What are closures in programming languages?

What are closures in programming languages?

Closures are functions that capture the lexical scope in which they were defined, allowing them to access variables from that scope even when invoked outside of it.

Can you give me an example of closures in JavaScript?

Sure! In JavaScript, a closure can be created like this:

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 work in Python?

In Python, closures work similarly. Here's an example:

def outer_function():
    outer_variable = 'I am outside!'
    def inner_function():
        print(outer_variable)
    return inner_function

my_closure = outer_function()
my_closure()  # Outputs: I am outside!

Are closures available in all programming languages?

Not all languages support closures, but many modern languages like JavaScript, Python, Ruby, and Swift do.