What are function factories and closures in JavaScript?

Can you explain the difference between function factories and closures in JavaScript?

Sure! A function factory is a function that returns another function, while a closure is a function that remembers its lexical scope even when the function is executed outside that scope.

Can you give me an example of a function factory?

Absolutely! Here's a simple function factory:

function makeCounter() {
    let count = 0;
    return function() {
        count += 1;
        return count;
    };
}
const counter = makeCounter();
console.log(counter()); // 1
console.log(counter()); // 2

This makeCounter function creates a new counter each time it's called.

And how does a closure work in this context?

In the example, the inner function returned by makeCounter forms a closure. It retains access to the count variable even after makeCounter has finished executing, allowing it to remember its state.

That's really interesting! Can closures be used for data privacy?

Yes, exactly! Closures can encapsulate private variables, making them inaccessible from the outside, which is a common pattern for data privacy in JavaScript.