AI frontend engineer interview with live coding

The 3 questions the AI interviewer asks

Word for word from the demo. In the demo and in a real interview, the AI also asks its own follow-ups from what the candidate says.

1. 1

   “Tell me about a UI feature you built recently that you are proud of. What made it tricky, and what did you do about it?”

   What a strong answer shows

   • Names one specific feature, their own part in it and who used it
   • Pins down the hard part: state, performance, accessibility or browser differences
   • Explains the trade-off they chose and what they would do differently now
2. 2In the code editor

   “In the code editor, write a JavaScript function groupBy(items, keyFn) that takes an array of objects and a function returning a grouping key, and returns an object mapping each key to the array of items in that group. Talk through your approach as you write it.”

   What a strong answer shows

   • Builds every group in a single pass, with reduce or a plain loop
   • Guards against empty input and keys that clash with Object.prototype, like constructor
   • Talks through the approach first, then checks it against a small example
3. 3

   “A page you own renders slowly after a data change. How do you find out why, and what are the usual causes you check first?”

   What a strong answer shows

   • Measures before changing anything: profiler, network tab, React DevTools
   • Checks usual causes: needless re-renders, heavy render work, long unvirtualized lists
   • Confirms the fix with a before-and-after measurement, not a hunch