Multinational companies (MNCs) like Google, Amazon, Netflix, and Microsoft focus less on syntax trivia and more on scalability, system design, and deep internal knowledge of the runtime. This guide covers the most high-impact topics. Part 1: Core JavaScript Deep Dives Focus: How the language actually works under the hood. 1. Explain the Event Loop in detail. How do microtasks differ from macrotasks? Answer: The Event Loop is the mechanism that allows Node.js to perform non-blocking I/O operations despite being single-threaded. It offloads operations to the system kernel whenever possible. Call Stack: Executes synchronous code. Macrotasks (Task Queue): setTimeout , setInterval , setImmediate , I/O callbacks. Microtasks (Microtask Queue): Promise callbacks ( .then / .catch ), process.nextTick . Critical Distinction: The Event Loop checks the Microtask Queue after every completed task in the Call Stack and before moving to the next Macrotask. This means process.nextTick and Prom...