- Redux and MobX - which is better and for what tasks? What other libraries are there for managing the state of an application?

- Server-Side Rendering?

- What is a Higher-Ordered Component?

- What is React Native? Why is it used? What's the difference from regular React? (yes, that's exactly how they asked me)

- How to render a component at a specified time?

Java Script

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- So what is a closure, finally!?

- How does the Event Loop work? Tasks, microtasks, queues, etc.?

- What is garbage collector in js and how does it work? (no references - no object, there is a reference - there is suffering)