Instruction: Explain the mechanisms JavaScript uses to handle asynchronous operations.
Context: This question is aimed at understanding the candidate's knowledge on JavaScript's event loop, callback queue, and how asynchronous code is executed.
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At its core, JavaScript is a single-threaded language, meaning it can only execute one command at a time. However, the language's design includes several features that allow it to perform non-blocking operations, which are essential for handling tasks like API requests, timers, and generally any operation that would otherwise stall the execution thread.
The main mechanism that JavaScript employs to achieve this is the "Event Loop." The Event Loop works by continuously checking if the call stack is empty. If so, it looks to see if there's any pending callback in the Callback Queue. If a callback is found, it is dequeued and executed. This model enables JavaScript to perform lengthy operations in the background (asynchronously), without interrupting the user interface....