Vibe codingMediumvc-g040

Subject Ai code reviewLevel Mid–Senior~14 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

An AI assistant wrote this JavaScript to deduplicate an array of order objects by their `id`, keeping the first occurrence:

javascript

1function dedupeById(orders) {2  const seen = new Set();3  return orders.filter((o) => {4    if (seen.has(o.id)) return false;5    seen.add(o.id);6  });7}

It returns the right length on a small test where all ids differ. What's the bug, and when does it bite?

What a strong answer looks like

Treat the AI’s output as a draft to verify, not an answer to trust. Name the specific flaw and the input that triggers it, say how you’d catch it — tests, edge cases, reading critically — and how you’d re-prompt or decompose to get it right.

Learn the concepts

Describe your solution

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.