feat: change RSS feed pubDate and items order (sveltejs#1077)

* feat: render day of week in RSS pubDate

* feat: sort rss feed by date desc

* Apply suggestions from code review

* simplify

---------

Co-authored-by: Rich Harris <[email protected]>
Co-authored-by: Rich Harris <[email protected]>

Author: jsafarik

apps/svelte.dev/src/routes/blog/rss.xml/+server.js

@@ -3,14 +3,6 @@ import { render_content } from '$lib/server/renderer';
 
 export const prerender = true;
 
-const months = ',Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec'.split(',');
-
-/** @param {string} str */
-function formatPubdate(str) {
-	const [y, m, d] = str.split('-');
-	return `${d} ${months[+m]} ${y} 12:00 +0000`;
-}
-
 /** @param {string} html */
 function escapeHTML(html) {
 	/** @type {{ [key: string]: string }} */
@@ -30,14 +22,15 @@ const get_rss = async (posts) => {
 	const renderedPosts = await Promise.all(
 		posts
 			.filter((post) => !post.metadata.draft)
+			.reverse()
 			.map(
 				async (post) => `
 		<item>
 			<title>${escapeHTML(post.metadata.title)}</title>
 			<link>https://svelte.dev/${post.slug}</link>
 			<author>${escapeHTML(post.metadata.author)}</author>
 			<description>${escapeHTML(await render_content(post.file, post.body))}</description>
-			<pubDate>${formatPubdate(/** @type {string} */ (post.file.split('/').pop()).slice(0, 10))}</pubDate>
+			<pubDate>${new Date(/** @type {string} */ (post.file.split('/').pop()).slice(0, 10)).toUTCString()}</pubDate>
 		</item>
 	`
 			)