watchEffect in Vue
Vue interview exercise on Computed & watchers, difficulty 1 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 Inbox with props `name` (string) and `unread` (number, default 0): an <h1> with the name and <p> with "N unread". With watchEffect, keep document.title at "(N) Inbox – <name>" while there are unread messages and "Inbox – <name>" otherwise, and restore the title that was there before when the component unmounts (onBeforeUnmount).
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.