NativeScript for Mobile App Development Data Binding and MVVM 2

Question 1

In NativeScript Vue, which directive provides two-way data binding on input elements?

Accepted Answer

v-model

Answer

v-model on TextField and other input components creates two-way binding between the input value and the Vue component's data property.

Question 2

What is the purpose of the `$` prefix in NativeScript data binding expressions?

Accepted Answer

References the current item in a list binding

Answer

In ListView item templates, `$value` references the current list item, and `$index` provides the item's index.

Question 3

How do you observe changes to an ObservableArray in NativeScript?

Accepted Answer

Listen to the 'change' event on the ObservableArray instance

Answer

ObservableArray emits a 'change' event whenever items are added, removed, or changed, allowing the ListView to update automatically.

Question 4

What happens when you assign a plain JavaScript object (not Observable) as bindingContext?

Accepted Answer

Initial values display but UI won't update when properties change

Answer

Without Observable, there are no change notifications, so the UI shows initial values but does not react to property mutations.

Question 5

In NativeScript Angular, how do you emit an event from a child component to its parent?

Accepted Answer

Use @Output() with EventEmitter

Answer

@Output() decorates an EventEmitter property on the child, and the parent listens with (eventName)='handler($event)' in the template.

NativeScript for Mobile App Development Practice Test