Angular Web Framework State Management & Change Detection

Question 1

Which Angular strategy checks only the current component and its ancestors when an input reference changes?

Accepted Answer

OnPush

Answer

OnPush change detection only runs for a component when its input references change, an event originates from it, or an async pipe resolves.

Question 2

What method on ChangeDetectorRef temporarily stops change detection for a component subtree?

Accepted Answer

detach()

Answer

detach() removes the component from the change detection tree until reattach() is called.

Question 3

Which NgRx building block is a pure function that takes the current state and an action, and returns a new state?

Accepted Answer

Reducer

Answer

A reducer is a pure function (state, action) => newState that never mutates the existing state object.

Question 4

In NgRx, which construct handles side effects such as HTTP calls and dispatches new actions on completion?

Accepted Answer

Effect

Answer

NgRx Effects listen for dispatched actions, perform side effects, and optionally dispatch new actions back to the store.

Question 5

Which NgRx function creates a memoized, reusable piece of state-derived data?

Accepted Answer

createSelector()

Answer

createSelector() returns a memoized selector that recomputes only when its input selectors produce new values.

Angular Web Framework Practice Test