Here’s a breakdown of your topics: 1. **Event Bubbling in JavaScript** - Explanation of event propagation (bubbling vs. capturing). - How to stop bubbling using `event.stopPropagation()`. - Practical examples, such as event delegation. 2. **Database Query Optimization** - Indexing strategies (B-Trees, Hash indexes). - Query execution plans (`EXPLAIN ANALYZE`). - Caching, denormalization, partitioning, and sharding. 3. **Production Debugging** - Tools like `Sentry`, `Datadog`, `New Relic`, `Grafana`, and `ELK Stack`. - Debugging slow queries, memory leaks, and CPU spikes. - Best practices for logging and monitoring. 4. **Senior Manager Questions** - Handling team conflicts. - Decision-making under uncertainty. - Aligning technical goals with business objectives. 5. **React.js Questions** - When to use hooks like `useMemo`, `useCallback`, `useEffect`. - Lifecycle methods in class components (`componentDidMount`, `componentDidUpdate`). - Optimizations like memoization, virtualized lists, and React Profiler.