25. What are closures?

Closures in JavaScript are functions that "remember" the variables from their outer scope even after the outer function has finished executing. A closure allows an inner function to access and manipulate variables from an outer function even after the outer function has returned.

Example:

javascript
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function outerFunction(outerVariable) {
    return function innerFunction(innerVariable) {
        console.log(`Outer: ${outerVariable}, Inner: ${innerVariable}`);
    };
}

const closureExample = outerFunction("Hello");
closureExample("World"); // Output: Outer: Hello, Inner: World

Explanation:

1. outerFunction returns innerFunction, which still has access to outerVariable even after outerFunction has executed.
2. When closureExample("World") is called, it retains the reference to outerVariable ("Hello").

Why Use Closures?

• Data Encapsulation: Helps in creating private variables.
• Callbacks & Event Listeners: Retains state information.
• Memoization & Caching: Stores previous computations.
• Functional Programming: Enables partial application and currying.

Would you like an example of closures in a real-world scenario? 🚀