LWC
Events and communication interview pack
Choose public properties, custom events, or messaging deliberately.
By Vishal Verma · Reviewed October 5, 2026
Practice these questions aloud. Give the principle, explain a concrete example, and finish with how you would verify the result.
1. How does a parent send data to a child?
Suggested answer: Expose a public property with @api and pass the value through markup. The parent owns the passed data; a child should not mutate the parent’s objects directly.
Scenario / follow-up: Copy data before editing it locally when appropriate.
2. How does a child communicate upward?
Suggested answer: Dispatch a CustomEvent with a small meaningful payload. The parent listens and decides how to update state. Choose bubbling and composition deliberately because propagation affects the component contract.
Scenario / follow-up: Send the selected record ID rather than the entire internal state.
3. When would you consider Lightning Message Service?
Suggested answer: For communication between components that do not share a convenient parent-child relationship, in supported containers. Confirm support and clean up subscriptions as required.
Scenario / follow-up: A utility component and a record-page component need coordinated selection.
Reviewed October 5, 2026. Check the linked documentation for your org’s API version and supported features.