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Fundamentals of Javascript 1 About Javascript Tutorial 2 Important Points about Javascript 3 Why Javascript! 4 JavaScript Cheatsheet

JavaScript Objects 1 JavaScript Object Prototypes

Map in javascript 1 Map in javascript

Overview of Javascript 1 Asynchronous programming in JavaScript ? 2 History of Javascript 3 First Program in Javascript, Hello World 4 Places to put JavaScript code 5 Comments in Javascript 6 Output Display in Javascript

Data Types in Javascript 1 Javascript Data Types MCQ 2 Data Types Introduction 3 Numbers 4 Booleans 5 JavaScript Strings 6 var and let in JavaScript

Variable in Javascript 1 Variable Introduction 2 Local and Global

Operators in Javascript 1 Operators Introduction

Decision Making of Javascript 1 Decision Making Introduction

Loop control in Javascript 1 JavaScript For-in Loop 2 JavaScript For-of Loop 3 JavaScript While Loop 4 Do While Loop JavaScript Language 5 JavaScript For Loop 6 Loop Control Introduction in JavaScript Language

Control Flow in Javascript 1 break statement in Javascript 2 continue statement

Array in Javascript 1 Array Introduction

Function in Javascript 1 make fullscreen 2 exit fullscreen 3 Event Listener in javascript 4 Function Introduction 5 Closure 6 What is block in JavaScript 7 Block scope in JavaScript 8 What is Shadowing in JavaScript

String and String functions in Javascript 1 String Introduction

Recursion in Javascript 1 Recursion Introduction

OOP Concept JavaScript 1 Oop Concept Introduction

DOM Manipulation 1 getElementById() 2 getElementsByClassName() Method 3 Introduction to DOM 4 DOM Selectors for Single Elements 5 DOM Selectors for Multiple Elements 6 Traversing the DOM 7 Traversing the DOM 8 Creating new HTML elements

JavaScript Events 1 JavaScript Events 2 DOM Load event 3 mouseover event Listener 4 mouseout event Listener 5 mousedown event Listener 6 Keydown event Listener 7 focus event Listener

AJAX and Javascript 1 XHR Request 2 Update the DOM using AJAX 3 JSON Files and AJAX 4 AJAX with JSON 5 XML data using AJAX 6 AJAX and Javascript

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Understanding Closures in JavaScript: Concepts and Examples

Rumman Ansari July 09, 2024 5,935 views

Understanding Closures in JavaScript: Concepts and Examples

Closure

A Closure is nothing but a function inside another function.
This closure function can access the variables inside its own scope, the outer function's variables and the global variables.

Example

In this example, whenever we call the myClosure function the value of i will be increased by one. i will be set to zero only once and only the inner function will be called everytime when myClosure is called

var myClosure = (function () {
    var i = 0;
    return function () {return i += 1;}
})();
myClosure();//i=1
myClosure();//i=2
myClosure();//i=3