async function fetchAllPages(baseUrl, initialParams = {}) {
  let allData = [];
  let nextPageUrl = baseUrl;
  let page = 1;

  while (nextPageUrl) {
    const url = new URL(nextPageUrl);
    // Merge initial parameters, ensuring 'page' is always the current page number
    for (const key in initialParams) {
      if (!url.searchParams.has(key)) {
        url.searchParams.set(key, initialParams[key]);
      }
    }
    url.searchParams.set('page', page);

    try {
      const response = await fetch(url.toString());
      if (!response.ok) {
        throw new Error(`HTTP error! status: ${response.status}`);
      }
      const data = await response.json();

      // Assuming API returns data in 'results' and a 'next' link for pagination
      allData = allData.concat(data.results || data.data || []); 
      nextPageUrl = data.next || null; // Or check if data.pagination.nextPage exists

      // If API uses page numbers instead of a 'next' link:
      if (!nextPageUrl && data.pagination && data.pagination.totalPages > page) {
        page++;
        nextPageUrl = baseUrl; // Keep fetching the base URL with incremented page
      } else if (!nextPageUrl) {
        break; // No more pages
      }

    } catch (error) {
      console.error('Error fetching page:', page, error);
      break; // Stop on error
    }
  }
  return allData;
}

// Example Usage:
// fetchAllPages('https://api.example.com/products', { limit: 10 })
//   .then(products => {
//     console.log('Fetched all products:', products.length);
//     console.log(products);
//   })
//   .catch(err => console.error('Failed to fetch all products:', err));