PD1 User Interface 5

Question 1

Which method of the NavigationMixin allows an LWC component to redirect the user to an external URL?

Accepted Answer

this[NavigationMixin.Navigate]({ type: 'standard__webPage', attributes: { url: 'https://...' } })

Answer

NavigationMixin.Navigate is called with a page reference object using type 'standard__webPage' to open an external URL.

Question 2

In Aura components, which event type propagates from a child component up through the component hierarchy without requiring explicit event passing?

Accepted Answer

Application event

Answer

Application events in Aura are fired globally and can be handled by any component in the hierarchy, unlike component events which only travel up through direct ancestors.

Question 3

A developer notices that changes to a nested object property in an LWC do not trigger a re-render. What is the most appropriate fix?

Accepted Answer

Use Object.assign() to create a new object reference and reassign the property

Answer

LWC's reactivity tracks object references; reassigning a new object (e.g., via spread or Object.assign) triggers re-render even without @track.

Question 4

Which Salesforce feature allows a Lightning Web Component to listen for platform events or Streaming API messages in real time?

Accepted Answer

Lightning Message Service or the empApi module

Answer

The lightning/empApi module in LWC subscribes to CometD-based Streaming API channels, including Platform Events and PushTopic events.

Question 5

What is the primary purpose of the Lightning Message Service (LMS)?

Accepted Answer

To enable communication between LWC, Aura, and Visualforce components on the same page

Answer

LMS provides a publish-subscribe messaging bus that allows LWC, Aura, and VF components (via a bridge) to communicate across different technology stacks on one page.

(PD1) Salesforce Certified Platform Developer 1 Practice Test

(PD1) Salesforce Certified Platform Developer 1 Practice Test

PD1 User Interface 5