Difficulty: 5/10interface extension, type augmentation, declaration mergingWe can add new fields to the interface but not to typejavascriptCopyScenario Questions0-2 years experience1We have an interface `User` with `name` and `email`. How would you add an optional `age` property without breaking the components that already use `User`?2You need to add a `timestamp` field to a type alias `ApiResponse`. Show the syntax you would use and explain why you chose it.2-5 years experience1A third‑party library exports a type `Config`. We need a `debug` flag across our codebase. How would you extend that type, and what pitfalls might you run into?Follow-up QuestionsWhat would change if you made the new field required instead of optional?How does adding a field affect code that uses excess property checks?Can you describe any runtime impact of these compile‑time changes?Suggest Improvement
