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Lesson 2 of 6 · 15 min · 1 hands-on step

Reviewing AI-Generated Code

Catch the bugs AI assistants commonly make before they reach production.

Review checklist

Use this every time you accept AI-written code, or review a teammate's PR:

  1. Does it do what was asked? Re-read the requirement, then the code.
  2. Edge cases: empty input, one item, exact boundaries, very large input, invalid input.
  3. Side effects: does it mutate its inputs? Change global state? Make network calls?
  4. Failure modes: what happens on bad input? Could it loop forever or crash?
  5. Security: user input in SQL or HTML? Secrets in code?
  6. Readability: would a teammate understand it in six months?
  7. Tests: write or run tests that prove it works. Don't just eyeball it.

Common AI mistakes to look for

Smell Example
Off-by-one i < arr.length - 1, while (len > size)
Mutating inputs splice, sort() or reverse() on a caller's array
Missing guards no check for size <= 0, null, empty strings
Hallucinated APIs array.chunk(), str.capitalize() (they don't exist in JavaScript)
Swallowed errors catch (e) {} that hides failures

In interviews

You may be asked to review a snippet or explain how you use AI. A strong answer:

"I use AI for first drafts and boilerplate, then I review it like a teammate's PR: check edge cases, run the tests, and make sure I understand every line before I commit it."

🧪 Practice

A developer asked an AI: "Write a function that splits an array into chunks of a given size." It produced the code in the editor.

It looks fine but has bugs. Review it like a senior engineer, then fix it so that:

  • chunk([1, 2, 3, 4, 5], 2) → [[1, 2], [3, 4], [5]] (the last chunk can be shorter)
  • chunk([], 3) → []
  • A size less than 1 throws an error instead of looping forever
  • The original array is not modified
JavaScript
// AI-generated. Review carefully before trusting it.
function chunk(arr, size) {
  const result = [];
  while (arr.length > size) {
    result.push(arr.splice(0, size));
  }
  return result;
}

console.log(chunk([1, 2, 3, 4, 5], 2));

Output appears here. Press Run or Ctrl/⌘ + Enter.

✅ Check your understanding

  1. Which review question catches the most AI bugs?

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