watch with cleanup in Vue
Vue interview exercise on Computed & watchers, difficulty 3 of 3. Solve it in the editor beside a worked example; the tests run the moment you do.
Write Search with a prop `lookup` ((term: string) => Promise<string[]>): an <input> bound to a query ref, a <ul> of <li> results and <p class="none">No matches</p> when a non-empty query has none. Watch the query: a blank query clears the results without calling lookup; otherwise call lookup with the trimmed query and show what it returns. Answers that arrive after the query has changed again must be ignored (use the watcher's onCleanup).
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Progress is saved in your browser, and in your account if you sign in.