A Telegram bot that sends notification when there is new blog post on https://devblogs.microsoft.com/typescript/feed/. You can also list blogs inline and send.

tsrelease.ts

import { Bot } from "https://deno.land/x/[email protected]/mod.ts";
import { parseFeed, Feed } from "https://deno.land/x/[email protected]/mod.ts";

const INTERVAL = 60 * 10 * 1000;
const RECIPIENT = -1001335202320;
const TOKEN = Deno.args[0];
if (!TOKEN) throw new Error("Please provide a bot token");

const bot = new Bot(TOKEN);

type ArrayElement<T extends unknown[]> = T extends (infer E)[] ? E : never;
type FeedEntry = ArrayElement<Feed["entries"]>;
type Post = { title: string; published: Date; link: string };
type Maybe<T> = T | null;

const escapables = {
	"<": "&lt;",
	">": "&gt;",
	"&": "&amp;",
	"'": "&#39;",
	'"': "&quot;",
};

const escape = (s: string) =>
	s.replace(/<|>|&|"|'/g, (r) => escapables[r as keyof typeof escapables] || r);

async function getPosts(attempt = 0): Promise<FeedEntry[]> {
	try {
		if (attempt > 2) throw new Error("Retry attempt count exceeded");
		const response = await fetch(
			"https://devblogs.microsoft.com/typescript/feed/"
		);
		const xml = await response.text();
		const feed = await parseFeed(xml);
		return feed.entries;
	} catch {
		await new Promise((res) => setTimeout(res, 60 * 1000));
		return getPosts(attempt + 1);
	}
}

const parser = (feed: FeedEntry): Maybe<Post> => {
	const published = feed.published;
	const title = feed.title?.value;
	const link = feed.links[0].href;
	if (title && published && link) return { title, published, link };
	return null;
};

const filterNewPosts = (post: Maybe<Post>) =>
	post &&
	post.published.getTime() > new Date("2022-02-09T18:45:19.000Z").getTime()
		? post
		: null;

const sendPost = (bot: Bot, post: Maybe<Post>) =>
	post &&
	bot.api.sendMessage(
		RECIPIENT,
		`<b>New TypeScript blog post published 📝</b>\n\n<a href="${
			post.link
		}">${escape(post.title)}</a>`,
		{
			parse_mode: "HTML",
		}
	);

setInterval(async () => {
	try {
		const posts = await getPosts();
		await Promise.all(
			posts
				.map(parser)
				.filter(filterNewPosts)
				.map((post) => sendPost(bot, post))
		);
	} catch (error) {
		console.trace(error);
	}
}, INTERVAL);

bot.command("start", (ctx) => ctx.reply("Welcome! Up and running.\nDev: https://github.com/darvesh"));

bot.on("inline_query", async (ctx) => {
	const posts = await getPosts();
	await ctx.answerInlineQuery(
		posts
			.map((post) => {
				const p = parser(post);
				return p
					? {
							type: "article" as const,
							title: p.title,
							id: Math.random().toString(),
							input_message_content: {
								message_text: `<b>New TypeScript blog post published 📝</b>\n\n<a href="${
									p.link
								}">${escape(p.title)}</a>`,
								parse_mode: "HTML" as const,
							},
					  }
					: null;
			})
			.filter(<T>(res: T): res is NonNullable<T> => Boolean(res))
	);
});

bot.catch(console.trace);
bot.start({
	onStart: () => console.log("Bot started"),
	drop_pending_updates: true,
});

deno run --allow-net https://gist.githubusercontent.com/darvesh/bc053a506f09e24c23b6eb45080252b8/raw/816d56ae340177f03cdef4acd6e26a8be78f570c/tsrelease.ts "<bot-token>"