Asynchronous JavaScript and Event Loop Questions

Comprehensive understanding of asynchronous programming in JavaScript including callback functions and the pitfalls of callback nesting, Promises including their lifecycle and state transitions, promise chaining, and common utility methods such as Promise.all, Promise.race, and Promise.allSettled. Knowledge of async and await as syntactic sugar over Promises, proper error handling patterns using try catch and promise catch, and avoiding unhandled rejections. Practical skills for working with multiple concurrent operations such as coordinating parallel requests, implementing retry logic, rate limiting, throttling and debouncing of async calls, and handling race conditions. Deep understanding of the JavaScript event loop model including the call stack, task queue, microtask queue, the ordering of macrotasks versus microtasks, how timers and promise callbacks are scheduled, and how this affects concurrency and ordering. Familiarity with implementing a simplified Promise from first principles to demonstrate internal behavior, diagnosing timing and ordering bugs, and designing solutions for real world asynchronous flows and performance considerations.