);
		candidates.splice(index, 1);

		if (!response.ok) return;
		const text = await response.text();
		if (text.toLocaleLowerCase().includes(config.name.toLocaleLowerCase())) {
			// simple check group name in response
			possible_urls.push(new_url);
		}
	} catch (error) {
		console.error(`error at ${candidate}:`, error.message);
	}
}

Basically this is a Brute Force.