Refactor for Readability and Performance | Dataford Interview Questions

Your question is Refactor for Readability and Performance. Take a moment with it on the right.

Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).

Problem

This function at Booking Holdings fetches hotel offers for a shortlist of candidate hotel IDs, then filters them by price and rating before returning results to the search results page. It's noticeably slow on searches with a large candidate list, and it occasionally crashes the whole search request instead of just excluding one bad result.

async function getFilteredOffers(hotelIds, maxPrice, minRating) {
  let offers = [];
  for (const id of hotelIds) {
    const offer = await fetchOfferFromSupplier(id);
    offers.push(offer);
  }

  let filtered = [];
  for (let i = 0; i < offers.length; i++) {
    if (offers[i].price <= maxPrice) {
      if (offers[i].rating >= minRating) {
        filtered.push(offers[i]);
      }
    }
  }

  filtered.sort((a, b) => {
    if (a.price > b.price) return 1;
    if (a.price < b.price) return -1;
  });

  return filtered;
}

Refactor this to improve both readability and performance. Explain what's actually causing the slowness and the crashes, since both are hurting a live search page.

Your question is Refactor for Readability and Performance. Take a moment with it on the right.

Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).

async function getFilteredOffers(hotelIds, maxPrice, minRating) {
  let offers = [];
  for (const id of hotelIds) {
    const offer = await fetchOfferFromSupplier(id);
    offers.push(offer);
  }

  let filtered = [];
  for (let i = 0; i < offers.length; i++) {
    if (offers[i].price <= maxPrice) {
      if (offers[i].rating >= minRating) {
        filtered.push(offers[i]);
      }
    }
  }

  filtered.sort((a, b) => {
    if (a.price > b.price) return 1;
    if (a.price < b.price) return -1;
  });

  return filtered;
}

Refactor this to improve both readability and performance. Explain what's actually causing the slowness and the crashes, since both are hurting a live search page.