What are scope and closures in JavaScript?

What are scope and closures in JavaScript?

In JavaScript, scope refers to the visibility of variables. Closures are functions that remember their outer variables even when executed outside their original 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 closureFunction = outerFunction();
closureFunction(); // Outputs: I am outside!

Why are closures useful?

Closures are useful for data encapsulation, allowing you to create private variables and functions, and they help in maintaining state in asynchronous programming.

How do closures relate to callbacks?

Closures are often used in callbacks to maintain access to the outer function's scope, allowing the callback to use variables defined in that scope.