What is a javascript Closures?

A closure is a JavaScript feature that allows a function to remember and access its outer (enclosing) function’s variables, even after that outer function has finished executing. In simpler terms, a closure “closes over” the variables from its parent function, preserving them for future use.

Let’s understand javascripts closures with an example 

Imagine you have a diary with a lock:

In this analogy:

• The diary is like a JavaScript function.

• The lock is like a closure.

• Your thoughts and secrets written inside the diary are like variables inside the function.

Here’s how it works:

1. You create a diary javascripts (function):

function createDiary(){
let diaryContent = " "  ;  //This is where you'll write your secrets. 

function writeSecret(secret){
diaryContent += secret + "\n" ;  //Add the secret to the diary.
}

function readDiary(){
return diaryContent ;  //Read the secrets from the diary 
}

return { 
write : writeSecret , 
read : readDiary ,
}
}

}

2. You get a diary with a lock (closures)

const myDiary = createDiary()

Now , myDiary is like your locked diary

3.You write secrets into your diary

myDiary.write("I like ice cream.");
myDiary.write("I have a pet turtle.");

4. You can read your secrets : 

const secrets = myDiary.read() ;
console.log(secrets) ;

you can still access your secrets even though you’ve finished creating the diary.

This is essentially how closures work in JavaScript. The createDiary function creates a closed environment where diaryContent is like a hidden secret. The writeSecret and readDiary’ functions have access to this secret even after ‘createDiary has finished running. It’s as if they “remember” the diary Content variable, just like a closure remembers variables from its parent function.