A store driven by a Subject in Angular

Angular interview exercise on RxJS interop, difficulty 3 of 3. Solve it in the editor beside a worked example; the tests run the moment you do.

TodoStore: a Subject of actions (add with a title, toggle with an id, remove with an id) reduced with scan into `todos …" /> …" /> …" /> …" /> …" /> …" /> …" /> (ids counted up from 1, new todos not done), seeded with [] and shared. TodoComponent shows the store's todos as <li> with the class "done" when done, an <input> adding on Enter, and per item a <button class="toggle"> and <button class="remove">.

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.

More RxJS interop in Angular

• An observable as a signal
• The async pipe
• Debounced search with switchMap
• Subscriptions that end with the component

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