Executing Parallel and Sequential Dependent API Calls

async function fetchUserData(userId) {
  console.log(`Fetching user ${userId}...`);
  const response = await fetch(`https://api.example.com/users/${userId}`);
  if (!response.ok) throw new Error(`Failed to fetch user ${userId}`);
  return response.json();
}

async function fetchUserPosts(userId) {
  console.log(`Fetching posts for user ${userId}...`);
  const response = await fetch(`https://api.example.com/users/${userId}/posts`);
  if (!response.ok) throw new Error(`Failed to fetch posts for user ${userId}`);
  return response.json();
}

async function fetchPostComments(postId) {
  console.log(`Fetching comments for post ${postId}...`);
  const response = await fetch(`https://api.example.com/posts/${postId}/comments`);
  if (!response.ok) throw new Error(`Failed to fetch comments for post ${postId}`);
  return response.json();
}

// --- Scenario 1: Parallel API Calls (Independent) ---
async function fetchDashboardData(userId) {
  try {
    console.log('--- Parallel Fetch for Dashboard ---');
    const [userData, userPosts] = await Promise.all([
      fetchUserData(userId),
      fetchUserPosts(userId)
    ]);
    console.log('Dashboard Data (Parallel):', { userData, userPosts });
    return { userData, userPosts };
  } catch (error) {
    console.error('Error fetching dashboard data:', error);
  }
}

// --- Scenario 2: Sequential Dependent API Calls ---
async function fetchUserActivityDetails(userId) {
  try {
    console.log('--- Sequential Fetch for User Activity ---');
    const userData = await fetchUserData(userId); // First, get user data
    console.log('Fetched user data:', userData);

    // Now, use data from the first call to make the second call
    if (userData && userData.latestPostId) {
      const comments = await fetchPostComments(userData.latestPostId);
      console.log('User Activity Details (Sequential):', { userData, latestPostComments: comments });
      return { userData, latestPostComments: comments };
    } else {
      console.log('User has no latest post or post ID missing.');
      return { userData };
    }
  } catch (error) {
    console.error('Error fetching user activity details:', error);
  }
}

// Example calls:
const sampleUserId = 123;
fetchDashboardData(sampleUserId);
// Simulate some latency for the sequential call
setTimeout(() => fetchUserActivityDetails(sampleUserId), 100);