index.js

const Options = "max_results=100&expansions=author_id&user.fields=name,profile_image_url";

addEventListener("scheduled", event => {
  event.waitUntil(handleScheduled(event.request))
})

async function handleScheduled(request) {
  await fetchTweets("user-screen-name-here");
}

async function fetchTweets(screenName) {
  console.log(`Fetching tweets for ${screenName}`);

  const authorization = `Bearer ${APP_TOKEN}`;
  const uid = await KV.get(`UID_${screenName}`);
  const sid = await KV.get(`SID_${screenName}`);

  const resp = await fetch(
    `https://api.twitter.com/2/users/${uid}/tweets?since_id=${sid}&${Options}`,
    {
      headers: { authorization }
    }
  );
  const { data, meta, includes } = await resp.json();
  console.log(`Processed ${meta.result_count} tweets`);
  if(!data) return;
  const { users } = includes;

  for(const d of data){
    const user = users.find(({ id }) => id === d.author_id);
    await writeDiscord(screenName, {
      content: `https://twitter.com/${screenName}/status/${d.id}`,
      username: user.name,
      avatar_url: user.profile_image_url,
    });
  }

  await KV.put(`SID_${screenName}`, meta.newest_id);
}

async function writeDiscord(screenName, content) {
  const uri = await KV.get(`WEBHOOK_${screenName}`);
  return fetch(uri, {
    method: "POST",
    headers: {
      "Content-Type": "application/json"
    },
    body: JSON.stringify(content)
  });
}