sapper-lut-site/src/routes/blog/index.json.js

import fs from 'fs';
import path from 'path';
import marked from 'marked';
import grayMatter from 'gray-matter';

function getAllPosts(filesPath) {
	const data = fs.readdirSync(filesPath).map((fileName) => {
		const post = fs.readFileSync(path.resolve(filesPath, fileName), "utf-8");
		
		// Parse Front matter from string
		const { data, content } = grayMatter(post);

		// Turns markdown into html
		const renderer = new marked.Renderer();
		const html = marked(content, { renderer });
		
		// Builds data
		return {
			...data,
			slug: fileName.substring(0, fileName.length - 3),
			html,
		};
	});
	return data;
}

function sortPosts(posts) {
  return posts.sort((post1, post2) => {
    const date1 = new Date(post1.date);
    const date2 = new Date(post2.date);
    return date2 - date1;
  })
}

export function get(req, res) {
	const posts = getAllPosts("src/posts");
	
  const sortedPosts = sortPosts(posts);

	res.writeHead(200, {
		'Content-Type': 'application/json'
	});

	res.end(JSON.stringify(sortedPosts));
}