Loading data, ignoring stale answers in React
React interview exercise on Effects & refs, difficulty 3 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Write UserCard with props `id` and `load(id)` (returns a promise of { name }): show <p className="loading">Loading…</p> while a request is in flight and <h2>{name}</h2> once it answered. When `id` changes, load the new one, and an answer to an OLD id that arrives later must be ignored.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.