Access modifer in javascript

function Circle(radius){

//Private field

var value=20;

//Privdelege field

this.Radius = radius;

// PI is static field

Circle.PI = 3.4;

//Privdelege function

this.CalculateArea = function(){

return Circle.PI * this.Radius * this.Radius;

}

//public function

Circle.prototype.getRadius = function (){

this.Radius ;

}

}