What are async closures in JavaScript?

What are async closures in JavaScript?

Async closures in JavaScript refer to closures that are used within asynchronous functions, allowing access to variables from the outer function even after it has executed.

Can you give me an example of how to use async closures?

Sure! Here's a simple example:

function outerFunction() {
    let outerVariable = 'I am from the outer function!';
    
    async function innerFunction() {
        console.log(outerVariable);
    }
    
    return innerFunction;
}

const asyncClosure = outerFunction();
asyncClosure(); // Logs: I am from the outer function!

What happens if I try to access a variable that doesn't exist in the closure?

If you try to access a variable that doesn't exist in the closure, you'll get a reference error. The closure only has access to its own scope and the outer function's scope.

Are there any performance implications of using async closures?

Yes, using async closures can have performance implications, especially if they capture large objects or if they're used in a tight loop, as they can lead to increased memory usage.