var v=Counter();
v();

function Counter()
{
    var count=0;
    this.counterIncrement = function() //used 'this' for create an object method which can access outside
    {
        count++;
        console.log(count);
    }
    //return counterIncrement;  //no need to return this method,

}

var v = new Counter();//used 'new' keyword to create an object of 'counter'
v.counterIncrement();//access ojbect method.

v.counterIncrement();//out put 2
v.counterIncrement();//out put 3

function Counter()
{
    var count=0;
    var counterIncrement=function()
    {
        count++;
        console.log(count);
    }
    return counterIncrement;// Here you are returning function
}

var v=Counter();
//v.counterIncrement();// This will not call like that
//Directly call
v();

var counter = (function() {
var count = 0;
return {
    counterIncrement: function() {
    count++;
    console.log(count);
    },
  };
})();