What are closures and how do they differ from regular functions?

What are closures in JavaScript?

Closures are functions that retain access to their lexical scope, even when the function is executed outside that scope.

Can you give me an example of a closure?

Sure! Here's a simple example:

function outerFunction() {
    let outerVariable = 'I am outside!';
    function innerFunction() {
        console.log(outerVariable);
    }
    return innerFunction;
}

const myClosure = outerFunction();
myClosure(); // Outputs: I am outside!

How do closures differ from regular functions?

Closures can access variables from their outer scope, while regular functions cannot retain that access once executed outside their original context.

Why are closures useful?

Closures are useful for data encapsulation, creating private variables, and maintaining state in asynchronous programming.