PDI Question #200: Real Exam Question with Answer & Explanation

Question

Which two characteristics are true for Lightning Web Component custom events? Choose 2 answers

Options

• AData may be passed In the payload of a custom event using a wire decorated properties.
• BBy default a custom event only propagates to its immediate container and to its immediate child
• CBy default a custom event only propagates to it's immediate container.
• DData may be passed in the payload of a custom event using a property called detail.

Explanation

Lightning Web Component custom events can pass data using the detail property, and when configured to propagate, their scope is typically limited to bubbling up to their immediate container.

Common mistakes.

• A. Data may not be passed in the payload of a custom event using wire decorated properties; wire is used for adapting a Salesforce function to a component's property or function, not for event payloads.
• C. The default behavior for LWC custom events is bubbles: false and composed: false, meaning they do not propagate beyond the component that dispatches them, making the statement that they propagate to the immediate container by default incorrect.

Concept tested. LWC custom event propagation and data passing

Reference. https://developer.salesforce.com/docs/component-library/documentation/en/lwc/lwc.events_create_dispatch

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