Understand JavaScript Closures With Ease

Posted By :Adarsh Singh |29th May 2019

Closures enable JavaScript programmers to write down the higher code. Creative, expressive, and crisp. we regularly use closures in JavaScript, and, regardless of your JavaScript experience, you'll undoubtedly encounter them time and once more.


Closures are a lot of simply understood and so more appealing for your everyday JavaScript programming tasks.


The function which inside the other one has access not only to the parent function’s variables, however additionally to the parent function’s parameters. Here the noticeable thing is the child function can't call the outer function’s arguments to object, however, even though it will call the parent function’s parameters directly.


You can create a closure by adding a function within another function.


function showName (firstName, lastName) {
var nameIntro = "Your name is ";

function function_name () {        
return nameIntro + firstName + lastName;    

return function_name ()

showName ("a", "b");


Closures are used in Node.js. They're workhorses in Node.js’ asynchronous, non-blocking development. Closures are also frequently used in jQuery language and just about every piece of JavaScript language.


A jQuery Example of Closures:

$(function() {

var selection = []; 
$(".niners").click(function() { // this one has access to the selection variable
selection.push (this.prop("name")); // update the selection variable in the outer function's scope



Closures have access to the parent function’s variable even after the parent function returns:

One of the most important features with closures is that the child function still has access to the parent function’s variables even after the parent function has returned. When a function in JavaScript executes, the scope chain always remains the same that was in effect when they were created. Means that even after the parent function has returned, the child function still has access to the parent function’s variables. Therefore, you can call the child function later in the code.

About Author

Adarsh Singh

Adarsh Singh is working as Front-End developer, having good knowledge of Angularjs, Javascript, Html, Less.

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