// closure in JS

// Function along with its lexical scope bundled together forms a closure.

// Closure is a combination of a function bundled together with its surrounding state. (lexical environment)

// A closure gives you access to an outer function's scope from an inner function. (this means inner function will have access to outer function's scope)

//example

/*

function x() {

var a = 8;

var a = 100;

function y() {

console.log(a);

}

return y;

}

var z = x();

z();

*/

// example 1

// change the let and var in for loop and see the result. you will understand the difference between block scope and global scope.

// let and const is blocked scope, so loop jitna bar chlta hai, every time ek block create hota hai jisme settimeout store rhta hai aur usme i ka value store rhta hai.

// var keyword jb hm use krte hain, wo block scope nhi hota hai, is time i ka value global scope me update hota jata hai, isliye last me hmko 6 milta hai jhan pe for loop stop hota hai.

/*

function y() {

for(let i=1; i<=5; i++){

setTimeout(() => {

console.log(i)

}, i * 1000);

}

console.log("bittu")

}

y();

*/

// example 2

function outer(){

var a=20;

function inner(){

console.log(a)

}

return inner;

}

var a=10;

console.log(a);

outer()();

// example 3

function test1(x){

return function test2(y){

return x+y;

}

}

console.log(test1(2)(3))

function createPerson(name,age){

//private variables

let privateName = name;

let privateAge = age;

//private method

function isAdult(){

return age>=18;

}

//public methods with closure access to private variables and private methods

return {

getName : function(){

return privateName;

},

getAge : function(){

return privateAge

},

setName : function(name){

privateName = name

},

setAge : function(age){

privateAge = age;

},

isAdult : isAdult

}

}

let person = createPerson('Bittu',21)

console.log(person.privateAge) //undefined as not allowed to access private variable

console.log(person.getName()); // Bittu

console.log(person.getAge()); // 21

console.log(person.isAdult()); // true

// Create a function in JavaScript that increments a counter each time it is called, using closures?