Vibe codingMediumvc-g522

Subject Ai code reviewLevel Mid–Senior~15 minCommon in Algorithms & data structures interviewsIndustries Software development, Technology

Question

This Lambda (JavaScript) opens a MongoDB connection inside the handler on every request. Latency is high and Atlas shows connection churn. The AI says opening per-request is 'safer.' Correct it and explain the trade-off it missed.

1const { MongoClient } = require("mongodb");2 3exports.handler = async (event) => {4  const client = new MongoClient(process.env.MONGO_URI);5  await client.connect();6  const doc = await client.db("app").collection("users").findOne({ _id: event.id });7  await client.close();8  return doc;9};

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.