Code Review

Code that already looks finished, and is wrong. Find the defect before you submit — the tests it came with all pass.

Review: a reducer that mutates, and a UI that stops updating

The todos reducer below passes its tests — the data is always right. Wire it into a component and the screen goes stale. Find what the tests could never see.

Review: a countdown stuck one second in

intermediatereview

The countdown hook below passes its test. Watch it for three seconds and it is still showing the same number. A classic closure bug — find where time froze.

Review: a fetch that loses the race to itself

advancedreview

The user-loading hook below passes its tests. Click between two profiles quickly and the first one wins the screen. Find why the slower response gets the last word.