sum(1)(2)(3)(4)..(n) (currying), implement debounce, implement Promise.all polyfill, and predict event loop output (sync, microtask, macrotask ordering).

Implement debounce and explain when to use it, explain and implement event delegation, implement a deep clone function, and implement map/filter/reduce polyfills.

Implement throttle from scratch, explain the difference between debouncing and throttling and when to use each, explain prototypal inheritance, and explain closures with a real example.