Top 3 Change detection Interview Questions
Browse 3 real-world technical and behavioral interview questions about Change detection. Review scenarios, edge cases, and architectural best practices.
An Angular component with OnPush change detection has stopped updating when its data changes. Walk me through why, and how Vue avoids the same problem.
OnPush checks a component only when an input arrives with a new reference, a template event fires, an async pipe or signal it reads emits, or you mark it. Mutating an object in place satisfies none of those, so the view never gets checked.
Angular, Vue and React are answers to the same problems. Compare how each handles change detection, reactivity and dependency injection.
Each must decide what to re-render when data changes, how derived values stay correct, and how a component gets a dependency it did not create. Angular answers with dirty checking now moving to signals plus a hierarchical injector, Vue with proxy-based per-property tracking, React with convention plus memoisation.
Draw me the boundary between your monitoring system and the plant's safety system. How would you know if the safety layer had been altered?
Your path may read from the safety layer and must never write to it, and independence means separate devices, separate logic and separate change control rather than a separate screen. You detect alteration by watching programme identity, key-switch position and proof-test records, not by assuming nobody would.