Two-way binding with model() in Angular
Angular interview exercise on Inputs & outputs, 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.
QuantityComponent has a `quantity` model (default 1) and `min` and `max` inputs (1 and 10). The minus and plus buttons move the quantity by one and are disabled at the bounds; the <output> shows it. The parent must be able to write [(quantity)]="amount".
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.