09 Crazy JS interview on Closures .js

//Example on closure
function outer() {
    var a = 10;
    function inner() {
        console.log(a);
    }
    return inner;
}
outer()();//It still remembers the value of a variable.

//Changing postion of variable
function outer() {
    // var a=10;
    function inner() {
        console.log(a);
    }
    var a = 10;//Even if we morve the position of variable declartion it is still closure
    return inner;
}
outer()();

//Changing var to let
function outer() {
    // var a=10;
    function inner() {
        console.log(a);
    }
    let a = 10;//Even if we change the var to let it is still closure
    return inner;
}
outer()();

//Pass an paramerter in outer function
function outer(b) {
    function inner() {
        console.log(a, b);
    }
    let a = 10;
    return inner;
}
var close = outer("Hello from Akshad");
close();

//Relation of scope chain and closure
function outest() {
    function outer(b) {
        var c = 20;
        function inner() {
            console.log(a, b, c);
        }
        let a = 10;
        return inner;
    }
    return outer;
}
var close = outest()("Hello from Akshad");
close();

//Conflicting name of global variable let in js
function outest() {
    function outer(b) {
        var c = 20;
        function inner() {
            console.log(a, b, c);
        }
        let a = 10;
        return inner;
    }
    return outer;
}
let a = 100;//but it will still print the value of a present in the function scope.
var close = outest()("Hello from Akshad");
close();

//Example of data privacy using closures
function counter() {
    count = 0;
    return function incrmentCounter() {
        count++;
        console.log(count);
    }
}
//console.log(count);// No one can access this count outside the closure.it will throw error.
var counter1 = counter();
counter1();
counter1();
counter1();
counter1();

//Function Constructor in javascript using closures
function Counter() {
    count = 0;
    this.incrementCounter = function () {
        count++;
        console.log(count);
    }
    this.decrementCounter = function () {
        count--;
        console.log(count);
    }
}
var counter1 = new Counter();
counter1.incrementCounter()
counter1.incrementCounter()
counter1.decrementCounter()
counter1.decrementCounter()
counter1.incrementCounter()