Derived validity in Angular
Angular interview exercise on Signals, 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.
Finish SignupComponent: `email` and `password` signals fed by the inputs, a `valid` computed that is true when the email contains "@" and the password has at least 8 characters, and submit() that sets `done` to true. The button must be disabled while the form is invalid.
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.