💢 Interview Questions: Event loop mechanism

#js #interview #eventLoop

Question: Give an explanatory note on the event loop mechanism.

answer:

The event loop mechanism mainly has the following processes:

🍉Synchronous tasks are executed on the main thread, forming an execution context stack.

🍓Once all synchronous tasks in the execution stack have been executed, the system will read the asynchronous tasks in the queue, such as Promise.then(), setTimeout, AJAX callbacks, etc.

🍆The asynchronous task will be added to the task queue

🥑Once the execution stack is cleared, the system checks the task queue. If it is not empty, the first task is taken out and placed on the execution stack for execution.

🥦The main thread repeats the process of alternating execution of the stack and queue, thereby realizing queued execution of threads.
The event loop allows synchronous tasks and asynchronous tasks to be executed alternately in the same thread, making full use of CPU resources. This is important for JavaScript that supports UI interaction and responsiveness.