Closures in JavaScript

What is Closure?

A closure in JavaScript is a function that remembers its lexical scope (the environment where it was created) even after the function is executed and that scope is no longer active.

You can say it’s like a backpack - Here this function carries the variable it needs even when it’s used later.

In Simple Terms:

When a function is defined inside another function, the inner function has access to:

• Its own variables

• Variables of the outer function

• Global variables

Closures allow you to remember and access variables even when the outer function has finished execution.

Example of a closure:

function counter() {
  let count = 0; // Private variable
  return function () {
    count++;
    console.log(`Count: ${count}`);
  };
}

const increment = counter();
increment(); // Count: 1
increment(); // Count: 2

Key Properties of Closures:

• Access to Outer Scope: Inner functions can access variables from their outer functions.

• Persistent Data: Values are stored even after the outer function completes.

• Encapsulation: Useful for hiding data (private variables).

• State Management: Maintain state between function calls (e.g., counters).