index.js

const url = "https://jsonplaceholder.typicode.com";

const getUser = async (id) => {
  const res = await fetch(`${url}/users?id=${id}`);
  const user = (await res.json())[0];

  return user;
}

const getPosts = async (user) => {
  const res = await fetch(`${url}/posts?userId=${user.id}&_limit=3`)
  const posts = await res.json();

  return posts;
}

const getCommentsForEachPost = async (posts) => {
  const res = await Promise.all(posts.map(post => 
    fetch(`${url}/comments?postId=${post.id}&_limit=2`)  
  ))
  const postComments = await Promise.all(res.map(r => r.json()));
  
  postComments.forEach((comments, i) => posts[i].comments = comments);
}
const renderHtml = (user, posts) => {
  const content = document.getElementById('content');
  content.innerHTML += `<h3>Posts del usuario ${user.email}</h3>`;
  
  posts.forEach(post => {
    content.innerHTML += `
    <div class="post">
      <h4>${post.title}</h4>
      <p>${post.body}</p>
      <br>
      ${post.comments.map(c => `<p><span>${c.email}:</span>${c.body}</p>`).join('')}
    </div>
    `;
  })
}
const getBlogContent = async () => {
  try {
    const user = await getUser(1);
    const posts = await getPosts(user);
    await getCommentsForEachPost(posts);

    renderHtml(user, posts);
  } catch (err) {
    console.log(err);
  }
}

getBlogContent();