closures.js

//* closures :
//* Closure is a function object that has access to its own scope, the outer function’s variables. Three characteristics of closures are:

const a = 10;
const f = () => {
  const a = 23;
  const f2 = () => {
    console.log(a); //23
  };
  f2();
};
f();
console.log(a); //10

//? Closures are used when you want to extend behavior such as passing variables, methods, or arrays from an outer function to an inner function.
//? JavaScript is not pure object-oriented language but you can achieve object-oriented behavior through closures

//todo ==> closure access

function counter() {
  var count = 0;
  this.incrementcounter = function () {
    count++;
    console.log(count);
  };
  this.decrementcounter = function () {
    count--;
    console.log(count);
  };
}
var cn = new counter();
for (let i = 1; i <= 50; i++) {
  cn.incrementcounter();
  cn.decrementcounter();
}

//* 50 times 1 and 0 values are printed

//! Disadvantages of closures :
//! 1) memory leakage: if we have a lot of nested functions, it can cause the browser to run out of memory.
//! 2) scope chain pollution: when you declare variables in a function that is inside another function, these variables become part of the outer function'