Lecture 188:- Closures

Closures are one of the fundamental concepts in JavaScript that is frequently used in web development. A closure is a combination of a function and the lexical environment within which that function was declared.

In simpler terms, a closure allows a function to access variables from an outer function that has already returned. When an inner function accesses the variables of its outer function, a closure is formed.

Here's an example:

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function outer() {  var name = 'John';  function inner() {    console.log(name);  }  return inner; } var innerFn = outer(); innerFn(); // Output: 'John'

In this example, outer returns the inner function. When inner is executed, it has access to the name variable declared in the outer function. This is possible because inner forms a closure that captures the environment of outer.

Closures are used in many JavaScript design patterns, such as the module pattern, where they provide encapsulation and privacy for variables and functions.