Subscriptions that end with the component in Angular
Angular interview exercise on RxJS interop, difficulty 2 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.
StopwatchComponent counts `ticks` (a signal) from an interval of 10 ms that starts on start() and is paused by stop(); the subscription must end when the component is destroyed. Render the ticks in <output> with Start and Stop buttons.
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.