Hacker News API and RSS feeds

// Markup: <ol id="stories"></ol>
const HN = 'https://hacker-news.firebaseio.com/v0';

async function getJson(url) {
  const response = await fetch(url);
  if (!response.ok) throw new Error(`Hacker News answered ${response.status} for ${url}`);
  return response.json();
}

async function stories(list = 'topstories', limit = 30) {
  const ids = await getJson(`${HN}/${list}.json`);
  const items = await Promise.all(ids.slice(0, limit).map((id) => getJson(`${HN}/item/${id}.json`)));

  return items
    .filter((item) => item && !item.deleted && !item.dead)
    .map((item) => ({
      title: item.title,
      url: item.url ?? `https://news.ycombinator.com/item?id=${item.id}`,
      points: item.score,
      comments: item.descendants ?? 0,
      by: item.by,
      posted: new Date(item.time * 1000),
    }));
}

const list = document.querySelector('#stories');
stories().then((top) => {
  list.replaceChildren(
    ...top.map((story) => {
      const entry = document.createElement('li');
      const link = document.createElement('a');
      if (/^https?:/.test(story.url)) link.href = story.url;
      link.textContent = story.title;
      entry.append(link, ` (${story.points} points, ${story.comments} comments)`);
      return entry;
    }),
  );
});

// Runs in a module script or the DevTools console
async function searchStories(query, { minPoints = 0, days = 30, newestFirst = false } = {}) {
  const since = Math.floor(Date.now() / 1000) - days * 86400;
  const params = new URLSearchParams({
    query,
    tags: 'story',
    numericFilters: `points>=${minPoints},created_at_i>${since}`,
    hitsPerPage: '20',
  });
  const endpoint = newestFirst ? 'search_by_date' : 'search';

  const response = await fetch(`https://hn.algolia.com/api/v1/${endpoint}?${params}`);
  if (!response.ok) throw new Error(`Algolia answered ${response.status}`);

  const { hits, nbHits } = await response.json();
  return {
    total: nbHits,
    stories: hits.map((hit) => ({
      title: hit.title,
      url: hit.url ?? `https://news.ycombinator.com/item?id=${hit.objectID}`,
      points: hit.points,
      comments: hit.num_comments,
      author: hit.author,
      posted: new Date(hit.created_at_i * 1000),
    })),
  };
}

const { total, stories } = await searchStories('rust', { minPoints: 100, days: 365 });
console.log(`${total} stories, showing ${stories.length}`);
console.table(stories);

// Markup: <ul id="feed"></ul>
const DC = 'http://purl.org/dc/elements/1.1/';

async function readFeed(feedUrl) {
  const response = await fetch('https://proxy.cors.dev/' + feedUrl, { credentials: 'omit' });
  if (!response.ok) {
    throw new Error(`Feed request failed: ${response.headers.get('X-Cors-Error') ?? response.status}`);
  }

  const xml = new DOMParser().parseFromString(await response.text(), 'application/xml');
  if (xml.querySelector('parsererror')) throw new Error('The feed is not valid XML');

  return [...xml.querySelectorAll('item')].map((item) => {
    const description = item.querySelector('description')?.textContent ?? '';
    return {
      title: item.querySelector('title')?.textContent.trim() ?? '',
      link: item.querySelector('link')?.textContent.trim() ?? '',
      comments: item.querySelector('comments')?.textContent.trim() ?? '',
      author: item.getElementsByTagNameNS(DC, 'creator')[0]?.textContent ?? '',
      posted: new Date(item.querySelector('pubDate')?.textContent ?? 0),
      points: Number(description.match(/Points: (\d+)/)?.[1] ?? 0),
    };
  });
}

const list = document.querySelector('#feed');
readFeed('https://hnrss.org/frontpage')
  .then((items) => {
    list.replaceChildren(
      ...items.map((item) => {
        const entry = document.createElement('li');
        const link = document.createElement('a');
        if (/^https?:/.test(item.link)) link.href = item.link;
        link.textContent = item.title;
        entry.append(link, ` (${item.points} points, by ${item.author})`);
        return entry;
      }),
    );
  })
  .catch((error) => {
    list.textContent = error.message;
  });