What is Closures in JavaScript | JavaScript Tutorials in Hindi | Interview Question #21

In JavaScript, a closure is a function that has access to variables in its outer lexical scope, even after the outer function has returned. Closures are created when a function is defined inside another function, and the inner function refers to variables from the outer function’s scope.

Closures are useful for creating functions with persistent state, and for creating private variables in JavaScript. By returning a function that has access to private variables, we can create a public interface that only exposes certain functionality while keeping the implementation details hidden.

It’s important to be aware of closures when writing JavaScript code, as they can affect memory usage and performance if not used correctly. Specifically, if closures are not cleaned up properly, they can cause memory leaks. To avoid this, make sure to remove any unnecessary references to functions that create closures when they are no longer needed.