Microtask in JavaScript

Microtasks are a category of asynchronous tasks in JavaScript that have a higher priority than regular asynchronous tasks, often referred to as macro tasks. They play a crucial role in the event loop, providing a way to efficiently handle time-sensitive operations, such as promises, NodeJs-specific mechanisms.

When an asynchronous operation is initiated, it can result in the creation of microtasks. These tasks are enqueued in the microtask queue, a data structure separate from the regular callback queue. Unlike macro tasks, which are handled during the next iteration of the event loop, micro-tasks are executed before the event loop moves on to the next macro task. This ensures a more responsive and predictable execution flow.

Promises are a primary use case for microtasks. When a promise is settled (either resolved or rejected), the associated callbacks, are executed using .then() or .catch() then they are added to the microtask queue. This process enables precise and sequential handling of promise resolutions, making it a powerful tool for managing asynchronous operations and dependencies.