More on Closures

Lecture 189:- More on Closures

Closures are a fundamental concept in JavaScript, and they allow for powerful programming techniques that would not be possible without them. In simple terms, a closure is a function that has access to the variables in its parent scope, even after the parent function has returned.

Here is an example:

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function outerFunction() {  var outerVariable = 'I am outside!';    function innerFunction() {    var innerVariable = 'I am inside!';    console.log(outerVariable + ' ' + innerVariable);  }    return innerFunction; } var myFunction = outerFunction(); myFunction(); // output: I am outside! I am inside!

In this example, outerFunction() returns the innerFunction() function, which is assigned to the myFunction variable. When myFunction() is called, it logs the value of outerVariable and innerVariable to the console. Notice that even though outerFunction() has already returned, the innerFunction() still has access to the outerVariable variable.

This is because innerFunction() forms a closure over the variables in the parent scope of outerFunction(). The variables in the parent scope are stored in the closure, and are accessible to the innerFunction() even after the outerFunction() has returned.

Closures are often used to create private variables and methods in JavaScript. Since a closure can access the variables in its parent scope, we can create variables and methods that are only accessible from within a certain function or object. This is a powerful technique that can help make our code more modular and easier to maintain.