closure in JavaScript

Understanding Closures in JavaScript

Closures in JavaScript allow an inner function to access the outer function’s variables, even after the outer function has completed execution.

How Closures Work

Consider the following example:

// JavaScript code to demonstrate closures
function outerFunction() {
    let outerVariable = "I'm outside!";

    function innerFunction() {
        console.log(outerVariable); // This can access the outerVariable
    }

    return innerFunction;
}

const myClosure = outerFunction();
myClosure(); // Outputs: "I'm outside!"
    

In this example, innerFunction can access outerVariable even after outerFunction has completed execution.

Why Closures Are Useful

• Data Encapsulation: Closures allow you to create functions with private variables, hidden from the global scope.
• Callbacks and Event Handlers: Closures help retain context in callbacks, especially useful for asynchronous code.
• Maintaining State: Closures are helpful in maintaining state between function calls.