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How does JavaScript’s event loop work?

Asked on Jul 11, 2025

Answer

The JavaScript event loop is a mechanism that allows JavaScript to perform non-blocking operations by handling asynchronous events. It continuously checks the call stack and the message queue to execute code, collect events, and process messages.

console.log("Start");

        setTimeout(() => {
            console.log("Timeout");
        }, 0);

        console.log("End");

Additional Comment:

The code above demonstrates the event loop in action.
"Start" is logged first because it is executed immediately.
"End" is logged next, as the `setTimeout` callback is placed in the message queue.
"Timeout" is logged last, after the call stack is empty and the event loop processes the message queue.
The event loop allows JavaScript to handle asynchronous operations efficiently.

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Ask any question about JavaScript here... and get an instant response.

How does JavaScript’s event loop work?

Asked on Jul 11, 2025

Answer

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