Perform Multiple API Requests Concurrently with Promise.allSettled

async function fetchMultipleEndpointsConcurrently(urls) {
  if (!Array.isArray(urls) || urls.length === 0) {
    console.warn('No URLs provided for concurrent fetching.');
    return [];
  }

  const fetchPromises = urls.map(url =>
    fetch(url)
      .then(response => {
        if (!response.ok) {
          throw new Error(`HTTP error! status: ${response.status} from ${url}`);
        }
        return response.json();
      })
      .catch(error => {
        console.error(`Error fetching ${url}:`, error);
        throw error; // Re-throw to be caught by Promise.allSettled as 'rejected'
      })
  );

  // Promise.allSettled waits for all promises to settle (either fulfilled or rejected)
  // without short-circuiting on the first rejection, unlike Promise.all.
  const results = await Promise.allSettled(fetchPromises);

  // Process results:
  const collectedData = [];
  const errors = [];

  results.forEach((result, index) => {
    if (result.status === 'fulfilled') {
      collectedData.push(result.value);
    } else {
      // result.reason contains the error thrown by the catch block above
      errors.push({ url: urls[index], error: result.reason });
    }
  });

  return { data: collectedData, errors: errors };
}

// Example usage:
// const apiEndpoints = [
//   'https://jsonplaceholder.typicode.com/posts/1',
//   'https://jsonplaceholder.typicode.com/users/1',
//   'https://jsonplaceholder.typicode.com/comments/1',
//   'https://invalid-url.typicode.com/data' // Example of a failing request
// ];

// fetchMultipleEndpointsConcurrently(apiEndpoints)
//   .then(({ data, errors }) => {
//     console.log('Successfully fetched data:', data);
//     if (errors.length > 0) {
//       console.error('Errors encountered:', errors);
//     }
//   })
//   .catch(overallError => {
//     // This catch block would only be hit if Promise.allSettled itself throws, which it doesn't.
//     // All individual errors are caught within the map and reported in the 'errors' array.
//     console.error('An unexpected overall error occurred:', overallError);
//   });